Poor Idle Quality when in Drive or Reverse
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New User
Joined: Jul 2002
Posts: 17
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From: Winnipeg Canada
Poor Idle Quality when in Drive or Reverse
92 Ranger XLT 4.0 4X4
Replaced within the last 6 months...
Fuel filter, O2 Sensor, TPS, Plugs, Wires, Air Filter, PCV
Man. Hub Conversion, Re-built Trans. Case Motor,
195,000km, U-Joints, Upper & Lower Ball Joints,
Fuel Pressure Regulator, Radius Arm Bushings
Truck starts and idles beautifully when in Park or Neutral - hot or cold. As soon as I put it in gear, very rough idling occurs. Rough idle seems to be consistent (not randomly rough - RPM's constant, still plenty of power with good throttle response) can't figure out what could be causing this problem. No codes on EEC either - which makes me think it's something mechanical? Had the tranny flushed recently, could this be related? Any ideas are welcome & Happy New Year!
Replaced within the last 6 months...
Fuel filter, O2 Sensor, TPS, Plugs, Wires, Air Filter, PCV
Man. Hub Conversion, Re-built Trans. Case Motor,
195,000km, U-Joints, Upper & Lower Ball Joints,
Fuel Pressure Regulator, Radius Arm Bushings
Truck starts and idles beautifully when in Park or Neutral - hot or cold. As soon as I put it in gear, very rough idling occurs. Rough idle seems to be consistent (not randomly rough - RPM's constant, still plenty of power with good throttle response) can't figure out what could be causing this problem. No codes on EEC either - which makes me think it's something mechanical? Had the tranny flushed recently, could this be related? Any ideas are welcome & Happy New Year!
Posting Legend
Joined: Sep 2001
Posts: 30,255
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Poor Idle Quality when in Drive or Reverse
Check the idle speed control also. If it is plugged or inoperative it can cause the same problem.
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Thread Starter
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New User
Joined: Jul 2002
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From: Winnipeg Canada
Poor Idle Quality when in Drive or Reverse
Don't have a manometer to check the vacuum, I'll have to find one from somebody, but I'll look into the Idle Speed Controller while I'm at it and let you guys know what I find. Thanks!
Hotshot
Joined: Aug 2002
Posts: 12,679
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From: BC, Canada
Poor Idle Quality when in Drive or Reverse
Check for a vacuum leak with some spray Carb Cleaner or carefully with an unlit propane torch. You aim the spray at the intake where the upper intake bolts to the lower and to the fuel rail. If the idle changes at all you have a leak.
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New User
Joined: Jul 2002
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From: Winnipeg Canada
Poor Idle Quality when in Drive or Reverse
I've combed the Haynes manual forward and backward - I can't even locate the Idle Speed Controller. Where is it located?
I'll give your Carb Cleaner Spray trick a shot and see what develops - thanks!
I'll give your Carb Cleaner Spray trick a shot and see what develops - thanks!
Post Fiend
Joined: Dec 2001
Posts: 10,562
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From: South Jersey
Poor Idle Quality when in Drive or Reverse
I have also heard that the 4.0s have a problem with that vacuum leak. The IAC is normally on or near the throttle body but I am not familar with the 4.0s layout.
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Posting Legend
Joined: Sep 2001
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Poor Idle Quality when in Drive or Reverse
On my 91 and 93 4.0's it is on the driver side of the upper manifold right behind the throttle body.
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Cargo Master
Joined: Mar 2001
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From: Elk River, MN
Poor Idle Quality when in Drive or Reverse
The 4.0L engine is a lean burn engine that gives a fairly rough idle at low rpm. When the A/T is in drive or reverse, the RMP's are pulled down into the rough idle range. To offset this, Ford included an engine idle damper between the engine and the frame that reduces the effect. Look on the driver side between the frame and the motor mount area and locate a thin shock absorber looking idle damper. You can replace the damper for an improved idle quality, but don't expect huge improvements if you have other problems with air/vacuum/fuel/elec. Dampers have a life span of about 70,000 miles then, they become less and less effective until they have no effect at all.
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New User
Joined: Jul 2002
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From: Winnipeg Canada
Poor Idle Quality when in Drive or Reverse
Couldn't find a vacuum leak, tried various angles and approaches to the upper/lower intake and surrounding area/hoses. The IAC was filthy, so I removed it then disassembled it to ensure it was cleaned right up. Cleaning the IAC did not improve the problem.
Took the Engine Idle Damper off and lo and behold I could move it with practically no resistance. I figure that's probably not right, so I phoned around to a few parts stores and they directed me to 'the local dealer, as that is not a common part.' Ford wants $240 CDN for one of these things! It's just a small shock absorber, with a custom bracket for mounting to the engine. At any rate, does anybody know if anybody else carries these things? What about a junkyard issue? Are they found on newer Ranger 4.0L's - I'm thinking maybe I could find one on a recently wrecked newer model...
BTW - thanks for your assistance folks.
Took the Engine Idle Damper off and lo and behold I could move it with practically no resistance. I figure that's probably not right, so I phoned around to a few parts stores and they directed me to 'the local dealer, as that is not a common part.' Ford wants $240 CDN for one of these things! It's just a small shock absorber, with a custom bracket for mounting to the engine. At any rate, does anybody know if anybody else carries these things? What about a junkyard issue? Are they found on newer Ranger 4.0L's - I'm thinking maybe I could find one on a recently wrecked newer model...
BTW - thanks for your assistance folks.
Posting Legend
Joined: Sep 2001
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Poor Idle Quality when in Drive or Reverse
Does unplugging the IAC make a difference?
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Thread Starter
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New User
Joined: Jul 2002
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From: Winnipeg Canada
Poor Idle Quality when in Drive or Reverse
I don't know why it didn't dawn on me to try that myself, but no, unplugging the IAC doesn't make one hint of a difference - runs exactly the same... Interestingly enough, unplugging the IAC didn't generate a 'Check Engine' light either... Does that mean when the IAC malfunctions, an indicator is not lit? Probably a lot easier to get my grubby hands on a new IAC than a new Idle Engine Damper!
Post Fiend
Joined: Jun 2002
Posts: 13,873
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From: Atlanta GA
Poor Idle Quality when in Drive or Reverse
For a $30 tester from Autozone, since your truck should be pre-OBDI/II, check the engine fault codes. This is the first place to start.
That being said, once you pull any codes what I would look at is what the engine is suppose to do when you put it in drive at idle. I bet you have A/C and the idle is not being kicked up. This is a sensor problem.
As for the flush, it is possible something got messed up since the compressor and transmission lines are on the same side. I would start looking at everything in harm's way that someone could have touched or set something on top of that would have broken a connection. Especially in the fan shroud area.
Look on your pass. fender under the hood and make sure everything is connected to everything. Then check your intake throttle body and make sure your MAP sensor is hooked up (I think this is where it is on a 94ish 4.0)and not broken.
That being said, once you pull any codes what I would look at is what the engine is suppose to do when you put it in drive at idle. I bet you have A/C and the idle is not being kicked up. This is a sensor problem.
As for the flush, it is possible something got messed up since the compressor and transmission lines are on the same side. I would start looking at everything in harm's way that someone could have touched or set something on top of that would have broken a connection. Especially in the fan shroud area.
Look on your pass. fender under the hood and make sure everything is connected to everything. Then check your intake throttle body and make sure your MAP sensor is hooked up (I think this is where it is on a 94ish 4.0)and not broken.
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New User
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From: Winnipeg Canada
Poor Idle Quality when in Drive or Reverse
Installed a new IAC but that didn't correct the problem. According to the Haynes manual, the MAP should be located on the pass. fender, but I can't find it anywhere (I thinkt the truck used for the photos is a 4 cyl or 3.0 V6). The 'check engine' light has not been activated, therefore I have yet to check for codes - but I suppose there could be some stored in memory. Once I poll them, I'll let you guys know what I find...
The truck is A/C equipped, although the high and low pressure hoses leak which means there is no refrigerant in the system. Without any refrigerant, I've noticed the compressor doesn't engage (not a big surprise). With no compressor engagement, turning on the A/C does not affect idle quality(and hasn't since the truck was purchased).
The truck is A/C equipped, although the high and low pressure hoses leak which means there is no refrigerant in the system. Without any refrigerant, I've noticed the compressor doesn't engage (not a big surprise). With no compressor engagement, turning on the A/C does not affect idle quality(and hasn't since the truck was purchased).
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New User
Joined: Jul 2002
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From: Winnipeg Canada
Poor Idle Quality when in Drive or Reverse
Found the main source of the problem with the idling! As my first post indicates, I've replaced a few parts since I purchased the truck (June of 2002). According to the 'dealer' (use that term loosely) who sold me the truck, the plugs and wires were replaced upon my purchase of it. Well, earlier today I thought, maybe I should just take a look-see and go from there. Plugs were older than I am! The electrode was practically worn flush with the ceramic insulator! I'm totally amazed the truck even started/ran (especially in this climate - Wpg, MB) with plugs like that. At any rate, went down to Canadian Tire, picked up some new Champions and some wires and took care of business. Just wanted to say thanks to those folks out there that gave me advice/tips on what to look for.
Incidentally, the original IAC was shot, as there was no high-idle on a cold-start - with the the new unit, the truck's running like new
Incidentally, the original IAC was shot, as there was no high-idle on a cold-start - with the the new unit, the truck's running like new