MAP Question?

[mopower98rt]

I recently installed a new style of throttle body with the injectors built into it and I am using the Megasquirt V2.2 with the MegaTune to tune it. Now the problem that I am running into is that my truck will not start with the MAP sensor plugged into the vacuum port. When I unplug the MAP sensor from the port the truck will fire right up and idle normally. The only problem with that is that I am not going to be able to tune the VE Table without a MAP reading.

Any help would be appreciated.

Thanks in advance.

[jakobsladderz]

sounds like you're running way lean and pulling off the vac connection is bringing the mixture up to target.
If the engine was running fine before and isn't now, increase the injector calibration constant until it runs fine again..

[mopower98rt]

Actually I am running way to rich, I mean really rich. I need to get it to lean up some and without the MAP I am having a hard time doing that.

[jakobsladderz]

Was it running ok before the change? Normally, pulling of the vac hose from the MAP sensor causes the pulsewidth to jump up (more load as the MS sees it)..

I guess the possibilities are: wiring - injectors open fulltime and extra air through vac port is just enough to idle, check wiring, etc..; injector cal too large and causing major flooding, check pulsewidths are reasonable and adjust cal one way or the other; other issue???

are all the readings ok (MAP, engine revs, temps, etc..).

[mopower98rt]

Before the change the truck was running great. I am using the MAP that came with the MS and wired it directly to the MS. I checked the wirring to the injectors and it all checks out, and I put a noid lite to the injectors also and all of them are getting the correct signal.

I will look at the injector calibration tonight.

The MAP of course reads wrong since it has no vacuum but all of the other readings are dead on.