Just wondering what the Quadzilla XZT Towing box does that screws up the overhead computer. I only wish that the mileage claimed by the overhead was true. Alas, it is not. Hand checked and I am not doing well at all in the mileage improvement department. After a few initial times dropping the hammer I have only been driving "normally", even tried to baby it a little. I am definitely getting worse not better mileage.

Thanks guys

Hondo

 

What I have read on here is that any pressure box will throw off the overhead. Boxes which use timing only such as TST do not affect the overhead.

Why. Don't know.

 

Don't baby it, just drive it. The CR engines do not do well when they are babied. I am not saying do burnouts at every stop light, but drive it like you drove it stock. You will see a gain in normal driving conditions.

Also babying it too much can be rough on the injectors, they will carbon up.

Also the overhead is affected anytime you change fueling, this includes duration or pressure. The overhead is calculated off of what the ECM thinks the duration and timing is. Anytime you alter this and the PCM does not know it then it will be different.

 

Speaking of babying, This will sound stupid but I was wondering, is it better to get up to speed quickly with a diesel or slowly build up speed to get the best mileage? I know fast acceleration with a gasser includes worse mileage. I ask 'cause it sounds like it is using more fuel and working harder when I slowly build momentum versus hitting it and going.

Hondo

 

The reason the overhead is off with most boxes is the overhead is figured by the computer, the signals sent by the computer are intercepted by the box and newer signals are sent form there to the engine. The computer thinks it is using less fuel than what is acutally being sent.