[camoman214]

1999 Ram, 5.9L, auto, 4x4

I just replaced the IAC valve on my truck 'cause it wouldn't idle and figured the IAC was bad. Now the truck idles at 1800 rpm and I can't get it to idle down to normal. I did the proper IAC adjustment which calls for driving at 40 mph to allow ECM to learn the setting. I unhooked the battery for a few days hoping it would reset the ECM, that didn't work. I took the NEW IAC back to the parts store and exchanged it for another one, still idles at 1800. What else should I check? I didn't see any vacuum leaks.

Thanks for your help.

 

[Stein]

try the (TPS) throttle position sensor I had some some idle isues on my 99 5.9 4x4. you can test them with a meter I don't have one so I just replaced the IAC and the tps and that fixed it. the iac came out in 2 pieces so I know that part was bad not sure on the tps. but the tps was 33 dollars and I replaced both within a 1/2 hr. and only spent about 70 for both. I use my Haynes for almost everything. but you can set up a free account at autozone and they have alot of helpful info on there as part local,diagrams,how to test, and what type of symtoms a failing part can cause

 

[camoman214]

I had figured the next thing I would try would be the TPS. I got one from Advance Auto Parts for under $30, so I'll slap that in and see how she reacts. Sometimes these trial and error steps can start costing a pretty good amount of money.

I'm gonna be putting it up for sale soon and it needs to be idling okay first. lol

 

[camoman214]

Stein - you hit it right on the head. Replaced the TPS and now it runs like new again.

Thanks for the quick and only reply.

 

[Stein]

your welcome, I'm no mechanic and I hate the trial and air thing to. mine didn't throw an engine code for either sensor. I have a cheap scanner witch has helped alot exept for that, but I knew I had to be somewhere in the ballpark. and without the code pretty much everywhere around here wanted $70-90 just to look at it, I've never had any sensors replaced on it and with 102,000 miles I figured what have I got to lose. so glad I was able to help, this forum is great I've saved alot of money reading stuff on here. the only thing I have paid to have done are my front axle shaft seals, mainly because it's winter and she wont fit in my garage, or I would have tried them to.

 

[camoman214]

Well I guess I spoke too soon. After replacing the TPS sensor and driving the truck last night, the truck ran fine and idled normal. Today, I started it up and now it's idling high again, just as it was before.

 

[Stein]

that sucks, did you reset again after you put in new tps

 

[camoman214]

I unhooked the battery again today for 12 hours to reset the ECM after the new TPS was installed. Still idles high between 1100 and 1600. Any other possibilities?

 

[evilsack]

re

I had the same issue going on and found that my throttle cable itself was frayed and got caughtup which made it not release completely (resulting in higher idle).

I actually resolved this issue after nearly killing myself when it stayed full throttle and wouldnt free up, i nearly went through someone house.

 

[Donmega884]

Have you ever tried taking out the throttle body off the manifold and making sure you clean the entire part with carb cleaner? I know it's a very cheap way too find the problem first. Also you can clean an IAC and make sure the tip is completely free of carb. Always remember to try and find the exact problem first, never throw money at and engine and hope for the best.

Sean

 

[camoman214]

Update 02-19-2012

Okay, here's the latest on my high engine idle problem. Within the past few days I took off the throttle body, removed all the sensors connected to it and cleaned it completely. I cleaned the butterflies and even in the IAC hole. I then replaced the IAC valve again (suspecting it was defective), replaced the TPS sensor, replaced the throttle body to intake gasket and replaced the PCV valve (it was cracked). I again looked for any apparent bad vacuum hoses. I put the throttle body back on, hooked up all the sensors and cranked it over... now the truck idles even higher... at 2700 rpm.

:4-dontknow:

 

[Donmega884]

How is your acceleration?

 

[camoman214]

Well now that you mention it, the acceleration is rather sluggish compared to what it used to be.

 

[Donmega884]

Ok first of all stop throwing money at your problems. You need to identify the source of the problem. Is your CEL on? Are your plugs and wires newer? Have you have a compression test? Fuel pressure test? How many miles on the truck? Might be the Cat converter??? Be absolutely sure before buying a new part. Most parts can be cleaned up and thrown back in.

 

[camoman214]

Ok first of all stop throwing money at your problems. You need to identify the source of the problem. Is your CEL on? Are your plugs and wires newer? Have you have a compression test? Fuel pressure test? How many miles on the truck? Might be the Cat converter??? Be absolutely sure before buying a new part. Most parts can be cleaned up and thrown back in.

CEL was on and code was an IAC malfunction, which is why I replaced the IAC sensor. I cleared the code to see if would repeat, but it hasn't just yet. I don't know the age of the plugs and wires, but they don't seem like the cause of high engine idle. Fuel pressure was tested and is normal. Possibly the cat, but I don't know how to check it.

 

[Donmega884]

http://youtu.be/IzyvL5tQLzU

http://youtu.be/5icTmYItwiE

These videos will show you how to check the cat and if its dirty how to clean it. If you can't be sure when the last time you replaced the plug and wires you should replace them. You would be surprised the problems associated with a bad wire or plug.

 

[camoman214]

Ok first of all stop throwing money at your problems. You need to identify the source of the problem.

If you can't be sure when the last time you replaced the plug and wires you should replace them. You would be surprised the problems associated with a bad wire or plug.

First you told me not to throw money at my problems. Now you want me to replace plugs and wires to see if that fixes anything? That seems like throwing money at it without identifiying the problem. lol

I didn't know the last time the sensors were replaced either, and being that they were only a few bucks, I replaced them to be sure.

 

[Donmega884]

You said "I don't remember" when asked how old the plugs and wires were. The book calls for them to be changed every 30,000 miles. When is the last time you had a tune-up?? Your obviously guessing wrong about your "ideas" and have little knowledge about high idle.. First get a "tune up" which would be new wires and plugs and new air filter if dirty etc etc... Are you still with me????? Then if you still have high idle grab a can of car cleaner and spray around the intanke, throttle body all the vacuum lines but be careful not too drench the engine and try to do it when the engine is cold.... If you hear a high pitch sound or change in the rpms you found the leak. IF you did not find a leak or the tune up did not work well then maybe your gonna start to check into other things such as the cat etc etc. Why ask questions if your not willing to learn???? You must not assume you know the problem unless you can prove it.. Got it Skip?

 

[camoman214]

You said "I don't remember" when asked how old the plugs and wires were. The book calls for them to be changed every 30,000 miles. When is the last time you had a tune-up?? Your obviously guessing wrong about your "ideas" and have little knowledge about high idle.. First get a "tune up" which would be new wires and plugs and new air filter if dirty etc etc... Are you still with me????? Then if you still have high idle grab a can of car cleaner and spray around the intanke, throttle body all the vacuum lines but be careful not too drench the engine and try to do it when the engine is cold.... If you hear a high pitch sound or change in the rpms you found the leak. IF you did not find a leak or the tune up did not work well then maybe your gonna start to check into other things such as the cat etc etc. Why ask questions if your not willing to learn???? You must not assume you know the problem unless you can prove it.. Got it Skip?

You contradicted yourself by telling me not to do one thing and then telling me to do it. So, basically you were wrong about informing me not to throw money at it, because now you decide it's okay. lol Oh and I've learned a lot from these forums. The most important thing I've learned is to not throw money at a problem until you have solved that problem. I didn't buy a new engine 'cause it was idling high, I bought a few sensors that were reported bad by the OBD scan. Seems logical to me. Who's Skip?

 

[Donmega884]

OK, Congratulations your truck probably has an even higher idle since you started tinkering with it. Nice Work

*If you listen you might learn something*