99 miata will not turn over

s0n1cm0nk3y · Postby **s0n1cm0nk3y** » Fri Oct 29, 2010 9:14

So I'm lost.I have a 99 miata with the bp-4w. So far, I've checked all the fuses both in the engine compartment, and in the cabin. I've tested and replaced the camshaft and crankshaft sensors. I've also tested the coils, so far there is no spark .there is a 12v power source directly to the coils and a good ground. Testing everything with a mutimeter,there is no signal to the coils to fire from the ecu. Also i do not hear anything from fuel pump.I checked and I also can't get a signal from the obd 2 port. Considering my o2 sensor behind my cat has been throwing a code, Im guessing thend result should be the ecu.

If anyone has any other ideas let me know asap

Ps. Forgive the typing mistajes using my phone.

Postby **RX-7 Chris** » Fri Oct 29, 2010 9:14

How have you been?

So the car isn't even cranking?

I assume you checked the battery and it is good. I would replace the power and ground cables to the battery. It could be a bad ground from the battery.

s0n1cm0nk3y · Postby **s0n1cm0nk3y** » Fri Oct 29, 2010 9:14

Thee car is cranking.check battery it is good.now I've also tried another ecu, and no luck.I'm lost.

iani1.1 · Postby **iani1.1** » Sat Oct 30, 2010 9:14

could be main relay, fuse or some type of switch. time to pull out a wiring diagram and see whats between the ecu and coils or ecu and fuel pump etc.

i believe a switch in between the ecu is the culprit. also a bad o2 will not prevent the car to start.

also check if you have power going to the ecu. even if you have a bad ecu, the car will still start but then stall or run like crap after a few moments. but then again no power to the obd port is quite questionable.

s0n1cm0nk3y · Postby **s0n1cm0nk3y** » Sat Oct 30, 2010 9:14

sadly I've been checking diagrams. Main fuse and other fuses check out. I'm pretty sure its no power to the ecu, though I can't find a pin out. So far no spark and can't hear any pump.got a 12v constant to the coil with the key on, but no signal to fire from the ecu.checked the sensors and the writing looks good.relays are mostly single poll, and switch on with power.checked all the martin ones I could find.

iani1.1 · Postby **iani1.1** » Sat Oct 30, 2010 9:14

ah, yea if you have voltage going to the ecu but giving a signal out to any of the other components then yes i say bad ecu. but the fuel pump is ecu controlled? id expect it to be some type of bosch type relay. then again i dont work on miata's that often lol

s0n1cm0nk3y · Postby **s0n1cm0nk3y** » Sat Oct 30, 2010 9:14

Well the peculiarity is I tried another ecu but with no luck.I've checked all known fuses and relays I could find.also what's odd is with the ecu in, I can't get my check engine light to power on as I turn the key to the on position.

s0n1cm0nk3y · Postby **s0n1cm0nk3y** » Sat Oct 30, 2010 9:14

http://www.madracki.com/miata/images/wiring/99sys.pdf = wiring diagrams for my car.

okay to sum it all up:

symptoms:
car attempts to turn over but is not able to fire up. Starter able to rotate engine, yet with lack of spark deduced by coil test, logical process of combustion is not able to be completed.

things that work:
internal lights, headlights, ac, power antenna, power windows, stereo system, turn signal lights, backup lights, brake lights, instrument panel illumination (sans mil light), cruise control, power mirrors, tape deck, and power locks. basically everything except spark, not sure on fuel, do not have a pressure tester to verify fuel pressure.

things tested:

timing belt (removed oil cap and checked for rotation of cams and belt, deduced the presence of compression by response observed)

ecu (replaced to see if a replacement works)

camshaft position sensor (replaced to see if a replacement works)

crankshaft angle sensor (replaced to see if a replace works and meticulously
repositioned over and over to make sure the air gap was well within the ranges specified)

fuses (all fuses both on the left kick panel and under the hood up towards the passenger side of the compartment checked)

relays (relays checked using the 9v power toggle method, both under the hood towards the passenger side of the cabin, and by the driver side headlight)

coils (checked resistance and continuancy to the coils from both terminals a and d {on the electrical connector} and resistances between the actual spark plug wire terminals {resistance was a 10.04 across both terminals while ranges specified by penkus was 8.29 - 12.59}. checked plug going into coils, 12v constant power is present with key on {per directions from all data} yet signal wire does not show any indication of working via tests with a standard multimeter, check both resistance and voltage in regards to signal wire)

obd2 (not ble to make connection to the obd2 scanner i have here at work, and also when i turn the key to the on position the mil light does not illuminate)

erod550 · Postby **erod550** » Sat Oct 30, 2010 9:14

Are you also posting on Miata.net? I've gotten a lot of help there for strange issues I've had with mine.

s0n1cm0nk3y · Postby **s0n1cm0nk3y** » Sat Oct 30, 2010 9:14

figured out the problem.it turns one of my relays in the fuse panel in the engine compartment had a loose wire going into the actual terminal, i resoldered it and it seems to be running. the peculiarity is that it blew the relay just enough out of resistance that the 9v trick worked but was still not able to power the ecu (gotta love/hate precision in regards to such things). So with some broke *** ingenuity, i took a spare bosche relay (with the help of some spade connectors) and made a temporary relay until my replacement comes in on tuesday. shes running a tiny bit rough, but then again the car has been sitting for a week with nothing but cold turn overs. one of the pros/cons is now that the mil light is on, gotta love miata cat's...

iani1.1 · Postby **iani1.1** » Sat Oct 30, 2010 9:14

hah i knew it. well kinda lol

99 miata will not turn over

99 miata will not turn over

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