Aight wtf is this about?
05-12-2004, 08:20 PM
#21
Originally Posted by SilverSurfer
From reading through some of your other posts about the problem you're having I got the impression that although you're getting misfires on all 8 cylinders, on a couple of them the condition is more chronic. If that's not the case, then maybe the problem lies elsewhere. It could then possibly be that they didn't street tune the car as you said.
I don't think it's the fuel pump because if it was crapping out you'd be going really lean at WOT. But if somehow the fuel pressure regulator went bad the car might be getting too much fuel at idle and part throttle. Not a problem at WOT because the rich mixture could have been turned down, by lowering injector pulse width, at Cartek when it was tuned. Hook a fuel pressure gauge to the motor and see what's up.
Did you notice the stumble at part throttle when you first drove the car after it was tuned? If the problem wasn't there at first then try reseting the PCM/ECM by unplugging the big 50 amp fuse and the small 10 amp fuse in the 2 fuse blocks. After letting the car sit for a while plug them back in and re-Atap the car. If it's a sensor problem it might not come into effect right away. When I do this to my car the problem I'm having with the 3.96* of knock does not manifest itself for about an hour's worth of driving and I get normal timing. But then the computer learns and it goes back to limp home mode and 15* of timing. Easy to do and worth a try.
You said once you go WOT it takes a couple of seconds before the car starts to boogey. Are you able to power brake the car? Maybe the converter went bad or there's a problem in the tranny and it's locking up the converter at part throttle.
Make a list for us of the things you've done so far to try and troubleshoot the problem. Might shed some light for us.
I don't think it's the fuel pump because if it was crapping out you'd be going really lean at WOT. But if somehow the fuel pressure regulator went bad the car might be getting too much fuel at idle and part throttle. Not a problem at WOT because the rich mixture could have been turned down, by lowering injector pulse width, at Cartek when it was tuned. Hook a fuel pressure gauge to the motor and see what's up.
Did you notice the stumble at part throttle when you first drove the car after it was tuned? If the problem wasn't there at first then try reseting the PCM/ECM by unplugging the big 50 amp fuse and the small 10 amp fuse in the 2 fuse blocks. After letting the car sit for a while plug them back in and re-Atap the car. If it's a sensor problem it might not come into effect right away. When I do this to my car the problem I'm having with the 3.96* of knock does not manifest itself for about an hour's worth of driving and I get normal timing. But then the computer learns and it goes back to limp home mode and 15* of timing. Easy to do and worth a try.
You said once you go WOT it takes a couple of seconds before the car starts to boogey. Are you able to power brake the car? Maybe the converter went bad or there's a problem in the tranny and it's locking up the converter at part throttle.
Make a list for us of the things you've done so far to try and troubleshoot the problem. Might shed some light for us.
Replaced the wires(msd's) with new stock wires
Regapped the plugs from .055 to .040
Checked for spark on #1 cylinder
Checked plugs for rich condition
Fuel filter less than 8 months old
05-12-2004, 08:21 PM
#22
Originally Posted by Pro Stock John
If the misfires are equally high on all cylinders also try borrowing a MAF T and leaning out the base idle, if the car is very rich at idle the plugs will load up.
lol
05-13-2004, 07:16 AM
#23
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I'm wondering if the tranny issue you had at first is completely fixed. Maybe the car's in 2nd gear when you're leaving the line or it goes into 2nd too soon at WOT. Could be some other parameters need attention.
What do your buds on NJfbody think? Any of them drive the car or ride in it? Maybe they could post and give us their input/observations.
When's Julio or Dave gonna look at the car? If it's not going to be in the very near future, then try borrowing a working stock/tuned PCM from a 98 car. As long as the car idles somewhat and drives with the stock PCM then you can test and see if the stumble/hesitation goes away.
Better yet, call up TSP and see if they can lend a hand. I'm sure they've got a real good tune for your setup already, maybe they can mail you a tuned PCM that you can swap in your car for test purposes. They seem to be very helpful and with you being a customer maybe they can do something for ya. Can't hurt to ask.
What do your buds on NJfbody think? Any of them drive the car or ride in it? Maybe they could post and give us their input/observations.
When's Julio or Dave gonna look at the car? If it's not going to be in the very near future, then try borrowing a working stock/tuned PCM from a 98 car. As long as the car idles somewhat and drives with the stock PCM then you can test and see if the stumble/hesitation goes away.
Better yet, call up TSP and see if they can lend a hand. I'm sure they've got a real good tune for your setup already, maybe they can mail you a tuned PCM that you can swap in your car for test purposes. They seem to be very helpful and with you being a customer maybe they can do something for ya. Can't hurt to ask.
05-13-2004, 08:44 AM
#24
Originally Posted by SilverSurfer
I'm wondering if the tranny issue you had at first is completely fixed. Maybe the car's in 2nd gear when you're leaving the line or it goes into 2nd too soon at WOT. Could be some other parameters need attention.
What do your buds on NJfbody think? Any of them drive the car or ride in it? Maybe they could post and give us their input/observations.
When's Julio or Dave gonna look at the car? If it's not going to be in the very near future, then try borrowing a working stock/tuned PCM from a 98 car. As long as the car idles somewhat and drives with the stock PCM then you can test and see if the stumble/hesitation goes away.
Better yet, call up TSP and see if they can lend a hand. I'm sure they've got a real good tune for your setup already, maybe they can mail you a tuned PCM that you can swap in your car for test purposes. They seem to be very helpful and with you being a customer maybe they can do something for ya. Can't hurt to ask.
What do your buds on NJfbody think? Any of them drive the car or ride in it? Maybe they could post and give us their input/observations.
When's Julio or Dave gonna look at the car? If it's not going to be in the very near future, then try borrowing a working stock/tuned PCM from a 98 car. As long as the car idles somewhat and drives with the stock PCM then you can test and see if the stumble/hesitation goes away.
Better yet, call up TSP and see if they can lend a hand. I'm sure they've got a real good tune for your setup already, maybe they can mail you a tuned PCM that you can swap in your car for test purposes. They seem to be very helpful and with you being a customer maybe they can do something for ya. Can't hurt to ask.
05-13-2004, 09:36 AM
#25
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Well if the car is rich at idle, it can load up the plugs and you can help fix this by leaning it out or burning it more efficiently. I would be more of a fan of leaning it out since that would improve fuel economy. MAF T is a quick way to check to see if it helps.
05-13-2004, 12:07 PM
#26
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OK. Here's a couple of things to do in the mean time. This is basic diagnosis but it might help rule out quite a few things that have been mentioned so far.
1. Hook a fuel pressure gauge to the car. I believe stock FP should be in the low to mid 50s. Someone correct me if I'm wrong.
2. Hook up a vaccum gauge to the car. You did experience a vaccum leak when you put the motor together. There may still be a slight leak somewhere that's going unnoticed. I won't venture to say how much vaccum you should be seeing, but I'm sure someone can shed some light. I figure at least 10 in/HG at idle.
3. Get/borrow/steal (lol) a timing light. Although pretty useless on our cars, it's still the easiest way to check for spark. Hook up the light to each plug wire one at a time and see if the light flashes. Check it at idle and 2-3000 rpm. If you know any mechanics and they can hook the car up to a scope, even better.
I believe these 3 things are very important for you to do.
1. Hook a fuel pressure gauge to the car. I believe stock FP should be in the low to mid 50s. Someone correct me if I'm wrong.
2. Hook up a vaccum gauge to the car. You did experience a vaccum leak when you put the motor together. There may still be a slight leak somewhere that's going unnoticed. I won't venture to say how much vaccum you should be seeing, but I'm sure someone can shed some light. I figure at least 10 in/HG at idle.
3. Get/borrow/steal (lol) a timing light. Although pretty useless on our cars, it's still the easiest way to check for spark. Hook up the light to each plug wire one at a time and see if the light flashes. Check it at idle and 2-3000 rpm. If you know any mechanics and they can hook the car up to a scope, even better.
I believe these 3 things are very important for you to do.
