Engine Howell 4.2 TBI ongoing idle and WOT fuel issues with new system

[CJKen51]

Hello All, I have around 1 hour of actual drive time on my Howell TBI it ran "mostly" well to begin with and I was excited to drive it. Then, it just started leaning out and dying. Was towed home, by my son, that day. That was back in early June. Anyway, I've messed with this forever. The list of tests is a long one.
When I unplug the MAP sensor, it will actually idle. It idles smooth. Granted, it's rich and in a limp mode, which lines up with the service manual that was included in my kit. Plug the MAP back in and back to dying within just a few seconds. Here's the kicker: I've tried two different MAP Sensors. I also picked up an extra computer, since they were $95. Tried both of those and switched the PROM over, of course. I've talked to Troy, at Howell, 3 or 4 times now and I checked and verified everything he asked. Looking for a tip on anything else I could check. Thanks, in advance.

 

[CJKen51]

Thank you very much. I did talk to Troy about this. He said there was an issue with the distance suggested, and had me cut the hose real short and plumb directly off the barb fitting (back of TBI) didn't make a difference. Any help is appreciated and i'll keep trying different hose lengths. Both MAP sensors react the same way, too.

 

[Placer Jeep]

Thank you very much. I did talk to Troy about this. He said there was an issue with the distance suggested, and had me cut the hose real short and plumb directly off the barb fitting (back of TBI) didn't make a difference. Any help is appreciated and i'll keep trying different hose lengths. Both MAP sensors react the same way, too.

Make sure your ECM is grounded.

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[Belizean]

What does the Howell use for an O2 sensor ?

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[KRUPP]

Troy had me shorten the vac hose for the MAP sensor as well. Seemed to help a little bit. New injectors were the eventual fix though.

According to the information in my Howell kit instructions, the O2 sensor is a Single Wire General Motors PN 25155816
or Heated Sensor General Motors PN 25312184.

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[TSB8C]

Use the heated sensor. My first attempt at EFI on a prior CJ5 had a single wire O2 sensor that worked just fine until it got wet driving in the rain. Cooled off and started throwing errors. Once dry and warmed back up, all was well again. Mine was mounted in the collector portion of a fenderwell exit header on one side.

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