Rough idle, missing, stalling

[06_vrscr]

I am working on an 87 gn and need help in a bad way. This has been an ongoing problem as I have been working on this car for my friend. I will try and cover everything I know so hang on. I started out with a diagnosis of a bad timing chain about a month ago, so that was checked and replaced, but the car still didnt have enough power (wouldnt spin the tires) so a lot of different things were checked and finally I found it to be a bad turbo. I have swapped a known good turbo off my dads car and that give it its pep back. Ok so all this time, even before I started working on the car it had a miss, the owner had just done a tune-up to try and get rid of the miss but it was still there. Now the car wont hardly run at all, when it is started it runs fine until it idles down then it starts missing and cutting out like it is going to die, and sometimes does. I have a known good running car to swap parts from if necessary. The car to me acts like the ignition is cutting out. I have an extra ignition module and coil pack and a caspers tester and both sets test good with it and both sets have been on the car with no change.

I have an otc scanner and have checked and reset the iac and tps. All other reading look to be normal and in range. Oxygen sensor was giving some crazy readings so that was replaced and readings were normal. it has a fuel pressure gauge mounted and fuel pressure stays steady during the missing and stalling. I have tried everything i know and am still lost for an answer. Any help is appreciated and if someone is willing to talk over the phone about this i will gladly pm you my number. Throw your suggestions out there as I will try anything at this point. thanks

[Keller]

- Is the behavior only at idle?
- Is the car stock or modified? If modified, give details.
- What are the MAF numbers at idle?
- Does disconnecting the MAF while running change anything? (it WILL set a code)

[06_vrscr]

Originally Posted by Keller

- Is the behavior only at idle?
- Is the car stock or modified? If modified, give details.
- What are the MAF numbers at idle?
- Does disconnecting the MAF while running change anything? (it WILL set a code)

It started out just doing this going down the road when it would shift into second at a moderate throttle

Maf - 6-7 at idle

Disconnecting maf doesnt change anything

Only code it has thrown while doing this was a MAP sensor code



car has stock turbo, 42.5 # injectors, reds chip to match injectors, bigger intercooler,

[Keller]

Originally Posted by 06_vrscr

Only code it has thrown while doing this was a MAP sensor code

The MAP is not ECM connected. It is only used for the dash boost gauge. There is no code related to it.

http://www.gnttype.org/maint/malf.html

[06_vrscr]

I must have looked at it wrong then. I'll have to see if I can get it to set it again but I am almost thinking it was 24 or 34. So i'll run the car some more and see what i get.


Ok I looked at it this morning and it is a 34 MAF code. the thing is that I have had one off of a good running car on there it it didnt change the car at all, but this was before it was throwing the code. i'll have to change it again this evening when i get home

[turbojd]

Disconnect the orange wire by the battery when you swap out the maf sensor.

[06_vrscr]

i have been disconnecting it when i make any changes

[kenmosher]

I wonder if you don't have a bad injector ...

Also, things to check ... cam sensor setting and if you have an O scope, crank/cam signals at the module (could be a bad crank sensor).

[06_vrscr]

ok i changed the maf and no more codes but it still runs rough, the otc scanner says its running rich and it sure seems that way so i am thinking it is a bad or stuck injector

cam sensor setting is good, checked with the tool
changed the crank sensor last night and no change and it had a new one on it

[06_vrscr]

if an injector was stuck open the rail wouldnt hold pressure would it ?