Idling problem - CEG Archives

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For a while now I have been having a problem with the idle. Whether in park or in drive the idle will jump 50 to 100 rpm's over and over. So, yesterday I pulled out the ole trusty Haynes manual and checked some components and their specs. I cleaned the maf, checked the idle increase solenoid and it's diode for proper operation, that checked out. This is where I got confused, I then checked the IAC valve, the manual says to connect 12 volt power source, + to the green/yellow and - to the black yellow and you should hear a distinct click noise, I did hear that noise. Then it says that if you don't hear that noise to check the resistance across the two terminal. The resistance was 17.6 ohms, but to be within specs the manual says it should be 6 to 14 ohms. Does this mean that even though the valve clicked, that it's faulty since it's resistance is out of range? Anyone that can offer help/advice please chime in. Thanks

So much for trying to get any help, huh?

i would say that it probably is not working...when mine whent bad, it would clik on and off repeatedly (or opened and closed) and it would casue the idle to rise and fall by over 1500 RMPS!!! my families mechanic replaced with my Timing belt, waterpump, serpentine belt and all my fluids...and a rear wheel bearing

I ordered a IAC from O'reilly's, cost me 50 bucks. I hope it solves my problem. I'll post my results once I get it on.

heh, good luck changing it, plan on a new IM gasket, cause you might have to remove it to get easier acess, its as much of a bitsh as the block heater/freeze plug...

Originally posted by Stryker:
heh, good luck changing it, plan on a new IM gasket, cause you might have to remove it to get easier acess, its as much of a bitsh as the block heater/freeze plug...

I can get to it pretty easily. When I tested it, all I did is remove all intake components and removed a torx screw from the bracket that holds the fuel lines and I just lifted them up out of the way to where I could get my hands in there. I'll just do the same thing when I go to take it out.

For me, if the idle started surging up and down, it was always just a dirty MAF symptom. Good to know there is another thing that can cause it.

Originally posted by Paul Kienitz:
For me, if the idle started surging up and down, it was always just a dirty MAF symptom. Good to know there is another thing that can cause it.

I wish that's all it was, would be a cheap fix. I have cleaned it and it didn't do anything. Anyways...here's an update to replacing the IAC. Took me about 30 minutes to get the old one off and put the new one on. Unfortunately, that didn't fix my problem

Anyone have any other suggestions? I have cleaned maf, replaced pcv valve, cleaned throttle body, replaced egr valve, replaced dpfe, checked idle increase solenoid (was good), the air filter is still clean. What am I missing? Maybe a new PCM

Originally posted by emartinez13:

Originally posted by Paul Kienitz:
For me, if the idle started surging up and down, it was always just a dirty MAF symptom. Good to know there is another thing that can cause it.

I wish that's all it was, would be a cheap fix. I have cleaned it and it didn't do anything. Anyways...here's an update to replacing the IAC. Took me about 30 minutes to get the old one off and put the new one on. Unfortunately, that didn't fix my problem Anyone have any other suggestions? I have cleaned maf, replaced pcv valve, cleaned throttle body, replaced egr valve, replaced dpfe, checked idle increase solenoid (was good), the air filter is still clean. What am I missing? Maybe a new PCM

Did you disconnect the negative battery cable for 15 minutes to re-set the computer? If not that could be your problem. After you remove it for 15 minutes and reconnect it the first thing you want to do it put it in Park for 1 minute at least, running so it re-learns idle, then drive all around, the see if your problem is still there.

You know what, I didn't do that and I thought about it but I didn't think it would make a difference. I am going to try it. Just out of curiousity, why should it be necessary to do that? I mean you would think that if you replace the malfunctioning part that it would automatically just work, but I guess not. Thanks for the suggestion.

Something I just remembered, shouldn't the computer be reset by pulling fuse 4 and 11 rather than by the negative cable? Or will both do the job?

Originally posted by emartinez13:
You know what, I didn't do that and I thought about it but I didn't think it would make a difference. I am going to try it. Just out of curiousity, why should it be necessary to do that? I mean you would think that if you replace the malfunctioning part that it would automatically just work, but I guess not. Thanks for the suggestion.

Something I just remembered, shouldn't the computer be reset by pulling fuse 4 and 11 rather than by the negative cable? Or will both do the job?

Yup, 4 and 11, less time/effort consuming.

Where are 4 and 11 at?

Originally posted by Kremithefrog:
Where are 4 and 11 at?

They are in the fuse box under the hood, next to the battery.

Originally posted by emartinez13:

Originally posted by Paul Kienitz:
For me, if the idle started surging up and down, it was always just a dirty MAF symptom. Good to know there is another thing that can cause it.

I wish that's all it was, would be a cheap fix. I have cleaned it and it didn't do anything. Anyways...here's an update to replacing the IAC. Took me about 30 minutes to get the old one off and put the new one on. Unfortunately, that didn't fix my problem Anyone have any other suggestions? I have cleaned maf, replaced pcv valve, cleaned throttle body, replaced egr valve, replaced dpfe, checked idle increase solenoid (was good), the air filter is still clean. What am I missing? Maybe a new PCM

I'd suggest checking the TPS sensor. It's just a 3 wire pot.

Originally posted by emartinez13:

Originally posted by Kremithefrog:
Where are 4 and 11 at?

They are in the fuse box under the hood, next to the battery.

I know, I meant like, how do you know which is 4 and 11?

Originally posted by Kremithefrog:

Originally posted by emartinez13:

Originally posted by Kremithefrog:
Where are 4 and 11 at?

They are in the fuse box under the hood, next to the battery.

I know, I meant like, how do you know which is 4 and 11?

When you take the cover off the fuse box, it has a diagram on the fuse box cover on the inside, and it tells you which fuse is which.

Originally posted by fdunford:

Originally posted by emartinez13:

Originally posted by Paul Kienitz:
For me, if the idle started surging up and down, it was always just a dirty MAF symptom. Good to know there is another thing that can cause it.

I wish that's all it was, would be a cheap fix. I have cleaned it and it didn't do anything. Anyways...here's an update to replacing the IAC. Took me about 30 minutes to get the old one off and put the new one on. Unfortunately, that didn't fix my problem Anyone have any other suggestions? I have cleaned maf, replaced pcv valve, cleaned throttle body, replaced egr valve, replaced dpfe, checked idle increase solenoid (was good), the air filter is still clean. What am I missing? Maybe a new PCM

I'd suggest checking the TPS sensor. It's just a 3 wire pot.

Well, I tried to test the TPS but I couldn't since it's so close to the firewall, couldn't get my hands behind it nor could I see the terminals to make sure i'm testing the correct ones. Any suggestions? Other than taking it off the throttle body?

Originally posted by emartinez13:

Originally posted by Kremithefrog:

Originally posted by emartinez13:

Originally posted by Kremithefrog:
Where are 4 and 11 at?

They are in the fuse box under the hood, next to the battery.

I know, I meant like, how do you know which is 4 and 11?

When you take the cover off the fuse box, it has a diagram on the fuse box cover on the inside, and it tells you which fuse is which.

Yeah, I found it, I don't know why I never noticed it before.

Hey just trying to do my part here- bad MAP sensor? I had a 89 Ford Tempo have one go bad, and it kept reving from low to high on it's own. That's my $.02...

I don't think these cars have MAP sensors...did you mean a MAF sensor, maybe?

Originally posted by Kremithefrog:

Originally posted by emartinez13:

Originally posted by Kremithefrog:

Originally posted by emartinez13:

Originally posted by Kremithefrog:
Where are 4 and 11 at?

They are in the fuse box under the hood, next to the battery.

I know, I meant like, how do you know which is 4 and 11?

When you take the cover off the fuse box, it has a diagram on the fuse box cover on the inside, and it tells you which fuse is which.

Yeah, I found it, I don't know why I never noticed it before.

U also have this thing on the inside of the fuse cover - to pull them fuses out - dunno whatchamacall it though

Originally posted by RGSOUNDF:

Originally posted by Kremithefrog:

Originally posted by emartinez13:

Originally posted by Kremithefrog:

Originally posted by emartinez13:

Originally posted by Kremithefrog:
Where are 4 and 11 at?

They are in the fuse box under the hood, next to the battery.

I know, I meant like, how do you know which is 4 and 11?

When you take the cover off the fuse box, it has a diagram on the fuse box cover on the inside, and it tells you which fuse is which.

Yeah, I found it, I don't know why I never noticed it before.

U also have this thing on the inside of the fuse cover - to pull them fuses out - dunno whatchamacall it though

Yeah I know all bout it. I just never even looked. I just always disconnected the battery.

Originally posted by emartinez13:

Well, I tried to test the TPS but I couldn't since it's so close to the firewall, couldn't get my hands behind it nor could I see the terminals to make sure i'm testing the correct ones. Any suggestions? Other than taking it off the throttle body?

Just throwing in some ideas...

A simple test is just to unplug it, drive the car around, and see what happens. Try disconnecting all the sensors you suspect (MAF, TPS, DPFE) one at a time and drive the car a bit.
(You'll have to reset the ECU after each).

did you check the ECT (the one pointing upwards) and the IAT ?

how much voltage do you measure at the battery while idling ? just a guess, but your symptoms can be caused by fluctuating voltage as a result of a misbehaving alternator or a sudden electric load increase by something.

Are you sure the idle surges are not related to the fan operation ?

T.

On my 98 Mercury Mystique it likes to idle funky from time to time. I had someone look at the IAC and they said it was fine. I did have a code once on the MAF, but cleaned it and now that is fine. I've also checked some other parts that controls the AC sensor (Forgot the Part) and it was fine as well.

I swear when I move some wires around in the front of the car it does the idle searching problem, but I can't pin point the problem.