Horrible problem

specops_SC

Registered User
hey guys. well, this is my sc nightmare number 3. just got my exhaust put in my 5spd today and while i have the car running it shuts off and wont start up. revs fine while its running but then just dies. if you wait a long time it starts back up fine, then does it again. things we have done (its me and paul meadows working on this thing..)
1. swapped computers
2. swapped dis modules
3. swapped coil packs
4. swapped crank sensor
5. put gas in car (had a mustang that did this when it ran out of gas. my gauge doesnt work)
6. jumped fuel pump relay in case that relay was bad
7. checked ignition switch
8. tried it with mafs disconnected
9. confirmed lack of spark by disconnecting a plug wire at the coil pack and looking for spark. it sparked once, started, ran, then the spark went out.

the only thing we didnt swap was the ircm relay box. we strongly suspect the exhaust shop didnt disconnect the battery on the car, then welded on the exhaust while it was installed. this could potentially damage critical ignition components. any takers? i'll post an update when i figure this mess out.
 
Did you check for any trouble codes?
Here's a little thing on checking the diss on a no start problem, maybe you can use it.
I don't remember them disconnecting my battery when i had my FloMaster stuff put on. And i didn't have any problems.

Tony
 

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yea, that would probably have been another bit of useful info. the cel never came on. and im talking about a couple of hours of tinkering.
 
well, swapping out the ircm didnt help. i think i have a fried computer. something in there is getting hot to the point of shutting down, which would explain the car running fine if you wait a few minutes. it just wont stay running. im going to try a swap here in a bit and see if that helps..
 
Mine did the same thing when the cam sensor failed. It would start if I let it sit for 20+ mins. But would not start if I warmed up the car, shut it off and then tried to restart it.
 
I had the same problem

When I had a problem like that it was when i put a new tranny in the car and both o2 sensor wires were broke. I guess It happened when I took the exhaust off. The bird would run for a few mins then shut off. I would check to see if the shop maybe disconnected them.
 
wouldnt the o2's set off a cel? its worth a try anyways. i'll take a look under there in a bit. im going to try the ignition switch, and if that doesnt work, i guess im shelling the money over for a reman on my computer.. i still have to pull it later and hopefully someone around here has a compatible one that i can get for cheaper than my other options.. i did a cam sensor swap just now and that sure didnt work..
 
hey guys. well, this is my sc nightmare number 3. just got my exhaust put in my 5spd today and while i have the car running it shuts off and wont start up. revs fine while its running but then just dies. if you wait a long time it starts back up fine, then does it again. things we have done (its me and paul meadows working on this thing..)
1. swapped computers
2. swapped dis modules
3. swapped coil packs
4. swapped crank sensor
5. put gas in car (had a mustang that did this when it ran out of gas. my gauge doesnt work)
6. jumped fuel pump relay in case that relay was bad
7. checked ignition switch
8. tried it with mafs disconnected
9. confirmed lack of spark by disconnecting a plug wire at the coil pack and looking for spark. it sparked once, started, ran, then the spark went out.

the only thing we didnt swap was the ircm relay box. we strongly suspect the exhaust shop didnt disconnect the battery on the car, then welded on the exhaust while it was installed. this could potentially damage critical ignition components. any takers? i'll post an update when i figure this mess out.

Did you replace cam sensor, usually they go out if never been replaced.

also, when you cranking it and it won't start. Does tach move?

Mine was running ruff and was in 17.9 sec first I tred then I was running 15.8 after cam sensor was replaced and motor mounts, currently 14.1 - STOCK
 
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after 3 days i find out that...

hey sc power, yea, i tried cam sensor swaps. the tach jumps around a little while starting and the upshift light goes out. sometimes it wont come on and the car still wont start, but usually right after it dies it'll stay on during cranking. also, the ignition switch swap did nothing to help the problem. we hooked up a voltmeter to the pip input wire right at the computer to verify it was receiving a signal which it did right to the very end. it was in the 6.0-6.2 volts range. wire 56 dark blue on the pcm module. so, this along with the 211 (pip signal loss) code that we got has led me to believe my computer is fried. going to try to get one here and if not, guess im spending 270 bucks on a reman.. thanks to everyone for their input and help.

Moses
 
hey sc power, yea, i tried cam sensor swaps. the tach jumps around a little while starting and the upshift light goes out. sometimes it wont come on and the car still wont start, but usually right after it dies it'll stay on during cranking. also, the ignition switch swap did nothing to help the problem. we hooked up a voltmeter to the pip input wire right at the computer to verify it was receiving a signal which it did right to the very end. it was in the 6.0-6.2 volts range. wire 56 dark blue on the pcm module. so, this along with the 211 (pip signal loss) code that we got has led me to believe my computer is fried. going to try to get one here and if not, guess im spending 270 bucks on a reman.. thanks to everyone for their input and help.

Moses

Did you check the EEC fuse in the box up front in engine bay?
 
actually, the sc model doesnt have a fuse for the eec in the fuse box in the engine bay. the eec works fine up to a certain point, then it just kills the car. with a koeo test, the system passes fine. however, everything is getting to the computer just fine, which leads to the ignition circuits in the computer being mest up somehow. it doesnt quite make sense, but its the last thing left..
 
actually, the sc model doesnt have a fuse for the eec in the fuse box in the engine bay.

You sure about that? My '93 SC does. It might be labeled something else, but it is for the EEC. Trying to draw from memory, I think it is the second to the last or the last fuse. I'll look when I get home.
 
actually, the sc model doesnt have a fuse for the eec in the fuse box in the engine bay. the eec works fine up to a certain point, then it just kills the car.

Well, it most likely isn't the EEC fuse since the car will restart eventually. But, for anyone reading this for info, there is an EEC fuse in the front high current fuse box. It is fuse G and is the fourth to the last fuse on the RH side of the front row. See pic.
 

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i mustve been thinking about something else. sry. i know there is something computer related in there that isnt on the sc's. but yea, that fuse is good. man, im tired of this already. heh.
 
If your car ran fine before you installed the headers perhaps something is unplugged. perhaps the coolant temp sensor is unplugged and when your car goes into closed loop,and the computer starts using the sensors the computer goes full rich and your engine dies. Just a guess, I am putting headers on my 95 now a pretty big job, I found a bad motor mount on the driver side, the passenger side has been changed (the easy side :) Good luck, I hope you find out whats wrong.
 
I am a newby here and I could be way off, but I believe you have a similar problem to the 02 sensor fix from a previos post. I believe when your engine cools down which is when your computer is going open loop your engine will start and run. But as soon as it warms up and reaches operating temperature and the computer goes into closed loop is when your engine dies.

The ecm uses information from the sensors which are usually variable resistors: thermo,electrical or mechanical based on a 5v reference voltage (your 02's are .01v to .9v they make their own low voltage) so if there is an open in the temp circuit or defective coolant sensor the computer will adjust the fuel ratio as if it is 50 below zero.

I would make sure you do not have spark when the engine dies, I suspect it does.

If it is dying at the same temp every time, it is dying when your engine is going into closed loop, I would check your sensors (including maf) and the circuits from the sensors back to the ecm particularly the wires that could have been disturbed while changing the exhaust.

Good Luck
 
hey sc power, yea, i tried cam sensor swaps. the tach jumps around a little while starting and the upshift light goes out. sometimes it wont come on and the car still wont start, but usually right after it dies it'll stay on during cranking. also, the ignition switch swap did nothing to help the problem. we hooked up a voltmeter to the pip input wire right at the computer to verify it was receiving a signal which it did right to the very end. it was in the 6.0-6.2 volts range. wire 56 dark blue on the pcm module. so, this along with the 211 (pip signal loss) code that we got has led me to believe my computer is fried. going to try to get one here and if not, guess im spending 270 bucks on a reman.. thanks to everyone for their input and help.

Moses

Is your DIS mounted above the A/C? If it is you may want to remove it and apply some heat sync compound to it. Either that it might be bad.
 
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