My 2005 Dodge Neon is still running rough at idle especially warmed up. I've been digging around for a definitive answer and this seems to be a common problem with neons. The symptoms point to the iac valve, rough idle/ low idle and occasional rpm surging after starting in the morning. I'm seeing prices ranging from $60 to $120 or so. Are there any brands that make much of a difference, BWD, etc. Can you clean these or is it a throw away once bad? I'm tired of the problem but don't want to drop tons of cash on it. Oddly enough no check engine light is ever triggered.
Idle Air control valve
- Thread starter 97prizm
- Start date
Try cleaning it out with throttle body clear first.
I'd do as already mentioned, check for codes, and clean it. I've cleaned the IAC in my 4.9L E-150 a few times over the years with good results.
Before you buy a new IAC valve really clean the throttle body using the red can CRC parts cleaner, carb cleaner, and a small brush (stiff nylon or soft brass) even if you have to remove the throttle body to do it. I replaced an IAC with what I thought was a good cleaning and the car didn't run much better, put the old IAC back on, ran the same way. I bought a new throttle body gasket, brushes and cleaners then removed the throttle body and cleaned it, and cleaned it again, I was amazed at the black gunk that I got out and how well it ran when I was done.
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Remove the valve and clean it. I don’t think just spraying into the throttle body will help you all that much. I’ve seen IAC valves and ports totally blocked with hard carbon. Spray isn’t going to help that...you may have to manually clean it with a metal brush or something.
Doesn't a 2005 Neon have an E-throttle? If so, there won't be an IAC valve. If it's an old school cable actuated throttle, it will have an IAC valve.
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IAC isn't the first thing I'd think of for rough idle. Air leak in the intake system (especially if the car's been worked on) or low compression (if high mileage or hard use) would be where I'd start. A bad air leak or low compression may also show up as a miss or hesitation when at a fairly low speed and you try to accelerate from a closed throttle -- most common IAC problems cannot cause this symptom..
Unless you've already done so, replace the PCV valve. They can crud up and stick open causing an air leak big enough to cause definite idle trouble and it's about a $5 part. Then look at all vacuum hoses and listen for a whistle -- cracks, loose hose, etc.
100k-up miles I'd do a compression test next. It's not beyond a driveway mechanic if you're comfortable changing plugs and finding specs on line; the tester can be rented at most auto parts places. Low compression often means exhaust gas leaks back into the cylinder interfering with pulling in fuel/air.
If compression meets specs then get serious about looking for an air leak. Look for instructions on
'net and focus on hoses (crack you didn't see) and gasketed joints, especially if the intake manifold or throttle valve have been worked on. (Bad/damaged/incorrect gasket or warped metal.) Throttle shaft has seals but they can crumble and cause a leak.
Air leaks can be a challenge.
All these problems will be worse after warmup because mixture is leaner then -- less room for dilution.
Even a good IAC may surge if leakage of exh. gas or air causes missing at normal idle speed: The miss causes loss of rpm, the IAC tries to compensate but the miss stops at slightly higher rpm so you get a surge causing the IAC to back 'er off ... repeat.
Once you know compression is good and no air leak i'd replace the IAC. Many of them can be serviced but not all problems are fixable and the work can be very fussy. Whether this is DIY depends on your skill and your car -- if that's a Mitsubishi engine replacement is medium skill.
Unless you've already done so, replace the PCV valve. They can crud up and stick open causing an air leak big enough to cause definite idle trouble and it's about a $5 part. Then look at all vacuum hoses and listen for a whistle -- cracks, loose hose, etc.
100k-up miles I'd do a compression test next. It's not beyond a driveway mechanic if you're comfortable changing plugs and finding specs on line; the tester can be rented at most auto parts places. Low compression often means exhaust gas leaks back into the cylinder interfering with pulling in fuel/air.
If compression meets specs then get serious about looking for an air leak. Look for instructions on
'net and focus on hoses (crack you didn't see) and gasketed joints, especially if the intake manifold or throttle valve have been worked on. (Bad/damaged/incorrect gasket or warped metal.) Throttle shaft has seals but they can crumble and cause a leak.
Air leaks can be a challenge.
All these problems will be worse after warmup because mixture is leaner then -- less room for dilution.
Even a good IAC may surge if leakage of exh. gas or air causes missing at normal idle speed: The miss causes loss of rpm, the IAC tries to compensate but the miss stops at slightly higher rpm so you get a surge causing the IAC to back 'er off ... repeat.
Once you know compression is good and no air leak i'd replace the IAC. Many of them can be serviced but not all problems are fixable and the work can be very fussy. Whether this is DIY depends on your skill and your car -- if that's a Mitsubishi engine replacement is medium skill.