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Old 01-18-2010, 01:09 AM   #1
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Default No-Start Diagnosis (wtf?)

On the track, 20 minutes into my session my car dies. No warning, no symptoms, just completely dead. Towed back to the paddocks, found out I have no spark, switched coil packs, no spark. Switched igniters, and the car ran. Went back out on track, 3 turns in, same thing happens again. Thought maybe a circuit problem is blowing igniters. Put it back on the car it came from and that other car starts fine...now things are getting strange.

I remember when you turn the key to On, the check engine light comes on and turns off. I noticed that now there is no check engine light. I jump it in the diagnostic box, and the light is still off. I jumped the fuel pump to make sure its running, but I'm assuming that bypasses the ECU, so that didn't accomplish much. I'm under the suspicion that my ECU is not getting power, or is fried(isn't that kind of unlikely on these cars?). Checked grounds, cleaned them, put 'em back, and nothing changes. (FYI, I have them on an intake manifold stud for EGR that is just there and serves no purpose, hasn't been a problem before, but did have a bouncy tach sometimes) Pretty much lost all my money/track time.

The second time the car died, I noticed EVERYTHING inside died. The tach usually stays operational if you shut the car off in gear and let it coast. This time the tach was completely dead, went straight to 0, even though it obviously wasn't at 0.

Basically I think switching the igniter was just luck, and I'm not sure what/where to check, I don't see any obvious, visible wiring problems, though the first thing I thought of was my extended CAS wiring from swapping to a 1.8 (this is a 1.6 car with a stock ECU). Had no access to internet or anything to find out if/where there is an ECU fuse, though that wouldn't explain why the car started and made it 3 turns onto the track and died again.

Anyone have any ideas/questions/comments/whatever, I'm out of thoughts on this...its my DD so any help is appreciated.
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Old 01-18-2010, 01:19 AM   #2
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you seem to be getting shitty ignitors are you using 1.6 ignitors? this is a sign from god that you need to step up to some cops with integrated ignitors and have less to worry about. If the ignitor is bad you wont see a tach signal to ecu or anything spark related.
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Old 01-18-2010, 01:56 AM   #3
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Originally Posted by magnamx-5 View Post
you seem to be getting shitty ignitors are you using 1.6 ignitors? this is a sign from god that you need to step up to some cops with integrated ignitors and have less to worry about. If the ignitor is bad you wont see a tach signal to ecu or anything spark related.
How would that make sense though if the igniter worked on the car it came from, AFTER my car stopped running on the same igniter?
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Old 01-18-2010, 03:23 AM   #4
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Did you check the ground under the throttle body? When loose it funks the tach and blows packs.
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Old 01-18-2010, 03:39 AM   #5
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The fuel pump isn't driven by the ECU at all on the '90-'93 cars- the relay is wired to the AFM and to the starter.

When you jumpered the fuel pump, did it in fact turn on?

There is an ECU fuse. A couple, actually. Main ECU power (white/red wire) comes through the 30A "INJ" fuse (under hood, near firewall on pax side) and then through the Main Relay. The Main Relay coil is energized by the 15A "ENGINE" fuse (inside car, by driver's feet).

But I'm going to go out on a limb here and say that this sounds like the work of either a defective main relay or a defective key switch.
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Old 01-18-2010, 04:54 AM   #6
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The fuel pump isn't driven by the ECU at all on the '90-'93 cars- the relay is wired to the AFM and to the starter.

When you jumpered the fuel pump, did it in fact turn on?

There is an ECU fuse. A couple, actually. Main ECU power (white/red wire) comes through the 30A "INJ" fuse (under hood, near firewall on pax side) and then through the Main Relay. The Main Relay coil is energized by the 15A "ENGINE" fuse (inside car, by driver's feet).

But I'm going to go out on a limb here and say that this sounds like the work of either a defective main relay or a defective key switch.
Fuel pump DID turn on. How would I check if the relay/switch is bad?
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Old 01-18-2010, 04:58 AM   #7
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Did you check the ground under the throttle body? When loose it funks the tach and blows packs.
I don't even remember there being a ground there honestly....another thing I will check tomorrow morning.
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Old 01-18-2010, 07:05 PM   #8
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So I checked both those fuses, and the relay in the passenger side fusebox clicks when I turn the key to on. Still no CEL...
I don't understand how bad CAS wiring would cause the ECU to not do anything...but I am checking my CAS wiring anyway.
Actually going to re-do all this CAS wiring.
By key switch do you mean ignition switch?

Re-tracing my steps...
-no tach signal
-no CEL
-cranks
-90% sure theres no spark
-ECU fuses are fine...

Is it possible that my ECU just crapped out?

EDIT: The first time it died on track the tach still read. The second time tach read 0. STUMPED...
I think maybe this is 2 problems at once...

Last edited by MartinezA92; 01-18-2010 at 08:59 PM.
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Old 01-18-2010, 10:20 PM   #9
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I'm going with Main relay. Check for continuity with the ign on between White/green and White/red or use a test light and check for 12v at White/Red with ign on.
You could wire the test light in semi permanently - if it goes out when your engine dies you'll know for sure.

(Relays can be a bitch - they click like they're working but contacts can be intermittent)
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Old 01-18-2010, 11:29 PM   #10
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Eliminated the ECU as a possible problem. What do you mean by checking continuity? Couldn't I just check white/red with a multimeter? (I'm an electrical retard.)
And where are the main relay and wires that you're describing? Is the main relay the one in the passenger side fusebox? If so, I see 2 white/red wires.

Last edited by MartinezA92; 01-18-2010 at 11:48 PM.
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Old 01-19-2010, 01:10 AM   #11
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Things are getting strange. The bigger of the 2 plugs that go into the ECU is half plugged in and the CEL is back on. It only stays on in a certain position, and that position is not plugged all the way in. It doesn't seem like the harness because I can move the harness and the CEL stays on. I don't know if its the plug but it doesn't seem like it either, the CEL stays on if I mess with the wires going to it. As soon as I move the actual connector IN the plug the CEL is intermittent. This is on 2 different ECU's, so we can rule out the ECU. Still have no spark, definitely have fuel. Car cranks but won't start when the CEL is on. CEL stays on permenantly unless the plug is moved. While I'm fidgeting with the plug, the tach jumps up to 750 rpm or so and kinda just bounces around, even though the car is not running.
Igniter and coil packs are warm to the touch after some cranking. But no spark...heat means resistance so is something wrong here?

Last edited by MartinezA92; 01-19-2010 at 01:22 AM.
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Old 01-19-2010, 04:11 AM   #12
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I also have a spare 1.6 cas if you wanna try that out when you return my ecu.
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Old 01-19-2010, 09:11 AM   #13
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Quote:
Originally Posted by MartinezA92 View Post
Eliminated the ECU as a possible problem. What do you mean by checking continuity? Couldn't I just check white/red with a multimeter? (I'm an electrical retard.)
Yes but with new wiring added are you sure there is no stray 12V on the White/red. Continuity - set meter to resistance and measure across.


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And where are the main relay and wires that you're describing? Is the main relay the one in the passenger side fusebox? If so, I see 2 white/red wires.
Yes, engine bay fuse box. 2 White/red is correct, either one.

BUT - If you have fuel when this is happening and your fuel pump is switched from the Main Relay - it ain't the relay, sorry.

Last edited by BarbyCar; 01-19-2010 at 09:12 AM. Reason: Added fuel pump comment
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Old 01-19-2010, 04:41 PM   #14
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I'm looking at a wiring diagram. I can't hear if the fuel pump runs when I crank, but if I ground the fuel pump at the diagnostic box, does that bypass the relay? I'm looking at "main relay" on this diagram and I see nothing that leads to a fuel pump.
Going to test the white/red under relay for bV
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Old 01-19-2010, 04:52 PM   #15
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I vote CAS. I had very similar symptoms, twice, and a replacement (used) CAS solved my problem both times.
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Old 01-19-2010, 05:08 PM   #16
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I'm checking that next, pending on thesnowboarder. It still doesn't explain my problem with the ECU not getting power/not sending a CEL.
EDIT: I'm getting power at ECU terminal 1B and at b+ at the diagnostic connector. Someone check my logic, that eliminates the main relay as a problem, right?

Last edited by MartinezA92; 01-19-2010 at 06:24 PM.
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Old 01-19-2010, 06:46 PM   #17
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Things are getting even weirder. I kinda mess around with the bigger of the 2 ECU plugs itself (NOT the wires, the plug, putting it in/out) while I crank and the car almost starts...
Its like if 2 things need to make contact but when one makes contact the other one loses it...I don't understand how this happened at the track when the ECU is bolted down...
Going to t-pin every single ecu wire to test voltage.

Last edited by MartinezA92; 01-19-2010 at 11:14 PM.
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Old 01-20-2010, 12:00 AM   #18
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Quote:
Originally Posted by MartinezA92 View Post
I'm checking that next, pending on thesnowboarder. It still doesn't explain my problem with the ECU not getting power/not sending a CEL.
EDIT: I'm getting power at ECU terminal 1B and at b+ at the diagnostic connector. Someone check my logic, that eliminates the main relay as a problem, right?
Sounds Right.
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Old 01-20-2010, 12:39 AM   #19
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You have a 12v and ground cross somewhere in the wiring related to that plug, so you're half right. Sounds like one relay is working correctly, and as soon as you plug it in it's opening when it should be staying closed, or another somewhere is. Don't focus on that plug though, that's just what turns the problem on and off, that's not nessecarily where it's at.

Check the stupid stuff. Main ground from firewall to head, and I think there's one somewhere on the PPF. Also check voltage at the battery, and that it's tied down properly with the ground towards the outside of the car and neither the ground or positive terminal touching anything. I'm suspect that this happened at the track. Usually tracks are smooth, but you introduce high G loads.
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Old 01-20-2010, 01:02 AM   #20
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You have a 12v and ground cross somewhere in the wiring related to that plug, so you're half right. Sounds like one relay is working correctly, and as soon as you plug it in it's opening when it should be staying closed, or another somewhere is. Don't focus on that plug though, that's just what turns the problem on and off, that's not nessecarily where it's at.

Check the stupid stuff. Main ground from firewall to head, and I think there's one somewhere on the PPF. Also check voltage at the battery, and that it's tied down properly with the ground towards the outside of the car and neither the ground or positive terminal touching anything. I'm suspect that this happened at the track. Usually tracks are smooth, but you introduce high G loads.
I was suspecting exactly this actually, now I don't feel so dumb.
Voltage at battery WAS good, now my battery is dead from cranking so damn much...
I'm assuming testing voltage at every single ecu pin would help me find where my problem is. Gonna borrow some diagnosis ****/pick at a friends brain and get some numbers.

The first 3 left turns ...everything was good. First right hander...car died. Makes perfect sense now...
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