Jeep Strokers

Built a 4.5 stroker a few weeks back, has a 239-4 comp cam and 24lb ford injectors. It will run good when i disconnect the battery and let the computer reset, but after running it and cranking it back up, it goes to running rich and throwing code for MAP sensor circuit open or shorted, voltage too low. My question is, is it possible the cam is causing low vacuum readings on the sensor and causing it too read incorrectly? Or is a MAP adjuster in order? Ive tried swapping MAP sensors with a friend and replacing the o2 sensor, but still running like crap.

MajorPain999 wrote:My question is, is it possible the cam is causing low vacuum readings on the sensor and causing it too read incorrectly?

Yes.

What is your idle manifold vacuum reading?

Good question, I haven't hooked it up to a guage yet. Is there any simple way to boost the vacuum so the sensors will read correctly? Like a vacuum canister or something?

I don't think boosting the vacuum is the way you want to go, try a voltage regulator to scale back the voltage to to map sensor output to the computer, I'm using split second, those injectors are slightly too large most of the time, they were too large for my .040 over 4.61, now I'm using black ev6 at 42-48 psi

Maybe your vacuum line is bad? Could have sucked up some crud or be kinked.
I doubt low vacuum is being caused by that cam, it's not a radical cam by any means.

the grey ghost wrote: ↑June 23rd, 2014, 11:51 am I don't think boosting the vacuum is the way you want to go, try a voltage regulator to scale back the voltage to to map sensor output to the computer, I'm using split second, those injectors are slightly too large most of the time, they were too large for my .040 over 4.61, now I'm using black ev6 at 42-48 psi

Did you get a good ss tune?

Would you be willing to share?