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I have a 06 cobalt ss 2.0 s/c that I am tuning. The tune is spot on 11.8 a/f with 16 psi and then the boost falls to 13 psi around 5600 - 5800 rpm. This happened once before with an 05... same thing. I have the tq management maxed along with the boost tables at 100 %. I have tuned 20 plus other 06 cars with no issues.
Has anyone ever had this happen to them? I looked in the forum and found one related post with no cure, or aleast they never posted it.
Thanks in advance
Have you talked to Ryan at P&P to see if he has had this issue before?
Stock pulley?
Does boost fall off in every gear or just 1 specific gear?
Yea, I asked Ryan on the other car last year... He said to try taking the dynamic air table to 300 and 400. It worked on the DYNO but not on the street. I tried it this time with no changes at all.
Bill, it is a 2.8 and it does it in every gear. It is not as noticeable in first because it pulls so fast on the DYNO. I would try it on the street, but they are covered in snow.
Don't mind my ignorance but is the 2.8 the stock pulley? Sorry I don't own an LSJ(have never tuned one either)
No the 2.8 is not the stock pulley. Stock is 3.35" I beleive.
Post your tune so we can see if theres something you missed.
Sounds like something in the tune. It could be a leak or bad boost bypass, but I would double check the tune first.
Does the pcm even control the boost bypass on these?
belt slip?
No belt slip. It is something I am missing... it did it with the stock tune as well. The boost is perfect and every time at 5600 it drops and holds at 13psi.
The max boost by gear table starts at 200 % and then changes to 100 %, if you try to change anything it drops the numbers to a max of 100 %. I know I have done 07 cars and I can go 200 % on the entire table and run over 18 psi with no issues. I think it is maxing out the desired torque table or is some how related to the max boost table.
http://www.hptuners.com/forum/showpo...51&postcount=5Quote:
Originally Posted by PBJ
I've posted this many times... but it apparently gets over looked quite often.
http://www.hptuners.com/forum/showth...834#post198834
omega 5,
yea, i moved those tables all over with no real results... they are maxed out on my final tune.
Bill,
i had read that also, i was just thinking out loud.
I just spoke to ryan @ pep and he thinks it could be in the valve assembly or solenoid itself... definately something to check. I have had tial pieces do weird things with big blowers and big boost as well.
Thanks again...
I'm almost betting its the Boost Bypass Actuator..... I have seen it a few times, but its been a while.... Let me know Joe!Quote:
Originally Posted by PBJ
Log your bypass solenoid duty cycle... that will tell you if it is a tune issue, or a mechanical issue.Quote:
Originally Posted by PBJ
Any time I've dealt with a busted solenoid or actuator, it generally fails 100% on or off... as in never related to RPM.
anyone ever solve this?