rough idling

bigjerm · Jul 17, 2009

After warming up for a while, the engine will idle rough and a bit low, and also dipping at times. The problem sounds similar to the tech article on cleaning the MAF, but tried that and it didn't make a difference. Changed the air filter, going to change the plugs tomorrow. Also, i tried the IAC check and it just stalled my engine completely, so that seems to be working. I looked for the PCV valve, but couldn't find it after looking very carefully behind the valve cover where the manual stated it would be. Any idea what I should try next?
btw, My truck is a 2001 v6 4.0 Fx4 ranger xlt. Thanks!! :icon_confused:

bigjerm · Jul 17, 2009

Could be anything huh.

Rifleman · Jul 17, 2009

How'd the plug change go?

bigjerm · Jul 18, 2009

was gonna get into it, but 3 of the plugs are super hard to get to, at least with my hands. Going to get some help from an actual mechanic tomorrow. That could be an indicator im guessing?

Rifleman · Jul 18, 2009

Well, since you're into it, change the plug wires too for good measure. If your mechanic has a pressure tester, have him check each cylinder as you go on the plug job (this is if he's working for beer or isn't going to charge extra). I'd wanna be right there seeing each reading though...

bigjerm · Jul 18, 2009

This guy is more along the lines of working for beer mechanic. He's got the knowledge, but who knows if he has a compression tester wrench. Hes a bit tweeky, but im confident in his plug changing ability. Could my rough idle be related to some compression prob? Truck runs strong on the highway, just seems to idle low at stops with an occasional dip. Also, it the rpms drop even lower and rougher when i put it in park??.....I really hope it's minor, i just had the tranny rebuilt.

bigjerm · Jul 18, 2009

also, placing my hand over the muffler while the truck is idling in park, the exhaust lets out a hard puff every few seconds. This thing is going to the shop im guessing. argh

Rifleman · Jul 18, 2009

The hard puff is common. If things straighten up at high RPM, I'd not worry about compression. I'd get those plugs and wires swapped and look to see if you have a dirty upper intake manifold and test the fuel rail pressure.

bigjerm · Jul 18, 2009

And it practically stalls when i put it in park...weird. Does that make it a tranny issue possibly as well?

bigjerm · Jul 20, 2009

Well, managed to change 4 of the 6 spark plugs. The other two were pretty much impossible, for me at least to change. The ones i pulled out were pretty much barbqd with the gaps all stretched out. looks like theyve got about 50k miles on em. Wasn't able to find the pcv valve, either was my buddy helping me able to. Didnt make any difference yet. still practically stalls when putting into park, and a little rough. Also, looks the alternator was replaced but one of the bolts was completely loose. Found out after noticing a spark arcing across to the Maf wire. Think i may need an actual mechanic.

tdaward · Jul 28, 2009

What did you ever find out?

bigjerm · Aug 5, 2009

Dang, this thing is still idling pretty rough. It's no longer stumbling and stalling when I put it in park, but just idles rough and around 700rpm(is that a bit low?). So far ive done, air filter, pcv, changed the plugs and wires, serviced the maf, iac, and cleaned the throttle body.......still pretty rough though. My truck has some miles, about 113k. Is this just the way these things run with the high mileage? any of the pros here have any advice? thanks!
Last

SoLongStang9499 · Aug 5, 2009

700 RPM is the ideal idle for these engines, as it may be rough, the rpm is correct. The PCV is located ON the drivers side valve cover near the firewall. I would replace those last 2 plugs, i imagine your talking about cylinder 5 and 6. Use a spark plug socket, 3-6" extension, and a swivel socket (3/8 driver if you can) i usually put both my hands between the shock tower and the block. Good luck. :icon_cheers:

iceracer60 · Aug 5, 2009

hey guys i actually just corrected this problem on my 02 with the 4.0 after goin through all your steps i found a vacuum boot with a slit in it under the throttle body cover on the right side. id check there if ur still looking. just remove the cover and follow the vacuum line round the valve cover.

bigjerm · Aug 6, 2009

I am still looking for sure!. thanks for those replies. Sounds like alot of rough idling going around...

rough idling

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