Howell TBI, California smog, high idle...

[Posi]

I am interested how this was solved. I am having the exact same issue now and the smog repair shop I went to won't even touch the vacuum lines to address the timing.

There is a mechanical and electric idle adjustment for gm FI. If neither corrects your idle the problem is the chip if all else is correct.

 

[LanceMaster]

Had the same problem. Drove me ape-shiet for years.

Download the Howell manual and set everything back to specs.
Engine is very happy at 8deg advance.

Consider replacing O2 & MAP sensors if they're old, just because.

Don't try to guess about a vacuum leak, just replace all hoses, doesn't cost that much.

Ensure there are no leaks around the base of the throttle body. There are also TB adapter mount holes under the TB that have to be silicone over per install instructions. If you replace the TB mount gasket look in the manual about where to put silicone.

Install a new IAC and set. Yes, you must jump the A & D terminals! Google it.

NOW, HERE'S THE KICKER; I did all that above and STILL had high idle (but I have peace of mind everything is in good shape) ... I got so frustrated I called Troy at Howell Ind. He suggested replacing the ignition module which is known to cause idle issues.

I replaced the ignition module and it seemed to get better, but not by much.

Lastly, out of desperation because there was nothing else left to replace, I changed the distributer!

That was it! I know the distributer is solid-state, but it had 292,000 miles on it and I knew everything else in the system was new or functioning properly.

I purchased a Cardone Select 84-4691 New Ignition Distributor on Amazon for 65$ and took 20 minutes to remove/install, time the engine and finish my beer. Idle has been perfect ever since.

You can jump right to changing the dist. but make sure the rest of the system is in good working order.

 

[Fender]

Thanks for all the input. I have some work ahead of me this weekend. Also found out my converter was for a 95 yj so that was interesting and expensive to replace.

 

[jzak]

I've never been able to get my Howell TBI to idle right. On a good day, it will fluctuate anywhere between 500 to 1000 rpm. Sometimes it will settle at 700rpm, but never consistently. I've replaced almost every part of the Howell TBI kit, including every sensor. It helped but didn't fix it.

The only thing I haven't explored is replacing the exhaust. I had a mechanic tell me that the old catalitic converter was creating backpressure, which could affect the idle speed.

 

[Posi]

What is your IAC count at idle?

 

[jzak]

Had the same problem. Drove me ape-shiet for years.

Download the Howell manual and set everything back to specs.
Engine is very happy at 8deg advance.

Consider replacing O2 & MAP sensors if they're old, just because.

Don't try to guess about a vacuum leak, just replace all hoses, doesn't cost that much.

Ensure there are no leaks around the base of the throttle body. There are also TB adapter mount holes under the TB that have to be silicone over per install instructions. If you replace the TB mount gasket look in the manual about where to put silicone.

Install a new IAC and set. Yes, you must jump the A & D terminals! Google it.

NOW, HERE'S THE KICKER; I did all that above and STILL had high idle (but I have peace of mind everything is in good shape) ... I got so frustrated I called Troy at Howell Ind. He suggested replacing the ignition module which is known to cause idle issues.

I replaced the ignition module and it seemed to get better, but not by much.

Lastly, out of desperation because there was nothing else left to replace, I changed the distributer!

That was it! I know the distributer is solid-state, but it had 292,000 miles on it and I knew everything else in the system was new or functioning properly.

I purchased a Cardone Select 84-4691 New Ignition Distributor on Amazon for 65$ and took 20 minutes to remove/install, time the engine and finish my beer. Idle has been perfect ever since.

You can jump right to changing the dist. but make sure the rest of the system is in good working order.

We should have a grief support group for Howell TBI owners with Idle issues! I've spent six years trying to get a proper idle speed, by replacing just about everything. The only thing I haven't touched is the distributor. I just bought that CARDONE Distributor you mentioned. Hopefully, it'll work for me.

 

[Posi]

There isn’t a need to guess when it comes to FI, there is a procedure to test sensors on GM FI so no one has to waste money and time removing perfectly good working sensors. If you own a GM FI (Howell) you should know your IAC counts at idle being it reflects rpm at idle. If you don’t you’re working blindly on correcting your FI issues.

 

[jzak]

Hey Guys! Based on the input from LanceMaster, I just installed a new distributor. After some last-minute adjustments to the advance, it's starting and running a lot better. The idle seems steady at 700 rpm (Operating Temp), but I'm going to need to drive it around for a while to see if it's really fixed. I'll keep you posted!

 

[Fender]

Thanks for all the input. I have some work ahead of me this weekend. Also found out my converter was for a 95 yj so that was interesting and expensive to replace.

Well I managed to get past smog. Went to a referee station and installed a new EGR. The timing was fine and turns out the original smog place I went to was wrong and didn't look up the CARB EO associated with the Howell FI for the vacuum tubing and the timing adjustment. I even had the sticker under the hood. The referee said that some smog check places will just fail an aftermarket system if they never seen one before. Anyways glad that is over. Now I can do something fun to the jeep instead of spending money on emissions.