Mechanics

IDLES GOOD NOT TIMEING ADVANCE

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.
Avatar
Onewolf1952
May 24, 2012.



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


ASEMaster6371
May 25, 2012.
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.


Tiny
Onewolf1952
May 25, 2012.
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


ASEMaster6371
May 25, 2012.
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.


Tiny
Onewolf1952
May 25, 2012.
Good luck

Roy


ASEMaster6371
May 25, 2012.