Rough Idle for about 10-20 seconds, vibration around 2300rpm's

[chrisnack]

First, awesome info on the site, love it!

I have a 1999 4.0 Ranger XLT 4x4. Whenever i start it cold, it will run rough for abotu 10-20 seconds. If i put it in drive/reverse it will buck a bit during this time. If i wait for 20 seconds it will be fine. Starting it warm it will be fine.

I have noticed my gas milage has decreased pretty well, get about 12 city and 14 hwy right now, used to get 14-16 city and 18-20 highway.

I recently replaced the spark plugs wires and put in double platinum spark plugs. I checked the resistance on the coil packs and that's fine and within spec, i also tried another coil pack to be safe and the issue still occurs.

I am planning ot pull the plugs again and double-check them, but was curious if anyone had ever encountered something similar?

I also have another issue where every once in awhile i'll get a good vibration/noise around 2300-2400 rpms when accelerating past that point, it's almost like the differential is grinding for a bit. This only happens once in awhile, but always in the same rpm range. Not sure if it's something with the transmission or maybe the torque converter, not sure where hte typical lockup is on these models.

Any help would be appreciated on the issues above.

 

[erocka1982]

try cleaning out your idle air control valve on the throttle body. 2 bolts and its out and spray the hell out of it with some carb cleaner. it helped for me but my idle was all over the place. also might want to check out the tps or mas air flow. check engine light on???

 

[chrisnack]

no check engine light

I'll try checking the IAC and MAF... thanks

 

[heptofite]

ditch the double plats, they are a bullshit plug, run some autolite single platinum or better yet some motorcraft.

 

[GoodOld85BlueBalls]

Heck, you would be better off with autolite's.

+1 for ditching the double plats. Way over priced for a DD.

 

[adsm08]

Yeah, get autolite or Motorcraft plugs. For some reason 2.9s and 4.0s run crappy on anything else. I've put all sorts of other after market plugs in my other cars, no trouble ever, but my 2.9 and my 4.0, Motorcraft/Autolite or nothing. As for your other vibration, is it always at 2300-2400 or is it in a particular gear/road speed as well. If its only at that engine speed with no other factors its an engine balance issue. If its affected by ground speed as well, I'd check U-joints.

 

[chrisnack]

Yeah, get autolite or Motorcraft plugs. For some reason 2.9s and 4.0s run crappy on anything else. I've put all sorts of other after market plugs in my other cars, no trouble ever, but my 2.9 and my 4.0, Motorcraft/Autolite or nothing. As for your other vibration, is it always at 2300-2400 or is it in a particular gear/road speed as well. If its only at that engine speed with no other factors its an engine balance issue. If its affected by ground speed as well, I'd check U-joints.

thanks for the tips..

so just go with single plats or copper? the double plats were ridiculous, i've never had to run those in any other car, even performance cars...

i'll try to figure out if its a certain gear, it's always in the same spot and always during acceleration... only happens once in awhile, so i'll see if i can narrow down any certain gears...

i'm going to clean the MAF and IAC tonight/tomorrow when i find the time...

let me know on the plugs and i'll replace those too...

 

[Doom's Day Custom]

If you having are using coolant too than you have a intake gasket leak !!!!

 

[chrisnack]

If you having are using coolant too than you have a intake gasket leak !!!!

is that a common thing on the 4.0?

 

[Doom's Day Custom]

i guess because my truck does the same thing as your and it runs like shit till the all the coolant is burned up or it goes out the exhaust...

 

[chrisnack]

i guess because my truck does the same thing as your and it runs like shit till the all the coolant is burned up or it goes out the exhaust...

Ah, i'll keep that in mind if it's still crappy after i do the other stuff..

coolant was low the other day, i'll keep an eye on it

 

[adsm08]

Single plats. Ford doesn't use doubles, trips, or quads on anything. All stock Ford plugs are single platinum. Don't put plats in a 2.9 tho. The duraspark/TFI systems tear them up for some reason.

It is rare to see a bad intake gasket leaking coolant on the 4.0s. In my experience I've seen many more vac leaks caused by intake gaskets than I have coolant leaks.

The thing that I just noticed about your rough run is that its only cold, closed loop operation. When was the last time your fuel filter was changed?