Check engine light, stumble, power loss - The 1947 - Present Chevrolet & GMC Truck Message Board Network

pat · 02-15-2008, 03:39 AM

Ive got an 90 Jimmy with a 350 and I will be driving down the road just fine when all of a sudden it will kinda stumble. Immediately the power will go down and it wont be very responsive, and the check engine light immediately comes on. I havent checked the code yet, that may help.
Any ideas?

**Captkaos** · 02-15-2008, 05:07 AM

Check the codes and tell us what they are.

pat · 02-15-2008, 10:22 AM

Code 42

ChevyTech · 02-15-2008, 10:49 AM

Code 42 can be set by a bad distributor module, a bad ECM, or wiring problems between the ECM and distributor.

A code 42 will get set when the set timing connector is unplugged to set the timing. Make sure you clear the codes after setting the timing.

When the problem is present that sets the code 42, the truck will be running in a backup mode without electronic spark controlled timing.

It sounds like heat could be causing the distributor module to break down. Many stores like NAPA in my area will test the module for free if you bring it in.

Make sure when you install or reinstall the distributor module that you use heat sink compound/grease under it. The grease helps dissipate heat from the module.

pat · 02-15-2008, 12:50 PM

Your knowledge never ceases to amaze me ChevyTech.
I guess Ill call around tomorrow to find a place to test the module first off.
Thanks

dadsbrew · 02-15-2008, 01:17 PM

My suburban just started doing the same thing last week, little different, it will stumble and run bad until shut off and restarted or stumbles and shuts off. same code 42. I guess I know what to check first now, thanks

CLASSIC87' · 02-15-2008, 07:45 PM

I have had this problem for A LONG time... and I did replace the distributor module. I also installed the grease... but I'm wondering if I installed enough underneath it?

Keep us posted on what you find..

Thanks,
Anthony

02-15-2008, 03:39 AM	#1
pat Senior Member Join Date: Jul 2002 Location: Lindsay, TX Posts: 1,245	Check engine light, stumble, power loss Ive got an 90 Jimmy with a 350 and I will be driving down the road just fine when all of a sudden it will kinda stumble. Immediately the power will go down and it wont be very responsive, and the check engine light immediately comes on. I havent checked the code yet, that may help. Any ideas? __________________ 68 Chevy 383/350 w/shift kit, 380hp/425ft-lbs, 4.5/5 drop, 17" TT2s 64 Cadillac Sedan DeVille

02-15-2008, 05:07 AM	#2
Captkaos www.73-87chevytrucks.com Join Date: Dec 1999 Location: Birmingham, AL Posts: 6,935	Re: Check engine light, stumble, power loss Check the codes and tell us what they are. __________________ Chris Lucas 1973 Chevy C-10 1978 GMC Jimmy (2WD) - SOLD 1987 R10 twin turbo LS 1991 R3500 SRW CrewCab 1985 K5 diesel swapped project 1989 K5 2WD conversion w/ Vette susp Project Captkaos Customs 73-87chevytrucks.com

02-15-2008, 10:22 AM	#3
pat Senior Member Join Date: Jul 2002 Location: Lindsay, TX Posts: 1,245	Re: Check engine light, stumble, power loss Code 42 __________________ 68 Chevy 383/350 w/shift kit, 380hp/425ft-lbs, 4.5/5 drop, 17" TT2s 64 Cadillac Sedan DeVille

02-15-2008, 10:49 AM	#4
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	Re: Check engine light, stumble, power loss Code 42 can be set by a bad distributor module, a bad ECM, or wiring problems between the ECM and distributor. A code 42 will get set when the set timing connector is unplugged to set the timing. Make sure you clear the codes after setting the timing. When the problem is present that sets the code 42, the truck will be running in a backup mode without electronic spark controlled timing. It sounds like heat could be causing the distributor module to break down. Many stores like NAPA in my area will test the module for free if you bring it in. Make sure when you install or reinstall the distributor module that you use heat sink compound/grease under it. The grease helps dissipate heat from the module.

02-15-2008, 12:50 PM	#5
pat Senior Member Join Date: Jul 2002 Location: Lindsay, TX Posts: 1,245	Re: Check engine light, stumble, power loss Your knowledge never ceases to amaze me ChevyTech. I guess Ill call around tomorrow to find a place to test the module first off. Thanks __________________ 68 Chevy 383/350 w/shift kit, 380hp/425ft-lbs, 4.5/5 drop, 17" TT2s 64 Cadillac Sedan DeVille

02-15-2008, 01:17 PM	#6
dadsbrew Registered User Join Date: Jan 2008 Location: Federal Way, WA Posts: 53	Re: Check engine light, stumble, power loss My suburban just started doing the same thing last week, little different, it will stumble and run bad until shut off and restarted or stumbles and shuts off. same code 42. I guess I know what to check first now, thanks __________________ 1970 K-10 400CID, to much cam--not enough compression Stan's Headers and a 4" lift / 1990 R1500 Suburban 4X4, 350CID with vortec heads, edlebrock intake, TBI, 10:1 compression and Stan's Headers "The probability of someone watching you is directly proportional to the stupidity of your actions"

02-15-2008, 07:45 PM	#7
CLASSIC87' OL BLUU Join Date: Mar 2004 Location: WICHITA, KS. Posts: 1,065	Re: Check engine light, stumble, power loss I have had this problem for A LONG time... and I did replace the distributor module. I also installed the grease... but I'm wondering if I installed enough underneath it? Keep us posted on what you find.. Thanks, Anthony

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