90 PA will not idle

I have a 90 Park Avenue that has just developed a problem idling. It is inconsistent but will not idle well. It falls off and will die. As long as I keep slight pressure on the accellerator it will idle but if I let the ECM control, it will die. Noticed it shortly after a tank fill up and thought it was bad gas but it runs great and will idle fine as long as I keep a little on the accelerator. Didn't get any codes for a long time. I changed the fuel filter and didn't fix it. took the breather off and noticed a lot of soot in the plenum, don't know why. Acted like the EGR (electronic pulser type with 3 solinoids) might be bad so I took it apart and cleaned it up good, didn't fix it. Checked the voltage off the battery, 13.5 stopped and 14.4 running. Cleanned battery terminals since they were corroded even though I don't think it's an electical problem. Finally got a code 23 (mixture control solinoid circuit) so I found the idle air control, took it out cleaned it, didn't fix it. So I bought a new one ($60), It seemed to fix it, but after a while it went back to doing the same thing just not as often or as bad. The new IAC took a little while of driving to settle in and calibrate it's self, which the instructions said it would. Determined that a code 34 was also generated at some point earlier in the process, high manifold pressure. I hope I have the correct code table, I'm not very happy with the repair manual I bought, it's way too general and covers too many makes and models although not well for my PA.

Any thoughts would be appreciated. Can't really afford to take it in and have a pro fix it. I don't give up easy on a troubleshooting problem.

Park Avenues are great cars... just wish I could afford a newer one.

maybe take the throttle body off and give it a clean as well. seeing as u got a new iac in there.
just a thought
layta

Use a can of carberator cleaner and spray it inside the throttle body. All the nooks and crannies. You will be amazed at what comes out. That sooty build up comes from the PCV and builds up over time.

If you sprayed carb cleaner in the TB then you killed your mass air sensor. the element cannot get exposed to cleaners and breaks down and dies. You will definetly have a bad idle and poor economy and performance once that was done.

If you sprayed carb cleaner in the TB then you killed your mass air sensor. the element cannot get exposed to cleaners and breaks down and dies. You will definetly have a bad idle and poor economy and performance once that was done.\


Then I better start ordering about 200 MAF sensors since I have been cleaning them with carb cleaner for the last 12 years. Carb cleaner has no effect on the MAF sensor.

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Then I better start ordering about 200 MAF sensors since I have been cleaning them with carb cleaner for the last 12 years. Carb cleaner has no effect on the MAF sensor.


http://www.automotiveforums.com/t195507.html

There it is on this Forum. The reason being is there is residues left behind that cause improper readings. Clean at will..

The reason i say this is I have seen and have done cleanings with TB cleaner and brake cleaner and gumout etc. it leaves a residue on the mass air sensor element that causes a improper reading. cleaning with electrical part cleaner at radio shack is best but it has to be oil free. we can agree to disagree, but my basis is on exprience in doing this also.

One word BULLSHIT!

Just because someone posted this in a topic doesn't make it true.

SaabJohan
The best way to clean an airmass sensor is by its self cleaning function which heats it up to around 1000 degC.

The does not happen, there is no self cleaning function. Even the part about 1000 deg C, think about it the MAF is a plastic part do you really think it can handle 1000 deg C?

I agree with you about the residue that is left using brake clean or some carb cleaners but the little that is left has no harmful effects on it. Matter of fact GM recommends using carb cleaner, BG products reccomends carb cleaner to use on MAF sensors.

Hay guys, thanks for the feedback. I had used gumout before my original post and remembered after having done so that I had problems on another ecm engine not running properly right after spraying carb cleaner. But it later cleared up fine. I avoided the AF sensor on my original spray down but later sprayed it with the engine running and it died. The car is running well now most of the time, without replacing the AF sensor (thank goodness). Although it still has a rough idle from time to time and will die at idle on occasion with the a/c running. I can tell that the exhaust smells strong and not normal. I am confident that this intermittent problem is in the sensing/controls because it all seems to be idle related. One thing I don't understand is the soot in the intake all of the way back to the air cleaner right up to the air filter. That is not normal in my experience. I am sure it is not from the pcv since it is clearly gas soot rather than oil burnt residue. And I replace the pcv from time to time. The only 2 things I can think of is the egr or a sticking intake valve. I have a hard time thinking a sticking valve would reach that far back so I think it is the egr. I will do further testing on the egr (2 solinoid pulsing type) to determine if it is the cause. I started my assessment with the egr since that is what it looked like.

Any additional help is appreciated. And btw I'm glad I didn't rush out to replace the AF sensor.

I have an Idea. Might want to check the Oxygen sensor. It can and will cause problems when not working properly :)

I replaced the oxygen sensor less than a year ago and really don't think it is the current cause. I replaced it at that time sense the error code came up for it and it would not run right.

When this idleing problem surfaced, I received no codes.

Does anyone know how long it takes the ecm to reset/learn and stabalize once power is taken away from it?

It depends onthe ECM. Some will restabilize right away, but others will take a while. The best way to reset the ECM is to disconnect the battery for at least 10 seconds. That way it starts over fresh. I have been able to get other codes to set this way, too. something the ECM now misses that should be there. I would still check on the o2 sensor. That might still be an issue. At any rate, you probably should reset the ECM. The longest it should take to be in great working order is about a week.