take the intake completely off and take a picture inside of the turbo at the inlet.

Many time we can see bent fins and scratch marks from the the wheel hitting the housing.

May have to add artificial light with a flash or flashlight.

 

Some more info that may help you. Shows the routing of some of those vac lines. Also a good photo of the lines on the turbo.

https://www.cobaltss.net/forums/08-1...a-asap-282107/


I remember there being a problem a while back where the wastegate actuator rod needed adjustment, symptoms included fluttering, intermittent boost, but also included was drop in boost pressure. dont think thats the problem.

 

Ill refrain from my thoughts on these pictures so I don't skew your opinions.

 

There does seem to be a minor scratch on the last few pictures. Near the edge of the blade on the housing. Not as bad as I have seen on other cars.

Hopefully get several opinions.

 

The pictures lost quality when going to photobucket but there is a nice healthy scratch around the inner housing. The little metal flakes that are everywhere when i run my finger around it as well as we're visible on the bypass valve make me think part of my problem lies here.

I can give it a decent wiggle up and down but not side to side.

 

From what I have read the turbo should not contact at all. Any hit against the housing would cause lots of noise. The rpm of that thing is so high.

I'm not going to say you need a new turbo, but you probably need a new turbo.

 

Haha I am stealing that for a sig line.

I already have a call to the dealer way up north (the good one) so I'm waiting on a call back.

 

Well I was hoping we could solve the issue without something major.

Sorry for not reading your back story. Was it tuned? Previously tuned? Sold to you with warranty?

This should be covered under powertrain but you need to fight.

 

I bought it used from a dealer with 24000mi on it. It had gms1 which I only found out after buying it.

Car is bone stock other than the charge pipe I put in to fix a leak.. I don't have a way to check if it was tuned but I do not think so.

It has power train warranty till 50,000 mi or 2015.

I wonder how much harm all the little shaved off metal bits have done to the engine...

 

powertrain is 5/100k. At least mine is

 

I'm probably wrong, but 2015 will get here before I put either of those figures on the odometer.

 

Maybe A Turbo ReplaEment Under Warranty Will Fix All That Hesitation And Maybe Magically Fix The High Ltft :/ Sorry For Your Luck. If It Only Wiggles In One Direction, ThatS Probably Not Good.

sTupid Worde Capitalizes every word

 

I have no idea why this would be contributing to high long term fuel trims but I'm glad I have at least found another problem that if un-noticed would have been bad.

I was planning to leave on a 300 mile trip to eastern washington today. I figured I'd check the engine out a little before just one last time and I am REALLY glad that I found this before trying to go over the North Cascades Mountain pass.

 

Dealer said they will cover under warranty with no hesitation. They were surprised when I told them the dealer closest to me would not.

Gettin a rental provided for me too. Now to see of they'll let me drive it so far...

 

If you plan to check out the engine, have a look under the valve cover and see if any rockers are knocked off. From what i've heard, you can have rockers busted and the car still runs like a champ. That could be the cause of the high LTFTs and slight hesitations as well. (Exhaust side rockers).

Heres an image of what im talking about







If a few rockers were busted off on the exhaust side, I feel that limits the flow of exhaust gases out of the engine, hence lower peak boost and the O_2 sensor has a more dilute exhaust reading. I may be talking out of my ass though cause exhaust gases have to go somewhere so they would probably all go through a single valve opening like an 8 valve DOHC. lol. If two exhaust rockers were busted per a single cylinder, then the engine probably wouldnt start.

Just thought Id give you other things to look at and put a half assed guess story to go with it. I know the cobalts still run with a few busted rockers but they sound like Subaru's. We call it the "Subaru of death" sound. Search that phrase and Im sure you'll find videos. Doesnt sound like you have that either though. Just something to look into if the previous owner ran E85 or had a tune over the GMS1 at one point and abused the car.

 

It honestly sounds more subaru than my 2007 ss but I'm not sure if that's just how they sound.

Ill ask the dealer if they plan on tearing the engine open due to possible foreign object and debris in the engine now. I want to try and get them to delve deeper I into it to see if there is something else while they're at it.

 

At a minimum have them pull the valve cover. Also do a compression test to make sure it's holding compression. Other than that I"m not sure they will do much.

 

And to add insult to injury, on the way up here I babied the car and tried to never go into boost, as luck would have it I get on the freeway and literally ten seconds later I get a huge rock into my window. Awesome.

Good thing I have comprehensive.

 

The mechanic just talked to me after a test drive and says he can't find anything wrong. He even tried telling me that seeing LTFts of 24 were normal for "those kind of performance engines cause you get on it" without check engine lights. Bullshit.

I then showed him the pictures, told him how i was able to give the shaft some play and hear it scrape the walls and told him about the metal flakes and he said he'd have to do a bit more work than that to see if he could "pass a new turbo off with chevy".

 

24 LTFT is not normal. Its not normal on a Bugatti Veyron, its not normal on a Corvette, its not normal period. lol.

24 LTFT means the ECU is adjust fueling by 24%!!!! Its adding 24% more fuel per injection than it originally controlled/calculated based on air flow from the MAF, MAPs, and mostly the exhaust gases racing past the O_2 sensor. It also says your lean, not enough fuel being added and thats its compensation. +24% LTFT would mean your O_2 sensor read an AFR of 18.23 at idle before correction!!!! Your AFR should be around 14.7 or stoich during idle or cruising conditions.

Any other cobalts on the lot? Hook the OBDII sensor up and see what they read at idle This whole forum is proof that high LTFTs are no good lol. We all know the car isnt suppose to have that high of an LTFT.

Other than that, he seems alright since he didnt immediately throw a no at you. Not surprising that he brought up the "No CELs" Thats the first thing they tackle to analyze a problem.

P.S. - Did they monitor the fuel trims? Do they have a device to do that? Or just a CEL code reader... I was curious if they saw those LTFTs too.

 

Anyone live near him with a mostly stock car so he can see what a LNF actually rides like? The whole test drive and everything seems fine is bullsh*t unless he knows a ton about LNFs at which point LTFT of 24 would seem very very wrong. Maybe ask him to pull the LTFT of a covette on the lot and see if they're anywhere near 24

 

I see what you were going for here. Thats pretty neat trick to finding vacuum leaks. Didnt even dawn on me :p Did you try the starter fluid method? See any idle changes?

 

I think thats a good idea too, but not for the same reason. Anybody live near you with a Cobalt SS turbo that you can hook your OBDII reader up too? Then theres your evidence that its not normal.

 

The only reason I suggested the covette is because the mechanic pulled the performance card

 

Nothing says performance like verge of throwing a CEL "bad performance"