strange sound in engine part ll

[lovehamr]

Paul, it being a 1988 I’m assuming that it doesn't have a mass air meter, right? If this is the case then just about anything you do that alters the amount of air that the engine can digest will negatively affect the way the thing runs. An engine using an open loop fuel injection system uses temp, throttle pos., manifold pres., RPM and a couple of other factors to mathematically figure the pulse width of the injectors based on tables loaded in the computer. If you change the engines requirements w/o changing the injection tables or the system to go along with it, it'll never run right. A "mass-air" system on the other hand uses a measurement device in the intake tract to "measure" the amount of air going into the engine. The computer uses this extra info in an algorithm to alter the air-fuel ratio, spark adv. etc. I know Ford used to market a conversion kit to change over Mustangs from speed density to mass-air but I have no idea about the trucks.

At this point I imagine that no more people are joining inn this discussion just because there is no way that this could be diagnosed over a web site or telephone because so much has been changed. To my limited self it looks like kayos theory! Too many changed factors to take into account. Who knows, maybe that’s the way your computer feels as well!

I would research the computer and engine combos to see what would work together befor I was to proceed.

Steve

Steve