hey i got a rough idle happening have replaced pretty much everything.
shops cant find anything
no codes
no misfire
no vacuum leaks
good fuel pressure
replaced fuel filter
got motovac done
new plugs wires
cleaned maf
new iac
wiggled all my wires
cleaned throttle plate
good compression all between 150 160
only 70 k original
new coolant temp sensor
my evap sensor wont run
my emission gasses are poor (my diaggnostic tool has red yellow and green light)
i get a yellow light and i only get 350k to a tank

ive read tons of forums about it but a lot of them dont ever post the solution.
so i would like to know if you ever had a rough idle what fixed it.

 

In a word....nothing I have tried worked either. The truck is at a mechanic friends shop and has been for 2 weeks and another week before that. I get 20.5MPG, it idles too high, I now have a piece of tape on the butterfly in the throttle body to slow the idle down so It is driveable in traffic. I've changed damn near everything you can change. The engine has more power but still rough idle, even without the tape. LOL

It acts like a vacuum leak. This will be the second smoke check he does. There are no vacuum leaks on the externals of the engine. I do get misfire codes.

Heads redone 20k miles ago,
new timing chain
throttle body checked
replaced IAC - aftermarket - I am about to get a Ford IAC as the idle is too high and it doesn't seem to respond like it should.
MAF cleaned - wasn't dirty
Cam position sensor replaced
EGR tested every way you could check it, even blocked it off - all operations checks on it were good.
Replaced coil
replaced wires
replaced plugs with the correct ones
removed the plenum- checked gaskets
removed valve cover
checked all sensors
replaced lines on pcv valve-and pcv
replaced all injectors - tested injector fire signals from computer - all good
tested fuel pressure
DPFE ?? checked
compression checked 3 times, all around 180PSI,
smoke checked for vacuum leaks
hours spent under the hood looking around listening and checking vacuum lines for leaks, spraying starting fluid to check engine response....what we did not do. LOL

It is a 2000, 3.0l with 296K miles. I'm not scared of the miles my other ranger went to 400K before I gave it away. :)

 

Did you replace the valve cover gaskets when you pulled them off and put them back on?

Maybe the dipstick isn't seated all the way into the tube?

Injector seals?

When you did the cam position sensor, did you replace the synchronizer as well? Maybe it decided it's time to go. Rough idle is one of the warning signs of failure, from what I read, as well as long cranking times when you're starting the engine.

Maybe there is a crappy ground off of the engine block/trans to frame, or from the frame to the battery.

Try giving it hard throttle runs more often. Maybe that's the problem, not enough actual 'driving' or throttle under hard load. From my experience, things seem to run better when you run the **** out of it every now and then.

Disconnect the battery to let the ECU reset itself, maybe it needs to relearn the idle setting and such since you replaced the IAC.

 

Thanks for the input. I/WE did all that and more. We did not reflash the ECU and that's coming.

I am about to fix it with a 4.0L !! It's not a vehicle I need very often but I've been driving it to work for a year 110 miles every day. I just got the engine back in my VW..... 43MPG....diesel. Expensive to fix pain in the butt to work on.... yadda yadda yadda. LOL In other words, the truck can SIT now.

Take Care

 

I bought my Ranger in 1998, 122,000 miles. It now has 264,000+ miles.

It's always had an intermittent rough idle which would clear after a few seconds.
I assumed it was inherent in V-6 engines, which in general aren't as easy to
balance as straight sixes and V-8s.

Most recently the auto trans was rebuilt (A4LD), after which the idle was
much rougher, with vibration up to 15 or 20 mph. The trans. shop said they'd
neglected to replace the rear (trans) mount, which they then did. Some
improvement. Another shop replaced the front mounts plus some other
work (replaced steering intermediate shaft, replaced broken exhaust manifold
bolt). Slight improvement.

New spark plugs, spark plug wires, distributor rotor and cap.

Cleaned electrical connectors in engine compartment (haven't done all so
far)---slight improvement: connectors for IAC, TPS, coolant temp. sensor,
intake air temp. sensor, two fuel injectors. Slight improvement (or was
it hope and faith?).

Replaced the IAC valve---slight improvement.

Made sure oil dipstick is not loose in its tube (it was)---biggest improvement.

Intend to locate and clean grounds. I have a 1993 Ford Ranger Wiring Diagram EVTM Manual. Its diagrams show ground locations.

Code reader shows no faults for KOEO test (code 111). Haven't (yet) done KOER tests.

More to report later.

pw2buz

 

is your friend just replacing things? a cam sensor that is not functioning will not let the engine run period. sounds like if you replace a few more things youll have a new engine lol

 

My Ranger's had an intermittent rough idle for several years, until about 3 months ago when it became much rougher. Also, it wouldn't pass California emissions because of high NOx.

Before taking it in to fix the emissions problem, I replaced spark plugs, plug wires, distributor cap and rotor, idle air control, checked for codes (none). The emissions shop replaced the mass airflow sensor and the catalytic converters. It then passed the emissions test.

A week or so later I replaced the coolant temperature sensor with a $16 one, made in China. Didn't help much. Yesterday I replaced it again, this time with a Motorcraft coolant temperature sensor. Much better! Now it idles pretty well---not like a straight 6 or a V8, but tolerably well.

My advice: if you're going to throw parts at your Ranger, start with the cheap stuff.

 

There are two TSBs (technical service bulletins) addressing the rough idle problem in 1993 Rangers (3.0 liter engine) which should be of interest to some forum members:

TSB 95-7-14 - idle-rough-after cold start during first minute of operation...
stall-after cold start during first minute of operation...

TSB 95-12-6 - idle-rough-3.0L vehicles - warm engine at all ambient temperatures-
1992 4X2 (with manual transmission)
all 1993 vehicles

The first one (95-7-14) theorizes the rough idle may occur because of low volatility fuel.
The second (95-12-6) advises installing "new front engine insulator assembly" and on some
vehicles (auto. trans. equipped) a new PCM if, after diagnosing using the 1993 Powertrain Control/
Emissions Diagnosis Service Manual, the concern still exists.

I just found these TSBs so have done nothing yet.

The engine insulator assembly is, according to the TSB, the Engine Insulator Kit (part #
F57Z-6K007-AA for 1992 4X2 man. trans. and 1993 4X2 auto.trans.). Part # for 1993 4X4 manual
and auto. trans is F57Z-6K007-BA.

I think the engine insulator is an engine mount.

This after replacing numerous parts, including all three engine mounts!

 

I had a rough idle and the thing that finally fixed it was replacing the coil pack.

 

I have a 97 4.0 ltr XLT that had idling issues where the engine would idle rough and was hard to restart when at operating tempurature.The engine worked well under load but would struggle to idle and would not code out.
After cleaning the usual supects and checking for vacuum leaks with no noticible improvements I focused my attention to the EGR valve.
I pulled the vacuum hose off the EGR and applied enough PSI with an air hose to blow the diaphram in the EGR .
It turns out that applying enough PSI's to blow the diaghram was not the smartest move, however the end result was the EGR closed and the engine idled perfectly and because the EGR valve had completely closed and was unable to open due to the diaghram being damaged the ECM finally coded out.
I replaced the EGR and the issue is entirely eliminated.

 

I to had problems with my idle, I replaced everything metioned above and belive it or not the thing that fixed it was rechargeing the ac with 134a. The low ac preasure messes with the idle air control valve sensor even when the ac is off more so when it is on.
Doing just this improved my throttle response and off idel acceleration.

 

I could set this thing on fire and watch it burn. After I removed the tires and rims and a few of the new parts I installed.

It is my yard/work truck. I use it around town every now and then. I' gonna play with it one more session. That means, new plugs, and recheck a few critical things like compression, wires and such.

Funny thing, it high idled on me for about 5 months, I replaced the IAC with no improvement and all of a sudden..... it returned to normal. I still think it is a computer problem. I've tried everything else. I thought of replacing the throttle body or borrowing one of a running vehicle just to see if that might be the problem. I checked everything at least 4 times. It isn't just idle, it lacks power as well.

I'm glad to hear you guys are figuring your stuff out.... I've never been lucky when it comes to that stuff. Normally, If I can't fix it..... using my resouces (technical people and such)... it is a very difficult problem. I have one more hope, a cousin that does driveability for GM. He is an excellent mechanic I just don't want to bother him.

I do have a whole vehicle with a 4.0 engine that I have been considering installing. Yep, it is that bad. LOL

 

My 2.9 has always had a rough idle and I have done all the usual things to try to mellow it out. I have yet to understand how the iaf control works, but have cleaned it several times with some success. I read on the forum somewhere that to test it just disconnect the wires. The eng. died is that a pass or fail? Last time I had it off I stuffed a plastic cap in each hole and it has ran much better ever since. Can anyone explain ?
Roaddawg
" still running against the wind "

 

There is a test for it which I performed but it has been a while. I don't think the engine is not suppose to quit running, just the idle RPM will be a specific value. Basically, when you unplug it, the idle RPM should change

 

Replaced my coil with an MSD coil (Ford TFI Coil, Hi Performance, Part No. 8227).
Link is http://www.msdperformance.com/product.aspx?id=5065.

Made a difference in the idle smoothness --- my 3.0 liter V6 idles more smoothly.
When the idle is rough (not too often), it is less rough than before the coil replacement.

One could argue the difference is merely a placebo effect.

My Ranger now has 273,000 + miles.

 

Well I'm sure u all know this and I can't say I'm mu h of a mechanic but I do know a few things. Three of my friends have cone to me with an idlei.g problem and I have just about done away with my Ford dealership. I tell my freinds to check here before they do anything. I started scanning through everything and found that our local dealiship needs new mechanics. Simply the firing order! The dealership should know better. Speaking of which. My dealership almost bought me a new truck. I went on for an oil change. Simple right. Wrong. I noticed when I had made to my drive way I was running hot. I turn truck off and check there work to find out I had oil all over the u.derside of my truck and I didn't have a filter on. How I made it fifty miles with no oil idk. But I havnt brought my truck near them since. If they can't manage an oil change then who knows wut they'll mess up. Ik this is off topic I'm just saying id ur using commercial mechanics double check. A lot of shops around here like to cut corners too keep u coming back. Just know who u can trust.

 

Other than basic maintenance on your truck i had a 2000 model 3.0l. I had a bad time dealing with some rough idle issues. I quit using the local mechanics for routine maintenance. They replaced spark plugs, wires, coilpack, fuel filter, and much more. The mechanics never gapped the plugs correctly and used cheap plugs. Along with loose plug wires that is without a doubt a common mistake. Just for laughs you might want to take a look at the harmonic balancer.

The cure was the correct maintenance and doing it right the first time. This is just my opinion but Royal Purple oil full synthetic has always done wonders. The fuel mileage increased slightly possibly 1mpg at the most. It cleared alot of the motor ping for the 3.0 and for my 4.0l sohc truly helped with the timing chain rattle.

 

When I finally address the problem with mine (my inherited truck from my son, LOL) I'll post up. I really think it is going to be the PCM or the Throttle body. No telling. We've done everything else. It's not just idle, it's power loss etc. #5 cyl. is the worst. Don't ask what I've done.... I've done it all... at least TWICE. LOL.

 

At one point cylinder 5 went on my 3.0l it turned out to be a burnt valve. It was a whole different kind of rough idle. It acted as if I had bad 02 sensors and never showed a single code. I can reference that to bad 02 sensors because that was a issue I ran across at one point. It idled rough but ran smooth when over a certain rpm. If it shifted into overdrive or the rpm dropped to a certain point you could feel it going down the road. Not just the physical shake but also the power felt like if had been sucked dry out of the peddle.

 

I'm back with my intermittent rough idle 1993 Ranger (3.0 liter engine).

Two years ago lots of stuff replaced to get it to pass the CA smog test: catalytic converter, mass air sensor, idle air control valve, engine temp. sensor.

It did pass the smog test with good scores except for NOx readings. 15 mph scores were 502 ppm (parts per million - maximum allowed 533), too close for my comfort. 25 mph readings were high but adequate: 350 ppm (maximum allowed 786 ppm).

I had no record of oxygen sensor replacement in the life of my Ranger (which has 278,000 miles on it), so decided to replace them. I paid $212, not much and saved the aggravation of working with inaccessible parts. I noticed an immediate improvement in idle quality. Reasnably smooth, and now more consistent.

It passed its smog test (March 2014) with much improved scores: 15 mph NOx of 267 ppm and 25 mph of 110 ppm.

Now I can do some upgrades (upholstery, paint) instead of junking the old beast!

 

2000 Ford Ranger XLT 100k service this week: rough idle fixed : replaced PVC Valve, Spark Plugs and wires, Changed Prem. coolant, Changed Accessory Drive Blts, 4-point multi inspection, replace oil filter - 5 qtrs of motor oil, change engine oil, vacuum, $600 which inc labor and tax. Joels Automotive in Montclair (only ford certified mechanics) NEXT will get 5 new Wrangler tires 225-70-15. What came on truck was Hancock (USA made) not to be confused with korean company called Hankook NOT THE SAME not USA tires. hope this helps.

 

got out the invoice: done on 4.4.14: Rough Idle and 100k service at same time: Cost $642.49 inc. tax/labor: Joels Automotive, Upland, CA 91786 (only hire 100% ford certified mechanics). Diagnostic Engine Perf: $97.45: changed spark plugs and wires (V6) $116.94, Fuel Filter - remove and replace -inline $61.39, 3-step fuel system cleaning $107.20: perform fuel injection cleaning throttle body cleaning and decarbonization of engine by adding additives to the gas tank, engine oil and fuel injection air intake system. Replaced Spark Plugs/wires, PCV Valve, Fuel Filter OE, 3-part induction Service. NO MORE ROUGH IDLE. Truck runs new again. Will have Joels do the smog test for DMV as well. ph for joels: 909.946.7667 (joel is cert ford mechanic with over 40 yrs).

 

anytime anyone experiences rough engine idle

run a FULL can of seafoam mixed in with the fuel in tank and run the fuel tank to near empty

sometimes rough idle is nothing more than partially clogged fuel injectors , or even just a clogged fuel filter

a lot of the newer fuel pumps at gas stations DO NOT ultiize storage tank to pump fuel filters anymore

 

The intake air hose (also known by Official Ford Parts Site | Buy Motorcraft & OEM Ford Parts Online | FordParts.com as the engine air box) goes from the throttle valve to MAF (mass air flow sensor). The attachment ends are rubber seals clamped by large hose clamps.

The rubber seal on the MAF end of mine was damaged (see photo), so I replaced the complete assembly with a new Motorcraft intake air hose. I was pleasantly surprised to find that the engine (3.0 liter V-6) idles and runs more smoothly.

I find it, ah, interesting that two shops probably did not check for this problem, nor check the oxygen sensors. One shop replaced the expensive parts, MAF, catalytic converter.

 

After wasting all summer incrementally cleaning and or replacing parts I kept getting rough idle. Why? It was summer, so I kept the AC on most of the time. Well, here in Michigan in the middle of October it got down below freezing this morning so I finally shut off the AC. The result was the worst rough idle I ever had in my 2000 Ranger XLT 3.0L 4x2 with 93,600 miles (original owner).

I found a post in this thread that said to add 134a and I did and the rough idle is gone!

The idle would be fine, but I'd turn the AC off to listen/feel it better and the problem would come back...because the AC was OFF and low on 134a. Lol, looking back the solution was right there!

Also, I believe the AC compressor kicks in if you use the heat with defrost on. Causing the same intermittent problem in the winter.

So, if you're Ranger runs rough, try blasting the AC on.

So I registered to say thanks. This thread helped me out.

Here's what didn't work:
Spark plugs (sp-500)
PCV replacement
Cleaning IAC, MAF, etc.
Seafoam then B12 Chemtool
STP additive
Cleaned battery posts.
Cleaned water out of fkex fuel sensor connector under truck near driver seat (but outside vehicle)
New fuel filter.

Now, after 15 years and 93k it was almost time to do that stuff anyway so no biggie.

The other thing that made a huge difference was the throttle mod: pull the cable slack past the accelerator and put 4 zip ties to keep it pulled up. Way more throttle!