Rough idle on warm restart

[cherylj]

When I restart my truck within 10-20 minutes of shutting it off, I get a really rough idle. It only happens after driving long enough to get completely warmed up. The sooner it is restarted, the rougher the idle. (With the Borla exhaust, it sounds kind of like a street-rod loping along but I'd rather have that sound with an engine that is running well!) Giving it a little bit of gas will smooth it out after some nasty sputtering; too much gas kills it. We thought a new throttle-position sensor might cure it but it didn't. Any other ideas??

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Rick & Cheryl J.
'94 XLT 4x4
Custom 2" lift, Rancho 5000s
Borla exhaust, over-size sway bars
More to come!

 

[murrajm5]

You may want to check this board for cleaning the Mass Air Flow Sensor. Also, try cleaning the Idle Air Control Valve.

 

[Seth]

My explorer is actually in the shop right now for that same problem. I told them to keep it until they figured it out. So hopefully they wil be able to figure it out. I'll notify you when i get it back of what their solution was.

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Seth M.
97 XLT 4X4 4.0L SOHC

 

[dmeis]

Matt and I have the same problem with our Explorers....mine did it to me last year all of a sudden on Mt. Antero....that was stressful. Dead Link Removed



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David
92EB-4.56-ARB-Custom Lift,skidplates-OBA-XD9000i-33MT's

 

[Seth]

Ok, well I talked to the people who are fixing my car right now. They "say" that it is because when the k&n filter charger was installed the mass air sensor was broken. Now this is hard to believe because a ford certified technicial helped me put the k&n in. Well anyways they are ordering me a new one thats going to cost me $180. If yours is messed up and cleaning it doesn't fix the problem then you might want to purchase a new mass air sensor. I'm not sure if this will fix the problem because I have not got my car back. But if the problem comes back after getting the new sensor I'll make sure to mention it in the forums. Hope this helps someone.

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Seth M.
97 XLT 4X4 4.0L SOHC

 

[Rob Slade]

My explorer was doing the same thing, and we tried a couple of times to let the dealer do something. They did nothing to fix it. I finally cleaned my mass air flow (MAF) sensor the way they told me to on this site, and the problem hasn't come back since. Give it a try and it should help your problem.

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Rob Slade
'95 XLT 4x4
30x9.5 All Terrain KO's
K&N Air Filter System
Manik: Grill Guard
Taillight Guards
Step-Up Bars
Surco Safari Rack
2 Hella Black Magic's
4 Hella 500's
2 Punch DVC 10's
More to come...

 

[cherylj]

HELP! Cleaned the MAF sensor and no improvement. I noticed tonight that the volt gauge was fluctuating while it was sputtering. Never noticed that before. I did have a one-year old battery go bad a couple of weeks ago and now the new one seems to be weakening. Could they be related? I kind of doubt it but...

 

[Seth]

I wanted to mention that the "supposed" fix by the dealer by replacing the mass air sensor did not work. It cost me 300$ for parts and installation but did not fix the problem. The rough idle happened last week and twice this week. So I will be bringing my explorer back to the dealership in a few weeks here (they are booked) and i'll post anything that I find.

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Seth M.
97 XLT 4X4 4.0L SOHC

 

[Navajo Joe]

Cherylj and Seth I think I have answers for both of you. If cleaning the MAF didn't fix the probelm try doing a carbon flush on it. It is what finally smoothed mine out. Boy was the engine carboned up. It blew smoke for 15 minutes. You can buy the carbon flush at the Ford dealership and do it youself for $5.17 or have the service department do it for a little over $100. I did it myself, it is easy. Just warm up the truck and while it is running pull the vaccum line that goes to your brake booster and put it in the can. The enine will suck it into the engine. Then if it doesn't stall the truck, sut it off right away. The service tech told me they leave them over night to give the product time to work. I tried following the directions on the can and it said to let it sit for 15 minutes. That really didn't help so the next time I left it in over night. Boy what a cloud of smoke, but she sure runs better now. The 4.0 engines carbon up really bad because the trannies are geared for milage. So the engine is always at an idle.
Also for Cherylj it sounds to me like you might want to check your battery cables. I have seen many posts of people having the voltage gage fluctuating and it was caused buy bad battery cables. If they are going bad it could possibly reduce the ability of the alternator to charge the battery. It could also be the alterbator. I would check those out. Hope this is some help.

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91 Navajo 4.0
Bosch Platinum plugs, K&N air filter, modified air box and Bilstien shocks.

 

[FMNavajo]

On this site are many posts about the carb buildup on the 4.0L V6's. Check the #5 plug and see if the carb buildup is worse than on another plug, (pick one). If the carb buildup is worse I suggest either re-tightening the intake manifold bolts or replacing the gasket for the intake manifold. I did the latter and it only took a couple of hours and I havn't had a problem with it since. When I had the intake man. off I used up about 4 cans of carb cleaner and when I put it back in it looked new. I also replaced the fuel pressure reg. and O2 sensor and oh my, what a difference.

*NOTE - you will have to remove the valve covers to get the intake manifold off so don't forget replacement gaskets for those.

This all cost me about $200.00 and a few hours in garage. I replaced the gaskets with Fel-Pro and a Bosch regulator. I got my parts via carparts.com and saved a bundle.

Hope this helps,
FMNavajo

 

[cherylj]

Well, we ran some carbon flush through my truck last night. Smoked the neighborhood up pretty good today but it did seem to help. Hopefully this is the end of it for awhile!

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Rick & Cheryl J.
'94 XLT 4x4
Custom 2" lift, Rancho 5000s
Borla exhaust, over-size sway bars
More to come!

 

[cherylj]

Well, the carbon flush apparently didn't work. The problem is still there. Next possibility might be the o2 sensor. Anybody got any other ideas?? This really getting on my nerves! It's embarassing too - a great looking truck that runs like an old tractor isn't very impressive!!

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Rick & Cheryl J.
'94 XLT 4x4
Custom 2" lift, Rancho 5000s
Borla exhaust, over-size sway bars
More to come!

 

[Hunter11]

I called my Ford place and they said that they never heard of the carbon flush. Is there another place that you can buy it and what is it called.

 

[ExploreMinnesota]

The carbon flush is really called "Tune-up Carburetor Cleaner." It carries the Ford name on it, so they should have it, or be able to get it.

I used it over the weekend. I left it sit for about 5 hours and then started it up to burn it all out. There has been a big improvement in the pinging . . . most of the time I can't get it to ping at all now, but I have noticed it very briefly a couple of times. I think I'll run some "Tune-up Carburetor Cleaner" through it again and see if i can get rid ofthe pinging all together.

I've never changed my O2 sensor, so it's still the original. How do I know if the sensor is still okay? Is it worth changing just because it has never been changed?

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ExploreMinnesota
91 EB 4x4 Stock

 

[TPLYNCH]

Cheryl, if you haven't done it yet you may also want to check your vacuum hoses, making sure they are all connected and that they are not cracked. Sometimes, something as simple as a bad vacuum line will cause problems.

 

[cherylj]

Well, if the fix ends up being that easy, I'm going to scream! Love to try it right now but the (*&&^%$ transmission went out again and its at the shop! I may have been premature in my praise of the transmission guy in an earlier thread... I will definitely check the hoses though. Probably end up changing the O2 sensor anyway. Not that expensive and it can't hurt.

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Rick & Cheryl J.
'94 XLT 4x4
Custom 2" lift, Rancho 5000s
Borla exhaust, over-size sway bars
More to come!

 

[Bill Kemp]

Rick & Cheryl, Have you had any luck on fixing the rough idle? I ask cause mine just started doing it today. About a month ago I cleaned the MAF, changed to Bosch P+4's and new plug wires. All vacume hoses look good although I'm going to try thr Gumout spray trick to test them.
I was hoping you found some easy(cheap) fix. I seem to be leaning to the fuel pressure reg. or the idle air controle. At 60,000 miles it acts like it's got a 160K.
Anyway thanks for any input.

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Bill Kemp 96 XLT 4x4 4. OHV

 

[ExplorGM]

Must be an epidemic! I've been working on this problem for a week now also.
I tried cleaning the MAF, replacing the wires, and plugs (which were gone anyway), and checked the EGR. The problem went away for a week and then came back.
I purchased an Actron Code reader with some help from Trace, and am still mistified. I've gotten inconsistent readings from the code reader.It reads pass even though I have had the check engine light come on.I'll have to try it next time the light comes on, on the spot.
Juan suggested a throttle clean.That is my next step before going after the Oxygen sensors and fuel regulator.
Good luck to everyone!
The Actron Code Reader part number is CP9015.(Thanks again Trace) It was only $34.95 and is a great tool for these newfangled computer cars!
Rick

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Rick
95 Explorer Sport Expedition
Dead Link Removed