Thread: Pulley drop time?

Originally Posted by hollas13

how does a tuned pcm get rid of kr? i have ported manifolds, cai, 180 tstat, al 104's, 3" dp and a 3.4 mps i want to put on. also i have a way to scan.

I am not an expert on tuning by a long shot but I know if you had a custom tune on a dyno they could tell right away what pulley you should run safely. They do this by an educated guess on the pulley size then dyno the car and pulley down a size or two if they can without KR. A lean fuel/air mixture can result in KR the stock PCM adjusts the amount of fuel based on the MAF and O2 readings. I'm guessing that some tunes may include adjustments to the fuel trims and increase the fuel mixture to eliminate a possible lean condition. I think with lightly modded cars with stock injectors this is not much of an issue with even a stock tune. The easiest way to get KR is to not have good exhaust flow and run a pulley too small. Your jamming to much hot compressed air into the cylinders and the hot gasses don't flow out fast enough causing excessive heat and early detonation (KR) I topped off my build with a tune from Intense. John really knows his stuff and you can call him with questions if you need to. INTENSE-Racing.com: INTENSEâ„¢ Reprogrammed 3800 Powertrain Control Module (PCM) The web site lets you choose a canned tune based on your mods.