I'm using BJKW broadcast code, but it seems all the broadcast codes for a 7.4L have a delay for power enrichment of 70 seconds. The delay bypass is set to 4300 RPM. This doesn't seem to make much sense. Before I go and change it, I'd like to know why it is there.

 

Your PCM has two different threasholds for PE.. One for PE and the other for WOT.. If you cross the threshold for PE, you are held out by the time delay or the rpm bypass. In WOT mode it automatically bypasses the PE delay.

 

The delayed PE is common to the truck cals. It allows closed loop or open loop operation at leaner than PE AFRs during towing and other transient high-load operating conditions. The goal is to minimize fuel consumption and limit rapid switching between CL and PE operation. Theres nothing wrong with bypassing it and just having PE come on right away, but you will use more fuel if you spend a good deal of time in PE at rich AFRs while towing or carying a heavy load.

 

Thnks for the reply. I was reading a hac a little more today and found a listing for Acceleration enrichment, and Power enrichment. My program was set up by Howell, and from testing, there is no Acceleration enrichment, only Power enrichment. They changed power enrichment to turn on at 1200 RPM, instead of 4300 RPM, and changed the delay to 1 second. This means that the only enrichment I get is at WOT. There is no Accelleration enrichment. There is a pump shot, but part throttle response is a bit dead, I'm trying now to understand everything that controls Acceleration enrichment, to see if I should try to make it active agian. Unfortunantly, the hac is a bit vague on details. Lists the line numbers and one or two word description, but no interpetation of the value in the memory location.

When I responded, I didn't see the last post about truck. This actually is in a 13K lbs motorhome. I'm not real worried about mileage, if I was, I'd be driving a car. Most the time at 70 mph, I'm running less than 35% throttle. If I could figure out how to get Acceleration or some sort of partial enrichment at 50% throttle, that would be fine. Under normal freeway grades, I rarely go above 50% throttle anyway.

 

So I found Accell Enrichment LMT option and enabled it. It looks like I'm now seeing some enrichment at 2/3rds throttle. It looks like it was programed, but just not enabled. The programing is pretty conservative, it would have to be an extreme load to really be a problem.