Stuttering in gear. | Ford Explorer Forums - Serious Explorations

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Stuttering in gear.


Well-Known Member
January 6, 2011
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City, State
Hacienda Heights, CA
Year, Model & Trim Level
I have a 99 explorer 4x4 4.0 ohv.
I just cleaned the injectors and replace the gaskets on the intake plenum.
And it starts up great and idles good but when I put it in gear it starts to shake and when I drive it misses a little and it takes a little time to get up to speed.

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I'm going to change the coil pack does anybody else have a suggestion on what I should look for.

Been going through some of the same problems. Replaced head gasket and intake and plenum gaskets. Starts fine, idles fine but in gear it is very sluggish getting up to speed. I have checked for intake leaks, EGR, DPFE, EVR, etc... All are okay. There are a lot of things to look at, such as the MAF, EGR system, fuel system, vacuum leaks around intake, even spark plugs and wires.
Good luck!

Check and make sure your catalytic converter is not clogged/melted down restricting the exhaust.

Question for ya: What brought the injector work in the first place??? If it was doing the same thing or worse before then you have more work to do...The non return line fuel system is not finicky...It just needs a sufficient supply of fuel to run properly...A partially clogged fuel filter will give all kinds of lean codes/drivability issues/performance lacking issues...Also the fuel pressure being low will do that as well...

What is your fuel pressure at the schrader valve??? Needs to be 57-65 psi according to Ford...If it is low, start with the filter then go to the tank to see if the supply hoses are leaking in the tank or the fuel pump is packing it in...Oh and if the tank or the fuel in the filter pours out rusty or coffee colored a new tank without rust is going to be in your future...

Geez, I've got the same problem, starts fine but won't go over 2Krpm. Went to dealer, said replace plugs and #5 ignition coil, clean injectors~ $1600! Did it on my own, ran injection cleaner, dry gas, cleaned throttle body too. Replaced fuel filter. Still dogging. Throwing no codes on my hand scanner. Midas wants to replace catalytics $1500! Not convinced (and not affordable). Thinking CAM sensor? MAF? Short somewharz? WTF?

YEAAAAA!!!!!!! Thanks for every ones help..
1999 explorer V6 4.0 OHV.
I replaced the o-rings gaskets and seals on the intake plenum, throttle body, and fuel injectors also cleaned the injectors.
New plugs and wires now runs GREAT.
My plug wires were toast thats why it ran rough in gear.
Here's a tip on taking off the plenum the pipe that go's into it on the driver side from the exhaust manifold it's kind of a pain to get off.
What I did after you take off the throttle body you can see where the pipe inside the plenum I got my 1/2 inch breaker bar and the nipple fits right in the pipe then you slowly apply pressure from the inside and it pops right out.
Let me tell you when I did it and it popped out I screamed in joy when it popped out.

2004 Explorer V8 4.6L SOHC After much consternation and BS diagnosis from brand named muffler shops and others, including Ford $tealers, I need to ask about problems with the EGR valve, if anyone has any performance problems with a stuck valve? Latest indication is the EGR valve is stuck and preventing RPMs over 2K. Suggests cleaning. How about it?

I checked my EGR by unplugging the rubber hose on top and attaching a longer hose. I started engine and then slightly sucked on hose. Engine rpm went down and back up when I released pressure meaning diaphragm was working. Not sure if you can clean out an EGR. I was told it's just a rubber diaphragm inside. If it's ripped or torn it probably won't let higher rpm.

Resolved!!! Mine was the catalytic converters! Clogged. Pulled the sensors out and BAM! The rpms revved up past 2K! Smoothly. Didn’t want to go through the hassle of possibly snapping a bolt to the block so had a local shop with some good bros do it for its laborsworth and parts. Didn’t snag me for anything else, like diagnosis or looksee fees! With all the trouble, getting good gas mileage and smooth running. Will keep for another 100K!

Solved mine, too... A friend told me to check the plug wires. I put an old set that I had on and it runs great again.