nevermind. read 160 and 152 ohms, CAS looks good. Now what!?

also, I just checked every wire with an inductive timing light. No flash on any, no spark

 

Do u have power at the coils?

If everything has checked out power and continuity and ground wise then bad ECU. Check the ohms at the TPS or ECU to see if the ECU ground is bad. If ground at ECU is good sounds like your ECU died.

 

how do I check for power at the coils?

 

and the only spare ecu ive got is out of an 88. this is a 90. guess that wont work right?

 

I have a stupid question for you, did you happen to check all the fuses in the cabin? I had a weird pulsing cabin power problem when a fuse popped for my radio.. It caused all of the cabin functions (including power to the ECU) to pulse.. one second of power, two seconds of nothing... check your other fuses as well.

And check the fuses in the engine bay using a multimeter set to continuity mode. I had trouble figuring out a no-start problem, when I had a hairline crack in one of those fuses.

 

ok ill try both of those things
thanks wonko.

keep the ideas coming guys. and how to I check for power at the coils?

 

it's pretty easy, actually.. .the black wire with the yellow stripe provides constant power to them, whenever the key is on. This will only check out if your main relay is good. double check that first (you may have, and I missed it). If not, it's easy.. at the main relay (cube in rubber sleve, located near the vacuum booster for the brakes), there's one round, one square connectors coming out it. When it's off, you should see 12V @ Black/white (black with a white stripe) to ground. When it's turned on, you should still get that, plus 12V to ground on the black/white coming out of the square connector, as well ast he Black/Yellow coming out of the square connector.

If you have +12 on the Black/Yellow wire, go to the coils, and double check that they both have +12V on that wire. The Traling ignitor will have two black/yellow wires, they should both give +12V. The Leading only has two wries, one black/yellow, and one going to the ECU, Green/Yellow. The B/Y should have +12v.

 

alright I will check the main relay after school tomorrow... its too late to crack out the multimeter for tongiht.

so if I have voltage, that means the problem lies within the coils and ignitiors? I have the pair from my crashed 88, will they be ok in a 90?

and if I have no voltage, does that mean bad relay, or bad ecu. or bad both?>

 

If you got power in the cabin the relay should be good. The coils fire from switching ground. You can test the coils as I posted. If you think the ignitor is bad the best thing to do is just swap a coil pack and test. If it all checks out look at ur ECU.

 

I agree, it should be good... but check it anyway.. there's actually two relays inside of the "main relay", and mine somehow had gotten moisture in it at one point, and the insides were basically a rust-colored goo.. If I recall, it smelled pretty nasty too.. either way, double check it, cause its' easy

 

Dude I am having the exact same problem right now and it is not your coilpack or ignitors its you CAS trust me I have replaced almost everything and now I am waiting on my CAS to get here. That is the last piece and the reason I know thats it is because I checked it with an ohm meter... I even checked the ECU to make sure it wasnt getting a pulse from the CAS and that is it. I almost guarentee you have power to the igniter and coil but it is a constant power with no fluctuation to cause the spark....

 

^ well that was out of place and worthless.

 

i checked the resistance of the two wires underneath the black cover on the coils (dont know the tech term)

front coil is 1.2 ohms, which is out of spec. rears were at 1.0. could that cause a problem?

I checked the voltage on the leading coil and it was getting 12V at the black and yellow wire, 0v at the green. didnt check the trailing, didnt want to take the whole thing off

 

even after checking the CAS resistance, is there a chance that is could still be faulty?

 

and after rechecking the leading coil resistance with a new ohm meter, it read 0.8, which puts it back in spec. I need help guys!!

 

Ecu

 

alright neato. ive got an s4 ecu sittin here, could I do a temp swap into my s5 jsut to see if it will fire? or is it all completely different.

 

hold the plug wire and see if you get zapped

 

Nop they are totaly different. Any S5 ECU will work though. If you dont have one both members gonzz and rotaryresurrection have ECUs on hand that I know of. you can try giving them a buzz.

 

is there an obvious way to tell if the ecu is actually gone? ie... will the pcb or anything inside be literly burned? or what

 

I agree with the above. First wet your fingers on one hand, hold the plug wires end, then put your other hand on some solid metal item, like the engine. Have someone spin the engine. Please make sure you put all the fuses back where they belong prior to doing that.

To see if the ECU is good enough to put out a spark signal, remove the boost/pressure sensors plug. Put your meter on DCVolts. Negative to a known ground, positive to the brown/white wire in the plug. Turn the key to ON. If you see approx 4-5vdc on the meter, then the ECU is good enough to put out a spark signal.

If you don't have 4-5vdc, then I'd suggest you don't have the ECU powered up or some thing is drowning out the 4-5vdc signal. Remove the plug off the afm and then check the voltage again.

Another way to check the ECU is to download the FUEL SECTION of the online, free fsm. Find the pages called CONTROL UNIT. It shows the output/input of each pin on the ECU with the plugs attached to the ECU. DO THAT or put the plug lead to your tongue and spin the engine. Your choice.

 

alright I will check teh voltage on the pressure sensor asap..

AGAIN, IF by some chance, I am getting the required 4-5vdc, what do I do next?

that would put the ECU at the correct voltage, the coils at the right voltage, the cas at the right voltage, and the coils at the right resistance. whats left?

 

If the voltage at the brown/white wire of the pressure sensor is good, and you CLAIM there is no spark, then it isn't going to hurt you to hold the end of the sparkplug wire in one hand with the other hand on the chassis/engine. Is it?

So that is the next step. I think you have spark and don't know it. I'm wrong, you say?? Then get a good grip on that sparkplug wire and spin the engine over to prove me wrong.

 

alrighty then :P

wouldnt have checking it with the timing light dont a good job though?

 

alright with both the AFM plugged in and out, im getting .4 volts at the brown with white wire.

so ecu is kaput?