Today's optispark thread - checking high res wire at ECU
Thread Starter
Safety Car
Joined: Jul 2001
Posts: 4,871
Likes: 15
From: Detroit's West Side MI
Originally Posted by SJW
1. A fault in the "Run" circuit of the ignition system. Sounds as though it's possible you have power to the ignition system when the switch is in Crank position, but not when it's in Run position.
The crank position of the key is replaced by the start button, so as long as the car is on and not in crank it should be in run. How would I check your suggestion? I assume that any line powered by ignition should have 12V regardless of whether the car is running or stalled (which they do). Is that what you meant?
Le Mans Master
Joined: May 2005
Posts: 7,343
Likes: 2,272
From: Central Maryland
Originally Posted by ScaryFast
SJW, you mentioned this earlier and I didn't pay attention to it. Let's explore this option further. I don't have a key cylinder, only an ignition switch and a start button. When the ig switch is on any circuits powered by ignition should get 12V. This would be equivilant to the run circuit being active at this time, right?
The crank position of the key is replaced by the start button, so as long as the car is on and not in crank it should be in run. How would I check your suggestion? I assume that any line powered by ignition should have 12V regardless of whether the car is running or stalled (which they do). Is that what you meant?
The crank position of the key is replaced by the start button, so as long as the car is on and not in crank it should be in run. How would I check your suggestion? I assume that any line powered by ignition should have 12V regardless of whether the car is running or stalled (which they do). Is that what you meant?
I don't have my manuals here in front of me, but I'd think there's someplace you can check for the presence or absence of +12v feeding the ECM and/or whatever else is required to provide juice to the ignition system when the key is in Run position.
If I understand correctly, you have the lock cylinder removed from the column, but have retained the stock ignition switch in the column, and have remote-mounted a momentary pushbutton starter switch. If this is the case, maybe you'll want to try to briefly hold the ignition switch in the Start position (with a screwdriver) while you try to start the car, and see if that gets it to start and run.
Have you verified that the fuel rail is adequately pressurized?
Le Mans Master
Joined: May 2005
Posts: 7,343
Likes: 2,272
From: Central Maryland
Originally Posted by ScaryFast
I never actually had a 36 or 16 code, I just probed the lines with a DVM and assumed based on what the manual defined as the problem I assumed those codes would be there. I wasn't able to check codes until today when I borrowed the scan tool and only had the two listed above.
I just tried to start the car again and it is back to the run for 2 seconds then stall.
The issue happened once months ago and then everything was fine until recently, which is why I assumed it was the powerwash ruining my Optispark. I was convinced of this based on everyone's input until I saw no opti codes today.
I will check all of the voltages on the circuits handled by QDM tomorrow and look for shorts. I have a large current draw which could also be explained by a problem in the fan or A/C circuits. Then it's full diagnosis of the ignition system and perhaps ultimately replacing the ECM. However, would problems with the ignition system or ECM be intermittant?
There are many connectors dangling unplugged in the engine compartment from the gutting, I'll also trace all of them back and remove them from the harness.
I just can't believe it's the fuel system since twice in two days the car has ran flawlessly for an extended period of time. Those types of problems are not intermittant...it HAS to be electrical.
I just tried to start the car again and it is back to the run for 2 seconds then stall.
The issue happened once months ago and then everything was fine until recently, which is why I assumed it was the powerwash ruining my Optispark. I was convinced of this based on everyone's input until I saw no opti codes today.
I will check all of the voltages on the circuits handled by QDM tomorrow and look for shorts. I have a large current draw which could also be explained by a problem in the fan or A/C circuits. Then it's full diagnosis of the ignition system and perhaps ultimately replacing the ECM. However, would problems with the ignition system or ECM be intermittant?
There are many connectors dangling unplugged in the engine compartment from the gutting, I'll also trace all of them back and remove them from the harness.
I just can't believe it's the fuel system since twice in two days the car has ran flawlessly for an extended period of time. Those types of problems are not intermittant...it HAS to be electrical.
Get the car to misbehave while you have a FP gauge in place, and then you'll be able to either rule out, or verify, a FP-related problem. If FP is good while the car dies, look to the ignition system and forget about the fuel system. If the FP is not holding good while the car dies, forget about chasing ignition gremlins.
Break the problem in half first -- figure out what's happening (or not happening) with the fuel system, as it's easy to diagnose and troubleshoot.
Thread Starter
Safety Car
Joined: Jul 2001
Posts: 4,871
Likes: 15
From: Detroit's West Side MI
Damn your logic! Makes good sense.
Ok, check here for the latest. I've ruled out the opti so I'm back to wiring and these suggestions discussed in this thread. I've sent an email to you (because I can't remember how to post pics in a thread) showing my ignition set-up. I have removed the stock column entirely.
http://forums.corvetteforum.com/show...18&forum_id=48
Fuel pressure checks out so it's on to injectors and/or ECM.
Thanks again!
Ok, check here for the latest. I've ruled out the opti so I'm back to wiring and these suggestions discussed in this thread. I've sent an email to you (because I can't remember how to post pics in a thread) showing my ignition set-up. I have removed the stock column entirely.
http://forums.corvetteforum.com/show...18&forum_id=48
Fuel pressure checks out so it's on to injectors and/or ECM.
Thanks again!
Le Mans Master
Joined: May 2005
Posts: 7,343
Likes: 2,272
From: Central Maryland
Originally Posted by ScaryFast
SJW, you mentioned this earlier and I didn't pay attention to it. Let's explore this option further. I don't have a key cylinder, only an ignition switch and a start button. When the ig switch is on any circuits powered by ignition should get 12V. This would be equivilant to the run circuit being active at this time, right?
The crank position of the key is replaced by the start button, so as long as the car is on and not in crank it should be in run. How would I check your suggestion? I assume that any line powered by ignition should have 12V regardless of whether the car is running or stalled (which they do). Is that what you meant?
The crank position of the key is replaced by the start button, so as long as the car is on and not in crank it should be in run. How would I check your suggestion? I assume that any line powered by ignition should have 12V regardless of whether the car is running or stalled (which they do). Is that what you meant?
SJW
