High idle
Thread Starter
Safety Car
Joined: Oct 2000
Posts: 4,282
Likes: 172
From: Lake Wylie, South Carolina
High idle
My 1990's idle is probably 1800. I am guessing a little since the tach doesn't work. I have looked all over for vac leaks but not found any. What else could it be?
Team Owner
Joined: Sep 2003
Posts: 25,393
Likes: 2,741
If the car is a C68 (ATC) RPM can be retrieved from the AC Control Panel. A C60 car it can't be. Get access to a scanner, hand held tach to get proper RPM I'd think for a start. A guess at 1800? 1800 is very high.
Last edited by WVZR-1; Apr 15, 2018 at 09:20 AM.
Thread Starter
Safety Car
Joined: Oct 2000
Posts: 4,282
Likes: 172
From: Lake Wylie, South Carolina
It is an ATC car. I am selling it so trying not to spend the money on a scanner. Is there a way to disagnose without a scanner?
Melting Slicks
Joined: Oct 2016
Posts: 2,024
Likes: 363
From: Central Alabama
Without a scanner you'll spend more money swapping parts then you'll spend on the scanner.
Too many inputs in the equation to guess. For example, temp sensor, MAF sensor, O2 sensor, IACV position.
Also could be worn throttle body bushings holding the butterflies open.
Data from the ECM will point to the problem.
Team Owner
Joined: Jul 2004
Posts: 28,460
Likes: 3,288
From: Hartford WI
Find a facility to do it for you? Throw parts till it works or hopefully someone nearby can lend you one. If I had to buy your car in that state, I'd definitely offer you way less since I have no idea what the problem is. It might be worth it to get a scanner or get it fixed or at least diagnosed.
Thread Starter
Safety Car
Joined: Oct 2000
Posts: 4,282
Likes: 172
From: Lake Wylie, South Carolina
Find a facility to do it for you? Throw parts till it works or hopefully someone nearby can lend you one. If I had to buy your car in that state, I'd definitely offer you way less since I have no idea what the problem is. It might be worth it to get a scanner or get it fixed or at least diagnosed.
Finding someone that has a clue working on these cars has been difficult. Supposedly Advance auto will run a scan and get at least some idea as to what is going on. At least that is what I have been told.
It also has a check engine light on it. I have replaced the temp switch, MAF and O2. I checked the IAC and the plunger is moving freely. Does that mean it is good or could it still be bad?
Thanks
Wade
Team Owner
Joined: Jul 2004
Posts: 28,460
Likes: 3,288
From: Hartford WI
Finding someone that has a clue working on these cars has been difficult. Supposedly Advance auto will run a scan and get at least some idea as to what is going on. At least that is what I have been told.
It also has a check engine light on it. I have replaced the temp switch, MAF and O2. I checked the IAC and the plunger is moving freely. Does that mean it is good or could it still be bad?
Thanks
Wade
It also has a check engine light on it. I have replaced the temp switch, MAF and O2. I checked the IAC and the plunger is moving freely. Does that mean it is good or could it still be bad?
Thanks
Wade
If it has a check engine light you can short the terminal to get the code that MAY give you a direction to look at
Thread Starter
Safety Car
Joined: Oct 2000
Posts: 4,282
Likes: 172
From: Lake Wylie, South Carolina
What you need is data that the ECM is seeing. What does it want idle to be? What does it see as coolant temp, oil temp. What IAC count is. Someone could chime in and give you a rough idea what the MAF value should be
If it has a check engine light you can short the terminal to get the code that MAY give you a direction to look at
If it has a check engine light you can short the terminal to get the code that MAY give you a direction to look at
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Team Owner
Joined: Jul 2004
Posts: 28,460
Likes: 3,288
From: Hartford WI
Have an infra red thermometer to scan the sensors while you are at it. It's nice to know that the ECM sees the IAT at 95 and the thermometer is pretty close to it on the scan, for example. Also, you will be able to see what the command idle is. If the ECM demands 2000, you need to know what makes it think that. If the ECM sees 0 IAC counts, turn the adjustment screw on the TB out, rev and repeat. If the screw is maxed out, you have an air leaks somewhere. Maybe in the mating surfaces or maybe on the hose. Ask me how I know.
