I have a 1992 Bronco 5.8. I recently replaced the computer with a remanufactured unit. I noticed 2 differences from my OEM. I now hear some knocking when trans shifts at low speed. Second the initial idle speed is about 1100 rpm vs the old speed of 600 rpm. The high idle returns to 600 after about a minute of warm up. The high idle doesn't bother me but the knock on shifting is unsettling. Any ideas how to correct?

AQ

 

High idle at warm-up is normal for a lot of tunes. You should see that settle down a little as the computer adapts.

As to the ping, sounds like the timing is advanted too much for the application. Unfortunately without a Ford PCM there's no way to know for certain because we're dealing with an unknown tune. Can you pull the spark spout and see if it goes away? That will retard the timing a bit. If the knock stays then the problem is something else.

 

When you replace the computer, you should always double check your timing.

Don't assume the timing stays the same from one computer to another.

Good Luck

 

Been runnin from and after the hurricanes for a week.
You are right, the timing changed about 2-3 advanced. Just set it back and will test tomorrow.
Got to board up again for Jeanne or maybe Ivan for the third time or maybe Lili is comin too - might as well live in bomb shelter this year.

Thanks,

Aquaries

 

OK the timing adjustment took care of the 99% knock.

I did not know that such a small amount would cause a knock. Moved from 12 to 10. In days prior to chips the timing i think spec tolerance was +- 2 degrees.