Howell TBI Code 22, High Idle, Lousy performance etc.

[timgreene1]

Hi, I am trying to fix/finish a Howell TBI on A 1990 Grand Wag, 360 V8.

Since the day it has been installed, it has thrown a 22 code. Been through 4 TPS with no change. So this past week I have ripped it apart and started over to see what I can find.

1. All vacuum lines have been run according to Howell. I actually find it runs better without the EGR and lower CTO port hooked up. EGR is currently plugged, lower CTO is open, and ported plug on charcoal canister (far left plug) is plugged. I move them around but I don't see any real change.

2. Vacuum is currrently 20

3. I have Win ALDL and have driven around quite a bit with it. TPS is at .02 or 0.00 and most everything else looks the way it is supposed to. I throw a Code 33 once in a while (high MAP) lately but until I get the TPS figured out I don't know if the other codes are really relevant right now.

4. I reset the TPS to .57 and it held for a few minutes. It then dropped to .02 and the idle went up. I can also drive around with perfect idle and when I put it back in park the idle jumps back up to 1200-1500.

5. I have reset the idle air control a number of times. It will usually start right up, go to 1200-1300 RPMS and then I can watch the IAC go from 145-0 and then settle in to 750. Drive around and then I am back at 1200-1500 RPM. It did get stuck at 100 a little while ago which gave it a really high idle as I was driving (nothing like going down the street at 40 mph without your foot on the pedal) but that was a random thing. I honestly think the computer told it to be open.

6. Acceleration is stumbling and it is running very rich. 108's all across the board on the tables. I just took it out an hour ago and then it didn't run rich, the BLM was between 120 and 140, and acceleration was smooth. Put it in park and back to 1500 with a TPS at .02.

7. I get 5 volts from the TPS. I can move the TPS and it will go from .57 up to 5 volts. Its not really smooth but it could be my hand. After 4 though I don't think number 5 will work any different. The TBI will increase speed with it bit its not smooth either. I believe the ground is fine on the TPS as the Coolant temp works on the same ground and that is flawless.

I honestly think the ECM is bad as sometimes it runs well and other times its terrible. The one constant has been code 22. Does anybody have any other ideas of what I should be looking at? Do these ECM's go bad? I can change the O2 sensor but I don't see how that correlates with the idle. I haven't checked fuel pressure yet but again sometimes it does run right so I can't believe that is the issue. Any input would be appreciated. Thanks. Tim

[babywag]

Bad ground/wiring...no reason to go through 4-5 sensors, something else is wrong.

Double check ground connection. Needs to be good clean engine block ground, not body/chassis ground.

If ground is good, and wiring is good, yes pcm could be faulty, but not common.

[timgreene1]

Hi, thanks for the reply. Do you mean the general engine ground or is there one specific to the tbi? Not to sound silly but where do you suggest the ground for the engine block be grounded to? Thanks!!

[babywag]

TBI harness should have a dedicated ground wire(s) and should be attached to the engine block/cylinder head.

Also double check the factory ground strap, and battery to body ground.
Bad ground will cause all kinds of problems.

[men in black]

I had a Howell TBI installed, it keep shutting off and would not start.
The problem was

In my hardness there was two black wires in the same StaKon with heat
shrink tubing them. That was the system ground, they were back by the heater core.

The wires were corroded inside the Stakon and losing connection. I don't know if Howell did this or if it was factory

I soldered the wires together and ran it over to the battery.

There has not been any problems since

[Bill USN-1]

Code 21 Throttle pos sensor above 2.5 volts for 2 seconds when engine speed below 1600 rpm
Code 22 Throttle pos sensor below .2 volt for 2 seconds while engine running

A couple things you mentioned all relate to the grounds since that is what the GM ECM system operates on.

I would recommend physically reading each gnd from the sensor connector to the ECM and to gnd.

Everything you need is listed in the wiring FAQ on binderplanet.
To include the voltage check/grounds spreadsheet you can download as an attachment in the thread.
A change in the TPS or Pk/n signal will cause an unstable idle speed.

[timgreene1]

Update

I ran a dedicated temp ground (some 16 guage wire I has lying around) from block where the ECM is grounded to the battery. Honestly, it seems to have helped a lot with driveability. The stumbling is gone and acceleration is smooth. It isn't running totally rich anymore and the new numbers are between 120-135 depending on how I am driving. Used to be 108 across the board. I have real grounding wires coming today so I can clean that up.

I am still throwing the 22 code and the RPM's are still very high. I reset the IAC to 450 RPM's (a little low), reset the computer, but now it seems that the IAC wants to do its own thing. Sometimes it stays at 145, sometimes it stays at 60, it very rarely goes to 0. Is there a way to test the IAC or is it just getting info from the computer. Put it in park and the RPM's go back to 1,500. I would think with a high RPM, the IAC would automatically close to 0. It doesn't seem to do that. But it does move open and shut so I don't think it is broken.

Jumper A&B
Wait 20-30 seconds, unplug IAC
remove jumper, plug in Winaldl to get RPM's
Adjust
Turn off, plug back in IAC
Turn back on

By plugging in Winaldl am I screwing this up. Also, how do you save these tables. I hit save but I can't find them anywhere? Thanks

[babywag]

seems to be a recurring theme with Howell systems

you may have more than one thing going on

a datalog would help

binderplanet has all kinds of info, read up and post a decent log

[timgreene1]

I will see if I can get a datalog. I have Windows 7 and for the life of me I can't find a log anywhere. I just drove for 30 minutes with the laptop and at the end pushed stop but that doesn't do anything. I hit save table but have no idea where they are going.

I tweaked the idle up a hair figuring that the IAC was over compensating for a low idle. It seemed to work a little better. One think I have noticed is I believe a main issue with the high idle is that the IAC goes open but when I put it in park it stays at the last value. I just put it in park and it was 93 for the longest time on win aldl and it never moved. I turn the car off and turn it back on and it starts out at 145 and then the IAC starts to close and it settles in around 20 with a 725RPM. Same with driving around. Sometimes it is at 100 and the RPM is 825 while the foot is on the brake in drive. I would like to think it is stuck but it can move at other times. Between the IAC and the TPS the whole side of this TBI has a life of its own!!

[addicted]

seems to be a recurring theme with Howell systems

I was thinking that same thing.

[Tripwire]

not quite the same but I had a issue with the same circuit TPS/CTO on my Chevy bucket truck with OEM ignition.

had a bad ground - and believe it or not I went thru two new TPS sensors from Nappa before resolution

Tuner pro clued me in to the issues with the TPS

[firedog]

I may be totally off here and unrelated, but having had some struggles getting my TBI system to play nice once and for all -- I can tell you a couple of things. These ECM's "learn" over a number of starts and drives...so big dramatic changes constantly seem to never get results you can really put your finger on. I would suggest making small changes and driving for 10 starts and drive around...give the ECM some time to play catch up with the new changes.

I also know, that since I put double platinum plugs in mine -- platinum cores and components --- I have gotten much much better performance, the smoothest idle i've ever had and less 'rich' smelling fuel. Make sure your plugs are gapped appropriately too....I think Howell suggests .50 - .55?

Other than that, in my experience...the devil is in the ground. Almost all electrical issues seem to be ground related when there isn't an "obvious" answer.

Don't know if any of that helps, but after monkeying with mine enough, I found those things have made the biggest difference for me.

cheers and good luck

[dahwillys]

Makes me want to keep my carb. I hope the best, I'll keep watch here.

[Bill USN-1]

When installing winaldl you can not allow it to install to the default directory.
Uninstall and then when you install, when it pops up with location, type in C: and then hit return.
That will install it to the c: drive.

Win 7 will save your files in your document history and you will not find them if you leave it at the default.
Also, never have wifi access for the laptop when connecting a data logging cable.
win default is to go to the web for the latest driver first and ignore the disk.

Most of this is covered on the binderplanet but just in case.....

Also ensure your cable does not have a 10k mode jumper enabled or it will affect the idle and log.

You should also follow the initial setup procedures on the binderplanet.
Do them as written.
If you can not properly perform a step then it needs fixed before moving on.

I have helped many, many frustrated Howell and AFI customers that made the mistake of buying one of their kits instead of mine!

Also make sure that all pats of your vehicle are bonded together.
bonding wires between the engine, body, frame, and battery.

[timgreene1]

Thanks for the advice. I have reinstalled Winaldl per the directions of Bill above and am going to take it out for a drive soon. Hopefully I can get some datalogs and post them.

I have run 0 gauge wires from the battery to the body, engine block, alternator, and directly to the grounds for the ECM.

Thanks for the tips and advice.