2007 Impala P1174

[crzydrvr]

I have a 2007 impala w/a 3.5 v6. Iam getting a code P1174 (fuel trim cylinder balance B1). No real guidance or explanation from solus pro. Troubleshooter only says that it is a manufacturer specific code. Anybody have any ideas? Also wanted to mention that scan tool also tells me that the TPS is always open to 29%. I do not think that this would be the problem. If something were wrong with air fuel intake/mixture ratio, wouldn't it effect both banks??


thank you

[Joe Rappa]

Please check your fuel trims for both banks at hot idle, and 1500 RPMs, then post them here. Just because there is only a code on one bank doesn't mean the problem is not on both banks.
The fuel trim data will help us help you.
Joe

[edrenth1]

hope this helps

Read and record the Freeze Frame/Failure Records data taking note of the speed and load at which the DTC set.
Diagnose any other DTCs that are set. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
With the engine idling and the transmission in the Park or Neutral position, observe the manifold absolute pressure (MAP) sensor parameter. The MAP sensor parameter should be between 19-42 kPa.
⇒ If the MAP sensor parameter is not between 19-42 kPa, refer to DTC P0106 or DTC P0107 or P0108 .

Inspect the air induction system for modified, damaged, leaking, or restricted components.
Inspect the crankcase ventilation system for improper operation.
Inspect the vacuum hoses for splits, kinks, and improper connections.
Inspect for vacuum leaks at the intake manifold, the throttle body, and the injector O-rings.
Test for a restricted, damaged, leaking, or modified exhaust system from the catalytic converter forward. Refer to Symptoms - Engine Exhaust .
Test the fuel injectors for improper operation. Refer to Fuel Injector Diagnosis .
Test for fuel contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
Test for excessive fuel in the crankcase due to leaking injectors.
Test the ignition system for improper operation. Refer to Electronic Ignition (EI) System Diagnosis .
Test the engine for any mechanical conditions such as sticking valves, lifters, etc., which could alter the flow into the combustion chamber. Refer to Symptoms - Engine Mechanical .

[dttech]

crzydrvr wrote: "Also wanted to mention that scan tool also tells me that the TPS is always open to 29%. I do not think that this would be the problem. "

Why wouldn't it be? If the computer is seeing 29% TPS with a closed throttle. don't you think that would effect your air-fuel ratio?

I personally would fix the obvious FIRST, then check all of the things that edrenth1 listed above.

[Crusty]

crzydrvr wrote: "Also wanted to mention that scan tool also tells me that the TPS is always open to 29%. I do not think that this would be the problem. "

Why wouldn't it be? If the computer is seeing 29% TPS with a closed throttle. don't you think that would effect your air-fuel ratio?

I personally would fix the obvious FIRST, then check all of the things that edrenth1 listed above.

I don't think you will ever see a "drive-by-wire" system show "0" percent. The feedback potentiometer tells the PCM that the throttle is part way open and the PCM has control of the motor/throttle plate. In the summer, with warm ambients, the % may be lower than in cold weather where the % may be higher.
If it doesn't move at all when you manually push the pedal, then yes, it would be an obvious thing to check but the original post isn't clear if it is frozen there or if it moves when he pushes the pedal.
Anyone have any input on drive-by-wire and related pids??

[Joe Rappa]

Anyone have any input on drive-by-wire and related pids??

I've got a scanner movie of that exact car. The TPS% never goes under 10%.
It tried posting a screenshot, buit I've got a terribly slow connection in my hotel tonight. It just wouldn't upload.

Joe

[Crusty]

Any of the drive-by-wire systems I've seen also never go under 10%.
Just as in the older systems waaaay back to 82-83, the old "minimum air rate" would always be something less than the lowest rpm the ECM would command. That way the ECM would always have full control of the idle speed.
I just havn't had a chance to "cold start" a vehicle at temperatures like 5-degrees-F. I'm sure it will be higher than a warm engine or am I not understanding the Pedal position sensor and the idle speed control motor and the feedback potentiometer that tells the PCM that it is at the desired throttle opening?

[gmtech08]

check the throttle body

check the throttle body and i had a simlar problem with a colbolt while at the dealer. i called gm tac and was told to replace the throttle body and the reflash the computer. the problem went away and the car never returned. after repair. could be something you might want to look in to.

[crzydrvr]

From what I was able to see and eventually figure iut is that the MAF sensor frequency was out of range. Waiting for the ok on the repair at this time.