Mechanical question

[QuadJunkies]

Ill try and explain this the best I can -Its about my truck .

The last couple of weeks I am noticing at idle, the idle keeps going up and down ,at close to 1000 RPMS.Sometimes it does it all day and sometimes it only does it for a few minutes then it seems to settle itself.
What would cause that? Its had a minor tune up a few months ago.
Ive asked a few freinds and we are a little stumped:confused:

[Scro]

That happened to my F-150. We took it to a stealership and it turned out to be a bad sensor. It had something to do with the emissions sensor. It regulated the amount of exhaust going back into the motor. This was causing it to become lean and rich sporadically, in turn causing the motor to idle up and down. $300 later it was fixed.

What kind of truck is it?

[Ghost-Rider]

Have a scan tool read out done, could be EGR valve, leak in a vacuum line.

[QuadJunkies]

Originally posted by Scro
That happened to my F-150. We took it to a stealership and it turned out to be a bad sensor. It had something to do with the emissions sensor. It regulated the amount of exhaust going back into the motor. This was causing it to become lean and rich sporadically, in turn causing the motor to idle up and down. $300 later it was fixed.

What kind of truck is it?

Its a 2000 Dodge Ram1500.
Its starting to get some miles put on it now ,I sure hate to trade it in,its been a great truck and better yet-its paid off!

[wilkin250r]

I've was on some truck forums a while back, and I noticed several people having similar problems, idle speeds up and down, and the cause was generally the EGR valve. I guess it's fairly common.

[Honda TRX250ex]

99.9% sure its the egr valve. Its not a rare problem.

[QuadJunkies]

Is the EGR Valve hard to fix? Expensive?

[300exOH]

Originally posted by QuadJunkies
Is the EGR Valve hard to fix? Expensive?

EGR isn't usually very hard to replace at all. A couple of bolts and a connector. You might have to move a couple things out of your way but it isn't bad at all. I would also check out your TPS (throttle position sensor) as well. Not sure if the ram is the same but I know my dakota with the 5.2L v8 is known to have problems with them. Id say if the EGR valve or TPS sensor aren't the problem then you could have a dirty mass air flow sensor but I would check the other 2 first.

The EGR isn't too pricey. Anywhere from $75-$200 depending on the car and where you get the part. The TPS sensor I can't remember what I paid but I'm sure it was cheaper than the EGR.

[300exOH]

BTW- I tried to find a price through autozone and napa's websites and I couldn't find a listing for the EGR so I'm thinking its a dealer only item. I'm sure you can find them on ebay as well but I would get the part number from the dealer so you are sure you get the right one.

[Ghost-Rider]

The EGR shouldn't be to expensive.

[QuadJunkies]

Thanks for all the great suggestions! :)
We will check into it!

[NacsMXer]

One other possibility to consider is the IAC (Idle Air Control valve). This is what regulates the amount of air entering the engine when the throttle body is closed at idle (maintains smooth idle). It's basically a small butterfly valve (solenoid-activated) similar to a choke on a carb. When they get gummed up from oil blowby, etc or just worn out from age it will produce a surging/erratic idle condition.

[QuadJunkies]

Ill put that down to check too-thanks!