I have a 2002 ranger with the sohc motor that will not idle right. it runs fine, and idles ok when cold. but when warm it idles at 600 rpm and will buck every few seconds. I replaced the IAC with no help. When I hold my hand over the exhaust pipe i can feel it blow when it bucks as if its firing when an exhaust valve is open. My question is can an CKP sensor fail like this and cause a problem only at idle? Thanks for any help.
Dave256

 

try cleaning your iac and maf first. also try this stuff called sea foam and reset your computer there is a very remote possibility that it is the camshaft position sensor

but sounds to me like you need new plugs

 

Thanks for the info. I don't know what sea foam is. can you explain?. I have a set of plugs and wires i am going to try this weekend. will let you know.
Dave

 

seafoam is this stuff that you suck into your engine via a vaccum line and it cleans the carbonout it smoothed out a lot of peoples idles out.

http://www.seafoamsales.com/motorTuneUpTechGas.htm

also if you have an explorer check out ford-trucks.com

 

Best bet is to put a vacuum guage on it and see what is happening. That will tell you a lot of info in a short time. The SeaFoam is great stuff if you need it but I'm not sure you do. Is the check engine light on? That is the first line of defense. Also check your brake lights. Some of these things will idle poorly if a brake light is burned out.

 

Ok, put a vacume gauge on it and it is steady at about 19 inches. when it bucks it drops a couple of inches and recovers. No Cel, but i pulled the codes and it had a p0300 (multi clynder misfire) and when i reset it it comes back when it bucks. I checked the timing and it looks to be bouncing around at idle. between 16 deg and as much as 27 deg. that might explain the bad idle. misfiring at low rpm and when at higher rpm the timing is advanced and steady. any ideas.
thanks
Dave.

PS: Anyway to disable the advance to see it cures the idle problem?

 

Well I changed plugs and wires and it didn't help. So I took it to the ford dealer and talked to the service rep. He had it checked and said they would change the ECM, but would not offer me any promises that that would fix it. I had them change it and figured if that dosen't do it I can change the rest of the senors. Low and behold the new ECM fixed it. live and learn i guess.
Dave

 

Glad to hear it's fixed. Just a shame you had to go to the dealer to get it done. ECM was going to be my next suggestion! (lol) Don't forget about the SeaFoam tho. It really is great stuff for the engine and transmission. I kept my plow truck tranny alive for about a year using that stuff. It got to be a routine between me and the truck. I would drink a cup of coffee; the truck would drink a pint of SeaFoam.