2007 H3, 5.7, a.t., 145.000 mi. Engine light keeps coming on as well as traction control warning. It cuts out at 41mph-46mph/kind of a flutter, and only at that speed. New parts: oil pressure sensor, both O2 sensors, plugs, mass air flow sensor, gas cap. Heat for water in fuel, Lucas engine treatment.
Codes:
lean(bank 1)
maf sensor (even tho its new),
purge valve canister (newest code)

This all started 2mo ago. Here's the kicker! Over 65* outside temp, if you clear the codes, there are no lights and the car runs just fine. When the weather gets cold, the symptoms come back immediately.
Any advise? My mechanic is baffled.

 

Welcome to Hf.

We would need the actual code stored to help, not someone's interpretation of a code they found.

Have your "mechanic" check and tighten the intake manifold bolts, put a scanner on it and watch what it does as it reaches full operating temperature.

A Traction Control warning can be cause by lots of stuff. One simple guess is a bad wheel sensor, connection to it, or wiring to the sensors. Could also have to do with a bad Transfer Case encoder. Too many possibilities to guess.

 

I will have the codes ran again and i will post them. Thank you. I will have my mech do what you suggested. I apprecise the help!.


QUOTE=Doc Olds;350771]Welcome to Hf.

We would need the actual code stored to help, not someone's interpretation of a code they found.

Have your "mechanic" check and tighten the intake manifold bolts, put a scanner on it and watch what it does as it reaches full operating temperature.

A Traction Control warning can be cause by lots of stuff. One simple guess is a bad wheel sensor, connection to it, or wiring to the sensors. Could also have to do with a bad Transfer Case encoder. Too many possibilities to guess.[/QUOTE]

 

Sounds like a bad vacuum leak. All of the codes indicate that. Have your mechanic test the purge solenoid first because there is a code for that. Next go with what the Doc suggested. Look for broken vacuum hoses while checking the intake bolts. Have the snorkel and air box between the MAF sensor and throttle body inspected for cracks and holes. Make sure the PCV hose at the back of the valve cover to the air box is connected and in good shape. A good mechanic should be able to find a big vacuum leak quickly. The traction light is probably on due to the MAF code because there is no ABS light on. Get those engine codes off first before tackling the traction light.

 

Thank you so much. We did end up finding the problem. The gasket on exhaust manf is leaking. Unfortunately my mechanic is laid up with back trouble, so I will have to wait to get it fixed, but it's nice to finally know where the problem is. I really appreciate your help!

So, is it only me, or does every Hummer owner get the UGH... whenever you want to talk to a mechanic or parts store when they find out it's a Hummer? The vehicle is hated by most of them. It's really frustrating.

 

You have listed a 2007 H3 5.7L. I assume there is a mistake and you mean 3.7L.
The exhaust manifold gasket is leaking. Highly possible. As well as a cracked manifold. It's a good place to start, however, based on the information given I don't believe this will solve your problem. Are you sure he didn't mean intake manifold? An exhaust manifold leak can cause oxygen sensor problems, like your lean code. The exhaust manifold leak will also cause some noises that are more prevalent on cold starts. Be prepared to look further once the exhaust manifold leak is fixed. I do hope it is just the exhaust manifold leak. I am also curious if it solves your issue for later. My exhaust manifold gasket leaks a little on cold starts.

 

Exhaust manifold is prone to cracking - here is what happened to mine