QuestionQUESTION: Roland, I have a 91 Acclaim 2.5 non turbo , and having a problem with it running really rough in drive at idle. I am getting a code 25 , its telling me to check AIS motor and for vacuum leaks. I can not find any vacuum leaks and don't know if i have a AIS motor on this car. I did put a full tune-up on it and if this helps, I have had 2 head gaskets install in the pass 10 years. will a bad head gasket cause a vacuum leak ? Trying to keep this good little car on the road ! It has 130,000 miles and burns a little oil. Please HELP!!!!!!
ANSWER: Hi Joe,
The head gasket is necessary of course in order to have a proper vacuum situation, but it is also necessary to have a compression situation. But I would not look at the head gasket as your problem unless you are finding oil in the coolant or coolant in the oil, or oil/coolant leaking from seam between the head and the block, or white smoke blowing out the tail pipe when the engine is first started.
I don't see a code 25 as pointing toward a vacuum leak, though it could be the case that either a vacuum leak or a slightly stuck ajar egr valve (applicable only to 2.2/2.5L with manual trans sold originally in California or Canada) is causing your rough idle. Because of the 25 pointing to the automatic idle control motor as having a short circuit and your having a rough idle it would appear then that you should check out that possibility. The AIS is mounted on the throttle body and has a 4-wire connector.
The wires are as follows:
violet/black to pin 59 of the pcm
yellow trace to pin 60 of the pcm
gray/red to pin 39 of the pcm
brown trace to pin 40 of the pcm.
I would remove the plug and check for continuity between each pin of the plug and the pin at the pcm. I would also check that none of the wires is shorted to ground or shorted to 12V when the plugs at the pcm and ais are disconnected.
Because of the heat generated by the nearby exhaust manifold in the vicinity of the throttle body, you might find by inspection that some of the insulation on the 4 wire may have melted which would be the location of the 'short circuit'. So do take a look at the harness from the ais plug to as far a you can trace it.
I would also suggest that you clean the throttle body throat and both sides of the moveable plate that constitutes the 'valve' and the side passageway whose air flow is controlled by the ais. Finally I would check that violet/black pin of the ais socket is connected to the brown trace pin, and that the gray/red is connected to the yellow trace as those are the two ais coils which have to be functional to get automatic idle control. Also verify that there is no electrical connection between the two pairs of wires, i.e. that they are isolated from each other and show therefor infinite resistance.
You might also remove the ais proper and clean the tip of it and hole in the side air passageway into which it fits.
Those are my ideas as to how to improve the idle. If you have an egr valve let me know and I will tell you how to service it. I can also xerox copy and postal mail you a service 'tree' for the 25 code if you want to try that approach and also a figure which shows the ais location so you can service it.
I am here for just the purpose you mentioned...to keep this good little car on the road.
Roland
---------- FOLLOW-UP ----------
QUESTION: Roland, Thanks for the info . i would like for you to mail me that service tree for code 25 . My address is
JOE DERIENZO
1010 RAINBOW DR.
ST. LOUIS MO. 63125
THANKS AGAIN
AnswerWill do, today.
I find that there are 16 pages which with the postage will cost me about $2.20 to send. Would you be so kind as to send me back five 44-cent stamps after you receive them?
Please 'rate' me and consider a 'nomination' to be volunteer of the month. Thanks
PS The pages are in the mail. My address is shown on the envelope. Thanks for the rating and nomination
