1999 GMC Suburban Service Engine

GRAY74

MEMBER
1999 GMC SUBURBAN
V8
4WD
AUTOMATIC
111,787 MILES

When light first came on code was pulled for MAF sensor. Replaced. Driven less than 10 miles, light comes on again. Code pulled showing bad MAF again. MAF replaced with OE brand from dealer. Driven less than 10 miles, light on again. Initially, when tested, no code can be pulled. Tested later code for MAF comes up along with cam position sensor. Rotor and cap replaced as well. Sensors replaced and a new pigtail added that connects to MAF sensor. Driven again less than 10 miles, light comes on. When codes are pulled again, none show up. Tested later, 2 down stream 02 sensor codes pulled as well as MAF sensor again! All replaced, light comes on at shop. Taken to local dealer who cant pull codes. CPU replaced. Driven 45 miles service engine light on again.

Fuel filter replaced and tune up completed 8 months ago. New transmission installed along with new catalytic converters. Additional tests were done along with the MAF repalcement to check the wiring and any potential vacuum issues. None were found. I am nearing the $2 grand mark on repairs and I still dont have a remedy. Local shop is frustrated and embarassed (didnt charge me labor the last two times it has been in) and the dealer cant seem to figure it out as well. Any suggestions or ideas short of pushing it off a cliff?

Sunday, August 9th, 2009 AT 12:53 AM

3 Replies

BRIAN 1

MECHANIC
1,030 POSTS

What was the code?

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Sunday, August 9th, 2009 AT 9:29 AM

GRAY74

MEMBER
4 POSTS

I just got back from Autozone and they pulled 3 codes: P0102, P0172, and P0175.

Do I now have an injector problem?

Thanks-Gordon

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Sunday, August 9th, 2009 AT 10:27 AM

BRIAN 1

MECHANIC
1,030 POSTS

For the p0102 check the MAF ignition positive voltage fuse, make sure its not blown, check"� Objects blocking the MAF sensor inlet screen.

"� Crankcase ventilation valve malfunction, missing, or incorrectly installed.

"� Vacuum leaks in the:

- Throttle body

- EGR valve flange and pipes

- MAP sensor seal

- EVAP canister purge valve seal

- Fuel meter body seal

for p0172 and p0175, indicates a rich condition. For this check the long term fuel trims, also check The air filter for being restricted.

"� The air intake duct for being collapsed or restricted

"� The MAF sensor for proper installation and any screen blockage.

"� IAC: If a low or unsteady idle is being experienced.

"� Check for throttle body coking or objects blocking the IAC passages.

"� Bank 2 HO2S1 electrical connector for contact with the exhaust system.

"� Check the fuel pressure regulator for proper operation or a slow diaphragm leak. Excessive fuel in the crankcase. Change oil if necessary. All the above will cause these dtcs to set, you have a rich condition, it could be an injector but before you put anymore parts in check this first.

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Sunday, August 9th, 2009 AT 12:17 PM