I have been having some problem's here. I took the car out the other night and got on it saw about 20lb's of boost, stop at a light and the car is smoking pop the hood and there is oil every were. dip stick is hanging out. just got done checking cylinder pressure I saw about 130 in each one so no holes in the piston. I put the car on auto tap to see what the plugs where doing well when I pulled them out they where lean so the tune I have in the car needs some work it is reading way lean about 880volts at full throttle so that's way lean and at idle that car misfires but as soon as I give it some gas it's fine. but thats not my problem I want to know why is it shooting out oil I put a breather on the car to see if that would help get rid of the crank pressure but it still does it.

 

This is a very very common issues on these cars...

 

were exactly is the oil commnig out? oil breather or the dipstick

 

I need to get a few idea's on how to fix it. it's blowing my mind on how the only is coming out

it looks like the dip stick because both times that it has happen the dip stick has been pushed out.

 

so your tuning with a narrowband?

 

This should help: https://www.cobaltss.net/forums/problems-service-maintenance-69/dip-stick-issues-42196/

 

I don't have Hp tuner's I had DOC put the tune in about 8 months ago I think, auto tap is all I have I just wanted to read the sencer to see what it was doiing

I just ordered up the new intake gasket for I'm going to try that and get the tune fixed and see what happens

 

.880 volts on a narrow band sensor is rich, not lean. and a narrow band sesnor is only accurate right close to 14.7:1 afr, wich is .450 volts. anything above .500 or bellow .400 and the sensor will shoot to one end of the scale, as its not accurate in those ranges.

basicly its telling you its richer than 14.7:1, but not how much. this is normal for any engine to be richer than that, optimal for power is 12.5-13.2, with boosted engines you always go richer to keep it safe. dont rely on the narrow band, engine damage can occur under boost if you are 13.5:1 or leaner, but the narrow band will still tell you its rich.

as for the problem, its the intake gasket. the more boost you have, the more likly you are to have this issue with the first design gasket.

 

thanks for the info guys, im going to try the gasket, but now I need to fix the tune it is misfiring like crazy at idle and is running really bad

thanks for the info guys, im going to try the gasket, but now I need to fix the tune it is misfiring like crazy at idle and is running really bad

 

not necessarily true on the intake gasket... I have an early 06 and never blew the dipstick out, also run 22.35 psi on a turbo flowing 53lb/min of air (a lot more than the s/c)

that sounds more like a popped piston man, sorry to say

 

I checked the compression and they all came back with the same. if I put a hole in the piston I wouldn't have got anything.

 

ya I work at a gm dealer and we are having an issue with the same type of car. it's an 07 cobalt and has a stock pulley. we replaced the dipstick, intake gasket with new design, intake manifold and valve cover. also did a compression test and all came back normal. but it still is blowing oil out the dip stick.

so if yall have any other ideas let me know.

 

Define "normal" - 130 is stupidly low, should be up around 180. Do a leakdown test.

 

Sounds like you checked the most likley parts.
Next check the pvc orfice in the cam cover to make sure it isnt plugged.

Other wise I would check that intake gasket again if your sure your piston rings are fine.
But I would also recommend the leak down test to be sure or a wet and dry compression test for comparison.

 

ya we have put a new cam cover and intake manifold. so I am going to rule out the pcv orfice. I will do the wet and dry test then a leak down test.

 

well I did a wet and dry compression test and found only a 15psi increase. so I am lost at this point

 

The compression test I bet you did was when the engine was cold (normal way)and you got a 15 psi difference between wet and dry.
When at operating temp things expand and that could then be considerably more.
That could be enough to pressurize the crankcase and blow the dipstick out at high revs.
at 6000 rpm thats a little leak that is multiplied really fast.
Well Im at a lose but putting my money on the piston rings at this point ,but that job is to much money to do on a maybe.

Another thing but just humor me,you put the new improved gasket on the intake
and your positive its on right ?

 

ya. I am actually not the one working on it. another tech is but I am trying to help him. the intake was put on correctly I hope. though it did look like the gasket was sitting to the right a little. you know how they have play in them left and right and up and down. I told him to reinstall the gasket and make sure it is over to the left. then go drive it. after that we will do the warm compression test..

thanks for the help. I will let you know what I find.

 

Yea 130 doesnt seem like a good compression #. Wayy wayy too low.

pull it before you damage the block and have to pay more to fix things.

 

This is right from the info sheet I have.
•If a cylinder has low compression, inject approximately 15 ml (1 tablespoon) of engine oil into the combustion chamber through the spark plug hole. Measure the compression again and record the reading.
•The minimum compression in any 1 cylinder should not be less than 70 percent of the highest cylinder. No cylinder should read less than 690 kPa (100 psi). For example, if the highest pressure in any 1 cylinder is 1 035 kPa (150 psi), the lowest allowable pressure for any other cylinder would be 725 kPa (105 psi). (1 035 x 70% = 725) (150 x 70% = 105).
• Normal -- Compression builds up quickly and evenly to the specified compression for each cylinder.

• Piston Rings Leaking -- Compression is low on the first stroke. Compression builds up with the following strokes, but does not reach normal. Compression improves considerably when you add oil.

• Valves Leaking -- Compression is low on the first stroke. Compression usually does not build up on the following strokes. Compression does not improve much when you add oil.

• If 2 adjacent cylinders have lower than normal compression, and injecting oil into the cylinders does not increase the compression, the cause may be a head gasket leaking between the cylinders.

 

ok here is what we found
dry wet
1. 195 210
2. 175 190
3. 175 190
4. 165 175

we are putting a brand new gasket on it. just to verify that it was just a parts failure on the new gasket we had previousley installed

 

soo just to let anybody know that was curious as to what the final verdict was. we are resleeving the engine and installing new piston rings. seem that the engine had perviously been worked on where a tech put rings in the 1 cylinder. so this is pretty much our last resort. but I am sure this will fix. it. I knida thought maybe an engine internal problem.

 

Let use know for sure thats what fixes it will you !!