Going back on this thread, there needs to be a different approach on this issue. I'm going on what has been stated so far on the steps taken so if you have done other things you can update me.
So far since the first post I have
Changed the upstream o2, cat, Cpas, used the bg44k, cleaned out the resonator, and changed the battery(if it even matters)
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Originally you had real bad MPG's, in the single digits and now you are somewhere between 10 and 12 city correct? Now this is stop and go NYC traffic so 12 isn't that bad, however based on the posts, you haven't performed all the suggested steps in your diagnosis so it's a little hard to try to figure this out without all the data.
Well those mpg seem to be gone I have for two days been at 9 - 9.3 mpg today it was at 9mpg exactly after driving like a grandma doing 25 or under and coasting to stop signs I got to 9mpg and its 40° out here so not really cold, I then reset it and after driving around the same few blocks stop sign to stop sign where it stood at 8.9mpg it went to a little over 9 after yielding through the signs I got to almost 11mpg
also if I had a more consistent 12mpg i would be ok and I can understand with the winter blend too. But it seems to be lower most of the time
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Compression test was done dry only and not dry then wet, but the compression when dry builded slowly. Slow build could be the gauge not fully seating or worn rings, this is why the follow up wet test is critical, you cannot omit this step.
I know I should of did the test correctly and I'll see if I can maybe do it again but wouldn't worn rings cause performance problems? Or lots of smoke out the pcv?
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You haven't reported a vacuum test reading, this is also key. You can pull the forward facing locking hose on the TB and use that port, or if the capped port facing the pass side in the front of the intake draws vacuum, that's a good one also.
(I will see if I can do this as well it sucks they don't rent this tool)
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Backpressure test, granted you changed your cat a backpressure test before the cat was changed and after, would tell if you have a restriction further down the exhaust. These resonators can clog up with their own internal media and cause a restriction. It doesn't take much restriction to really bog down the engine, I'm talking 3 PSI is alot on this motor and the OE is roughly 0-.5, when you get above 3 PSI on your setup then things start to get interesting.
Once again I'll see if I can do this
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You could easily have a shop with a Tech 2 let you know if all the components like the fan clutch, CPAS, fuel injector duty cycle, fuel trims are within a normal range but I know this is $$$.
I think there was a video I saw, I think it was from may03lt that showed all the normal sensor reading from a tech2 I can compare mines to his
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Which leads me to another area which is the fan clutch. When I replaced my fan clutch it made a noticeable difference. If your's is acting up, like engaging when cold and on cold startups, loud jet engine sound or just not releasing which can be carefully checked by trying to stop the fan with a rag on the smooth edge. Granted only do this when the A/C is off and the coolant is below normal.
The fan clutch was changed before I got the vehicle, the fan has only kicked on once while on a cold start it never has sticked on while driving and when it was on from the cold start it disengaged when revving it. I never hear the fan on, only when revving the engine with the hood open I can see it spinning faster than at idle but my brothers 05 does the same. The fan never is stopped is it?
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Also the fact your coolant temp is struggling to get to 185 is a concern. I would take it out on the highway at crusing speed for about 10 min after it warms and see if it ever gets to 195, looks like at one point it almost made 190 so there's hope but in traffic 175 to 185 is not good.
I think i posted that it does get to 210 but only with more continuous driving such as high way or even stop and go but on certain stopping and driving it goes lower but only on colder days it seems to do it, I'll make another log
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Let us know, but we need all the data.
Also I'll post a list of what I can log and you tell me what to.
gmcman said:
Forgot....a fuel pressure test is also good and I think some members have had weird trim numbers from a bad fuel pressure regulator.
The 05's don't have a fuel pressure regulator I have a returnless fuel system
first mpg seems to be up a bit also it drives better shifts are smoother and it pulls better, and stronger also for anyone else reading this DONT BUY DORMAN not only did it break in a few months, it was also lighter, smaller than the real GM part.
