I know you hate to hear these horrible things but my car drove excellent both times the only indication I had was loss of boost and minor black soot on the exhaust tip. Save yourself the guessing game and just do the simple leakdown check and get it over with. I simpithize however you are wasting time continuing to drive it is just causing more damage it takes about 20 mins and a compression guage. Just pull the fuel pump relay, pull the number one spark plug, insert the compression gauge, have a buddy crank it over 10-15 times. It should read from 180 to about 220ish this is the normal range. let it sit for 2 minutes. Look at the gauge again if it is within 30psi then your safe if it is more then thirty psi engine is TOASTEY!!!!!!!! do it on 2,3 and four could be a piston ring, could be a valve seat os seal depending on how bad you beat on your car?

 

-Don't have a compression gauge, never done a compression test either.
It's just more money i don't necessary have to spend. I'll look at cost here in a second...

and I'm not hard on the car. Never been to the track, never raced another car, I WOT onto the on ramp when given the chance, but the car has never seen above 100mph. When driving around town, shifts are between 2.5-5k depending on my mood.

I've never roasted the tires either. Generally, I'm pretty nice to the car. I got a bit throttle happy when I installed everything and it was running smoothly and planned to take it to the track the first time this year, but I'm obviously holding off on that.

Seems gauges are around $30 or so. I may just do this test yet.

 

see if you can rent a compression tester from autozone. shouldnt cost you anything...

and no, tunes cannot "go bad". if theres a difference in boost or afr, it's because something in the car itself changed. clogged air filter, exhaust problems, screwed up maf, Vac leak, compression leak , etc

 

Like others said, do a compression test. The gauges can be rented or bought very cheap. It's the simplest thing to check IMO.

 

that's what i'm making plans to do when i get off of work here. go buy an extension and compression tester and see where i stand.

i swear to god if i blew something because of this rich ass tune....

 

You don't need an extension it only has to be hand tight. The threads are fine and tapered hand tight is enoughf trust me. I no you don't want to say on the forum but you have to go wide open to tell there is an issue with boost, right? It only takes one good pull to hurt the hyputectic pistons or the shity ass rings! By the way there was a recall on the 2006
G85 ss/sc's the ring galley in the pistons where a thousandth to big causing this issue. I don't know your year? Hopefully an 06?

 

I need the extension to take out the spark plugs, that's what I was referring too is all. Making mental note by typing it out.

and I said I go WOT when getting on the highway, and I do whenever I merge. That's when I noticed my boost going down from time to time. I have no problem admitting how fast I drive and where I do it at. To make sure I wasn't crazy when I noticed 15lbs instead of 17, i did a few 1st gear WOT pulls coming out of my apartment complex to make sure I had accurate information.

I also don't have a G85, just the regular SS/SC.

 

first gear? thats way too short to tell anything. and usually we spin through 1st anyways. not long enough to build full boost.

 

well, the highway on ramp pulls were 2nd-3rd gear, stopping around 80-90mph.

no, first gear doesn't last long, but i'm also not about to tear ass down my street. i'd say i've done around 5-6 highway pulls to get my numbers, and 2-3 street pulls.

 

But the elements of the atmosphere can cause a tune to fall out of what it was programmed to run. Tune in witner for an 11.8, come summer it'll be 10's from the change in the environment.

Keep this in mind. The tune will not change on the car, but the way it performs, can

People, stop trying to diagnose this **** over the net. There are too many variables. This is why we are meeting and correcting the issues unless it is found to be mechanical.

Which I bet it's just needing adjusted

 

^that's why i trust this guy to touch my car

however, someone local has a compression tester, so i may do that too just for ***** and giggles tomorrow.

 

^^ Wont hurt.

 

That's what I figured. it wont cost me anything but time, so meh.

 

THANK YOU
QFTMFT
i was just about to say that.
i did my WINTER tune last december with vince and got 11 lbs of boost, and wot was 11.5ish.
now that its summer, and freaking hot in texas its more like....10.5
i need a retune.
my car is fine otherwise.

 

well, i installed everything about a month ago. it's not like this stuff has been on the car for a year

 

hmmm, well still in just that month.
its gone from mostly 70-80s to really close to 100.
thats enough to throw stuff off.
but still you may have some problem with some leak.
either way, good luck with it
i'm sure you'll get it.
report back and let us know whatsup

 

so why is this not needed when u drive a new car off the lot? is the dealer tune wheater sensing or what.......i would think that with the iat maf and scip..and baro sensor this would all adjust itself and with a command air fuel ratio at wot lets say 11.8 wouldnt the pcm automatically adjust accordingly from sniffing the 02 and getting inputs from the other sensors listed above? i mean i know when its colder outside u can get more power cuz of the air density put actual a/f/r shouldnt change should it?

 

It does get effected. Stock tunes are conservative, not self adjusting. Well to a point it self adjusts, to learn the fuel trims.... Most aftermarket are not conervative.

 

The MFG probably takes into account that most drivers don't run WOT alot or install after market parts. Computer keeps a nice 14.7 under normal driving conditions by "sniffing" the O2 along with MAF and MAP sensors to adjust the fuel trims as needed to maintain the 14.7 AFR.

I'm sure they test and place a safe WOT calibration for the occasional times the owner needs to just apply a little force on the accelerator. Probably runs rich in the warmer climates and lean in the colder climates.

When you enter WOT the fuel trims hit zero and it's entirely dependent on the MAF and MAP. There are different tables that will increase and decrease the timing and commanded AFR most of these tables are temp related.

 

when its hot the air molecules spread apart and are not as dense as when it is cold.
that being said...when you mix the hot air with the same tune that is injecting the same fuel you did than when it was colder it'll run richer because there isn't as much air packed into the same volume it did when it was....say 50-60 degrees. when i got my tune from vince it was around 60 avg. now its really close to 100. thats a huge difference.
also tuners do not generally mess with the trims when cruising or not using boost, those all stay the same thats why stock cars don't need fuel adjustments because those tables are never changed. the only thing tuners adjust is the fuel trims when at wot.
i have an ls, and when i cruised i was around 14-15. i still am right around there now even though im supercharged. that is not something vince messed with. the only part that was changed is wot, instead of being around 13 (if i remember right)or so when i used to floor it before i was charged its now at 10.5....which is still off. should have around 11.5ish

x2
exactly what vince explained to me. completely based on boost and temp

 

On most MAF cars, temperature is not an issue because there is an air temp sensor that accounts for the air denesity. Between the MAF and IAT sensor, it can accurately demand the proper amount of fuel.

 

its not the temperature as much as it is the density of the air

 

The computer can calculate the density of the air by baro and temp. The problem with his tune is that the maf curve is off to the high side. This is due to every rebel intake having the maf sensor in a different spot.

 

oh well, guess I better expierment with these tables to see why my AFR's lean out during the winter......

 

Cobalt's don't seem to compensate for air's density. Fail Cobalts.