another idle thread

plasticpower02 · Sep 20, 2009

the car:
'90 5-speed gsx

description of issue:
When i start the car,it idles steady at 1,500 rpm. then almost immediately climbs up to 3,000 rpm,again steady and stays there.

parts changed/checked:
IAC (black one)
rebuilt eprom '90 ECU (old one DID have bad IAC drivers)
spark plugs and wires
TPS set at .49 ohms (checked 3 times)
BISS is all the way in

This is the last thing keeping me from driving this car since I bought it from a friend a few months ago.Although I havent checked for boost leaks yet (waiting for a tester from boostpro), I am pretty confident this isnt the problem or atleast not the whole problem.What else could it be?

plasticpower02 · Sep 20, 2009

come on guys.nothing?

Dsmj89 · Sep 20, 2009

Have you done a boost leak test ?
Also not sure but i myself am having idle problems as well and have thought about changing my temp. sensor, i'd say take a look at this, as well as check to see if you have a stuck thermostat.

plasticpower02 · Sep 20, 2009

Dsmj89 said:
Have you done a boost leak test ?
Also not sure but i myself am having idle problems as well and have thought about changing my temp. sensor, i'd say take a look at this, as well as check to see if you have a stuck thermostat.

At this point,it couldn't hurt.I'll check tomorrow after work.Thanks for suggestion.

Dsmj89 · Sep 20, 2009

No problem. Let me know if it worked.

yokotabrat · Sep 20, 2009

Couple other things to check:

Make sure the throttle cable isn't pulling the throttle plate open.
Make sure your idle switch is working properly.
Has the throttle body been rebuilt? If so, was the idle switch moved at all? There's a very specific procedure in the manual for setting the idle switch as it's also the throttle stop.

steve · Sep 21, 2009

plasticpower02 said:
description of issue:
When i start the car,it idles steady at 1,500 rpm. then almost immediately climbs up to 3,000 rpm,again steady and stays there.

parts changed/checked:
IAC (black one)
rebuilt eprom '90 ECU (old one DID have bad IAC drivers)
spark plugs and wires
TPS set at .49 ohms (checked 3 times)
BISS is all the way in

Sounds like it no longer has a 90 Throttle Body. Make sure that the new TB has a ground to the intake or firewall. This is required to make the IPS work.

It's time to make a fourth pass on the TPS and this time set it correctly. 0.49 ohms isn't a valid measurement. It should be 0.48 to 0.52 volts with the throttle closed. That the same as about 10% on a datalogger.

You seem to have some serious vacuum leaks or the throttle cable is holding the throttle open. Make sure you have 1-2mm of slack in the cable. If the IPS was working correctly you would see idle surging badly.

plasticpower02 · Sep 21, 2009

steve said:
Sounds like it no longer has a 90 Throttle Body. Make sure that the new TB has a ground to the intake or firewall. This is required to make the IPS work.

It's time to make a fourth pass on the TPS and this time set it correctly. 0.49 ohms isn't a valid measurement. It should be 0.48 to 0.52 volts with the throttle closed. That the same as about 10% on a datalogger.

You seem to have some serious vacuum leaks or the throttle cable is holding the throttle open. Make sure you have 1-2mm of slack in the cable. If the IPS was working correctly you would see idle surging badly.

I'll take a picture of the throttle body in a few minutes so someone can confirm.And your right about measuring the TPS.I was having a VERY bad day saturday so I accidentally measured in ohms :shhh:

.Ok so I'll do those two things and post my results.

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another idle thread

plasticpower02

plasticpower02

Dsmj89

plasticpower02

Dsmj89

yokotabrat

steve

plasticpower02

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