OK before I get jumped for not searching archives on this all too common problem, I have done so. Here is my issue and what I have done so far in my troubleshooting efforts. My engine will idle around 3k sometimes, well most of the time but not consistantly ALL the time. I was getting a code 22 (TPS low voltage) I bought a new TPS and unlike my stock one, this one was adjustable. The guy told me to bolt it on centered and the ECM would take care of the rest. I installed it, removed the fuse to the ECM for 30 seconds, replaced it and started it up. Idle was fine till I went to drive it, stumbled like crazy on take off. I went to the wrecking yards this weekend and got 4 TPS modules, 4 IAC modules, and 2 injectors. (I havn't messed with my injector, was just collecting em) I then spent some time swaping through the TPS modules I had (no stumble with the stock ones) removing the ECM fuse between each TPS swap (I read here on another post that this can be done instead of removing the Neg batt cable) Now I began to see code 35 (IAC fault) I then began swapping out the IAC module in the same manner as I did with the TPS untill I went through all 4 of them. No change. Most of the time it idles at 3k but not always. I checked for vacuum leaks in the vicintity of the Throttle body. I also read that a good way to test for vacuum leaks is with the IAC removed and the engine running, plug the hole where the IAC goes... if engine continues to run; there is a vacuum leak... this was not the case. I have replaced all my old vacuum tubing. But if there is a problem caused by a vacuum leak, won't the problem be consistent? The next thing I was planning to do was buy a rebuild kit for the Throttle body, Maybe the gasket between the throttle body and intake is bad? I thought before I go spending all kinds of $$ I would check in here to see if I missed something like other places to check for leaks, etc...? I am currently getting codes 22 and 35 all the time now. Oh I forgot to mention I also swapped out the MAP sensor a couple times, just because I had them on hand, didn't change anything.

Thanks for reading my troubleshooting novel...hope I was thorough enough

Mike

The ECM needs to relearn the engine after every time it's reset or something is changed. To do so, you need to drive it at speeds above ~45 MPH. If you haven't, you'll have no way of knowing what your changes have done.

For how long will I need to drive over 45? I took it on my commute today (30 miles each way average 70-75mph)

Only for a few minutes. This just needs to be done every time the ECM is reset for changing out TPS or IACs.

3000rpms is just to high of a idle, did you check your egr tube, its sounds like a vacum of some sort , the reason being is the 3000rpms, it should be 1/2 of that on cold start up, then idle down to the general area of 850-950rpms, another way to avoid throwing money at it is to run the winaldl on it, that will pin it down pretty quick.
www.aldlcable.com
http://winaldl.joby.se

FYI: there is a common misconception out there that pulling the ECM fuse will clear its memory.

It will not.

The 10 amp ECM fuse is for the circuit which powers up the ECM when the key is turned to run, start, or bulb test. Pulling this fuse is just like leaving the key in off or acc.

If you want to clear the ECM's memory, you have to either disconnect the negative battery cable, or disconnect the single orange wire with a weather pak connector which can be found near the battery, just below C500. This orange wire supplies 12v to the ECM at all times to keep its memory "alive".


BTW the code 35 doesn't necessarily mean that the IAC is bad, it simply means that the ECM was unable to maintain the idle within 50rpm of spec. Since you haven't yet actually reset the memory properly, there's no way of knowing whether the trouble codes you're seeing are current, or old ones. Try a full reset, go for re-learning drive, and evaluate the results.

Regarding your code 22--key on, engine off, try probing pins A and C of the TPS connector with a voltmeter. Pin A (grey wire) should show a steady +5v. Pin C (black wire) should show a ground. The reading from each pin should not fluctuate, even if you shake the harness about.

edit: and you do know that a used TPS may be just as faulty as your original one, right? TPS's have a tendancy to physically wear out in the section that the throttle spends most of its time moving through. If you have access to an osciliscope or an analog ohm meter, set up to measure the resistance between the TPS's center pin and one of the end pins while slowly moving the lever from one end of its travel to the other. A worn TPS will look like a bunch of electrical noise on the 'scope, or jumpy movement from the analog meter.

[This message has been edited by dguy (edited 06-13-2006).]

Thank you 3800 for the links, I have ordered the aldl cable. I noticed when I clicked

https://www.aldlcable.com/sc/pages.asp?pageid=20

There is like 15 different programs including winaldl. Are all these pretty much the same or is one easier to use for beginners.

I have a brand new TPS, but it's adjustable. Can it be mounted at the center of it's adjustment and after resetting the ECM function properly or do I need to manually adjust it?

Thanks for all the info

I know you said you searched the archives, but this thread has a lot of relavant info.

Also, the 2.5L engine doesnt have an EGR tube, only the V6 does.

I disconnected my negative battery cable and re-installed the new adjustable TPS, then reconnected the battery cable. Before starting the car I checked for codes. All was clear. After my first drive (to work) with reset ECM and new TPS, I imediately got a check engine light. Checked it when I got to work, code 22 TPS low voltage, Idles a sweet 900rpm now but under swift accelleration it always stumbles after shifting to 2nd (not so much if I am slowly accellerating) it has been 60 freeway miles and still stumbles in 2nd with a code 22. Thank you USFiero for that link it was very helpful.

Mike

Damn! All was fine for a while, now back to that intermittent High idle. Gonna try rebuilding the throttle body next. Would a bad o2 sensor cause periodic high idle? Not getting a code for o2 sensor, but it's the only thing I havn't yet checked, aside from my pending TB rebuild...

Have you tried winaldl yet ?

Can't get it to work on my 87 duke 2.5, and after researching this, found out here in a few posts that winaldl won't support this ECM, at least not without some programming tweeks that are a bit over my head.

I did get the cable you recommended though and am in the process of getting it working for my 88GT which I found IS supported by winaldl

[This message has been edited by perceptionist (edited 06-22-2006).]

I had this same problem with my 86 Duke, it would idle at 3000 rpm, and stutter under acceleration, then when sitting at idle at a light it would rough idle at 700 rpm and spit black smoke out the tail pipe. So I changed my O2 sensor which cost me $32(canadian) and the problem was solved. I still have a vacuum leak which makes my car idle at 2500 rpm or so.

From what I recall when I was posting on this topic asking for help, everyone told me that for a Duke, 3000 rpm is relatively normal for cold start idles.

Oh, BTW, the new TPS from the store has to be adjusted, your ECM does not adjust to it, I beleive there is some sort of set screw or notches on the TPS and it has to be installed at a certain angle in the TB for it to be correct. Your best bet is to use one of the used TPS's that dont set the code and trouble shoot from there. IAC's and TPS's are expensive, its best to start with the little things that need to be replaced anyways as regular maintenence like your O2 sensor. Give it a shot...

Thanks indyfiero2m4 for you info. Maybe It's time for another trip to the wrecking yards. I can collect some o2 sensors to go through. I might be able to adjust that TPS if Winaldl worked on this ECM I gought a kit yesterday and am going to clean/rebuild my TB this weekend and check for this carbon build up I hear so much about in the EGR passage. My high idle only happens some of the time which is why I have ruled out a vacuum leak... we'll see...

I've had idle problems as well on my '87 duke auto. I replaced the TPS and had start up idle change from 2000-2500 to the "normal" 1500.

I also had several instances where the idle would get stuck at 3000-3500rpm when in nuetral or park. The day after I replaced the TPS and about two weeks later, I had this high idle "stuck" problem again. Been ok for a month or so since then.

My 2 cent contribution: Another thread mentioned the throttle cable will wear out and stick. In my case, in the "stuck" mode, pushing the gas while in nuetral usually resulted in a higher idle and it eventually slowly comes down and everything is normal. If it happens again, I'm looking at the cables before it returns to normal idle.

Brian

Ok I disconnected my Neg batt cable and cleaned/rebuilt my TB last night. In the process I checked resistance on one of the TPS units I got from the junkyard, it had no flat spots so I used it. TB was pretty clean but I am glad I replaced the gaskets. When I finished, I needed to set the idle screw a few turns more than it was before just so it would start/Idle without giving it gas. Took it for a test drive on the freeway for about 10 miles. It ran and idled PERFECT!! I was still a bit concerned about the idle screw set higher than usual as after my test drive it was idling a bit high so I backed out the Idle screw till it was idling smoothly at around 900 RPM. At this point my Service engine soon light came on. (code 35 IAC) I turned the car off and tried to start again, wouldn't start without giving it some gas or turning the idle screw back in. I tried a couple different 'Salvaged' IAC units with same results. Is there a way to check the IAC unit or the signal/current supply that goes to the IAC? I am pretty sure it's one or the other and want to be sure before wasting $$$ on a new IAC for no reason.

The service manual has the iac connector test --I think it also has the iac out lined, look up dodgerunner for a easy manual check of the iac--or it will be in the archives. If I had a scanner I would be glad to run it off for you--but unfortunatley I don`t have one.