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Matt, Engineer
Category: Ford
Satisfied Customers: 21881
Experience:  BEng hons Mech engineering, in auto industry 22 years
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E-250: , I have a 2000 Ford E-250 4.2L van. I have

Customer Question

I have a 2000 Ford E-250 4.2L van. I have been having problems with engine surge over the last year that has gotten worst. its most noticeable on acceleration. When accelerating at a steady rate the engine will suddenly increase in speed as if the gas pedal had been press down most of the way. Originally this would happen once in a while but now it is a near daily occurrence. The engine seems to run well with no misses or complaints except for the surge. I checked a week or so ago and there were no codes stored.
I have already done the following.
Replaced the plugs and wires with Motorcraft products
Replaced the fuel filter
Looked/listened for vacuum leaks
I would like to get this resolved before it gets worst.
Thank you for your help
Submitted: 2 years ago.
Category: Ford
Expert:  Matt replied 2 years ago.

it would be worth cleaning the airflow meter by removing it from the car and spraying the exposed sensor wires inside the tube with a brake or switch cleaner - ensure that the cleaner is one of the old fashioned, non Eco type that does not leave a residue

On no account touch the sensor wires with anything physical as they are extremely fragile

if its OK then its possible the clutch is slipping ? If there's a 'hot' smell from under the van and if it struggles to accelerate up hills then this would bear it out

if its an automatic transmission then check the fluid levels in the transmission

Customer: replied 2 years ago.

Hi Matt,

I forgot to mention that I did clean the MAF sensor a couple different times now. I used CRC MAF Sensor Cleaner.

The problem is not transmission related.

I'll try to better explain whats happening. When accelerating at slow and steady pace the van will seem to be fine then all of the sudden it will jump to life as if the throttle was suddenly pressed 3/4 or more to the floor. It's as if its bogged down, starved for fuel??? plugged up??? on a slow acceleration and then all of the sudden its running well. It's hard to explain.... It just all of the sudden will spark to life like the throttle was stomped on.

I have been working on vehicles for nearly 20 years and this one has me scratching my head.

Any other help would me much appreciated.

Expert:  Matt replied 2 years ago.
HelloOk in that case its well worth removing the intake and cleaning the throttle as they can gum up over time and its possible that the issue is a sticking throttle
Customer: replied 2 years ago.


I tried that a couple of times as well.

Is it possible that a bad catalytic converter could be causing the trouble? I dont understand how it would but my cats aren't in the best condition

Expert:  Matt replied 2 years ago.
a blocked cat would normally cause a loss of power all the time, unless the cat brick was broken and then moving around inside the exhaust,its worth a look inside, if you remove the O2 sensor in front of the cat then you can peer inside
Customer: replied 2 years ago.

Ok I was thinking the same that it would be a consistent power loss.

Any other suggestions?

Expert:  Matt replied 2 years ago.
Hello Ok in that case I'd measure fuel pressure with a running engine as while a new filter is a good idea, if you have a faulty lift pump that can falter and not dleiver full pressure intermittantly
Customer: replied 2 years ago.


I can recheck the fuel pressure. I checked it a couple months ago and it stayed constant. There is also a new fuel pump on the van. The old one was sticking when first started and about to fail. unfortunately the problems i'm having now didn't change at all with the replacement of the pump. I'm doubtful that the pump but I haven't checked pressures with the new pump.

I can change the filter again too.

Expert:  Matt replied 2 years ago.
OK that sounds fine so its likely the fuel pressure is good
This could be a wiring issue as things tend to expand when hot and its possible a poor or partial electrical connection is being pushed apart on one of the major sensors so check the connection plug and wiring to the following;Airflow meterCrank position sensorCam position sensorO2 sensorThrottle position sensor and also unplug and inspect the main power relays and fuses for signs of overheating or corroded terminals - so the ones for the ECU and the fuel pumpAnd also unplug the wiring loom connections in the engine bay one at time and inspect for corroded or recessed pins.
Customer: replied 2 years ago.

Hi Matt,

Sorry for my slow reply. Had a family situation the last few days.

I will check the wiring ASAP. It's possible that it could be an electrical problem. I discovered yesterday that I have a bad diode in my alternator. I know that faulty alt's can cause strange engine/trans problems. I will be replacing the alt today.

I also checked my codes and came up with 2. P0325 Knock sensor and P0401 which is EGR related.

I know the 4.2 engines are notorious for plugged EGR passages as well as the ports under the intake. I don't know that this is the cause of my problem since it is inconstant. I assume that blocked ports etc would cause a more consistent problem. What do you think?

As far as the knock sensor code. I'm wondering if the sensor is faulty and retarding the engine which would cause the problems I am having. What are your thoughts on this? Do you have the test procedure for this sensor?

Thank you much

Expert:  Matt replied 2 years ago.
Hello TIm

sorry to hear about your family troubles

thanks for the extra information

a faulty / intermittant knock sensor is a good fit or the issues you've been having as these can come and go and retard the ignition when the sensor does 'go faulty'

I'd 1st check that the sensor is firmly attached as if its loose then this too will generate a false signal

then check its wiring for any short damage as this too will generate a false signal

and if that checks out then replace the sensor
Customer: replied 2 years ago.

Hi Matt,

Do you have the test procedures for the knock sensor? There must be some way to test it with a meter

Expert:  Matt replied 2 years ago.

Hello Tim

they can be tested like this

trouble is this test won't show up a sensor thats 'noisy' and so sending false signals

Customer: replied 2 years ago.


That makes sense. Thank you for the info. I will report back ASAP.

Expert:  Matt replied 2 years ago.
No problem Tim

Good luck