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So about a year ago I bought a 1987 Grand Wagoneer. In about 1999, a previous owner had put in a fresh 401 and a Howell efi system. It looks like it has a non stock distributor as well. I am now having problems with it. It starts hard. When it does start, it chugs and blows black smoke and does not want to move until it warms up, and I live in Arizona. It acts like an old carb with a stuck choke. Once warm, it seems to lack power and also surges at idle from 700 to 900 rpm. So far I have replaced the oxygen sensor and the IAC valve. Does anyone have any other ideas? Or should I ditch the howell and go to a different EFI system? Please help!!!

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Howell is a great proven system. Have you called Howell? They are very good at this. Timing has a lot to do with the way the system runs. I would mess with timing first. I'm here in Phoenix.

Locked and Loaded wrote:Howell is a great proven system. Have you called Howell? They are very good at this. Timing has a lot to do with the way the system runs. I would mess with timing first. I'm here in Phoenix.

I sent them a message. Waiting for a reply.

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scramble96 wrote: ↑Fri Jul 30, 2021 8:02 am

Locked and Loaded wrote:Howell is a great proven system. Have you called Howell? They are very good at this. Timing has a lot to do with the way the system runs. I would mess with timing first. I'm here in Phoenix.

I sent them a message. Waiting for a reply.

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Call.

Yeah, I would call them.

Could be a lot of things causing it. A data log would go long way to finding out what. Could be as simple as a bad O2 sensor.

The Howell stuff is all mostly-unmodified GM Rochester original equipment throttle body injection (TBI). They use all GM parts and program the computer with air-fuel tables to match your engine. Your local garage should be able to read the diagnostics just as if it were an '85 GM pickup. This is discussed in the Howell installation instructions on their site. Or look up how to diagnose one of the GM TBI vehicles, buy a scanner and read the codes.

Lots of info online about this - I looked for 2 minutes and found this - http://www.73-87chevytrucks.com/techinf ... ystems.pdf - plenty more info out there.

Re the distributor, the factory GM TBI has spark control, which uses a special distributor and connects to the EFI computer. Howell disables spark control, and the system they sell is basically an electronic carburetor. Aftermarket distributors are a popular upgrade (with debatable merit) for these engines. I would expect the distributor has nothing to do with the Howell fuel injection.

sounds like typical failed coolant temp sensor
when they go bad engine thinks it's way cold and they're absolutely pig rich

easy to check with $10 usb cable and tunerpro software