So last week i picked up a 1997 2.5L Avenger (which btw so far i am loving) to replace the saturn i was driving (oil pump went.... that was a mess not worth fixing). Here is all the info i know to start things off.

Car has:
Right at 150,000 miles on it
Previous owner was decently regular about oil changes (never lapsed more than maybe 100 miles)
Car has no major issues like smoking (doesn't eat oil), knocking, etc.
Last owner replaced the CPS, Distributor, Distributor Cap, Fuel Filter, Fuel Pump, Fuel Tank to fix the random shut-off issue.
Since the last owner has had the car, its been fed 91 octane.

My issue i am having now is as follows. Upon starting the car for the first time or when its sat long enough to cool down, idle is where is should be (bout a pinch below the 1krpm mark). After the car warms up, no matter if its in neutral, coasting, or in any gear... idle sticks around the 450 - 550 rpm mark (low imho). The car has a tendency to dip real low and almost die at idle when the a/c kicks off (like when its running for defog). Its also died on me a few times on real cold days at idle. The car also on a rare occasion will stutter decently hard going down the road with cruise on (though i somewhat attribute this to ethanol in the gas).

Does this sound like the IAC Sensor? What should i do to fix the issue? Any help would be appreciated.

 

IAC is a possible cause ... First I'd try to run some seafoam thru the intake tract and see if that clears up the issue ...

 

Sorry its taken so long for an update. It has been busy around here and i just now have had time to work on the car.

So i ran seafoam (1/3rd of the can as it said) through the intake via the brake booster vacuum line like everyone had suggested for this car in other threads. Judging by the resulting exhaust cloud that followed it defiantly did some cleaning to the engine. However, it did no good for the idle issue. Idle still seems low (450 - 550 rpm range once everything warms up coolant wise), and it still about stalls the car in idle when the ac compressor kicks off. It also still has the occasional stutter going down the road, depending on what mood it is in.

Any suggestions? If i can get under some shelter and heat (aka a garage) i plan on taking the throttle body off and changing out the plugs since the seafoam has been ran through the system now (was holding off until i did that). While its off i could tinker with anything that has to do with the IAC System.

 

I'd also take the EGR off therear of the intake and give it a good cleaning

 

Well i am mid way through working on things. I have the intake off and i am about ready to give it a good cleaning.

I noticed a lack of pictures or write-ups around here for the technically challenged or the first time with this car people to follow as i was researching myself (hey, never can be too safe or too informed) so i am trying to grab tons of pictures of everything so they can be put up here later.

 

One quick question about the RPMs. I was looking at the RPM gauge on my avenger and noticed that mine starts at 500 RPM. I was just wondering if it was the bigger line is where it is after it warms up or what because I have noticed that after my car warms up it is around 600 - 800 RPM depending on outside temp and current load. So I was just wondering if you overlooked that the gauge starts at 500 or if it is really that low however my gauge is a 2.0 and not the 2.5 so I don't know where your starts.

 

There was a right up with pictures on plenum removal ... unfortunately on the board crash/transfer I lost all the pics and haven't had to pull one to retake them ... If all else fails buy the Service manual/Chiltons ect ...

 

Well I've drove her a little since yesterday when i finished working on things. Other than a few jerks on the first trip out (figure it was burning things off from the clean that may have got missed) it seems like all is going well. There is a definite power pickup, though that may just be from the ecu reset. Still idles around the same place, but it hasn't dipped down low or stalled yet from it. There are still a few things i wanted to clean out (i figured while i had things apart, clean everything) but i started running out of light outside... and days off from work.

bad venge, wasn't aware of the old write-up, being new and all. I figured something along the lines existed but i was either missing it or it was buried somewhere. I figured i would at least post pictures with labels for people that end up in my situation. Stuff like service manuals / Haynes - Chilton books are hard to get around here without shipping them in from online... and around the holidays that was gonna mean two or so weeks of waiting for something i had a day or two off from work to fiddle with, lol.

Mavman, my first thick line on my tach is 0, or i am assuming... same place the needle rest with the car off. It warm idles solidly between that first line and 1k, so i am assuming its around 500rpm.

 

may sound weird but check the local library ... mine has the service manual ...

 

So this problem never seemed to fix itself and reared back up after i posted this.... and i just lived with it until today.

Today i put in a brand new egr and gasket for that, a brand new IAC, and a new set of plug wires. I also got a can of TB cleaner and cleaned as much as i could of the air plenum and the throttle body. I also unplugged my battery and i am letting that sit now so i can get things all reset.

I shall post back how that is going.