116 bhp = 1.6 Mk1 before the 1.8 came out
Early 1.6 (up to mid '91) cars had weak front crank pulley/crank the first year, less than 500 of those were shipped to the UK. Strengthened crankshaft was fitted to cars with UK chassis numbers from 00110630 (final digits). If your Miata is a 1990 or 1991 with VIN 209446 or less, you have a crankshaft with a smaller diameter nose. VIN numbers not 100% accurate If you'd like, verify the stronger/later crankshaft and larger bolt are fitted by measuring the bolt shoulder diameter to be 1.455 inches. The old/weaker pulley bolt shoulder diameter is 1.128 inches. There is an intermediate fix in the form of a longer nosed crankshaft with the same small diameter supplied by Mazda. This fault can and does still turn up on all the engines. Other odd one is con rods breaking – this seems more prone on post ’99 cars. Both failures are rare in the main.
http://www.fortunecity.com/marina/pontoon/3/miata/igncurve/igncurve.html to show it is nearer 105hp
90 bhp = 1.6 Mk1 after '94
130 bhp = 1.8 Mk1
110 bhp = 1.6 Mk2
140 bhp = 1.8 Mk2
90 v 116 bhp 1.6; has a different ECU, different cams, and lower compression. Runs pretty well (better than the old 1.6 (115hp) in the very low range) up to about 5.5 k RPM, than the difference becomes obvious. A tach redline at 6500 and rev limit at 6750. Some indicate >7000 but so far they all show 6750 upon datalogging. No need for a higher rev limit because the power drops bec. the cams are milder (same as US 1.6 auto tranny cams) and peak at 4000. The injector pulses narrow after 6500 with a matching drop in torque. This is probably so the driver will feel the drop and shift up instead of banging into the limiter all the time.http://www.fortunecity.com/marina/pontoon/3/miata/bobhall.txt has Bob Hall’s take on this.
Autocar Road Test Data:
Original 1.6i - actually 1598cc - 115bhp - tested 14 March 1999
Top (mean) 114mph - 6065rpm
Top(best) 116mph - 6170rpm
0-60 - 9.1 secs
1.8i - actually 1839cc - 128bhp - tested 9 February 1994
Top 115mph - 5800rpm
0-60 - 10.1 secs (wet track)
Reasons for little difference in figures:
1. Greater weight - up from 949kg to 1020kg
2. Longer final drive ratio
From the original brochure
‘89 1.6 figure (Mk 1)
Max Power : 114bhp@6500rpm
Max Torque : 100lb/ft@ 5500rpm
Max speed : 121mph
0-62mph : 8.75s
Urban Cycle : 29.4mpg
Constant 56mph : 46.3mpg
Constant 75mph : 36.2mpg
Weight = 949 kg
45 litre fuel tank
‘97 1.6 figure (Mk1):
Max Power : 90bhp@6000rpm
Max Torque : 97lb/ft@ 4000rpm
Max speed : 109mph
0-62mph : 10.6s
Urban Cycle : 25.7mpg
Extra Urban : 39.8mpg
Combined : 33.2mpg
Weight = 1020 kg
48 litre fuel tank
‘97 1.8 figure (Mk1):
Max Power : 131bhp@6500rpm
Max Torque : 114lb/ft@ 5000rpm
Max speed : 123mph
0-62mph : 8.6s
Urban Cycle : 23.7mpg
Extra Urban : 38.2mpg
Combined : 31.0mpg
Weight = 1014 for 1.8I and 1040 kg for 1.8i
48 litre fuel tank
Autocar list 1.6i - 8.9secs, 1.8iS - 7.8secs
MX-5 1.6i : 0-62 9.7s 1015 Kg
MX-5 1.8i : 0-62 8.5s 1025 Kg
MX-5 1.8iS : 0-62 8.5s 1047 Kg
Top 193 km/h
Top 191 km/h
Weight: 1015 kgs
Consumption: (litres per 100 km at constant speed of 90 120 km/h and urban
Top 205 km/h
Weight 1025 kgs
Consumption: (litres per 100 km at constant speed of 90 120 km/h and urban
Fuel tank sizes;
Pre '94 cars (i.e. 1.6) 45 litres
Post '94 cars (i.e 1.8 & later 1.6) 48 litres
Mk2 cars 50 litres..
Engine belt numbers;
Gates Catalogue MX5 Miata 1.6
Alternator = 6466MC OEM = B6SF-18-381B AND B6SF-18-381A
Power Steering = 48353 OEM = B61P-15-907A
A/C+P/S belt B63H-15-909
Alternator belt'92 Miata B6S7-18-381B-9F.
US oil filters are bigger than UK/European oil filters – so US filter tools do not work on European filters.
oil filter from a '94 Prelude/Accord an option for a larger filter in the stock location.http://minimopar.simplenet.com/oilfilterstudy.html has a comparison of various oil filters
"You should not go wrong with a Mazda filter. My favorite oil filter is the PureOne, part number PL14459. This is a slightly larger filter made for the 323. I have cut open some different brands of oil filters and I have found the PureOne to have the maximum possible amount of filter media plus a steel bypass valve. Compare this to a Fram which has so little media I (and others) have noticed a drop in oil pressure just by using this filter. Plus
it's valve is plastic." Tom Graham in US
1.8 Mk1 oil capacity;
Dry engine: 4l
Refill only: 3.6l
Refill and new filter: 3.75l
Oil filter cooler adapter
"I have the sandwich adapter specified for the Mazda from JC Whitney or Summit, made by Perma Coolhttp://perma-cool.com/Catalog/Cat_page28.html Part 186" email@example.com
To hot flush oil change your engine;
This clears out your oil galleries and may help with noisy HLA/tappets
Oil flushing agent from Dealer (no longer sold as Mazda UK forbad it..so just use Halfords best!);
Run car until hot - cooling fan comes on (good check as well), Add to oil, run for 10 minutes, drain while hot (as you always should - I leave it as long as possible too - 1.5 hours minimum).
Dealer in Aberdeen supplied FORTE motor flush;
Forte, 22 Mopedi Rd, Sebenza, Edenvale, Rep of South Africa
- Cleans and frees piston rings
- frees valves and hydraulic lifters
- removes sludge and varnish
- cleans internals of engine
- removes harmful insolubles
Above is mostly pure marketing speak - you prove it!!
Unipart fuel filter listed for the '5. Part No. GFE7081 RRP £15.38
List a different filter for the turbos, this is a GFE7082 with RRP £22.31
Percentage of total intake restriction on 1.6 stock;
intake snorkel/front of airbox: 20%
air filter (paper, dirty): 7.5%
entry bend to AFM: 19%
air flow meter: 40%
duct to inlet manifold: 12.5%
1) The stock filter is pretty free flowing. Not much to gain by replacing it.
2) The AFM is the single most restrictive element. (ie Randy is right)
3) A well designed inlet to the AFM (eg the RB elbow) can be just as effective as replacing the AFM. Of course, doing both would be better.
4) The effect of replacing the AFM cannot be regarded alone, as the bend leading into the stock AFM represents a significant restriction, that obviously is removed when the AFM is replaced.
Posted by Matty in Aussie land
"I think the FM2 old air filter is RD-0720 63mm throat, 89Dx152L, flows to 125bhp NA.." Simon Knapton
K&N p/n 62-2480 is for the engine breather
1.8 fits 1.6 and allows use of larger 1.8 clutch
BSP has a lightened one (by 4 pounds) for $185.
A machine shop could only get 3 pounds off a standard 1.8 flywheel
Jun do one at 5kg = 11lbs
B6-ZE4.6kg #2001M-Z001 Y40,000 .
BP-ZE (NA6CE)5.0kg #2001M-Z002 Y50,000 http://www.takakaira.co.jp/
Trust 1.6 =#12458 NA6CE B6 4.8kg
"Toda racing do 1.6 one. (8.4 lbs vs 17.7lbs claimed for 1.6t) but the quality and workmanship is stunning. They have artfully machined away the back surface of the flywheel, and added holes all around the perimeter to reduce moment of inertia. Looks like a good buy to me, cheaper than most aluminum ones in my case($420).
Machining a stock 1.6 will only get you to about 15lbs.
The aluminum ones are in the 8-12 lb range, Aluminum Mazda comp/tilton(I think) 9 lb
8 lb Mazdaspeed chromoly flywheel. 1.8 style
"It seems that, as a *very* rough approximation, lightening the flywheel by about 5lb is equivalent, in 1st or 2nd gear, to lightening the car by a hundredweight. Not bad" Carrick, M. (Mike)
"compare the kinetic energy in you flywheel with the kinetic energy in your car;
flywheel (disc) - J = 1/2 * M * r^2 say M 20kg and r 15cm gives 0,225kgm^2 w at 6000rpm this is 100Hz so w is 630rads/s energy = 1/2 J w^2 = 44650joules
Car M = 1000kg at 100kph v = 27.8m/s energy = 1/2 * M * v^2 = 386420joules
the flywheel energy is just over 11% of the overall kinetic energy. 6000revs at 100kph is a bit higher than 2nd gear. A lightened flywheel at one half standard weight (!) would thus accelerate about 6% faster in 2nd gear. "Robert Carter
"Loss of driveability is a non-issue. Noise does increase, mainly on decel in lower gears (mostly first) and at idle with air on. How much noise will depend on the clutch selected. The stiffer the center section, the more possible noise. We have our Fidanzas spec'd out slightly heavier than everyone else's to try to combat this." Bill Cardell
Vernir Adjustable cam pulleys
The Mazda Comp gears have the center cut out of stock gears and a new center made that is a disc with slots in it. The spokes of the original gears are drilled and tapped...you end up with adj. gears.
HK$ are $378 at Corksport.
Mazda Competions supply cam blanks.http://www.mazdamotorsports.com The bearing journals already ground, they are 99 OEM without lobe grinding so timing and max lift with stock base circle is similar to 99-00 cams. Part numbers; Dealers do not have access to this part number. Must be obtained from Mazda Compition. USA toll free # 800-435-2508. 949-222-2652 outside US $160/pair? http://www.mazdamotorsports.com/webapp/wcs/stores/servlet/Catalog?storeId=1000
Randy Stockers aftermarket cam specs at:http://www.solomiata.com/street.html using ’99 cam blanks
Stock cams at:http://www.solomiata.com/cams.html
See ‘Power general’ for more cam picking details etc
Sealed Power VS-855 valve springs are used by Randy
Sealed Power springs can be found atwww.racesearch.com (714)755-1788
.... crack test, polish and balance = ??? hp stock 1.6/1.8 con rods (with nuts) weighs in at 562g There seems to be weaker ones on ’99 onward cars although they are external identical. Stock ones have survived 300rwhp or broken even when NA.. you just encounter more breakages as the power rises. Shot peening adds about 15% tensile strength (higher rpm), but no compressive strength - which is experiencing in a boosted engines so possible a waste of money. "The stock rod is a forging. All the marks on the rod indicate the forge process. Typically a rod is heat treated to the 115/130 ksi range, still quite ductile. The quality of the material and the uniformity of the heat treat would perhaps be the harder things to determine" Corky
Mazda 323 Turbo/GTX con-rod
(this is similar to 1.6 and 1.8 con-rod, some have fitted it and it is stronger) £423 UK $670 US. May be fitted to 1600 EGI 323 engine; Mazda now supply the 1.6/1.8 Miata rod and this heavier rod is obsolete. (stock power 220hp @ 7500 rpm) Aberdeen storeman muttered about it being fitted to 1600 EGI 323
Raceparts (UK) Ltd
6-8 weeks delivery from drawing. By South American Co. called SAENZ. Give them the HP + rpm and drawing and they make them to suit. Have forged steel blanks they machine from. Cost £140-160 + VAT each = £660 min per set. firstname.lastname@example.org Tel 01491 837740. They are on a par with Carrillo rods. (Have done 900 bhp 4 cylinder drag car before now). Made from SAE 4340 steel, forged, stress relieved, machined and finally heat treated.
Arial Pistons in UK; David Jackson Tel 01403 784 022 Material 4340 Nickel Chrome Vanadium Steel with I beam section (others possible) 7,500 rpm and 300 bhp was my target = OK, want more then ask for it.
engine. (made in US) 10wks, £138ea = £660
are available in 4340 steel billet. Cost is $157 per rod. Delivery is about 8 weeks (took Frank Mowry 4 months for first ones….). 50% deposit required. Stroker cranks are available in billet only. Cost is $2300 and delivery is about 15 weeks.
Crower Cams & Equipment Co., Inc. 3333 Main Street Chula Vista, CA 91911-5899 USA http://www.crower.com/
are $824 list/$659 jobber. www.pauter.com
The best according to most. FM sell at $800 = £1036
Larry Widner (TOO, the old one) uses them for his Honda rods… he is making ‘5’ rods sometime.. well sometime!
catalog lists a set of rods, (presumably forged), for the Roadster,(Miata), @ 46000 yen or approx. $400.00.
Holby, Cosworth, Olliver(US), Charles+Albert, linoleum , Cunningham or see Race Engineering under pistons http://www.cunninghamrods.com
323 GTX turbo rods 580 grams 93.00 each( 1 wk wait)
Crower rods 667.00 543grams (12 week wait)
Pauter rods 720.00 493 grams( 6 wk wait)
Carillo rods 998.00 442 grams( wait ?)
Original pistons are cast. All Forged pistons are prone to slapping... warm your motor up well before flogging it
83mm stock, 85mm = max of stock 1.8 cylinder head gasket 4.8%= 1929cc car – but questions over this much.. +2x2 = 4mm stroker = 5% on 80?mm stroke = 2028cc total
1.6 323 GTX pistons are 7.9:1
Arial Pistons in UK; David Jackson Tel 01403 784 022
Pistons = 60 to 140mm bore, 105 piston blanks. for 83mm pistons 108+tax each on 5-6 wks delivery including 3 rings, pins and circlips
Mazda 1.6 turbo
Mazda 323GTX pistons are available @ $482.60 for the set in US. (lower CR)
J&Ehttp://www.jepistons.com/ make pistons for $80-$95 each; has some low comp. patterns for both the 1.6 & 1.8 motors. delivery 3 wks. "I have never had piston slap problems with either of my 1929cc engines, both equipped with JE pistons" Kurt Summers, now bought over by Wiseco UK Total Seal Agent Mike Loman, 020 8592 1180.. sells J&E for £475 + 6wks +V/d = £570
FM sell $525 - £464 by post into UK Delivery 3 wks.
Accralite performance forged pistons
Spon Lane South, Smethwick, West Middlelands, B66 1QJ Tel 0121 525 6450 Fac 0121 553 5951
Sportsman Racing Products - heard off but not found…
Race Engineering in Florida
Race Engineering (561) 533-5500 fax: (561) 533-0151www.raceeng.com Race Engineering Inc., 2602 Park St., Lake Worth, FL 33460 Ron = rfife@Raceeng.com
Priced over phone in spring 2000; Pauter rods @ $659 & 6 wks (comes with little end, pins & clips) Wiseco/J&E pistons total $1020 Hasting/Federal mogal chromed rings $60-65 Total $1100 =£940 in UK 50% deposit of $600
Delivery 5-6 weeks Needs bore, power, CR, quoted as 18 psi boost & 100 hp nitrous
http://www.totalseal.co.uk/gapless.htm UK total seal piston rings at £140/set
To run in rings .. dry install, run hard, Dino oil, no idle, no constant speed, no synethetic oil
"Forged pistons expand More than cast pistons and therefore require more clearance. The coatings should be of great benefit. I had my JE pistons ceramic coated on the tops and a hard film lube put on the skirts. Supposed to have a similar benefit *if* the skirt should come into contact with the cylinder wall. It is my understanding that this doesn't happen with well fitted pistons very often. Also, I understand that forged piston clearance is smaller than what is used on cast pistons due to less thermal expansion " Eric Valincourt
To run in rings .. dry install, run hard, Dino oil, no idle, no constant speed, no synthetic oil.
All BP Cranks appear to be forged.
All BP Cranks are cross drilled.
Doug Kiddie Engineering Ltd
(£1000) Enterprise House, Leicester Road, Sapcote, Leicestershire, Telephone: 01455 27 37 38, Facsimile: 01455 27 44 35 Email:email@example.com http://www.racecar.co.uk/dkecrankshafts/main.htm
PAECO in US do welded and ground offset pin cranks – billet from Kiddie is far better
"Stroker kits for most 4-cylinder engines will cost $1299.00...these are exchange prices, and assume you will be sending in your old crankshaft. If you don't send in your old crank, then add a core charge." They guarantee their crankshafts as long as you own the crankshaft, with no time or mileage limit, providing oil pressure is maintained and bearing failure has not occurred. That $1299 gets your crank reworked and guaranteed practically indefinitely, gets you new larger pistons with the wrist pins in the proper location for the altered stroke, and Deves piston rings. And the crank and pistons are balanced as well... ~ Fred Hubert
SCAT in US
FM - the stroker kit we're working on for the 1.8 will be 2mm overbore and 3mm stroke, for 1996 displacement.
Mazdaspeed made one from UK for 1.6
"Mazdaspeed makes a 3mm stroker crank for the 1.8 'B' motor. This crank is used in the Japanese only market 2.0 liter C-Spec Miata (85x88). It is part number 9E3A-11-300 and costs $2,258.66 USD. It is basically a forged racing prepped unit and that is why it costs so much. It is available for import from Mazda Competition at 800-435-2508.
Also, Toda Racing in Japan offers a race prepped forged stroker crank for the 1.6 'B' engine as well. According to their web page (http://www.todaracing.com), it offers a total of 1854cc. It currently sells for 300,000 Yen which is $2112 @142 Yen/USD. " from Solomiata
(took Frank Mowry 4 months for first conrods)50% deposit required. Stroker cranks are available in billet only. Cost is $2300 and delivery is about 15 weeks.
Crower Cams & Equipment Co., Inc. 3333 Main Street Chula Vista, CA 91911-5899 USAhttp://www.crower.com/
I came across a really sweet deal on knife edged cranks. $375 with Exchange + Shipping. (1.8 l Only) Send me and email if you are interested. Mark Peugeot PS - I still have the head stud kits in stock as well.
Power tweak is
Extended Reach Plugs
ZFR4F-11 (this is a Hotter plug)
ZFR6F-11 (this is a Colder plug)
ZFR7F-11 is extend reach in a colder plug; colder because the plug is nearer the centre of hot combustion chamber... probably needs timing retarded relative to peak power on the standard plugs and the metal side tang may run hotter than the stock plug... this should not cause knocking (as it is at the initiation of the flame front) but could possible cause
pre-detonation. Rated by some in US as HP gainer. ( -11 at the end = large gap (i.e. 0.040" is not standard , a lesser gap is)
From a conversation with a NGK UK technical help person ( the only spark plugs to fit!);
(Hemel Hempstead, 01442 281 000)
Triple electrodes = long life without using platinum, they are for life not for high performance e.g. BCP6ET
PFR6B (order code 2340); This is a double platinum plug - this means both electrode and earth tag are platinum coated so the wasted spark should not affect the earth tag. Small electrode gives a dense spark which is meant to be better. Packed in pack of 4 for RRP of 14.04 GBP ea = $22.46 each plug or 56.16 GBP/4 or $89.94/4
94-99 BKR5E-11 but grade 5,6 and 7 listed as an option in US 1.8 workshop manual
BKR5E-11 is a hotter plug = less likely to foul, more likely to burn out
BKR6E-11 is standard plug
BKR7E-11 is a colder plug = more likely to foul at idle but you can run the engine hotter
http://members.tripod.com/~Angelo_Lee/personal/ngk.html shows how to read an NGK plug
NGK and Bosch numbers work the same way, Champion work the opposite way. There is not set pattern with 50% of available plugs running opposite to NGK but why bother with the rest as NGK are the best!
"From a physicist point of view, the splitfire idea is very good and it should perform better than the standard design ... until the sharp edges of the electrodes get rounded off by the heat or coated with oil/fuel
additives. The Bosch 4-electrode shouldn't be expected to perform any better than the standard design when new, but it will most likely last longer." Ray Ayala
Spark plug leads
spark plug leads often break down in under 30,000 miles.. replace before it kills your cat – they will be provoked by new spark plugs. Magnecors 8.5mm are reckoned to be the best; telephone 01675 46711 45 +VAT if you tell them the MX-5 OC sent you. 01675 465166. http://www.magnecore.com/
Mail Order from Demon Tweeks - Part No 4549 - 01978 664466
"Miata.net recommends advancing timing from 10 degrees to 14 or more .. this is meant to mean more bottom end torque but some have commented that you lose power at the top end". It seems to depend what the build tolerances are for your engine … but an empirical test in UK revealed…
The results of the dyno test of maximum power at various timing settings:
10 degrees = 100bhp
12 degrees = 98bhp
14 degrees = 97bhp
The technician doing the test commented that the engine felt smoother at 10 degrees as opposed to 14 – owner agreed. Car was a January 1993 1.6 SE (116 bhp engine). Everything is completely as stock, except for the exhaust which is a replacement with no cat - the manifold is standard.
The full power curve (at 10 degrees timing) was:
25 bhp @ 2000 rpm
38 bhp @ 3000 rpm
60 bhp @ 4000 rpm
79 bhp @ 5000 rpm
80 bhp @ 5500 rpm
100 bhp @ 6300 rpm
So the results are that, for my car, the manufacturers recommended setting of 10 degrees gives the highest maximum power and the smoothest delivery. My speedo is reading 12% over the top, ie the speedo reads 112 mph when I'm only doing 100mph. An indicated 79 is a true 70, and 90 equals 80. Tyres; 215/45 15 inch "Phil Hawkridgewww.miataforum.com/ubb/Forum6/HTML/002173.html talks about this on a Mk2
Ground TEN and GND in diagnostic plug in engine bay.
Adjust pick up head at the back of camshafts – only one cam has 3" round bump with wires coming out of it.
Note there are two notches on front pulley with 1.8 (one on 1.6) – they align on 10 and 0 when at standard 10 BTDC timing. The one on the 10 is the one to watch to move to 14 DBTDC (i.e LHS as you look down on to pulley)…. Check with screwdriver in plug hole if you do not believe you have the right notch – TDC is when the right one is at 0.
Spec timing is 10 deg, advance to 14 deg is probably advantageous.
"Warm engine to normal temp.
Connect a jumper between "TEN" and "GND" in the diagnostic connector box. If your terminals are not labelled, see diagrams on miata.net
Locate camshaft/crankshaft position sensor. On early cars it's at the back of the inlet side camshaft. On mid-age cars it's at the back of the exhaust side camshaft. On later cars, it's at the front of the engine by the crankshaft pulley.
Locate the timing mark on the Crankshaft pulley. If there are two, you want the one to your left - often painted yellow.
Locate the timing scale on the cambelt cover. Note that TDC is one notch in from (your) right hand end, 10 deg is the longer notch in the middle and 14 deg is two notches further to your left. (ie it kind of reads backwards) The
last notch is 16 deg.BTDC.
Connect up your timing light (power available from blue connector behind n/s headlight - pickup from no 1 plug lead)
Start engine - observe timing marks.
Rotate camshaft/crankshaft position sensor so that crankshaft mark appears to move to your left by two notches.
Retighten position sensor.
Remove jumper." John Cookson
Ground TEN and GND in diagnostic plug in engine bay.
Set idle at 850 +/- 50 rpm – manual idle control screw is about 2" higher and nearer the engine than the throttle butterfly on the inlet manifold .. alternative is that engine speed should not change when link is removed from diagnostic plug.
Remove and enjoy.
If you still have idle droop – i.e. car stalls when coming to junction then screw idle out, if hanging up then screw in.
Ignition Coil problem on ’93 1.8
Left ignition on for a few hours while fitting radio; this burnt out the integral ignitor circuit in the coil pack.
Used £100 New set £200 inc VAT.
History; there was a revision of the coil-pack for the 1.8 – I have seen four wire coil packs on ’93/’94 Eunos cars but 3 wires on ’95 UK car. The new 3 wire version loses the feedback loop from the coils to the ECU – fitting 3 wire coil packs to 4 wire car results in no rev counter; hence the later cars must have a new ECU with rev counter driver – I built a circuit to do this on my car. When it burns out the coil pack casing splits from heat. Later coil packs may be more resistant to this failure. Part numbers...4 wire version: BPE8 18 10XA 3 wire version: BPE8 18 10XB
Engine ECU error codes;
General discussion and making a warning light
1. Dashboard light, bottom left of central lower group of four; on MX5 this is fog light warning, on Miata it is MIL (engine diagnostics), on Eunos it is the 'your Cat has just burnt up' light.
2. Because the MIL light is not wired up on MX5/Eunos the diagnostics as featured in the garage section of Miata.net will not work in a straight forward way.
3. On 1.8 '94 Eunos (my only sample!) there is a diagnostic socket (open bonnet - on RHS beside strut top and air intake, cap on top, 4 rows of female receptacles - only 9 used). This can be used for the diagnostic routine;
To make tester;
Buy LED and appropriate resistor (red = 1kOhm, green/yellow/amber = 470 Ohm). Alternative is 12V dc packaged LED from electronics store.
Make up test lead with following routing; So to follow the wiring;
+B socket (12V)
Red wire (solder end of wire to make acceptable stiff end to stick in diagnostic socket)
Resistor (red = 1kOhm, green/yellow/amber = 470 Ohm) - insulate
Longest leg of LED (positive) - insulate
Shortest leg of LED (negative)
Stiff Paper clip or MIG wire leg with insulation
FEN socket (diagnostics)
Alternatively buy a packaged 12V LED and ignore the resistor.
Bend paperclip so the LED is visible from drivers seat
Use another paperclip between TEN and GND on diagnostics socket. Ensure it cannot touch anything else (insulating it is even better).
Now as standard car diagnostics on miata.net. The codes are identical;
To test ECU codes;
1. Do above
2. Try/run engine
3. Turn off engine
4. Turn ignition back on
5. Observe LED
Car is OK then LED lights up like the dash lights e.g. for 4 seconds and then goes dark.
Fault code is one second light/ one second dark followed by 4 second intervals for a new fault code. e.g. Disconnect air mass flow meter, run car and you get 8 +1, disconnect timing pickup on camshaft and try and run
car then you get 8 + 4+ 1 (codes are stored until you erase them).
6. To erase the codes - make sure you stereo etc is not code protected, then remove battery terminal for 30 seconds.
Note it is also possible to force the fuel pump (F/P), coolant fans (TFA) and have an electronic source for a timing device (IG-) from the diagnostic socket.
There is still the MEM tag -
Note on FEN to +B signal - this will only source 35.7mA maximum current drain so a normal 12V test bulb will not light. I was using the test bulb to drag the voltage up then measuring the voltage of FEN, it would dip to 11.57V but the scan/refresh rate of my digital multimeter is about 0.5 second hence difficult to be certain of pulses. This practice is strictly dubious - hence the need for an LED circuit or similar. The Miata must have a driver circuit built into the ECU.
Normally disclaimer i.e. try any of this at your own peril and ECU!!
John Cookson’s Roadater ECU: B63H 18 881B 079700-2632.
Miata Engine Computer Self Diagnostics
By Glenn A. Stephens -firstname.lastname@example.org
(Information from Miata Factory Service Manual and Miata Magazine)
The Miata engine computer continuously monitors many of the parameters related to engine performance such as fuel, spark, air, rpm, etc. It uses this information to get the most performance and fuel economy possible from
the engine. A nice side effect is that it can detect many problems your engine may be experiencing and it even has a way to tell you about them.
When an out-of-range condition is detected a fault code is recorded in the engine computer. To read the codes, first open the diagnosis connector that is positioned just on top of the driver's side shock absorber under the hood. Raise the lid on the small black box to reveal the legend for the connector.
To test your engine, first start it up and let it reach normal operating temperature. Then shut the engine off and proceed with work at the diagnosis connector. Using an unfolded paper clip, connect the GND and the TEN pins together. Return to the driver's seat and turn your ignition key to "ON" but do not start the engine.
Observe the LED you have inserted in the diagnostic socket. It will flash a certain number of times to indicate a malfunction in your engine's control system. Count the number of flashes to indicate the malfunction code.
If the code is a two-digit number, the "tens" digit will be displayed first, then for a short 1.6-second period the light will be dark, then the "ones" digit will be displayed. This will repeat after a four-second dark pause. If there are multiple codes, they will each be separated by a four-second pause and may include two-digit codes, so pay attention.
Take as long as you need to record the codes and then refer to the chart below or section "F" of your factory service manual.
1 Ignition pulse – from ignitor circuit on inner wing or in coil pack up to ‘94
2 Ne signal
3 G signal
4 SGT signal (1.8L)
8 Airflow meter
9 Water thermistor
10 Intake air thermistor in airflow meter
12 Throttle position sensor
14 Atmospheric pressure sensor
15 Oxygen sensor (output too low)
16 EGR function sensor (1.8L)
17 Oxygen sensor (output not changing)
25 PRC solenoid valve (1.8L)
26 Solenoid valve (Evaporative canister purge)
27 EGR solenoid valve (vacuum)(1.8L)
28 EGR solenoid valve (vent)(1.8L)
34 Idle air control (1.8L)
36 Idle speed control valve
MOT Emissions (UK)
Early cars had cats fitted but do not need them for MOTs as they were not legally required. You need a cat if the first registration date was 1 August 1992 or later.
For later Roadsters .. it could be a ‘non listed’ (then not in the MoT computers) if it was registered before July '95 = it would have to do a non-cat test;(3.5% CO and 1200 PPM HC). The real question is does the MOT man call it an MX5 .. trouble is he should go by engine numbers and then a 1.8 becomes a NA18P2 and a UK car test = 0.5% CO at 800/900 rpm and 0.3% CO at 2400/2600 rpm..
If built after July '95 it has to do a general cat test = 0.3% CO and 200 PPM HC
Petrol Octane numbers
There are two octane ratings, Research Octane Number (RON), and Motoring Octane Number (MON).
"Roughly, US 87 = UK 92 and US 92 = UK 97. Normal Premium unleaded in UK is 95 (RON) and super unleaded is 97." John Cookson
"Down here in Australia and NZ, our pump fuel is advertised on RON only, whereas in the USA yours is rated on the average of the RON and MON, so the same fuel will have different ratings in different countries. From what I can tell, RON is generally higher than MON, so our 91,95, and 98 may not be too dissimilar to your 87,89 and 93 ????"
The tests are defined by ASTM D-2699 (RON) and D-2700 (MON) respectively. A standard single cylinder, overhead valve motor is used. It has variable compression ratio between 3 and 30. Bore is 3.25 in and stroke is 4.5 inch.
The difference in the to ratings is the conditions on the standard engine are adjusted to be more severe.
inlet T 125F 300F
rpm 600 900
ig timing 13 BTDC 19-26 BTDC (varied with compression ratio)
The compression setup is calibrated with reference fuels of n-heptane and isooctane. Yes, there is a 3 bowl carburettor with reference fuels and test fuel. Air fuel ratio is adjusted for maximum knock. Knock is measured to a standard intensity with a magnetostriction detector.
The octane is calculated by interpolating between the reference fuels and for octanes over 100 there is a formula involving the number of milliliters of TEL added.
Standard unleaded 95RON in UK (92 in Japan? and elsewhere)
Super unleaded 98RON in UK (100RON in Japan)
"Australia, New Zealand, and Europe report only the RON (Research Octane Number). on the pump.
America have their pump gas rated as the average of the RON and the MON (Motoring Octane Number).
Generally, RON is higher than MON, so non US fuel needs to have a higher number to have the same anti-knock properties as an American one...
I suspect our 91 and 96 RON are similar to US 89 and 93 ((RON+MON)/2)" Fletcher Blades
Modern Engine Tuning by A.Graham Bell .. explained in more detail on MON, RON and PON Octane ratings ..
MON is at 150C inlet air temp, RON at 65C
Both engine's water at 100C
MON is at 900 rpm, RON is 600 rpm.
So MON is at higher air intake temps and higher rpm .. so it is the one to look at for real engine use.
PON is used in US which is the average .. and we use RON in the UK ..
Unfortunately it is easy to brew up a 95 RON fuel that is only 87 MON .. so the quality of fuel can vary a lot .. however you cannot gain from the extra power from higher Octane unless the timing is optimised .. so you end up on the lowest workable timing advance and so never see the gains of that 'good' tank of fuel (unless in used when hot conditions like a track/dyno).
Tests showed power from various fuels and two unnamed brands. (4.1 litre Buick at 5,000 rpm)
Hp@degrees advance with (space) and without heated inlet manifold (read this as without/with CAI)
92 PON unleaded summer A = 212@28 220@31deg
92 PON unleaded summer B = 219@30 223@32
92 PON unleaded winter B = 208@26 215@29
97 PON unleaded summer A = 215@30 222@30
97 PON unleaded summer A = 218@40 224@44
100/130 aviation fuel = 222@40 224@44
100/130 aviation fuel = 210@30 213@33
last aviation fuel had timing deliberately cut to show power loss with the higher Octane fuel but non optimised timing.. and the best run in the real world is the second on lower octane summer fuel (winter fuel has more
volatile elements for cold starting)
"Apparently LRP starts off as Super Unleaded and the additive is mixed in the tanker which carries it, which is interesting as LRP is cheaper than Super Unleaded! Anyone smell a rip-off? The upshot of this is that LRP in a car that does not require valve lubrication will perform no different than Super Unleaded. The only advantage you will get is from the higher octane which would allow greater timing advance. People running LRP and feeling it was better were just seeing the effect of the higher octane. The additive in LRP will slowly damage the Oxygen sensor." Simon Phillips
Mazda Europe numbers;
Part nr for radiator 90-93 MX-5 1600 = b61p-15-200b
Part nr for radiator 94 MX-5 1600 = b61p-15-200b .. superceded by ’94 1.8 rad below
Part nr for radiator 94 MX-5 1800 = bpe8-15-200
Part nr for radiator 99 MX-5 Mark2 1600 and 1800 = bp4w-15-200a
So for the Mark 1 there should be a difference between the radiator for a 1600 or a 1800.
For the Mark2 MX-5 the radiator stays the same for both the 1600 and the 1800.
On the parts list it says CALSONIC after the part nr. This is the make of the radiator but Denso were also factory fitted.
SPAL's testing of DA rad with various fans;
"Stock fan 1400cfm measured
a/c fan 1320 cfm measured
Noisy SPAL rated 1390 cfm, 1975 cfm measured
Quiet SPAL rated 970 cfm 1610 cfm measured.
These were measured through our race radiator. The quiet ones would work with stock wiring, the noisy ones draw double the stock current." Bill Cardell
Fluid capacities of rads ;Stock 50 fl oz, PBC double core 66 fl oz, FM race radiator 77 fl oz
Mazdaspeed rad caps (19psi);
MazdaComp for $21. Any Mazdaspeed reseller,:Moss, RacingBeat, Corksport sells them too but likely for a few more dollars. The design differs between the Denso and Calsonic radiators so be prepared to tell them your type. Seehttp://www.tamahito.com/poweraxel/mazdaspeed/news/ms95.html
"The thermostat is a valve, not a switch. A 160 degree thermostat starts to open when coolant temperature reaches 160 degrees, but doesn't fully open until about 185 degrees.
The factory thermostat is a 2 stage device. The smaller valve starts to open when coolant (at the thermostat) reaches 182-188 degrees, and the larger valve starts to open when the coolant reaches 188-193 degrees. The
thermostat is not fully open until the water temperature is 212 degrees.
Just for completeness, the electric cooling fan kicks on at 207 degrees in the 1.6 based on the thermoswitch in the water pump inlet. " Brian K Dore
4 wire Oxygen sensor fitted to 1.8 cars; Bosch 13275
"Bosch makes a lot of 4-wire sensors. I use one originally meant for a Mercedes application. It works fine." Werner
1.6 Miata has a compression ratio of 9.4 to 1. So 14.7 psi times 9.4 equals 138 psi. But the Shop Manual lists 192 psi due to heat raise from dynamic compression. Cam timing also affects the pressure reached on the gauge. The longer duration the cam, the less the pressure.
From 1992 Mazda workshop manual (1.6L).
Compression ratio: 9.4:1 (manual), 9.0:1 (auto).
Compression pressure for both;
Standard; 192 psi,
Minimum; 135 psi,
Maximum difference between each cylinder; 28 psi.
From 1995 Mazda workshop manual (1.8L)
Compression ratio; 9.0:1 (manual and auto)
Standard; 182 psi,
Minimum; 128 psi,
Maximum difference between each cylinder; 28 psi.
in Mk2 1.8 209 is standard, 146 is minimum, max difference between cylinders 28 PSI.
"9.4:1 is the "blueprint" spec. There is a great variance in the head and deck heights as cast. 10 hp and 4 ft lbs
of torque is not an uncommon range in 1.6 stock motors. When I had my 1.6 head done back in 1993 we measured the total height and was able to take a substantial amount of material off with the head shave to make the spec height." Randy Stocker
"…I just went out to my car and used feeler gauges to measure between the block and head to get an installed thickness. 1.14mm at one end, and 1.09 at the other Obviously there is some elasticity, and the gasket un-squishes as it is removed. So what CR ratio would we get with a nominal 1.12mm (average of my two figures) gasket and your .4mm piston above deck figure realize? Wahoo, up from 9.02 to 9.07.... still not 9.4 is it?"
Mazdaspeed; The closest European dealer appears to be Mazda Racing Team Sweden, who can be contacted email@example.com The man to 'talk' to is Lucas Nylund.
PCV; replacement part to fit to s/c or t/c cars to reduce crankcase pressurising/oil loss from inlet manifold to crankcase = 323 turbo part (GTX in US)= E-301-13-890A
You do realize that a set of HLA's are $640
Mazdaspeed 4 barrel throttle kit http://www.vitesse-j.com/poweraxel/mazdaspeed/news/ms93.html
Check the Fuel Pressure Regulator.. It should go rich on low vacuum, so pinch (or cap) the vacuum line and see if the idle speeds up. (That's assuming that you've done the usual tune-up/plug wire stuff)
Under Drive front pulley;
Attain; 11551 Eunos Roadster NA6CE=11552 Eunos Roadster NA8CE (Before M/C) = not availablehttp://www.takakaira.co.jp/
Picture of the OBDII connector at:http://www.obdii/connector.html It's a 16 pin computer D-type socket (two rows of 8 pins) See http://www.obdii.com for general info about OBDII
$165 for the whole gasket head set including the seals for 1.8 at DA
The Mazda head gasket set doesn't include the camshaft oil seals (two required), the o-ring around the CAS, or the o-ring where the thermostat housing mounts to the camshaft.
fits the four places - ie the sump plug, the gearbox drain plug, the diff drain plug and the diff filler/level plug.
measures 24.0mm outside diameter, 18.3mm inside diameter.
1.6 Longblock - Can ship in two pieces to get under UPS's cutoff of 150 pounds. Head by itself (no manifold or cam cover) weighed 47 pounds. Bottom end including oil pan (no accessories other than oil and water pumps) weighed 128 pounds.
The Mk2 inlet manifold VICS switch at 5250 rpm. (variable intake ? system)
Loctite sell something called Ultra Grey which is similar to the instant gasket used by Mazda
Oil pump gaskets; "I've been putting them together with just silicone on the oil pump. IIRC, that's how the newer ones come from the factory. " Bill Cardell
If you look at the cylinders before boring, you'll see that Mazda didn't use a bore plate. You can spot four shiny spots at the top of the bores, corresponding to the head bolt holes. Bill Cardell
OEM head gasket set (#8AN2-10-235A) to rebuild a 1.8 head
- included: valve cover gasket intake manifold gasket exhaust manifold gasket 16 valve seals heater hose-to-rear-block water fitting gasket 2 camshaft seals 33mm I.D./48mm O.D. 1 bigger round seal 36mm I.D./51mm O.D. crank seal.
- not included: valve guides cam angle sensor 0-ring thermostat-to-front-block water fitting 0-ring
Looks like the '2001 uses a much heavier windage tray, bolted to four of the main bearing caps to act as a girdle. Bill Cardell