Dodge Shadow, idles badly when cold

My O.L. has an '89 dodge shadow, 2.5L non-turbo, auto tranny and it has started to idle very badly when started 1st thing in the morning, on a cold or warm morning. It sounds like it's "loading up", but there is no black smoke coming from the tailpipe. When you step on the gas it smoothes right out, and runs fine down the road. Also, if you let it idle long enough to warm up, eventually it will idle normally, it's only when the engine is COLD, (not been run for many hours), that it idles rough. I wonder if there isn't a bad sensor somewhere that controls the idle mixture and makes it run that way when cold. Within the last 10K miles we replaced the spark plugs, distributor cap and rotor, plug wires, and coil, (for a different problem, and also to tune it up. Turns out it was a cracked coil and the car would barely start when it was wet outside). Anyway, I feel I can pretty much rule out an ignition problem because of this. Has anyone had this happen, or read about a fix?

Thanks, Snydley

Reply to
Snydley
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Does the check engine light work? Are there any fault codes stored in the engine controller?

Reply to
Peter N

Thanks for the help. I changed that yesterday thinking that might have something to do with it, but not knowing. I changed that one, and the sensor that screws into the head in the front. The temp. guage stopped working awhile ago, and not knowing which one of those 2 sensors controlled the temp guage I replaced them both.

Thanks, Snydley

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Reply to
Snydley

The codes I get are:

33 - air conditioner clutch relay, (there's no air cond. in this car) 34 - open or shorted condition detected in the speed control vacuum or vent solenoid circuits. (not sure of this one) 55 - end of message code

I don't know what 34 is, but I'll have to check that one out. One thing though, when the car started idling badly I took the air cleaner off to check the filter. It was stuffed with Maple tree seed "wings" that my O.L. must have run over and got sucked up into the air cleaner. I got my shop vac and vacuumed them out. I figured if I missed anything it would have gotten sucked down into a cylinder, burned and that would be that. Now I'm wondering if something didn't get wedged in somewhere enough to change the fuel mixture when cold. I'm afraid I'm going to have take the throttle body and manifold apart and thoroughly clean them. I don't know what else to do. So far I've replaced the air filter, and replaced the coolant temp. and temp. gauge sensors, checked all of the vacuum lines,(ok), and find nothing wrong. It's something that isn't generating a fault code, yet is making the engine idle so badly it will hardly run when cold. I hate to take it to a shop, it's an '89, yet only has 39K miles on it, I hate to put a lot of money into it, but it's in great shape and has been a strong runner until now.

Thanks, Snydley

Reply to
Snydley

33 is normal in cars with no A/C

Does the car have cruise control? If not, this code is normal. If it does, this could point to a potential cause of the rough idling.

That is possible. The air cleaner on these cars is not particularly well designed -- there are crevices and crannies where crud can collect, and the air filter element itself is undersized for the job.

Before that, remove, disassemble and service the air cleaner assembly. Replacing the air filter itself is barely just one part of the job. See my post here:

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Don't be such a cheapskate. If it's only got 39K on it, what does it matter that it's an '89? Fix it! Why do you "hate to put a lot of money into it"? If a simple inspection and/or replacement of wear parts in the air cleaner and crankcase vent system doesn't do it, I guess you have three choices: Sell/junk it because you "don't want to spend money", continue to randomly throw parts at it that you guess might be the problem but really aren't, or get it in for proper diagnosis that will probably show the problem to be easily and inexpensively repairable.

DS

Reply to
Daniel J. Stern

No, the car has no cruise control. I guess the computer codes are ok then.

I put a new element in the air cleaner. I was thinking maybe something got sucked into the throttle body, or manifold somewhere and causes the car to idle badly when cold. I don't have any black smoke coming out of the tailpipe so I'm assuming it's running too lean not rich. My next move is to remove the throttle body, and thoroughly clean it. I'm wondering if the AIS motor is somehow stuck open, creating too lean a mixture when cold, and then when the engine is warm the mixture is ok. I don't really understand how all of this works. When I was in High School in the '70's, and took mechanics in BOCES, a type of trade school, cars were carbureated. If there was a problem with the mixture when the engine was cold adjusting the choke would usually fix it. I haven't "kept up" with cars since fuel injection and computer control became the norm and I am somewhat lost here.

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I'll go through the proceedure. I believe that replacing the air filter would be enough to straighten out too rich a mixture, if that was the case, which I don't believe is.

I guess I didn't make myself clear, or you misunderstood me. What I meant by "I hate to put a lot of money into it" is that I hate to have to take it to a dealer and pay their price. That's why I'm on here. I'm trying to get some tips and fix it myself. I also don't want to "randomly throw parts at it", which I haven't done yet. "Push comes shove", if I have to I'll take it to a local repair shop and have them fix it.

Thanks, Snydley

Reply to
Snydley

Yes, you mentioned that, and that is why I went to the effort to explain why that's not a complete job of servicing the air cleaner assembly.

When you remove and disassemble the air cleaner, pay special attention to the hot air "stove pipe". If it is disconnected, crushed or obstructed, the car won't run right when cold.

Very doubtful -- it doesn't work this way.

Assuming usually costs more money than diagnosis.

Feel free, but it's not likely to get you anywhere -- this throttle body is self-cleaning by design, and does not get crudded up the way the 3.0 throttle body does.

Doesn't work this way. The AIS motor controls idle *speed*, not idle

*mixture*.

The point of giving you the procedure for completely servicing the air cleaner and crankcase vent system was to indicate to you that simply replacing the air filter is NOT enough to address all the possible causes of an incorrect mixture when cold.

Thought you said you had begun replacing various sensors.

DS

Reply to
Daniel J. Stern

Reply to
Delbe Comeau

Reply to
Delbe Comeau

Hi Delbe, Can I say, YOU'RE A GENIUS!!!!!!! That took care of the problem!! I torqued it down to 175 in-lbs, (only turned the bolts 1/16 of a turn or so). I started it up and it purrs like a kitten!!! Gosh, it just goes to show you sometimes when we think it's the most complex of problems it turns out to be something so simple!!

Thanks so much!!, Snydley

Reply to
Snydley

My 88 Aries 2.5L had the same problem. Went to 3 different shops.

They replaced between them:

MAP sensor Cam Sensor Engine Control Computer Distance Speed Sensor Oxygen Sensor AIS motor All the vacuum hoses

After having no repair help for more than 3 days, I replaced the injector in the TBI myself and that solved it. However, you will not get any codes for a mechanically worn out injector.

Dan

Reply to
Dan Fraser

Hi Dan, After thinking the problem was solved, I went to start the car Wed. morning and the same problem arose. I replaced the throttle body to manifold gasket and that seemed to solve it. I let it sit for 5 hrs. started it up and it was idling like crap again. I'm so confused now. When I re-torqued the T.B. and then changed the gasket it ran great until it thoroughly cooled down. I may try the injector next.

Thanks, Snydley

Reply to
Snydley

Re-torque the T.B. when it's *COLD*.

Reply to
Dan C

It WAS cold. Here's how it went:

I let the car sit all night. I drove my Saturn to work in the morning. I stopped at an auto parts on the way home and got the gasket. I went home and installed it, (removed the T.B., cleaned both surfaces, reinstalled it using Locktite on the screws, partially torquing in a criss-cross pattern 4 times until finally torquing to 175 in.-lbs. At this point it hadn't been started in over 24 hrs ). It started up and it idled great, (thought the problem was solved). I shut it off, went back in the house. Returned about 5 hrs. later to check it, started it up and it was idling badly again. I'm so confused! Any ideas?

Thanks, Snydley

Reply to
Snydley

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