I have a 91 F150 5speed manual, 302. I just had the engine rebuilt, larger valves, a crane cam (#13002), smoothed intakes. Nothing crazy. I put 24# injectors in, thinking "it doesn't matter, the computer will compensate." After listening to a surging idle, smelling the rich exhaust, and failing to smog - I started to think "oops."

From what I'm reading, it seems the computer assumes it has a certain size injector, which I think was supposed to be 19#. So I think I have three choices at this point -
1) put stock injectors in (lots of unbolting and bolting - $250 for the set)
2) get a recalibrated MAP sensor (not sure what they cost - but I get the feeling I'll be even worse off in the end - and no one will be able to fix my truck)
3) get a chip (no unbolting, about $300)

Couple questions:
1)Does anything I've said make sense? You're talking to a carb guy - this computer thing is uncharted territory for me.
2)What benefits could I expect from a chip - I'm not looking for any kind of crazy performance, I need enough reliable power to haul a camper and two big motorcycles around the country at interstate speeds.
3)How do I know if my truck is MAF or speed density? It seems to be an important thing to know....

Thanks VERY much in advance for any advice or help...

- dazed

 

In a situation such as yours the biggest benefit of a chip is getting the driveability issues under control. Given the changes, its suggested you get a dyno pull of the engine done so you can supply that to us along with a custom sheet. Its the best way to insure the chip will give smooth performance. Your truck is speed density. 1994 is the year F150's changed over to MAF. The chip will give a performance increase but I can't give an exact number given your changes.