93 4.0 briefly hesitates, sometimes bucks
#1
10-21-2017
Join Date: Aug 2015
Location: Atlanta, Ga
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93 4.0 briefly hesitates, sometimes bucks
Hello, I am having some driving issues with my 94 ranger 4.0.
When revving in neutral, the Rpms drop slightly (about 50-100 rpms) before it revs up. "Gas, slight rpm drop, then it revs up". You can feel this brief delay at anywhere in the throttle range under 3000 or so.
The problem above also occurs while driving. There is always a brief delay in throttle response. If I don't slowly change the throttle position my truck does nothing for a half second then slightly jerks then goes faster.
I think that this issue could be related to the bucking issue I am having only while it's warming up. The truck also wants to buck after each gear if I don't accelerate like an old man.
The truck is a 5 speed and this revving up issue is driving me insane because it makes the truck hard to drive smoothly being a 5 speed.
When revving in neutral, the Rpms drop slightly (about 50-100 rpms) before it revs up. "Gas, slight rpm drop, then it revs up". You can feel this brief delay at anywhere in the throttle range under 3000 or so.
The problem above also occurs while driving. There is always a brief delay in throttle response. If I don't slowly change the throttle position my truck does nothing for a half second then slightly jerks then goes faster.
I think that this issue could be related to the bucking issue I am having only while it's warming up. The truck also wants to buck after each gear if I don't accelerate like an old man.
The truck is a 5 speed and this revving up issue is driving me insane because it makes the truck hard to drive smoothly being a 5 speed.
#2
10-21-2017
Start with the basics.
Any codes, it should be checked at any rate even if there is no "check engine light" ?
Does you CEL first come on when you turn the ignition to "ON" ?
Clean you MAF sensor, there is a special cleaner for this, don't touch the probes on the actual MAF sensor itself, they are fragile, use only the cleaner.
Check your PCV valve and make sure it's not blocked up and that the lines and connections are in good order.
Check your plugs, worn plugs that have a very large gap can cause this, old wires too that have too much resistance.
Coil pack is next, although being a 94, it may have a distributor.
However there is still a coil pack that can go wrong.
Next thing would be to check out the cam shaft synchronizer itself and the sensor on top of it.
Not an easy thing to do on a 4 litre, I've never worked on one, but it's buried under the upper intake manifold at the back of the engine.
Note that a damaged synchronizer sensor from a worn synchronizer may cause the truck to run poorly, it may not give any codes until the damage really gets bad.
A dirty and or faulty IAC valve and TPS can be the problem too, but this should give you a code.
Sometimes the connection plugs can get dirty, remove them and inspect them.
Same with a faulty DPFE sensor, if you're still running the metal one, you should replace it, the two lines running to it as well.
Also, when was the last time the oxygen sensors were replaced ?
Any codes, it should be checked at any rate even if there is no "check engine light" ?
Does you CEL first come on when you turn the ignition to "ON" ?
Clean you MAF sensor, there is a special cleaner for this, don't touch the probes on the actual MAF sensor itself, they are fragile, use only the cleaner.
Check your PCV valve and make sure it's not blocked up and that the lines and connections are in good order.
Check your plugs, worn plugs that have a very large gap can cause this, old wires too that have too much resistance.
Coil pack is next, although being a 94, it may have a distributor.
However there is still a coil pack that can go wrong.
Next thing would be to check out the cam shaft synchronizer itself and the sensor on top of it.
Not an easy thing to do on a 4 litre, I've never worked on one, but it's buried under the upper intake manifold at the back of the engine.
Note that a damaged synchronizer sensor from a worn synchronizer may cause the truck to run poorly, it may not give any codes until the damage really gets bad.
A dirty and or faulty IAC valve and TPS can be the problem too, but this should give you a code.
Sometimes the connection plugs can get dirty, remove them and inspect them.
Same with a faulty DPFE sensor, if you're still running the metal one, you should replace it, the two lines running to it as well.
Also, when was the last time the oxygen sensors were replaced ?
Last edited by Jeff R 1; 10-21-2017 at 06:54 PM.
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11-08-2016 07:54 PM
