87 with high idle: no codes
Thread Starter
Drifting
Joined: Jul 2001
Posts: 1,477
Likes: 0
87 with high idle: no codes
Well my father and favorite mechanic is out riding his hog again and won't be back for a few weeks so I am turning to you guys.
The car runs fine and strong, no work has been done to the engine or anything (mods etc), normal maintenance is a given.
it has been sitting for 2 months for the most part, rarely getting ran. Charged up the battery and getting ready to get back to school.
It starts up right away without hesitation.
it idles at 700 or 800rpms when in drive (automatic) normal for this car is 500 or 600.
In park it idles 10k-13k
I have not recieved check engine lights. codes are not showing up with the tester.
ran it on the freeway without a problem, still idles high at 180 degrees and up. have normal thermostat in it and no performance chips.
vaccumm leak or something?
have replaced MAf and relays already a year ago. all fluids are new (even flushed and replaced the brake fluid not that has anything to do with my problem, but you get the idea that I maintain the car)
thanks...
The car runs fine and strong, no work has been done to the engine or anything (mods etc), normal maintenance is a given.
it has been sitting for 2 months for the most part, rarely getting ran. Charged up the battery and getting ready to get back to school.
It starts up right away without hesitation.
it idles at 700 or 800rpms when in drive (automatic) normal for this car is 500 or 600.
In park it idles 10k-13k
I have not recieved check engine lights. codes are not showing up with the tester.
ran it on the freeway without a problem, still idles high at 180 degrees and up. have normal thermostat in it and no performance chips.
vaccumm leak or something?
have replaced MAf and relays already a year ago. all fluids are new (even flushed and replaced the brake fluid not that has anything to do with my problem, but you get the idea that I maintain the car)
thanks...
Drifting
Joined: Mar 2001
Posts: 1,636
Likes: 3
From: Lafayette IN
Re: 87 with high idle: no codes (Lv2Driv)
Sounds like a vacuum leak of sorts. I would reset the IAC (as per Lars' tech tip) since you mention the battery had to be charged. Any time I disconnect the battery, I try to remember to check out my IAC counts to make sure it is still acting like it needs to. Every once in a while, it gets "confused" but usually only when combined with another small problem.
If you don't have a scanner to check IAC counts, just reset it. If the problem is still there, check for vacuum leaks...mainly under the TB and the line for the brake power booster.
Good luck, -Matt-
If you don't have a scanner to check IAC counts, just reset it. If the problem is still there, check for vacuum leaks...mainly under the TB and the line for the brake power booster.
Good luck, -Matt-
Advanced
Joined: May 2002
Posts: 53
Likes: 1
From: Los Altos CA
Re: 87 with high idle: no codes (Lv2Driv)
Check to see if your IAC is working. I believe you can do this by unscrewing the IAC motor from the throttle body. With the connector on, turn the ignition on. The motor should extend fully out to seat the pintle and then retract. This happens either when the ignition switch is first turned on, or when it's switched off. It's been a long time, but I used to work at GM on emission control systems.
The other thing to check is to see if you have a zero setting from the throttle position sensor (TPS). Check the service manual to see what the right voltage (or resistance) should be at idle and then check with a multimeter. If the manual says voltage, you check with the ignition switched on. If it says resistance, you check by disconnecting the connector from the TPS, and measuring the resistance across the right terminals. If the engine computer doesn't see the right voltage, it thinks the car is not at idle and the idle control algorithm doesn't kick in to control the idle speed.
The other thing to check is to see if you have a zero setting from the throttle position sensor (TPS). Check the service manual to see what the right voltage (or resistance) should be at idle and then check with a multimeter. If the manual says voltage, you check with the ignition switched on. If it says resistance, you check by disconnecting the connector from the TPS, and measuring the resistance across the right terminals. If the engine computer doesn't see the right voltage, it thinks the car is not at idle and the idle control algorithm doesn't kick in to control the idle speed.
