IDLES GOOD NOT TIMEING ADVANCE

  • Tiny
  • onewolf1952
  • 2000 GMC Jimmy
  • 112,000 miles

At idle timing is 30.5 TPS is at 3.1%. Smooth idle no miss fires, Increase throttle timing goes all over TPS at 11% timing is 30, 29, 28.5, 28, 27.5, At TPS The high TPS goes the lower timing drops at 100% TPS goes to 12 on down to -1.5then hangs around 6 to 2 deg.

Cad is clear, no vacuum leaks, MAF, new, ICM new, cap and rotor new, wires new, crank position senor new, computer new.

I am at a loss.

Thursday, May 24th, 2012 AT 11:35 PM

5 Answers

  • Tiny
  • ASEMaster6371
  • Expert
  • 25,502 posts

Wow, lots of new parts. Did you have a shop check this for you?

A big issue with the distributors is the lower gear wears out and has all kinds of slop thus changing the cam retard. You should have this checked.

Roy

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Friday, May 25th, 2012 AT 12:32 AM
  • Tiny
  • onewolf1952
  • Member

Thanks,
I ve had nothing but trouble from this truck so yeah replaced a lot of parts. Took it to dealership one time they said fuel pump bad but wires were cut from the gas tank band from a previous change, it was running great then slowly this problem came about over a period of a week. Some one said in is the knock senor but I really need a solution so I can trade it in for something to get me going down the road.

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Friday, May 25th, 2012 AT 1:04 AM
  • Tiny
  • ASEMaster6371
  • Expert
  • 25,502 posts

The knock sensor will retard the timing in 4 degree incriments for a total of 4 times. If you disconnect it, it should remian stable. If not then it is something else.

Roy

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Friday, May 25th, 2012 AT 1:11 AM
  • Tiny
  • onewolf1952
  • Member

Ok I got to find it lol I understand it is a pain to get to. A distributor problem wearing is a great way to go, it came on over time and wear is consistent with your solution.

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Friday, May 25th, 2012 AT 1:19 AM
  • Tiny
  • ASEMaster6371
  • Expert
  • 25,502 posts

Good luck

Roy

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Friday, May 25th, 2012 AT 1:28 AM

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