Engine misses at idle speed

Tiny
MONFILSD
  • MEMBER
  • PONTIAC GRAND AM
I have a 2001 pontiac grand am with a 2.4l engine the mileage is 99000 km. My engine misses at idle speed, it will idle at 600 rpm and then it will drop at 400 rpm for a split second. i can hear from the muffler a backfire of air. I had it checked with a computer and it says that the 4th cylinder has a random misfire. I have changed the plugs, boots, fuel filter and checked the coils they still have a 6.4 ohm rating. What can be the cause?
Please Help!

I found the problem.... Never use "bosh" spark plugs. They do not have the proper heat range so they do not provide a proper spark causing a misfire code in the pcm.


http://www.2carpros.com/forum/automotive_pictures/90091_Cars_RPM64_L_1.jpg

Thursday, August 2nd, 2007 AT 6:22 AM

2 Replies

Tiny
MONFILSD
  • MEMBER
  • 2 POSTS
DO NOT BUY BOSH SPARK PLUGS FOR GM VEHICLES.
This was my problem. They do not output enough HEAT to burn fuel properly. So use DELCO OR NGK plugs and your car will work fine.
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Friday, March 28th, 2008 AT 4:33 PM
Tiny
MASTERTECHTIM
  • MECHANIC
  • 4,749 POSTS
Has it been skipping since august? Did the skip start right after you put in the bosch plugs? Are you sure it wasnt cracked? Im curious why it skipped. I never liked bosch plugs, I always use ac delco if possible.
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Friday, March 28th, 2008 AT 5:24 PM

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