Last night I raced a rice burner. He only slightly beat me and it really was a lot of fun. I noticed that when my truck shifted from1 - 2 and the 2 - 3 I got a tiny little bit of detonation. Less than a 1/4 of duration. It seemed to happen when the truck shifts. I've got a stock 4R70W tranny. It takes about 4 months for it to shift gears. It's real slow and soft. (I have the shift kit and I almost have the stones to install it).

Does anyone know why I'm getting this tiny amount of detonation. At 4900 rpms, no detonation, but then when the tranny shift, I can feel the truck slow down. It's almost like the PCM is leaning the WOT p/w a little. I think I've heard that these PCMs also retard the timing at shift too to make the truck perform like a 1978 lincoln mark 5.

Thoughts?

 

I've heard of this happening with NA trucks as well. My theory is that the "base" for the timing after the shift is slightly too high.

Since the EEC on these trucks is load sensitive, the load as the truck grabs the next gear increases. Too agressive of a curve at this point will cause detonation, and the knock sensor will pull out timing to compensate.

On a blower equipped truck I would first ensure everything in the fuel system is operating properly, especially the FMU. If the problem persists after that I would consider a chip reburn.

 

I'm already thinking about 42# injectors, chip, and FPR. I think that could solve a lot of deficiencies.

 

Thanks, Derek.

On another note, do you have a reference for a store that I can buy an S&B airfilter at? Thanks,

Frank

 

What are PhD5150 and overtaxed? Punk rock groups? Sorry, kinda in silly mood. But seriously, do you know what those products are?