1200-1900rpm high idle, still dont know what it is

[n0rt0npr0]

89 Chevy Celebrity 2.8L

Vacuum at 1200rpm is 22lbs
Can't find any vacuum leaks

New IAC

And this is an intermittant high idle; fixed if I unplug the battery for a minute.

If anyone has any suggestions after looking at the attached data, I'd appreciate them.

~Will

[pontiacdohc@gmail.com]

have you tryed the idel relearn http://60degreev6.com/showthread.php?t=25023

[n0rt0npr0]

have you tryed the idel relearn http://60degreev6.com/showthread.php?t=25023

Yes I have, and if I do that, it gives me the least amount of time before it goes into high idle. really strange

[pontiacdohc@gmail.com]

did u replace to TPS? and has someone messed with the set screw befor u owned this

[n0rt0npr0]

did u replace to TPS? and has someone messed with the set screw befor u owned this

Yeah I replaced the TPS(it ran fine after for a bit, but went right back to being wierd), why is the voltage wrong or off in the picture? Throttle is closed in the pic...

The set screw has never been touched.

[pontiacdohc@gmail.com]

i have no clue on data but i had a 86 cleb that had a 2.8 and the my tps was messed up so i moved the set screw up a little so it wouldnt stall and when i put the new one on i forgot i mesed with the set screw and my RPM's were about that,did the same thing with my GTP,GTP reved to 3000 and hit limter that sucked!

[TazMan]

Do you get a check engine light? Have you checked for computer codes? You don't need a scanner. With the ignition off just short pins "A" and "B" (the 2 pins on the top right and bending a paper clip works great for this) on the 12 pin Data Link Connector. Then turn the key to the on position but DON'T try to start the car. The electric fan will probably come one and the check engine light will blink a code "12" (First 1 blink, then 2) three times to let you know it is doing the diagnostic. Then if there are any codes it will blink each code three times. Then it will blink the code 12 again to let you know it is finished. Turn it off and pull out the jumper. If all you get is "12", then the codes are good. IF you get any codes, check a haynes manual or if you don't have one, post them and I will check mine.

[n0rt0npr0]

No Codes

I wish I did have SES codes, but I have nothing. Just a high idle. It's learning to high idle for some reason, I don't know.

I DO get code 12, system okay fyi
And I've tried another computer, no codes with it either, just same high idle

[bszopi]

IAC valve issues? When you unplug the battery, then hook it back up, the IAC may cycle to allow for a good idle. But as the ECM "learns", it could be commanding the IAC to do something different? Just a thought... Although I am leaning towards to TPS as well. Its an older TPS, so it has the elongated holes to allow for adjustments. Loosen the screws and rotate the TPS and see if that does anything.

[n0rt0npr0]

IAC valve issues? When you unplug the battery, then hook it back up, the IAC may cycle to allow for a good idle. But as the ECM "learns", it could be commanding the IAC to do something different? Just a thought... Although I am leaning towards to TPS as well. Its an older TPS, so it has the elongated holes to allow for adjustments. Loosen the screws and rotate the TPS and see if that does anything.

I don't know what the steps on the IAC are after a fresh restart yet, but I bet I will find that they are way different than 40 like in the picture. So for some reason its learning to use the IAC to high idle. So I will try moving the TPS around (it is the adjustable design) first, then I will reset and record the step count on the the IAC. I'll let you know...
Thanks,
~Will

[n0rt0npr0]

I loosened the tps and moved it(it only has 3/4 of a millimeter worth of movement anyway), no change whatsoever. Later on tonight I will check the step count as I have reset the ECU. till then...

[geoffinbc]

Ok hang on one sec here.

First test. Turn the key on (engine off) and jump pins A and B. This commands the IAC closed you should hear it driving. Then start the car and see if the high idle is gone. If it is then your IAC is being commanded open. If it still idles high there is something else going on.

Your printout does not say if you aere in open or closed loop. But if it was in closed loop your BLM is way off and it should be around 128.

Try those tests first and get the car in closed loop, if it can.

[n0rt0npr0]

Alright I've yet to reset using the a+b method, but last week I reset by cutting power to the ecm and when I did the step count after idle re-learn mode had finished up was 16, 690rpm idle. BUT after 4 hours of driving, it kicks up the step count to 41 with the foot off the throttle. (1300-1800rpm)

I'll try the a+b reset method as soon as I can and post here... and yes the ecm goes into closed loop. (quickly too)

[geoffinbc]

Was that printout done in closed loop?

[n0rt0npr0]

Was that printout done in closed loop?

Yes that printout was during closed loop. And I just tried that a+b reset and the idle still raises up. The idle will quickly but gradually climb up to like 1800 rpm. I think the IAC is learning to be commanded open. Especially since the step count at ecm reset is only 16, but 4 hours later is 41.