rough idle problem and can't find solution

1996 FORD RANGER

197,100 MILES

CARDETAILER18

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5 POSTS
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I have a 96 Ford Ranger 2.3l 5 speed that has been having a rough idle problem for the past 2 or 3 weeks. My truck was running fine and then I had the CEL come on and the code was P0401 or EGR Flow is insufficient. I proceeded to change the EGR Valve and when I did this and started up my truck it was idling rough, so I put the old EGR back on and it didn't fix the rough idle problem. Since then I have changed the EGR Valve, EGR Vacuum Solenoid, EGR Sensor, IAC Valve, Air Filter, Fuel Filter, Upper Oxygen Sensor, Spark Plugs and Wires, and I have cleaned the MAF Sensor and the Intake Manifold and Throttle Body. When I took off the Intake Manifold the hole that goes to the EGR valve was completely clogged and since I cleaned it the CEL has not come back on. I have also had 2 instances of the CEL coming on and it being a Cylinder #2 misfire. Ever since I cleaned the Intake Manifold a week ago I have not had any CEL's. My truck is still idling rough. I took it to Ford and had them do a diagnostic on it and they told me that it wasn't misfiring and that it didn't have any codes stored in the computer. They also did a compression test, which said that cylinder #1 had a low compression by 1% and that cylinder #4 had low compression by 4%. They sent me on my way after telling me that it might be a slightly stretched timing belt and that they would charge $600 to replace it. What a joke! I am at a loss as to what might be the problem. I don't know how to check for vacuum leaks, but that may be the problem. The only other thing I can think of are the fuel injectors, which I don't know how to test. My truck's temperature gauge is also slowing going up and down between 1/4 and 1/2 when it is idling.

I have changed the DPFE otherwise known as EGR Sensor and I have changed the Idle air control and I have cleaned the throttle body.

My P0401 code is gone. It was a plugged up intake manifold port going to the EGR valve.

Thanks for your help!

Apr 20, 2013 at 2:39 PM

STRAILER

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53,854 POSTS

With that many miles I would think you have an intake valve that is leaking which would account for the rough idle. Let confirm the problem by doing a compression check

https://www.2carpros.com/articles/how-to-test-engine-compression

This guide may help as well.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Please let us know what you find so it will help others.

Best, Ken

Mar 9, 2017 at 2:16 PM

EDDIE1329

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1 POST

Replaced plug wires. Code read cylinder one foul.
Put new wires on. Read a lot on this topic and I cannot just throw money at it trying to diagnose. Drove truck day before a one hundred mile round trip no issues. Next day started up and idle is terrible shakes bad in first, second and third gear.
Help!

Mar 9, 2017 at 2:17 PM (Merged)

BRODERICK1

MEMBER
8 POSTS

Engine Performance problem
1998 Ford Ranger 4 cyl Two Wheel Drive Manual 51000 miles
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My ranger has a rough idle. I have cleaned the maps sensor and the trottle body. can you help?

Mar 9, 2017 at 2:17 PM (Merged)

BLACKOP555

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10,386 POSTS

Your PCV valve could be bad OR the EGR valve could be plugged.

Also take off the IAC and make sure the pintle is moving freely.

Mar 9, 2017 at 2:17 PM (Merged)

BRODERICK1

MEMBER
8 POSTS

Would the idle air control valve play a part with rough idle? also how do you clean the EGR valve? There is no pcv on my truck. Thanks.

Mar 9, 2017 at 2:17 PM (Merged)

BLACKOP555

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10,386 POSTS

to clean the EGR you have to unbolt it and clean its ports and the ports on the engine.

The IAC is the idle control valve and it is a big part of how the vehicle idles.

Mar 9, 2017 at 2:17 PM (Merged)

BLACKOP555

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10,386 POSTS

Yes it could cause it to idle rough by telling the injectors to pulse out extra fuel causing it to rev up and down.

Mar 9, 2017 at 2:17 PM (Merged)

BRODERICK1

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8 POSTS

Is there a certian type of cleaner for the throttle body etc.

Mar 9, 2017 at 2:17 PM (Merged)

JBS111096

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2 POSTS

Engine Mechanical problem
1994 Ford Ranger 4 cyl Two Wheel Drive Automatic 92,000 miles

Hello,

I have replaced spark plugs ( they were jacked ) and had the injectors cleaned. I have plug wires to put on but haven't done that yet. I still have a vibraton/ rough idle to the point where you can feel it in the steering wheel and see it on the dash and even feel it on the floor. Runs like a top when moving and gets great gas mileage.

My buddy said mounts are fine. What could this possibly be ?

Mar 9, 2017 at 2:17 PM (Merged)

BLACKOP555

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10,386 POSTS

Carb cleaner mainly would be for the throttle body, you can use brake cleaner or QD contact cleaner for it. I use the carby cleaner.

Mar 9, 2017 at 2:17 PM (Merged)

JACOBANDNICKOLAS

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110,175 POSTS

Has the check engine light come on? this guide will help

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please run down this guide and report back.

Mar 9, 2017 at 2:17 PM (Merged)

BRODERICK1

MEMBER
8 POSTS

I have a 5 speed manual tran. How much play should there be on the drive shaft where it goes in the extension housing? When I take the truck out of gear the small viburation goes away. The truck has a new clutch.

Mar 9, 2017 at 2:17 PM (Merged)

JBS111096

MEMBER
2 POSTS

No check engine light problems and I think we have ruled out a vacuum leak. Could it be that the timing is off ? Again , no issue at all other than idle.

Mar 9, 2017 at 2:17 PM (Merged)

BLACKOP555

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Yes. This could be a timing issue so we should start with checking it.

I am attaching the info from the manual on how to do this.

Images (Click to enlarge)

Mar 9, 2017 at 2:17 PM (Merged)

JACOBANDNICKOLAS

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110,175 POSTS

I would think that if it was timing, it would be felt all of the time. To me, it sounds like a vacuum leak or maybe there is a carbon build up in the EGR and it isn't working properly. Also, I don't know the history of the truck. If it has had a rough life, you may want to check compression to make sure that you don't have a weak cylender.

Mar 9, 2017 at 2:17 PM (Merged)

BRODERICK1

MEMBER
8 POSTS

I have cleaned all parts you mentioned except the EGR , when i rev the engine it comes back to idleal most all the way, then in about 5 to 10 sec. it comes all the way back. any help? thanks for your helping me.

Mar 9, 2017 at 2:17 PM (Merged)

BRODERICK1

MEMBER
8 POSTS

Please help. I have replaced the egr,Iac, cleaned the TB,MAF, Also done a Motor vac. replaced plugs and wires,
there are no codes,this only happens while driving the truck does not want to return to idle. It wants to stay reved when i let off the accelerator for about 15 sec. In nuteral clutch in it operates fine.

Mar 9, 2017 at 2:17 PM (Merged)

SUPERRAT

MEMBER
2 POSTS

94 Ranger, 2.3 with manual trans. Developed rough idle or miss. Runs good at hi rpm's. When warmed up rough idle at startup or miss.Really notice at stop sign when I take off sputters around till engine reaches higher RPM'S then runs good. I noticed if engine does idle normal then suddenly rpm's will drop & engine runs rough for a few minutes then takes off & runs normal. Thank you for any information on this problem.

Mar 9, 2017 at 2:17 PM (Merged)

BOCHEVY13

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1 POST

with the engine running and hood up, spray some ether around the intake manifold where the gasket should be. may be a blown plenum gasket, had a ford explorer do that in the past. It was a V6, but I am also having that same problem but havent gotten a chance to fix it yet.

Mar 9, 2017 at 2:17 PM (Merged)

HMAC300

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48,601 POSTS

check fuel pressure and scan for codes first

Mar 9, 2017 at 2:17 PM (Merged)

SROZAR

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1 POST

i have a 94 ford ranger extended cab 4.0l 5spd 4x4. engine has a rough idle when first turned on (gets worse if its restarted after warmed up), has steam and water dripping out the exhaust, chocolate milky residue on the backside of the throttle body butterfly but no water in the oil when dipstick is pulled however the oil does have a hint of gas to the smell, very heavy smell of gas from the exhaust smells way rich but plugs dont look like they are getting too much fuel however i am changing spark plugs every couple months because they keep burning up. this time though, the middle plug on the passenger side was soaked in this very heavy gummy kind of wetish fuelish goo, intermittent hesitation/ power loss/ misfire under acceleration above 2500 rpm, has stalled on me leaving me on the side of the highway. ive replaced plugs, wires, coilpack, fuel pump relay, fuel filter, cleaned the MAF properly, cleaned the throttle body and IAC valve, visually checked vacuum lines for cracks, none, checked the fuel pressure regulator vacuum line for any trace of fuel, none, MAF has 14.3V between "a" and "b" and 0.98V between "c" and "d" which i believe is correct, IAC valve has 12.3V to it and a resistance of 11.1 but no change in idle when the plug is disconnected. check engine light never comes on while running. ran the self test on it results being KOEO- 111, 111 (system checks out) with the same stored in continuous memory, KOER- 412, and 411 in that order. that describes the IAC valve, but i dont see with what that has to do with making it stall while maintaining constant highway speed at 3000RPM. im at a loss. O2 sensors? fuel pump? leaking injector? ECT? PCM/ECU?

Mar 9, 2017 at 2:17 PM (Merged)

HMAC300

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48,601 POSTS

have coolant system pressure checked for a head gasket leak, check fuel pressure and clean throttle plate on both sides with choke cleaner and iac hole.

Mar 9, 2017 at 2:17 PM (Merged)

KENT1959

MEMBER
1 POST

Engine Performance problem
1997 Ford Ranger 6 cyl Two Wheel Drive Manual 180000 miles

my 97 Ranger has a rough idle, idles slow then races up a bit then slows again

Mar 9, 2017 at 2:17 PM (Merged)

RASMATAZ

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75,992 POSTS

Engine running rough or misfiring can be cause by the following:

1.Defective spark plug
2.Inadequate spark/coil,defective spark plug wire.
3.Lack of compression
4.False air leakage.
5.Faulty fuel injectors.
6.Insufficient fuel pressure.
7.Contaminated fuel.
8.EGR valve that is leaking.
9.Oxygen sensors.
10.Throttle position sensor.
11.Idle air control valve.

Mar 9, 2017 at 2:17 PM (Merged)

GAETANOR

MEMBER
1 POST

Engine Performance problem
1994 Ford Ranger 6 cyl Two Wheel Drive Automatic 105000 miles
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Recent replacements included tune-up with new plugs and wires, new fuel filter, and fuel injector cleaner run through the fuel tank. The truck has a rough idle and acceleration feels sluggish. There is an odd odor that comes out of the exhaust however (fuel mixture running rich?). Anyway, I heard the intake sensor might be an easy fix - should I give it a try?

Mar 9, 2017 at 2:18 PM (Merged)

MERLIN2021

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17,250 POSTS

You may have a vacuum leak, get a can of spray gumout, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs! If that doesnt do it, you may need a new idle air control valve, it's bolted to the throttlebody. Stuck EGR can be another cause.

Mar 9, 2017 at 2:18 PM (Merged)

BADMECHANIC2

MEMBER
3 POSTS

I have a 98 ford ranger 4.0 V6 with 135,000 miles. My problem started over 2 years ago. It started to stumble and hesitate and had a rough idle. I got a tune up with new wires and plugs. it ran good for about 4 to 6 months and progressively got worse. took it in and they did another tune up and worked good for another 6 months. This keeps happening over every 6 months. I have changed the EGR, coil pack, crankshaft sensor, camshaft sensor, all the oxygen sensors, cleaned and checked MAF sensor, the #4 fuel injector, fuel filter, and again the plugs and wires. When an error code come on it is P0304. I had fuel pressure checked, compression checked, and checked for vacuum leaks. All were good. Mechanic checked the timing chain and it was in good shape. No leaks, no overheating, no loss of oil. I do change oil regularly. Mechanic says engine is in good shape. The #4 plug does seem to go every 6 months. Throws the same P0304 code. Changing the plug seems to keep it running ok for the 6 months. I don't know what this could be. the fact that it runs good for that amount of time and then just goes bad again is very confusing. Any help would be great. Tell how to troubleshoot this. If you can give me steps I would appreciate any help. Thank you.

Mar 9, 2017 at 2:18 PM (Merged)

CARADIODOC

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Rather than replacing the spark plug, switch it with one of the other ones, then see if the misfire changes to that cylinder. I suspect you aren't really solving the problem by installing a new spark plug. You're just overcoming the symptom for a little while. Ford has had a lot of trouble with their ignition coils, and if you have one that is not able to develop the needed voltage to create a spark, intermittent misfires will be the first symptom.

You also have to look at the mating spark plug that is fired by the same coil as # 4. As either spark plug wears, it's going to require more voltage to fire the pair of them. As an example, one plug may only need 10,000 volts to make a spark, and its mate might need 13,000 volts. That's fine if the coil can produce 23,00 volts or more, but if it gets weak or arcs internally, the plug needing the higher voltage will usually be the first one to not fire. Both spark plugs should not fire when one doesn't, but you have to consider that the one coming up on the compression stroke will need the higher voltage. When it's on the exhaust stroke, it won't need as much voltage, so both plugs will fire.

Mar 9, 2017 at 2:18 PM (Merged)

TK9274

MEMBER
2 POSTS

Engine Performance problem
1997 Ford Ranger 6 cyl Two Wheel Drive Automatic

My buddy has this truck, the inlet for the radiator had a hole and was losing fluid. He has been filling it with water ever since. We replace the inlet, put in a new thermostat, everything has been running great till about two weeks ago. The truck stated losing fluid again, checked and there is a rotted freeze plug. Now the truck idles rough, lacks power, and is starting to misfire. Would the freeze plug cause all that?

Mar 9, 2017 at 2:19 PM (Merged)

RASMATAZ

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75,992 POSTS

rotted freeze plug. Now the truck idles rough, lacks power, and is starting to misfire. Would the freeze plug cause all that?

No the freeze plug won't do that-When was the last time you gave it a tune-up and is the CEL on?

Mar 9, 2017 at 2:19 PM (Merged)

TK9274

MEMBER
2 POSTS

[quote:90005f66a4="rasmataz"]rotted freeze plug. Now the truck idles rough, lacks power, and is starting to misfire. Would the freeze plug cause all that?

No the freeze plug won't do that-When was the last time you gave it a tune-up and is the CEL on?[/quote:90005f66a4]

Not sure when he had it tuned up last, I will check with him on that, and no the CEL is not on.

Mar 9, 2017 at 2:19 PM (Merged)

MIKEHARRIS

MEMBER
1 POST

Engine Mechanical problem
2003 Ford Ranger 6 cyl Two Wheel Drive Automatic 95,000 miles

I have a problem with the check engine light on and rough idling. My mechanic said that it is the code for the #6 cylinder. Since then, we have replaced the fuel filter, plugs, wires, and the fuel pump reads good pressure. We have also rebuilt the heads. We have done a pressure test and everything checks out normal. We have also replaced the fuel injectors and the computer says that both banks are flowing smoothly into both injectors. We can take the spark plug wire off and there is no change in the idling but when we take any other wire off, the engine drops off more. What else can I do to fix this truck that is only running on 5 cylinders? Thanks. M. Harris

Mar 9, 2017 at 2:19 PM (Merged)

RASMATAZ

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75,992 POSTS

Check the no.6 cylinder's compression both dry and wet tests if its withn specs

Mar 9, 2017 at 2:19 PM (Merged)

BIGD11775

MEMBER
3 POSTS

Engine Performance problem
2005 Ford Ranger 6 cyl Two Wheel Drive Automatic 73040 miles

My truck runs fine while driving. But when I stop at a light the truck has a rough idle to it. Before I changed the fuel filter, it actually would almost die in neutral or park. So the filter seemed to have fixed that part. I have also replaced the plugs and wires to try to fix it. Nothing helps. No noticible vacuum leaks that I can hear and the check engine light is not on. It came on about a year ago, I unplugged the negative from the battery for 15 min, and it was fine since. The rpms at idle seem normal and it doesn't feel like a low idle, cause it feels more like a slight miss. I can still feel it if i raise the rpms up a little around 1000-1500. I did pull and check the IAC and it was perfect. Also a fresh oil change today didn't help either. Injector cleaners aren't helping either.........so im puzzled ????

Mar 9, 2017 at 2:19 PM (Merged)

LEGITIMATE007

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5,121 POSTS

I think that maybe a simple throttle body/bore cleaning might just fix the issue, clean it up with some cleaner and an old rag, also try to clean the throttle plate as best that you can mostly on the inside where all the soot seems to be overlooked, give that a try first and let me know how it goes

Mar 9, 2017 at 2:19 PM (Merged)

BIGD11775

MEMBER
3 POSTS

Thanks leg for the response. I did pull the intake hose off today. The bore up to the butterfly was spotless. But I opened the butterfly, and wiped inside with a rag soaked with carb cleaner. It was very dirty behind the butterfly, and I can only reach in about a half inch past. I do feel that the bore opens up wider right after the butterfly, but I cannot reach it. I didn't currently have the right tool to get the bottom two bolts out on the throttle body housing. From that, the only thing I noticed on the way to work, was a better throttle response than before. I was unsure whether to just spray carb cleaner inside, because of what might happen when I start it.....Should I try that before I go buy a tool set?

Mar 9, 2017 at 2:19 PM (Merged)

LEGITIMATE007

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5,121 POSTS

well you can leave the truck running and toggle the throttle as you spray the cleaner every couple of seconds while keeping it from shuttting off.

Mar 9, 2017 at 2:19 PM (Merged)

MARK A ROGERS

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1 POST

I have had my Ford Ranger to two different garages for a rough idle diagnostic. Both put the scan tool on and found misfiring on two cylinders. The local Ford dealer said they did an air pressure test and found low compression on two cylinders. Both shops suggested that an engine replacement was the only repair. What other options may I have for this problem and a potential repair.

Mar 9, 2017 at 2:19 PM (Merged)

CARADIODOC

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Assuming a compression test showed low compression on two cylinders and the test was done properly, the next step would be to do a more involved cylinder leakage test. By looking and listening, that will tell if the leakage is through the intake valve, exhaust valve, past the piston rings, or through a leaking cylinder head gasket. You also didn't say how much those two cylinders were low. There are other potential causes of low compression. Either valve could be not opening fully due to a worn lobe on the camshaft or a broken rocker arm. For things like that you don't replace an entire engine with a used one that could have the same problem waiting to occur. You would typically repair what is broken. Have the cylinder leakage test done first. It takes quite a bit longer but I would want to know WHY I'm replacing the entire engine before I agreed to that.

'96 and newer models have misfire monitors in the Engine Computer as part of the emissions package and there should be diagnostic fault codes stored in the computer indicating which cylinders are responsible for the misfires. Did anyone read those codes? The Check Engine light should have been on too. Do those codes indicate the same cylinders as were identified in the compression test?

Mar 9, 2017 at 2:19 PM (Merged)

AGLABANZAT

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2 POSTS

Engine Performance problem
2004 Ford Ranger 6 cyl Two Wheel Drive Automatic 167000 miles

My truck suddently began to idel rough and I felt a strong vibration. I heard a whining from the cranck shaft pulley, so I replaced the serperntine belt, idler pulley, and pulley tensioner assembly. I also replaced spark plugs and wires, and crank shaft position sensor. The engine still runs rough, either idling or running, too rough to drive

Mar 9, 2017 at 2:19 PM (Merged)