idles for a minute

[mounty02]

When I warm up my car in the mornings and after work, the engine will rev up and down around 1000 rpm, it only does it for about the 1st minute. Now i have 2 codes present p0305 and p0340 I believe. Please let me know any ideas of what it could be. Thank you very much in advance.

 

[jrford]

no way to check codes now. . .sounds like an IAC thats dirty.
IAC - Idle Air Controller, think choke, does the same thing.

 

[mounty02]

Would this be a repair or cleaning?

 

[jrford]

i'd try cleaning it first, you may also want to clean the MAF sensor (careful with this one), after that i hate to throw money at it, may want to see if the dealer can figure it out. .. . .find those codes and post back it might already be telling you whats wrong.

 

[jrford]

Found the code for you, it almost sounds like you have a problem with one of the Cylinders, after it runs for a little it starts 'hitting' . .
A code P0305 may mean that one or more of the following has happened:

* Faulty spark plug or wire
* Faulty coil (pack)
* Faulty oxygen sensor(s)
* Faulty fuel injector
* Burned exhaust valve
* Faulty catalytic converter(s)
* Running out of fuel
* Poor compression
* Defective computer

A code P0340 could mean one or more of the following has happened:

* a wire or connector in the circuit could be grounded/shorted/broken
* the camshaft position sensor may have failed
* the PCM may have failed
* there exists an open circuit
* the crankshaft position sensor may have failed

 

[mounty02]

Mechanic cleaned it 2 weeks ago when it was at the shop, it didnt rev the first time i started it up. Later that night it went back to doing it. I have cleaned the maf about 5 months ago. This just started about a month ago. Should i have the iac replaced? Do a tune up (plugs and wires), or try the fuel pump? Thanks

 

[jrford]

how much is an IAC? if its cheap enough . . .

more or less do it in that order above. . .i'd be leaning towards plug/wires but i've been wrong before.

 

[mounty02]

Jim i appreciate all of your info. I think iac are about $40-60. My truck is at 94000 so when would be a good time to do a tune up?

 

[jrford]

tuneup my v8 its recommended at 100k. . .imo would be anything greater than 75k.

 

[mounty02]

Thank you for all your info!

 

[bradweezy]

clean your t.b.(throttle body) and check for vac leaks. change air filter, did your mech. clean the little felt breather on your IAC? id check that before you bought another,and id clean the t.b. before also. but i had that idle problem right before my pdfe sensor pooped out (with no cel)then pow cel bad pdfe

 

[irocdupi]

eventhough they say the recommended tuneup is at 100k my plugs were way off gap at 80,000 miles. I would try plugs and wires first

 

[mounty02]

Would we replace plugs and wires or plugs and coils?

 

[mounty02]

update, I was driving home from work last night and my check engine light was not on. It has been on for years! The only thing done was that my buddy took the coil out to check it put it back cleared my codes but they came on right after leaving the shop. So I don't know if when we. Moved the wires around if that helped. I had the p0355 and p0340 codes. One is the the number 5 coil and the other code is for the cam shaft sensor right under the coil location. I noticed the wires were attached at some point. So maybe there is a wire issue.

 

[Bluebee74]

Rough Idle

I've been having some of the issues mention in this thread and this is what I've done so far. New spark plugs (much needed @ 80,000) a new coil (engine was misfiring once in a while, RPMs will not change and no "check engine light.")

New fuel filter and air filter. SeaFoam and Throttle Body cleaned manually also removed and clean the "Idle Air Control" valve and now it runs really smooth.

NOTE: Be careful about using SeaFoam you can Hydro-block your engine! READ READ READ the instructions! Also careful how you clean your MAF sensor.

Original Motorcraft platinum spark plugs is what I used!

Peace!
MM :exporange