Car has been in and out of a shop and things still dont seem to change! I first the problem was noticeable with the car running rough in all gears. Then a clean of a ground and the problem seemed to have gone away until i hit the highway and was getting 17.5 mpg going 70mph for 40 minutes and this id feel the car bog in and out slightly. Got home and hooked up the HP tuner and got this reading which ill attach.
Im trying to get some info from people on here who might be able to read this log. No im not tuned but im not sure if thats all im needing because i dont want to mask a problem if there is one.
stock intake
ttr ic
injen hot side piping
cat less to a turbo xs exhaust
Dont know where else to put this but if its not allowed here let me know
Thanks guys!

 

Looks like boost or major vacuum leak dude

 

Woah that was quick! thanks for the input man.
But thats what i was thinking but they said they didnt "think" it was the issue, not sure if they tested that. Doubt they did.

 

Check for a major boost leak and then check the wiring to your wideband, the lamdba is all over the map under semi steady conditions. Your wideband doesnt seem to be responding like it should, look at the frames 2:38.7 to 3:04.1, the wideband is at 1.99 like DFCO yet you have throttle input and a commanded ratio of 1.00.

Also you're getting some serious KR in lower rpm mid range load, and it looks like real KR but I don't have your tune to see if it actually is.

Then check for codes via hptuners if you take it for a drive again, although I don't honestly recommend driving it the way that log looks until you get things fixed.

 

Can someone explain how to know if it's false or real knock? I know the LNF loves to show knock.

 

I just took at the log and wow.

Your fuel trims are tarded. Boost leak is a major possibility

 

You look at the tune file and compare for the load and rpm range, if it's hitting the timing the tune calls for then it's KR for other reasons. If it's lower the amount the KR is then it's real knock. The OP is hitting 10* in some areas which is indicating some potential serious issue, but with fuel trims in the +25% and not having the tune file it's hard to say.

 

Thanks guys. Ill post the tune after work.
But it should be stock because its a new ECM. It was after they installed it that things got like this.

 

Who installed the new ECM?
Is your car on the stock tune or GM Stage 1?

 

The mechanic did but a chevy dealership installed the tune and programmed it i guess.
And i was told it was stock.

 

All that stuff, and if it all checks out, check ur valves . may need cleaning

 

heres with file i got after getting the new ecm

 

Looks like a pretty stock file. You need to do a boost leak test and check the wiring for the primary o2 sensor. If the wiring is good I'd replace the primary o2 sensor

 

back with something interesting.
I went to a different mechanic. They found that there was a loose wire that wasnt making contact with was messing with the fuel pump regulator.
connected the scanner after driving around fine for like an hour. and i saw i had some knock retard and the timing is off 0.o followed but the STFT shooting straight up and down then up again later. (theory: wire got loose again but the mechanic will have to get in it again.)
Anyway, will get back with more info.
PS i hate my cobalt right now..

 

Your car LTFT is the in the +20-40% still.

That's unacceptable and dangerous. Do not floor it until this is fixed.


At the 18:21:18 minute mark, your car goes from reading 1.00 lamda, which is correct, to reading 2.00 lamda, It never leaves 2.00 lamda for the rest of the log. Up until that point, your STFT and LTFT were acceptable. Also I noticed your Primary 02 Sensor reads 0 mA up until that exact point as well. Then it reads 2 mA for the rest of the trip.

Check all the wiring on your primary 02 sensor and replace the 02 sensor. The 02 sensor plug rests on the the right side of the head and likes to rub through. Ask me how I know.

That's at least where I would start.

Your fuel pressure goes all the way up to 15 Mpa at one point in the log so your car had good fuel pressure. It could be possible that it isn't getting good pressure due to wiring or something. Especially the wiring to the high pressure fuel pump. But that usually sets a code.