Random starting - I'm puzzled
Thread Starter
Advanced
Joined: May 2001
Posts: 69
Likes: 0
From: Ida, Michigan, USA
Random starting - I'm puzzled
My 94 6sp just died on me the other week on my way home. After a bit of cranking it started and I carried on with my drive. It later died about 20 minutes later. I finally got it started and parked it. I had it towed to a nearby mechanic that said it was the opti. I just put in a Dynaspark a few months ago and it ran beautifully ever since. I got it home (I wasn't going to pay the $1100 quoted) and emmidiately I tried to start it. It fired right up and ran great but after about 5 minutes it died. I couldn't start it again. I waited until the next morning and tried it. It fired right up and ran for about 3 minutes. I am able to start it after it sits for a long time but not right after it dies. I checked the battery and alternator. The weird thing is I do not have any codes show up and it runs great when it is running. Wouldn't it run like crap or at least throw some kind of code with an opti failure and why would it fire right up after I let it sit for a good long while? Fuel pressure is good when it runs and seems good on key on. I haven't been able to see if it mysteriously shuts off while running.I don't think so since it still has good pressure when it dies. This is weird.
Melting Slicks
Joined: Apr 2002
Posts: 2,546
Likes: 0
From: Orlando FL
I dont have much knowledge of the newer c4s. But it sounds similar to the problems i've had and read about regarding the factory alarm. Not sure if its vats in that year or not? Can you provide the rest of the techies with a lil more information?
Is the car turning over, but not firing?
Clicking ect?
This added info might be of more assistance to them.
Good luck on getting it fixed. I will certainly be watching this thread as I am always eger to learn new things.
Is the car turning over, but not firing?
Clicking ect?
This added info might be of more assistance to them.
Good luck on getting it fixed. I will certainly be watching this thread as I am always eger to learn new things.
Thread Starter
Advanced
Joined: May 2001
Posts: 69
Likes: 0
From: Ida, Michigan, USA
More info
When I try to start, if it is the first try of the day it fires up emmediately (no extra cranking at all). After it dies (30 sec to 5 minutes) it will crank strong but will not start. When I trun the key on I hear the fuel pump turn on then off (assuming it reached it's pressure). When I crank I hear the fuel pump turn on then off. Seems like the fuel is there but no spark. I do not get spark at the coil which is before opti. I'm wondering is the PCM is not giving a signal. I will check on that.
When I try to start, if it is the first try of the day it fires up emmediately (no extra cranking at all). After it dies (30 sec to 5 minutes) it will crank strong but will not start. When I trun the key on I hear the fuel pump turn on then off (assuming it reached it's pressure). When I crank I hear the fuel pump turn on then off. Seems like the fuel is there but no spark. I do not get spark at the coil which is before opti. I'm wondering is the PCM is not giving a signal. I will check on that.
Le Mans Master
Joined: May 2005
Posts: 7,374
Likes: 2,290
From: Central Maryland
If the optical side of the DynaSpark were failing, the ECM would throw codes because the low-res and/or high-res pulses would be absent (the car will run with only the low-res pulses present, BTW, but not with only the high-res pulses present).
If the high-voltage side of the DynaSpark were failing, you'd almost surely have substantial misfiring, backfiring, etc, rather than having the car just die. Also, as you correctly noted, the absence of spark out of the coil pretty well exonerates the high-voltage side of the Dyna.
The absence of codes suggests to me that the problem is at or near the coil, coil controller, or harness connections. It could be the ECM, but I'd look elsewhere first.
It can't hurt to verify the fuel pressure, but the absence of spark at the coil suggests it's not a fuel delivery problem.
Be well,
SJW
If the high-voltage side of the DynaSpark were failing, you'd almost surely have substantial misfiring, backfiring, etc, rather than having the car just die. Also, as you correctly noted, the absence of spark out of the coil pretty well exonerates the high-voltage side of the Dyna.
The absence of codes suggests to me that the problem is at or near the coil, coil controller, or harness connections. It could be the ECM, but I'd look elsewhere first.
It can't hurt to verify the fuel pressure, but the absence of spark at the coil suggests it's not a fuel delivery problem.
Be well,
SJW
