I have a friend who installed a procharger on a 2003 Z71. The truck pulls good until you hit 3rd gear then it is like you pull 100hp from the truck. The truck has a preditor on it with 101 octane and autolite plugs gapped at 32. We took it for several passes today. The highest we could get the timing was 18 degrees and that was at the end of first gear. Second would reach a max of 14 and third wouldn't get above 11. The predator never showed any knock retard and the IAT's would reach mid 130's by the end of 3rd gear. We had the preditor set at plus 10% for the spark advance and 18 was the max we could get out of the truck. we drove another 03 truck with the 6.0 motor and it had around 22-25 degrees in all gears. What gives? I am at loss as why the truck wouldn't make any power in 3rd and why we couldn't get it to give the truck more timing. Any ideas would be great.


Thanks,
Jason

 

What is the peak boost he is seeing? How much boost is he seeing in third? My experience with a procharger(on my car) is that you really don't see most of the boost until after 4500rpm. Maybe he just isn't high enough in the rpms in third to see good boost.

What gears, tires is he running and what speed did he shut it down.

The timing could be getting pulled from the high IAT's. The computer has a table that will pull timing at that high a temperature. It is the IAT vs. MAP timing adjustment table. My stock file shows up to 5 degrees can be pulled at that temperature.

John

 

Would be nice to know how much boost he is seeing wouldn't it. He doen't have a boost gauge yet. Waiting on parts. He has stock 3.73's and we ran it to a speed limited 125 twice. But I swear it is like a stock truck all the way through 3rd gear. It is lucky to see 11 degrees of timing. The owner is going to order LS1 edit for the truck this week. It makes sense for the computer to pull timing if the IAT's were that high. That is why I said what they were by the end of 3rd. Say the computer is pulling the whole 5 it still leaves a max of 15-16 degrees. I don't think that is enough. Is it? I would think it should be in the 18-22 range. Any more ideas?

 

Well, he should be seeing pretty good boost by 125 which should be somewhere above 5000rpm.

I don't know what the deal is with the timing on these trucks. It has a mind of it's own it seems sometimes.

Maybe the people at Diablo could help out with the timing issue before he buys Edit. Some people have problems changing the timing with Edit. There is a post that parish8 started about the timing/EDIT issue on the first page of this forum.

 

Tell him to invest in a torque converter
If it's falling on it's face that bad the Yank 3000 did wonders for my truck
also is he running stock injectors with the Procharger setup ?
you might wanna watch the 02 sensor readings as i was very lean with stock injectors
best way is to get it dyno'd and check the a/f on it


jim