PLease help desperate with ignition timing problem

[r_swaynie]

I have a 94 explorer and I am having an ignition timing problem. under load it stumbles all over itself and backfires through the intake. dpfe replaced didnt help, new dpfe lasted about a day replaced didnt help, went through about 3 new dpfe's all would last 1/2 to 1 day before crapping out. tested egr vaccuum modulator its fine removed egr it was clean, used vacuum pump to test egr valve operation fine. removed vaccuum line from egr valve and capped to eliminate that as part of the problem....oh the onle codes i get are dpfe bad, duh i know, and some tranny codes because i swapped from auto to manual. hookede up timing light and noticed the light strobe had a regular irregular miss, also at idle timing was jumping around a lot. cleaned tone ring for crank sensor with wire brush because it was covered with rust remnants from have a leaky radiator, problem got a lot better but still definately there. replaced crank sensor, no change. checked timing again same thing this time i smacked top of coil pack and the regular irregular miss of strobe changed but was still there, replaced coil pack regular irregular strobe went away at idle, but no change in drivability. checked timing again this time with pip removed timing steady at 10 deg btdc. rev motor and timing doesnt change but strobe on timing light goes wacky again. rev with pip in both strobe and timing go wacky. replace ignition control module, test drive and no change.....WTF?????? oh and plugs and wires are new. oh and did compression check 145-155 all cyl, vaccum gauge reads solid 21in hg. as i understand it every part of the ignition system has been replaced except the ecm with has "some" effect on it but they almost never go bad, literally 90% of all "bad" ecm's returned are tested and perfectly fine.please help DD with expired tags and cant smog......oh and as i understand it the cam sensor is for injector timing only fyi. thank you and sorry for long post ...but ive done everything!!!

 

[wood1]

I believe that if you still have the auto computer it thinks you are still in park and is not allowing the timing to react to engine speed/load. You have to swap to a manual or trick the auto computer into believing you shifted into gear. There is a reason that the RMP's react to that first shift into drive, even before the transmission reacts. Wouldn't have thought it would cause that much of an issue mind you, should have just been really sluggish... there must be another issue too. What plug wires crossed (arcing) or miswired? So did you try a new computer?

 

[r_swaynie]

its not the computer because the swap had been done for 6mo before this happened....and a friend did the same to his 93 a few mo b4 i did mine and he has had no problems,

 

[MrShorty]

During the KOER test, the computer sets a fixed value of base (10*) + 20* for the timing (SPOUT connected). See my notes on pulling EEC-IV codes thread for a more detail on when to read the timing. What do you get?

Any sign of damage to the ICM?

 

[r_swaynie]

ttt