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2011 Chevy 3.6L

D

David G

Well-known Member
My wife 2011 Chevy Malibu with 37K is having problems.

I was driving it the other day on the highway and noticed it shifted down going up every hill, it is lacking torque.

It threw a P172 and P175 code which means running too rich, but does not smell.

I hooked tool up to it today.

Coolant temp seems OK
Outside temp seems OK
Intake manifold temp seems OK
Baro sensor seems OK
MAP sensor seems OK
MAF runs 1 lb/min at idle and 4 lb/min on highway which seems OK.
TPS reads 24% at idle and is linear up to 90% when fully depressed.

The load % seems to be running real high, it seems to run at 40% load when in gear and 70% on highway, step down and it quickly goes to 100% load.

What else should I look for?
 
Does it coast in neutral. If there is a real load and something is binding, it will get hot rapidly. If coasting is OK I suspect it is in limp mode. (guess) Jim
 
What are your Bank 1 and 2 fuel trims? For a rich code to set, they should be really high negative. Two things I would suspect on that engine. First, with it running, unplug the purge valve electrically, then disconnect the hose from the tank side of the valve. If there is vacuum at the port, the valve is bad and is allowing the engine to pull fuel vapor from the tank when the computer is not expecting it. Pretty high failure rate on the 3.6. Second thing to check is if the oil is over full and/or smells of fuel. If so, the high pressure fuel pump has failed and is putting fuel in the crankcase, which the PCV system then pulls in and causes a rich condition. FYI, if you have to replace the high pressure pump, the steel fuel line from pump to rail is a single use part and must be replaced when removed.
 
Looking at the engine with the beauty cover off, front of intake, slightly to the right. It is a small valve with a two wire connector.
 
Hello Richard G,

It has been way too many years since I turned wrenches as an auto mechanic!. You have two issues: One the rich code. Two The TPS @ idle. Seems to me that @ 40% at idle, the TPS is lying. I would think maybe 10%?
I would think that at 40% throttle it would be more like highway position-speed then idle?. That is my guess,

Guido.
 
Our 2006 impala (3.5 liter) threw a P172 code a few months ago..it was shifting hard into every gear...like it had a B&M shift kit (remember those days?) in the transmission..so I put the scanner on..it said p172 running rich...I cleaned the map sensor..didn't help any...took battery cable off....no good either..ended up clearing the code and taking off the gas cap a few times...and now its been fine for a few months....knock on wood.....lol. I tend to over fill the gas tank when I fill up too...I always try and get a couple more bucks in the tank and that can cause problems also with the evaporator system....so I don't do that anymore either.

Keith
 
(quoted from post at 08:24:40 10/22/17) What are your Bank 1 and 2 fuel trims? For a rich code to set, they should be really high negative. Two things I would suspect on that engine. First, with it running, unplug the purge valve electrically, then disconnect the hose from the tank side of the valve. If there is vacuum at the port, the valve is bad and is allowing the engine to pull fuel vapor from the tank when the computer is not expecting it. Pretty high failure rate on the 3.6. Second thing to check is if the oil is over full and/or smells of fuel. If so, the high pressure fuel pump has failed and is putting fuel in the crankcase, which the PCV system then pulls in and causes a rich condition. FYI, if you have to replace the high pressure pump, the steel fuel line from pump to rail is a single use part and must be replaced when removed.
Click to expand...

I know others don't appreciate the info you posted they want a silver bullet.. You are spot on its NOT EZ I would like to add CHECK THE OIL I have seen them low in oil and it cause drivabilty issues..

Myself I would get rid of a chebby with a 3.6 they are garbage...
 
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