High Idle 98 S10 2.2L
I'm not clear on your response to one of George's question when you stated you had checked voltages...but did you check the voltage on your 5v reference wire? Meaning:
-Unplug the TPS
-Using a DVOM on the harness side connector, black lead to B(-) post, red lead to 5VREF terminal on the TPS harness side connector (should be gray wire). Just touch the test lead to the terminal, don't stuff it in the connector.
-KOEO you should see 5v. What are you reading?
If you did that already, what voltage did you see?
Second, so I can insure I'm looking at correct wiring diagram, do you have manual or automatic HVAC controls? It is the 2WD truck, correct?
-Unplug the TPS
-Using a DVOM on the harness side connector, black lead to B(-) post, red lead to 5VREF terminal on the TPS harness side connector (should be gray wire). Just touch the test lead to the terminal, don't stuff it in the connector.
-KOEO you should see 5v. What are you reading?
If you did that already, what voltage did you see?
Second, so I can insure I'm looking at correct wiring diagram, do you have manual or automatic HVAC controls? It is the 2WD truck, correct?
From what I've found it looks like there are only three real fixes for this very common issue on 2.2L (seems always after TB/IAC cleaning). Besides the myraid of 'solutions' I read (almost to include standing on your head, rubbing your belly with your left hand as you adjust the TP with your right hand). Assuming everything thing else is good (no vac leak, no component/circuit issue):
1. Some techs found that there can be a backfeed of voltage on the A/C High Pressure Switch 5VREF wire. I would plug the TPS back in, record the TPS and IAC readings for closed and open throttle like you've been doing, then unplug the A/C High Pressure Switch. Then KOEO see if there is any difference in the TPS/IAC readings. I might even cycle the key a few times. I'd even let the truck idle a bit if I didn't see any changes initially. I'd probably do all of the above with the A/C Clutch unplugged next (leaving the High pressure switched unplugged also).
2. Other techs (more the majority) have had to have the PCM flashed.
3. Driving time. This seems to work but apparently it might take a lot of driving and could take days or weeks. PCM has to 'rewrite' all those adaptive values cells under all conditions. No guarantees either.
Some more DVOM circuit diag you can do to rule out the high pressure switch circuit itself. Let us know if unplugging doesn't do anything and we can go more in depth going into that circuit if you need any help there.
1. Some techs found that there can be a backfeed of voltage on the A/C High Pressure Switch 5VREF wire. I would plug the TPS back in, record the TPS and IAC readings for closed and open throttle like you've been doing, then unplug the A/C High Pressure Switch. Then KOEO see if there is any difference in the TPS/IAC readings. I might even cycle the key a few times. I'd even let the truck idle a bit if I didn't see any changes initially. I'd probably do all of the above with the A/C Clutch unplugged next (leaving the High pressure switched unplugged also).
2. Other techs (more the majority) have had to have the PCM flashed.
3. Driving time. This seems to work but apparently it might take a lot of driving and could take days or weeks. PCM has to 'rewrite' all those adaptive values cells under all conditions. No guarantees either.
Some more DVOM circuit diag you can do to rule out the high pressure switch circuit itself. Let us know if unplugging doesn't do anything and we can go more in depth going into that circuit if you need any help there.
Tps voltage is now .44 with throttle closed and 4.2 at wot. It the same whether AC pressure and clutch switches connected. New map sensor reads the same as the old, but the barometric pressure reads below atmospheric pressure for some reason. This new map has no effect on the idle. The truck just wants to idle around 900 RPMs. I guess I'll just have to drive it and see If it eventually goes down since I'm not going to pay to have the computer flashed. I may smoke the intake too, but the idle is always the same no matter what. It seems that it has to commanded to this RPMs.
Thanks for the update. Interested in this case. It just stuns me that so many 2.2L have the same problem after doing TB cleaning.
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JustJerry
1st Generation S-series (1983-1994) Tech
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Feb 1, 2011 01:10 PM




