The truck is a 2001 ranger 4x4 with a 4.0 and automatic transmission. While idleing the truck with miss a little bit which will get progressively worse the longer it idles. After a while it sounds like it is actually going to die, the rpm's drop to about 400, but then it recovers and idles alright for a little bit before doing it again. At first the tach won't show the miss but as it gets worse the tach will start to dip. We changed the plugs and wires but it didn't help. Also, while you don't notice it while driving, if you put the truck in neutral and rev the engine you can hear the truck miss at all rpm's whether it's idleing, accelerating slowly, or holding at a higher rpm. I held a piece of paper at the tailpipe and the exhaust would keep it steadily blown away from the tailpipe, however when the truck would miss it was like the paper was actually trying to be sucked into the pipe for a split second. There are no check engine lights. Does anybody have any ideas on this??? Thanks, Morgan.

 

Try replacing your fuel filter and adding some heet to the lines. sounds like you may have some water in the tank. You can also go try to pull some codes. You may have something that isn't throwing a code or your ight is burnt out. How many miles are on it? Does it only do this when the truck gets warm or is it all the time?

 

check the lower intake gasket. just fixed this problem on mine. same symptoms and everything

 

I just thought of one more thing. Check your air flow meter. It may have a little dust on it. That would cause your computer to read a false amount of air flowing into your engine.

 

His is the OHC engine, I beleive the intake manifold problem is only on the OHV engine.

 

I agree With Woody completly, but what do you think about throttle position sensor(TPS), or posible mass airflow sensor problems(MAF)???? I've got a 2.5 that does the idle dip once and a while at a light, but mine does not miss at any speed or rev position....

 

claymore_mo, sounds like you may have more than one poblem.

The miss & rpm drop at idle, sure sounds like it could be the common IAC problem.

The constant miss at higher rpm, sounds like it could be a fuel delivery or spark problem.

Fuel delivery can be messed with by several things, like a dirty MAF, as has been mentioned, dirty injectors, low fuel pressure, from a clogged fuel filter, bad fuel pressure regulator, or weak pump, lazy O2 sensors, ect, ect.

If it's a spark related problem, it could be a faulty coil pack or it's ground connection, plugs or wires, or both.

If you haven't had the computor scanned for codes, I'd probably do that first as has been suggested & see if it'll offer up a good clue on where best to next look.

Post all the set, or pending codes found.

Is the truck up to date on past & present scheduled maintenance????

 

All right, here's the real kicker. The computer is not throwing any codes,
it says everything is fine? I don't understand how it couldn't trigger at
least some code? Oh, and this is a buddy's truck, but he is pretty good
about maintenance. He said he changed the fuel filter last summer.

 

Then my next step would be to clean the MAF. Just be very careful when cleaning it so you don't break it. Also use something that won't leave a residue like break or carb cleaner or even better, rubbing alcohol. If there is no code that just means there is nothing wrong that isn't affecting any sensors that the computer uses to motor your engine. Try cleaning the MAF and post up results!

 

We'll try the MAF. A visual inspection looked spotless, but I guess being as sensitive as it is, it might not take much. I was looking at all of the possible codes in the book, and I still don't see how something could affect the engine that much and not throw a code. Thanks, I'll update again.

 

Just seen this, so sorry for being late and all. Check all the vacuum lines and make sure one isn't loose, cracked or missing. My dad's old ranger had a similar issue turned out one of the extra vacuum fittings lost a cap coming off the manifold. Blocked it off and truck screamed.

 

Ken,

I hope you're right for the sake of claymore_mo, but I've got at least one post here that says otherwise on another forum...

http://www.shareamemory.com/radio/faults.htm

01/02/2002 - Rough Idle at Start Up - Recall Repair 0012MC

At 46,XXX miles, I took it in for a problem with the engine running rough for the first couple of minutes when you started the engine in cold weather. I normally don't start the engine in the cold since the vehicle is garaged 99% of the time. However, we were traveling to the Washington DC area and had the Explorer parked outside (for probably the first time ever) and I started noticing this problem.

My dealer did the recall repair for 0012MC which calls for replacing tensioners and low intake manifold gasket. This fixed the problem (the rough idle was caused by a leaking gasket...the tensioner was a side item to replaced under the same recall).

 

Nice find Alfred!!

Keep in mind this recall does not apply to Rangers


OWNER NOTIFICATION PROGRAM
00M12 Certain 1997 through 2000 Explorer/Mountaineer and 2001 Explorer Sport/Sport-Trac Vehicles Equipped with 4.0L SOHC Engines - Camshaft Chain Tensioner and Lower Intake Manifold Gasket Additional Coverage

--------------------------------------------------------------------------------





November 2000

To:
All Ford and Lincoln Mercury Dealers

Subject:
Owner Notification Program 00M12 - Certain 1997 through 2000 Explorer/Mountaineer and 2001 Explorer Sport/Sport-Trac Vehicles Equipped with 4.0L SOHC Engines - Camshaft Chain Tensioner and Lower Intake Manifold Gasket Additional Coverage

OASIS:

Yes

OWNER LIST:

Yes

PARTS RETURN:

No

PROGRAM TERMS:

On the affected vehicles, this program extends the coverage for the 4.0L SOHC camshaft chain tensioner and lower intake manifold gasket to 6 years or 72,000 miles from the vehicle’s warranty start date, whichever occurs first. This coverage will automatically transfer to subsequent owners. If the vehicle already has more than 72,000 miles, this coverage will last until April 30, 2001.

AFFECTED VEHICLES


Certain 1997 through 2000 Explorer and Mountaineer vehicles equipped with 4.0L SOHC engines built at the Louisville Assembly Plant and St. Louis Assembly Plants from Job #1, 1997 through April 7, 2000.
Certain 2001 Explorer Sport and Sport-Trac vehicles equipped with 4.0L SOHC engines built at the Louisville Assembly Plant from Job #1 through April 7, 2000.
SERVICE ACTION


Owners of affected vehicles are being notified that Ford Motor Company is providing additional coverage for the affected engine camshaft chain tensioner and lower intake manifold gaskets.
If either the camshaft chain tensioner or lower intake manifold gasket should require replacement, dealers are instructed to install both of these upgraded parts at the same time, at no charge to the customer.
The no charge coverage for this condition is available for 6 years or 72,000 miles from the vehicle’s warranty start date, whichever occurs first, and will automatically transfer to subsequent owners. If the vehicle already has more than 72,000 miles, this coverage will last until April 30, 2001.
Please read Attachment IV (Question & Answer Sheet) for more details.
REASONS FOR THIS PROGRAM

We have incorporated enhancements into newly produced Explorer 4.0L SOHC engines. The long-term benefits of these improvements are being offered to prior customers.

The need to install a replacement camshaft chain tensioner is typically indicated by an engine rattling noise that occurs just after cold engine start up and goes away within a few minutes after the engine is running. Rough idle and low idle are symptoms which may, in some cases, indicate an intake manifold leak.

The condition of either or both of these components will not cause engine damage or failure, but may decrease the customer's satisfaction with their vehicle.