Howell TBI, California smog, high idle...

[Tremelune]

I just picked up an '83 CJ7 with the AMC 258 i6 / 4.2l motor and the California-CARB-certified Howell JP1 throttle body fuel injection kit. I'm now trying to get it legitimately through smog, and I'm currently held up on a high idle.

It runs and idles well. It sometimes stumbles when warming up, but always starts and very rarely stalls. When warm, it idles at 900-1,000rpm and I need it to idle at 700-800rpm to pass.

The first thing I tried was to adjust the idle screw. When I turned it in a turn or two, idle sped up. When I turned it out, idle stayed at 1,000rpm even with the screw completely unthreaded.

Then I stumbled on this thread which talks about jumping the ALDL to reset the IAC, but it didn't seem to have any effect for me. The IAC did a bunch of clicking until I disconnected it. Idle stayed at 1,000rpm and turning the screw did not lower it. Maybe it only works if vacuum leaks are found...?

Eventually I found some issues with vacuum. After squeezing and plugging and poking, it seems the only way I can get the idle to drop reliably is by pulling the thick PCV/canister line (with a "T") and plugging the inlet with my thumb. The motor then gets a tad bit surgy every now and then, but more or less idles from 700-800rpm. I'm not sure where to go from here.

This system was installed in like 2003, so anything could be wrong, but from what I've read there's no great reason why this thing shouldn't start, idle, and run well cold and hot while passing smog. I'm happy to replace vacuum lines or sensors or whatever, but I'm struggling to isolate issues...

 

[mtnwhlr]

Have you tried backing the timing off some?

 

[Tremelune]

I have no timing light, though it is a tool I should own by now...

It needs to be 8° to pass, and it passed a year ago so I doubt the previous owner made changes...That said, who knows how it really passed smog or what previous owners do...

I'll see if I can get my hands on one...Maybe try and smoke out any vacuum leaks...

 

[Posi]

Buy a vacuum gauge if you don't already have one, best diagnostic tool you can own. They can be had for $20. Post your findings.
Do you have any codes?
Are you sure the IAC was fully closed when you disconnected the plug?
The rubber tip of the IAC should be pushed into the hole on the side of the TB (throttle body) closing off any air to the TB. You can look down into the TB to check this.
Even if you had a vacuum leak the idle should drop doing the idle adjustment procedures correctly. The results may change if you have something else going on.
What is your voltage at the TPS with key in the on position with engine off?

 

[Manic Mechanic]

does the howell inject have return springs like the stock carburetor? if so they could be wore out and not pulling the throttle back far enough to allow it to drop correctly. i had a mc2100 that had the same problem. just a thought as i have not messed with the howell kits yet but im looking more and more into them

 

[Posi]

They do have a spring, but the spring design is different then on a carb and far less likely to fail. That doesn't mean they don't lose their pull back strength but I've never seen a TB coil spring fail. You can see the spring in the photo above.

 

[Lumpy Grits]

In CA, the seller has to SMOG it-Not the buyer.......
Use a bottle of very soapy water to look for vacuum leaks.
Get a timing light and a vacuum gauge........
LG

 

[jzak]

I was having idle/surging issues with my Howell TBI. I tried troubleshooting it for months to no avail, so out of frustration I bought a completely refurbushed throttle body unit on ebay for like $AMC 150 . It was easy to switch out, and it solved most of my problems.

 

[mriplaybass]

I had the same problem with a Sniper on a AMC 304 last year. Turned out that the throttle cable would work it's way out of the mounting bracket, and wouldn't allow the throttle to close all the way.

 

[Torxhead]

That timing could very well be the issue as Mtnwhlr suggested, I have mine set at 6 degrees to pass smog and get a good timing advance. If you don't already have a Howell installation manual, you can get one from their website and download it. You did not mention if the check engine light was on or not to indicate any trouble codes. I think you should first make sure your idle air control valve is good as it can get sticky and cause the idle to be on the high side. There is an iac setting procedure which involves jumping the a and b terminal on the aldl connector, turning the ignition to the on position, and listening to the iac click for about 30 seconds. The suggestions of a vacuum leak or throttle linkage are good to consider. If you give up, take it to a GM mechanic and they should be able to figure it out.

 

[Tremelune]

This was a bit half-assed, but I wanted to squeeze in some measurements today...

I think I screwd up resetting the IAC last time I did, because it was not all the way in. Unfortunately, with it confirmed all the way in, there wasn't much of a change.

Timing seems on at 8°, with a fluxuation of maybe 1°.

I attached my vacuum gauge to the "T" pictured above. Seemed like a solid 20Hg, though it varied when revved.

The tube below the "T" with vacuum above had no vacuum, presumably because it's not a vacuum tube...I wasn't particularly scientific...





Some videos (that I don't know how to embed):

http://ensaster.com/pics/vehicles/seasons/smog/timing.mp4

http://ensaster.com/pics/vehicles/seasons/smog/vacuum.mp4

 

[Torxhead]

There are only three ways air can get into the engine: open throttle valve, i.a.c. valve, and vacuum leak. At this point, you might want to bump that ignition timing down even more to see what happens. That i.a.c. valve does look like it is extended all the way also. You might want to try blocking off the iac air inlet on top of the t.b.i. to be sure. Another thing you might want to try is removing all the ground wires from the battery for at least 30 seconds to reset the computer.

 

[Wellstercraft]

I have the same setup in my 1980 CJ7 . When I first installed the kit several years ago, I was living in Ca. and had to get it smoged at the referee station since every other smog station was afraid to touch it. Does your vehicle have an auto Transmission ? If so, the idle will be around 900 rpm in park and will drop to 700 rpm in gear. I pointed this out to the tech who passed the vehicle after verifying my claim.

On a side note, the tech tried to fail my Jeep three times. Once for not having a MAP censor (which it did), once for the high idle, and once for not having the proper egr (which it did). Moving to Nevada was the best thing I ever did!

 

[Posi]

I have the same setup in my 1980 CJ7 . When I first installed the kit several years ago, I was living in Ca. and had to get it smoged at the referee station since every other smog station was afraid to touch it. Does your vehicle have an auto Transmission ? If so, the idle will be around 900 rpm in park and will drop to 700 rpm in gear. I pointed this out to the tech who passed the vehicle after verifying my claim.

I believe your thinking of the AMC 258 i6 / 4.2l manual, and only when the vacuum actuator is energized. Curb idle for a manual is 650-700. Auto 550 in gear and 700 in park.

 

[Tremelune]

I punted. Gave it to a shop and they got it through.

 

[Torxhead]

So just what was the issue?

 

[Lumpy Grits]

YES-tell us what they did.
LG

 

[Fender]

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.

 

[hole]

Cant help with the Howell set-up, but I had to search around for a shop that had an idea how to test our "altered" cars. Out of frustration and anger, I found myself interrogating the smog tech about his knowledge of my set-up (Mopar MPI). I would drive up and open the hood and ask if he knew what I had and how to properly test it. If they stuttered or cocked their head like a confused dog, we were done. It tested my patience and Im sure I offended some guys along the way, but in the end I found The Man. After he ran the test and it passed fine, I asked how/why since the other shop(s) failed it. Without disclosing the "reward" he said the state "rewards" shops that fail older "gross polluters" in their ultimate goal of removing them from the roadway. What he did different was to run the vehicle in a higher gear to keep the Nox down during the MPH test. Born and raised here, but I cant wait to leave this craphole Nanny state.
Rant over... Find yourself a smog guy that loves cars and will work with you to correct the issue(s). If you find yourself in SoCal (Inland Empire), I can point you to an honest shop

 

[Tremelune]

I never really found a solution. I got the idle pretty close with a timing light and some new "T" vacuum fittings, but the smog place I brought it to said the catalytic converter lacked the correct magic numbers on it, so it wouldn't have passed anyway.