1994 4.0 engine shudders
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1994 4.0 engine shudders
My 1994 4.0 engine shudders under load, i.e. when accelerating when going up an incline in top gear. I have new plugs, wires. When I accelerate hard from a stand still it shudders momentarily then smooths out. At a steady speed it runs smooth.
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The wires are Bosch 8mm, plugs autolite. Before I replace the plugs and wires it had a minor shudder. Afterward it was less but still there. It will shudder in any gear if it's under a load.
Now that I think about it I also had a slight pinging originally with the minor shudder while accelerating at highway speed in top gear.
Think it could be a fuel pressure regulator?
The MAF and O2 sensor have been replaced about a year ago due to t/s codes. Haven't check codes yet.
Now that I think about it I also had a slight pinging originally with the minor shudder while accelerating at highway speed in top gear.
Think it could be a fuel pressure regulator?
The MAF and O2 sensor have been replaced about a year ago due to t/s codes. Haven't check codes yet.
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From: Mitchell, SD
Before replacing anything, I would fill up with a tank of higher octane fuel 89/91. (I assume that you are currently using 85/87 octane with current gas prices. 
) If this solves you shudder problem then I believe you have carbon buildup in the engine that is causing pre-ignition (ping/shudder). Common problem with the 4.0L. Several years ago there was a TSB for the Explorer 4.0L (same engine) for decarbing. A quick search in the Explorer forum (Decarbon) will tell you how to do it.
If that does not solve your problem, then I would look at when your fuel filter was replaced.
Also the Bosch Wires might not be delivering enough juice to keep the engine running at top performance. A quick check for leakage is to 'mist' some water in the engine bay with a spray bottle and look for arching. If that happens, replace with motorcraft wires.
) If this solves you shudder problem then I believe you have carbon buildup in the engine that is causing pre-ignition (ping/shudder). Common problem with the 4.0L. Several years ago there was a TSB for the Explorer 4.0L (same engine) for decarbing. A quick search in the Explorer forum (Decarbon) will tell you how to do it.If that does not solve your problem, then I would look at when your fuel filter was replaced.
Also the Bosch Wires might not be delivering enough juice to keep the engine running at top performance. A quick check for leakage is to 'mist' some water in the engine bay with a spray bottle and look for arching. If that happens, replace with motorcraft wires.
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Joined: Sep 2003
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From: Southern California
I believe you should check two things:
1) Ditch the Bosch wires. We put a brand new set of Bosch wires ($40) on my brother's Explorer, and had to take it off. A set of Autolite wires (cheaper and better) fixed his problem.
2) You have pinging going uphill? Check your transmission modulator vacuum line to see if you have tranny fluid in it. I had this on my 3.0L for a long time and that's what it turned out to be.
By the way, the MAF sensor doesn't have to be replaced. You can remove it and spray the wire elements with throttle body cleaner.
1) Ditch the Bosch wires. We put a brand new set of Bosch wires ($40) on my brother's Explorer, and had to take it off. A set of Autolite wires (cheaper and better) fixed his problem.
2) You have pinging going uphill? Check your transmission modulator vacuum line to see if you have tranny fluid in it. I had this on my 3.0L for a long time and that's what it turned out to be.
By the way, the MAF sensor doesn't have to be replaced. You can remove it and spray the wire elements with throttle body cleaner.
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Pulled all the spark plugs and they were all clean. No signs of carbon or other deposits.
Test drove it and it still shudders/misses.
My description of the shudder is the engine vibrating quite a bit during acceleration. Will do it by doing a 2nd gear start so I don't think it's the transmission/torque converter. It resembles what a carburated car used to do when it was loaded up...running real rich, but plugs are clean. Cannot detect any pinging.
Went to get a fuel pressure regulator but need a part number do to several types. Unable to get a number off the old one as it's buried under coolant/heater hoses. Will take it out this weekend and also check for fuel in it's vacuum line.
I also plan to do a Seafoam carbon clean and also add it to the gas tank.
Could it be injectors??
Test drove it and it still shudders/misses.
My description of the shudder is the engine vibrating quite a bit during acceleration. Will do it by doing a 2nd gear start so I don't think it's the transmission/torque converter. It resembles what a carburated car used to do when it was loaded up...running real rich, but plugs are clean. Cannot detect any pinging.
Went to get a fuel pressure regulator but need a part number do to several types. Unable to get a number off the old one as it's buried under coolant/heater hoses. Will take it out this weekend and also check for fuel in it's vacuum line.
I also plan to do a Seafoam carbon clean and also add it to the gas tank.
Could it be injectors??
Laughing Gas
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From: Dallas, Texas
I had a plug go bad and it did the samething. Felt like it was shaking all over. These were new plugs. I replaced them with autolite platimun and it went away.
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Originally Posted by Muffinman
I had a plug go bad and it did the samething. Felt like it was shaking all over. These were new plugs. I replaced them with autolite platimun and it went away.
I'll get some in the morn...if that's it it will be a cheap fix!!
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Laughing Gas
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From: Dallas, Texas
Yes they were all the same color, They wee 3 weeks old and then one day going up a hill "Small Hill' it felt tlike a motor mount was coming apart.
I checked O2, Mounts, Wires you name it. Then I said what was the last think I did the plugs and so i changed them with Factory plugs from the dealer and never did it again. My MPG also went back up to 24.
I checked O2, Mounts, Wires you name it. Then I said what was the last think I did the plugs and so i changed them with Factory plugs from the dealer and never did it again. My MPG also went back up to 24.
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Re: 1994 4.0 engine shudders
Originally Posted by georgemu
The wires are Bosch 8mm, plugs autolite. Before I replace the plugs and wires it had a minor shudder. Afterward it was less but still there. It will shudder in any gear if it's under a load.
Now that I think about it I also had a slight pinging originally with the minor shudder while accelerating at highway speed in top gear.
Think it could be a fuel pressure regulator?
The MAF and O2 sensor have been replaced about a year ago due to t/s codes. Haven't check codes yet.
Now that I think about it I also had a slight pinging originally with the minor shudder while accelerating at highway speed in top gear.
Think it could be a fuel pressure regulator?
The MAF and O2 sensor have been replaced about a year ago due to t/s codes. Haven't check codes yet.
Anyone have problems with the coil pack?
Fleet Mechanic
Joined: Mar 2004
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From: Kansas
Originally Posted by georgemu
My 1994 4.0 engine shudders under load, i.e. when accelerating when going up an incline in top gear. I have new plugs, wires. When I accelerate hard from a stand still it shudders momentarily then smooths out. At a steady speed it runs smooth.
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Coil pack wiring
One of my books shows ign wire position as:
From front pass side of coil pack 1,2,3 drivers side 6,5,4
Other config pass side 1,2,3 drivers side 5,6,4
in the 6,5,4 config it misses bad.
Which is correct ??
From front pass side of coil pack 1,2,3 drivers side 6,5,4
Other config pass side 1,2,3 drivers side 5,6,4
in the 6,5,4 config it misses bad.
Which is correct ??
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Re: Engine shudder
Scanned for codes, none shown.
Added a can of Seafoam to the tank and also did the decarbon with Seafoam.
Replaced fuel filter, no help.
Will the fault codes show a bad coil pack?
Sure seems ignition related to me, almost like a rev limiter going off.
Was gonna check the fuel pressure but can't get a gauge on the valve as a fuel injector electrical connector is right against it!!!
Guess a compression check is next???
Or could it be a bad injector/injectors?
Added a can of Seafoam to the tank and also did the decarbon with Seafoam.
Replaced fuel filter, no help.
Will the fault codes show a bad coil pack?
Sure seems ignition related to me, almost like a rev limiter going off.
Was gonna check the fuel pressure but can't get a gauge on the valve as a fuel injector electrical connector is right against it!!!
Guess a compression check is next???
Or could it be a bad injector/injectors?
Last edited by georgemu; Mar 14, 2005 at 02:10 PM. Reason: Added t/s info