when I get my rpms up around 2800 it feels like the engine cuts out for a millisecond, then comes back on but not as strong. I was screwing around with my map sensor, if you read the map sensor mod thread I made youll know what Im talking about. I 'bushed' the MAP sensor to restrict the reading it gets, and now Im getting more fuel. So that means Im making a bit more boost right? More fuel in, more exhuast out, more volume to spin the turbine= more boost? So then I could be de-fuelling right?
Im just checking, I hardly rev it up past 2500 rpm anyways, but it had me worried when I did and the engine had a cut out/sputter.
-Al

 

Seems to me that if the actual boost is higher than the PCM thinks it is, the less fuel you are actually getting/need. That being said, I don't think it's defueling, you are just not getting enough fuel for the amount of air you're putting into the cylinders (lean).

The higher rpm range should suffer if my thinking is right.

Hope that makes sense.

 

yeah what youre saying makes sense to me too, and I thought of it that way. Thats why the whole thing does not make sense that with the bushing in, and the Bronco map hooked up, I get black smoke coming out of each gear change for a few hundred (400-500ish) rpm, and way more accelleration. The truck pulls at 1500rpm now like it used to at 2000. I just took it for a drive, and its more around 3100 rpm where it starts the cut out.

 

With a stock MAP sensor it will continue to add fuel until you reach the top of the PCM's fuel map. Above that it will defuel. We "regulate" the amount of boost the PCM sees in order to keep the maximum amount of available fuel without letting it defuel.

Without knowing what signal the Bronco MAP is sending to the PCM it's difficult to even speculate what's happening. When the stock MAP tells the PCM to defuel it turns on the check engine light. If I were going to guess, I'd say the Bronco MAP is sending an out of range voltage signal to the PCM and it is having trouble compensating.

 

it almost seems like faint wheel hop (its not tho), and it does it earlier in the rpm up a hill than on flat.
How do you check the output voltage for the bronco MAP, or find a reference to it?