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Prev Professional Automotive Repair Technical Discussions for November 5, 2007
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Open Help Requests for GM
Help Request Answers
1995 Buick Park Avenue 3.8L No Start VIN: 1G4CW52K8S
This vehicle is not sending the reference pulse through terminal D of the ICM. The ICM is receiving a 3X pulse from the CKP sensor. While all testing points to ICM, we have replaced it twice with no change in symptoms. According to ALDATA, the ICM can "decide"...
1989 Cadillac Eldorado 4.5L Excessive Emissions, Poor Fuel Economy VIN: 1G6EL1152K
This car came in with a complaint of black smoke and excessive fuel consumption. No codes stored in ecm. Checked and replaced o2 sensor, it now stays at .99v after running 2 minutes. The integrator drops to 97 from 128 when it goes into closed loop. Fuel press...
1982 Chevrolet Corvette 5.7L Poor Idle Quality, Hesitation VIN: 1G1AY878XC
Hello, You may need to ask some old timers about this one.My main concern here is the hesitation.At one point it was horrible and would barely make it around the block with backfireing through the throttle bodies and stalling.fuel pressure was low ( about 8-9 ...
1986 Chevrolet S10 2.5L Stall VIN: 1GCDT14R2G
this truck will stall intermittently when comming to a stop or making a turn. basically when the clutch is depressed or the trans is put into neutral. this stalling occures after 10 to 15 min. of drive time. it doesnt matter if the vehicle is cold or hot. the ...
1995 Chevrolet K2500 Cheyenne 6.5L Surge, Cuts out VIN: 1GCGK24SXS
Truck has been to dealer several times. It has a surge type symptom under light accel from 45 mph. You can duplicate it every time. Accel to 45, back out of it, the lightly accel. It feels like a gas vehicle with a bad plug wire-it jerks like an ignition miss ...
1997 Chevrolet Cavalier 2.2L Misfire VIN: 1G1JF5241V
rough Idle slight hesitation and misses all the time seems to be worse when cold. I have checked for vacuum leaks, checked fuel injectors compression iac motor all test o.k Trouble codes: P0300
1999 Chevrolet Camaro 5.7L 3rd gear
I'm sorry I don't have the VIN. Got to thinking about this thing here at home. Car came in today with the complaint that it wouldn't go any faster than 40. Keep in mind that this POS is modded. Checked the oil, was 2 qt low. MIL on from having no cats, I check...
2001 Chevrolet Suburban 1500 5.3L long crank VIN: 3GNFK16T91
We have what appears to be a fuel pump job. Before so, I just wanted to find out more about the subtleties of this diagnosis before pulling the trigger to better understand this problematic system. With guage attached at rail, and key turned on without startin... Trouble codes: U1301
2001 Chevrolet Malibu 3.1L long crank VIN: 1G1ND52J01
Car came in last week with an intermittent long crank. Found that we didn't always have 2 second prime on fuel pump. Had power to relay all the times we were checking, but not always energizing. Replaced relay seemed to take care of it for the rest of that day...
2002 Chevrolet Monte Carlo LS 3.4L No Start VIN: 2G1WW12E32
Thanks in advance for your help! Vehicle came in for an intermittent spin / no start. Vehicle would not start in parking lot. Put fuel pressure guage on, and spark checker. Good fuel pressure, no spark. Hooked up vantage to look at waveform from 7x crank senso... Trouble codes: P0336 (ckp sensor ckt), P0716 (input shaft speed sensor performance prob), P0717 (input shaft speed sensor low/no signal), P1189 (engine oil pressure switch problem), P1811 (transmission internal mode switch malfunction)
2004 Chevrolet Astro 4.3L Differential VIN: 1GNEL19X74
Hey guys i have a 04 chevy astro all wheel drive with a massive vibration when in a full turn at a very slow rpm left and right i put in a new differental and u joints and still there.Help please
1996 Geo Metro 1.0L Rear wheel bearings VIN: 2C1MR2264T
The rear wheel bearings have failed 4 times in the last 2 months. I have installed 2 sets, had another tech install 1 set and yet a different one install a set and they keep failing. I do not believe it is an instalation error. Don't know where to go next, get...
1994 GMC K2500 Suburban SLE 7.4L Excessive Emissions VIN: 1GKGK26N7R
HEY GUYS! THIS TRUCK CAME IN FOR SMOG FAILURE,(NOX)AND TIMMING OFF [...] set to 0. Reset timming to 4"before. failed 15mph at 1337ppm/ failed 25mph at 1012ppm. lambda test results were 1.001 at both speeds. we replaced cat.(w/ heavy duty afkt.type)now teste...
1997 Oldsmobile Aurora 4.0L Poor Idle Quality, Misfire VIN: 1G3GR62C6V
We have an Oldsmobilr Aurora that has misfires on cylinders #2,4,6,8. Most of the misfires are on # 6 & 8. Only at idle. Perfored an injector balance test and all are even. Injectors all have a good signal. Smoked the intake but can not see any leaks. Not sure... Trouble codes: P0300 (random misfire detected)
1970 Pontiac LEMANS 400CID engine VIN: 237670Z138
This is a friends car that was restored (replacement sheetmetal,paint,convert top & rebuilt engine)The machine work and assembly was done by a machine shop in the area that builds a fair amount of engines.What is happening is warm or cold the lifters sound lik...
1991 Pontiac Grand Prix SE 3.4L No Start VIN: 1G2WJ14X2M
moter will sometimes start fine cold or hot . other times it takes excesive cranking and will not start. it has fuel presser of 40psi. injectors are blinking and i have spark. what i have notice is if i give it a battery boost it will start or shoot b12 carb. ...
1996 Pontiac Grand Prix SE 3.1L No Start, MIL Lamp on VIN: 1G2WJ12M8T
This is a weird one. I pulled these codes from the computer's history codes. I have had the anti theft problems before with GM but usually trying the key on for 10 minutes to send signal works but I can leave the key on for a half hour and the flashers still f... Trouble codes: P1629 (Theft deterrent cranking signal), P1672 (Low engine oil level lamp control circuit)
1999 Pontiac Sunfire SE 2.2L Excessive Emissions VIN: 1G2JB5244X
hello my fellow techs i have this sunfire that is going no were.everything passes but nox under load.i scan this car and i get the egr code which could cuz the high nox p0405 exust gas recirculation valve sensor signal hlow.this car has no egr and i have check... Trouble codes: P0405 (exhust gas recirculation valve sensor signal low)
2000 Pontiac Grand Prix SE 3.8L Charging System
Sorry guys, this is my first post & forgot the VIN at work. We are the 3rd or 4th facility to look at this problem. Engine idles rough & misfires when hot. I have noticed that the voltage is low when this is occuring. I am assuming the driveability concerns ar...
2003 Saturn Vue 2.2L MIL Lamp on VIN: 5GZCZ43D73
PROBLEM: Came in because of maintenance they wanted done AND check engine light on (they thought was a "service" light) Can't read codes OR data stream - no communication. Both Snappy and Genisys. Read post on disconnecting other computers and retrying (other ...

Fixes & Summaries for GM
Fix/Summary Answers
1997 Buick Regal LS 3.8L Excessive Emissions VIN: 2G4WB52K9T
Reference voltage was correct at 5v, must have checked wrong terminal. decarbed engine with very little change. Cat failed hc reduction test so I replaced it and vehicle passed emissions test. Thanks for all your replies.
1998 Buick Regal 25th Anniversary Edition 3.8L injectors VIN: 2G4WF5219W
Well, I think I've tried everything I can for now, THANK YOU for the replies, most of them pointed to the security system, the customer has declined any more diagnostics at this time. possibly again in the future.
1988 Cadillac Eldorado 4.5L Excessive Emissions VIN: 1G6EL1157J
The fix was a simple one, I missed it because I had just repaired another Cadillac (89 model w/carb) with a different EGR system. When I tested the EGR valve on the carb engine it wouldn't open even with straight manifold vacuum. The EGR valve on this 88 4.5 a... Trouble codes: 44 (Lean exhaust).
1985 Chevrolet Celebrity 2.5L No Start, NO SPARK VIN: 1G1AW35R7F
1995 Chevrolet Lumina 3.1L No Start VIN: 2G1WL52M9S
well thanks for all the replies we finally found our cause and it was the exciter ring on the crankshaft for the sensor on the back of the block there should be two notches close to each other to give #1 position and it is broke off - customer declined tearing...
1997 Chevrolet K1500 Cheyenne 5.7L Cuts out, Misfire, MIL Lamp on VIN: 2GCEK19R6V
sorry for the late post. I wanted to be sure of the fix. After checking wiring and rechecking all grounds, we replaced the distributor with a delco unite. Drove the vehicle throughout two weeks just to be sure. all is well. Thnaks everyone for the help. Trouble codes: P0340 (cam position sensor circuit), P0341 (cmp perfromance), P1345 (ckp/cmp position sensor correlation).
1998 Chevrolet Express 2500 5.0L steering wheel VIN: 1GCFG25M1W
thanks to all how help me on this one ...it was as simple as a gear box to fix this !!if you take all the bells and whisles off ... it is still a p/s system!!
2000 Chevrolet Express 3500 5.7L Misfire VIN: 1GHC39R3Y1
After pulling my hair out a maf sensor was the cause, thanks guys Trouble codes: P0141, P0171, P0175.
2005 Chevrolet Cobalt 2.2L Power Door Lock VIN: 1G1AK52F65
The fix is in, part of the problem was myself making the problem more difficult than to needed to be, after playing with the scan tool some and being able to make sense of the info it was giving me I was able to determine that we needed to replace the switch f...
1993 GMC C1500 Sierra 5.7L Cuts out, Stall VIN: 2GCEC19KSP
Well just talked to the customers wife and all is well. The Daughter has beeen driving for over a week know and had not acted up once with the new distributor in it. I think the key was the tach jumping around, it is directly controled by the module, no comput...
2002 GMC Sonoma SL 2.2L Poor Idle Quality, Surge, MIL Lamp on VIN: 1GTCS14582
Thank you for your help in resolving our problem child. Replies included ECT problems, defective IAC or ECM, EGR plumbing or gasket, and a cracked head. We were leaning towards the defective ECM as we could command the idle up and down w/ our Maastertech, howe... Trouble codes: P0171 (system too lean), P0507 (idle speed too high).
2002 GMC Envoy SLE 4.2L Parking brake VIN: 1GKDS13S62
And the winner is ... David. A shot of WD40 fixed it. Note: I found a small lever at the front of the auto adjusting pawl. When i pulled up on it i felt a spring wind up. It did nothing before i lubed it. Thanks for all the replies.
2005 GMC c6500 8.1L dome lights VIN: 1GDG5C1E05
after chasing wiring for three days found a broken connector at main power distribution block under hood. repaired and now working correctly.thank every one for their assistance,
1999 Oldsmobile Intrigue GLS 3.5L bogs down VIN: 1G3WX52H2X
Thanks to all who replied, fuel trims were perfect, all data from scanner was perfect.all diagnostis that were performed showed no faults, decided to replace mass air flow sensor on a educated guess and this took care of it vehicle runs perfect now for the fir... Trouble codes: P0442.
1994 Pontiac Grand Am GT 3.1L No Start, Stall VIN: 1G2NW15M1R
Many,many thanks to all that replied. Turned out to be two grounds, the main one at the transaxle stud and one on the left fender well. Once cleaned and reattached car runs great. Thanks to everyone who took the time to help me with clearing my head and get...
2000 Pontiac Grand Am SE 3.4L ebcm VIN: 1G2NF52E9Y
Thanks to Eric from South Dakota, George from New Yersey and Glenn from Ontario, a did replace de ignicion switch because i did not feel confortable with it, but still did not have comunnication with de EBCM then i replace it and now i have comunnication no ...
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