It's been a while since I've been on, but i recent graduated tech school and started working a vw/audi independent shop. While the experienced tech's have already helped me immensely, I don't feel like taking anymore of there time up if i can help it. I bother them enough during work for me to ask them to stay after and help me fix my car (though they have been anyways).
When i say cold in this i mean under the blue lines.
A little history of the problem:
Almost a year ago now the oil light came on one day (it had oil and pressure). The next morning cylinder 4 is missing but under these conditions...
*only if the car is cold and i rev it.
*The harder the initial rev is it the more it misses and continues to miss. After missing for a minute it gradually evens out and runs great (even if its still cold).
*If i let it idle till it warms up, it runs with no misses at all.
*if the initial rev is over 4grand it dies and wont start for a while.
*once it stops missing it wont act up at all, till the next cold start.
Recently i tried to adapt the throttle thinking that it might fix it. Wouldn't communicate. Try another throttle body, still no communication. Tried an ecu, communication restored. check my grounds, turns out my ground cable connection from the block to frame is bad, dropping 3v. Now i'm assuming that the car grounded its self, first through the oil pressure sensor, then must have found its way to the ECU and fried it.
However!! While the car does seem to be running better (idle is so much smoother) with the new ECU, it did not fix my "cyl 4 miss fire while cold problem" at all:thumbdown
So i switch coils, nothing. I switch plugs, nothing, I switch injectors, nothing.
I'm going to test the ignition circuit and injector circuit next.
any idea are appreciated. but i though i'd at least share the story.
When i say cold in this i mean under the blue lines.
A little history of the problem:
Almost a year ago now the oil light came on one day (it had oil and pressure). The next morning cylinder 4 is missing but under these conditions...
*only if the car is cold and i rev it.
*The harder the initial rev is it the more it misses and continues to miss. After missing for a minute it gradually evens out and runs great (even if its still cold).
*If i let it idle till it warms up, it runs with no misses at all.
*if the initial rev is over 4grand it dies and wont start for a while.
*once it stops missing it wont act up at all, till the next cold start.
Recently i tried to adapt the throttle thinking that it might fix it. Wouldn't communicate. Try another throttle body, still no communication. Tried an ecu, communication restored. check my grounds, turns out my ground cable connection from the block to frame is bad, dropping 3v. Now i'm assuming that the car grounded its self, first through the oil pressure sensor, then must have found its way to the ECU and fried it.
However!! While the car does seem to be running better (idle is so much smoother) with the new ECU, it did not fix my "cyl 4 miss fire while cold problem" at all:thumbdown
So i switch coils, nothing. I switch plugs, nothing, I switch injectors, nothing.
I'm going to test the ignition circuit and injector circuit next.
any idea are appreciated. but i though i'd at least share the story.
