Carlo_Carrera

It really sounds like a solenoid or sensor has gone bad. When you were doing the plugs did you by chance look at the cam solenoids brackets? There is one on each side just above the center plug. They have been known to crack and when they do it can cause the whole side to misfire.

judd944

I was reading about the cam solenoid bracket like crazy last night on here and 6-speed. it sounds "common" and the error was misfires on one bank.

I am kicking myself for not looking at it better when I had it apart. I am going to check vacuum tonight if I get a chance to see how it responds when I hit the throttle.

judd944

I do have kevin's datalogger program on my laptop so I can record data as I drive

Danyol

Sorry for your miss-fortune, Kevin's logger should show up something. BTW, I know it's not related, but did you notice whether your plugs were loose?

judd944

The plugs were all tight. no issues there. I bought a vacuum gauge tonight and checked the vacuum. I was getting 20" at idle and when I had my father blip the throttle it would drop to zero then jump right back up to 20" That all seems normal or even a little high. (I was told the spec was 15-18") I am also using a 14.99 Harbor Freight vacuum gauge so it could be slightly out of spec

Carlo_Carrera

Don't feel bad. Nobody mentioned it and you didn't know.

judd944

This saturday I plan on removing the intercoolers again and looking at the bracket for the cam solenoid. if it is cracked I am going to replace it. if it is not I am going to swap the solenoid side to side. if the misfires follow the solenoid I know what to replace.

judd944

have a few more data points. When running Kevin's Datalogger on the interstate today I captured the car getting misfires. It appears my bank 2 is the one running lean while bank 1 is the one getting normal numbers and yet bank 1 is the one side logging misfires !
Any thoughts on where to go from here?

The divergence from one bank to another does not happen at high RPM when I was doing some 3-4 gear pulls and recording it. When it is over 3k RPM both banks stick together with lambda values of .81-.85

neanicu

Can you read any info about your Short and Long fuel trims?
At higher RPM like WOT the O2s go in Open Loop so the computer doesn't adjust the mixture according to info received from the O2 sensor.

Kevinmacd

Since you are running lean have you checked fuel pressure?

judd944

I have not checked fuel pressure but the misfire goes away at high RPM and the Lambda values look good there.

here is a 3rd gear low RPM to high RPM 4th gear run

judd944

I do not have access to long term fuel trims. only short term.

The lambda values are what give the air/ fuel ratio

here is a good explanation
http://www.austincc.edu/wkibbe/lambda.htm

neanicu

You need to understand the operation of the lambda sensors. This is from your link :

" Although misfires may combine with normal feedback (closed-loop) operation to produce a counterintuitive rich condition, lambda analysis remains a powerful diagnostic tool. Routine use of lambda can quickly narrow your diagnostic focus for many driveability complaints, ruling mixture problems in or out in a very few minutes. Lambda analysis can pinpoint oxygen sensor faults such as biased sensors more quickly than other techniques. Lambda analysis coupled with fuel trim analysis can often quickly identify contaminated or faulty MAF sensors. And lambda analysis in conjunction with conventional exhaust gas readings can conclusively pinpoint faulty catalytic converters in a matter of seconds. "


Your car doesn't misfire soon after start up and at WOT because the lambda sensors are in Open Loop at that time. As I've stated before,lambda values are useless in those conditions(Open Loop).
What's your Short Fuel trim? It should be close to 0%. It can be + a certain value or - a certain value. A CEL will be triggered approximately at +15 or -15. Anything below or above is considered within range. You need to determine these values to realize if your car is running LEAN or RICH so we can continue with the diagnostic and pinpoint the problem.
Use an OBD2 scanner with Live Data and post your Short and Long fuel trims. This is very important because your Long Fuel trim is controlling your Short Fuel trim and will continue to try to adjust it and bring it as close to 0% as possible.
How long has it been since you've reset your CEL? You need to drive the car to get those readings.

judd944

Ahhh, that is why is is showing the same readings at idle and at WOT .
I need to get another OBD2 scanner. My generic one does not read live data and my datalogger from Kevin is what I generated the graphs above with.
I reset the CEL yesterday, about 20 miles earlier than the car is at now.
Thank you neanicu !

judd944

doublepost