Engine Cuts out for Split second

[ahodges]

I am having a problem with the engine cutting out for a second while acclerating between 40 and 50 mph. It does it so fast that if you weren't expecting it you would wonder, "what was that?" It is just enough to cause a drivetrain clunk in the transmission and driveshaft.

When the engine is cold, it runs normally, no problems. It only begins to do this after it has been run for quite a while and the engine is hot.

I also noticed that as long as I am moving faster than 40 mph and let off the gas to coast, and then hit the gas to maintain speed again it will do it. As long as I don't let off the pedal to idle, it will run normally (ex. 100 miles straight down the highway with no problems until I let off to coast).

I know it is the engine because my RPM's drop from what every they were previously at down to a 1000ish really fast and then back to what it was with the blink of an eye. Seriously if I were to blink I would miss it.

It is a 96 explorer with the 4.0 OHV. 125,000k

Thoughts?

 

[ahodges]

I should also mention that only a few thousand miles ago I replaced all of the parts on the EGR system and a year ago replaced the spark plugs and wires.
I thought that it might be the throttle position sensor but it isn't acting exactly like that is what's wrong.

 

[burndout]

I'm having the same issue, year ago I thought it was fixed after new battery and it came back. Did plugs, wires and fuel filter and it was good for 2 months. Now I'm having the same issue and like you it only happens after driving it for a while. I just priced out a new fuel pump at $99 at AutoZone and think thats the problem, pump is getting hot and then failing. This would also be supported due to a new battery to the pump giving it the "extra" it needed, then the second time was due to the filter being a little dirty and the pump just not being able to keep up. This is only a speculation as I have NOT replaced the pump at this time. I dont have one (or the money) but there is a kit for around $45 that you can test the fuel pressure at the rail when it is "happening". If I can scrap up the cash for a pump I will let you know, if you find anything PLEASE PM me, thanks!

 

[ahodges]

ok. will do.
I personally know a guy that is also having this problem with a 96 ranger with the 4.0 and hasn't figured it out yet either. I really don't think that it is the fuel pump though because it happens when I'm going roughly the same speed everytime. That would be too much of a coincidence for that to be happening.

 

[burndout]

Well, I check the fuel pressure, not when it was running bad because I never know when it will start doing it, and was at 58-65psi and held for 5 minutes at 62 with the motor off. Also I did a plugs, wires, fuel filter, and a coil pack. SAME PROBLEM. HAd the guy at AutoZone check the alt and battery and both came back good. He said that he thinks it the EGR or EVAP. He said that if the EGR is not working well it will cause the problem I am having, the EGR and all its parts total around 150$. I will say that when I checked the fuel pressure there was a lot of air in the line when I purged it after testing. After the test was done I have not had any problems and I did drive in the heat quite a bit today ( to the Ford dealer to look at new trucks!) Maybe it is boiling the fuel and vapor locking? Can a returnless system do that like the older motors?

 

[ahodges]

Well, I check the fuel pressure, not when it was running bad because I never know when it will start doing it, and was at 58-65psi and held for 5 minutes at 62 with the motor off. Also I did a plugs, wires, fuel filter, and a coil pack. SAME PROBLEM. HAd the guy at AutoZone check the alt and battery and both came back good. He said that he thinks it the EGR or EVAP. He said that if the EGR is not working well it will cause the problem I am having, the EGR and all its parts total around 150$. I will say that when I checked the fuel pressure there was a lot of air in the line when I purged it after testing. After the test was done I have not had any problems and I did drive in the heat quite a bit today ( to the Ford dealer to look at new trucks!) Maybe it is boiling the fuel and vapor locking? Can a returnless system do that like the older motors?

I don't know if they can vapor lock. I would think with a pressurized system they couldn't but mine does do it more when its hotter outside. I replaced the throttle position sensor and that didn't fix it either. I also have just replace all of the EGR componets with original ford parts about 2k ago.

 

[Turdle]

Check the throttle position sensor, with the key turned on, engine off. You want to see a slow--steady rise in voltage, from <1v to about 4.5v as the throttle is pulled open. If you see the voltage drop out or spike a bit, that is the problem

Then check the sensors resistance-disconnected from the harness.

 

[ahodges]

Check the throttle position sensor, with the key turned on, engine off. You want to see a slow--steady rise in voltage, from <1v to about 4.5v as the throttle is pulled open. If you see the voltage drop out or spike a bit, that is the problem

Then check the sensors resistance-disconnected from the harness.

Jon,

I haven't checked the voltage in the sensor yet but I can't imagine that being the problem since I just replaced it with a new Motorcraft sensor and I am still having the exact same problem. It doesn't matter which throttle position I am at. It seems to be temperature and speed sensitive. Any other ideas?

 

[ahodges]

ok. Here is an update to my problem. I had my truck at the ford dealer for over 2 weeks and they checked everything they could think of and could not figure it out!! $400 later and really no new information that I didn't know..

List of things done.

-Used the diagnostic computer on it but the cut-out happened too fast for them to trace it back to the source of the problem. (caught it dropping to only about 600 RMP)
-swapped coil pack
-crank position sensor
-check cam sensor
-wasted a bunch of my gas driving it and ideling it.

The only thing they suggested was trying to replace the computer and have it re-flashed by them; which they said they would do for free.

I'm really getting mad throwing money at it because I'm trying to save up for 5.0 conversion soon..

 

[Xplorer82]

i'm having a similar problem, But mine only cuts out from a dead stop for a split second. never has a issue while driving. just taking off from a stop sign/light. it does not happen to often, but it is bothersome when it does happen.

once i get settled in my new house i will be swapping injectors with flow-matched ones from ebay and probably a new fuel pump (money permitting).. also going to check for vacuum leaks again for the hell of it. as my coil pack, plugs-n-wires and fuel filter are all new'ish also my TPS checks out fine on the Fluke.


keep us updated tho.

 

[ahodges]

ok, so quick update. I went to the bone yard to pick up a different computer and I met a guy there who I was talking to about my problem. He thought that there is no way it is the computer. Instead he is telling me it's either the crank or cam sensor. Last winter I just installed a factory new motorcraft Harmonic balancer and crank sensor so I would like to think that isn't my problem. The cam sensor is original and it has 126k on it. However, those list for $125 at the dealer and they are willing to sell it to me for $73ish. I can't see just throwing that much more money at it. Autozone carries them for $31.

Any thoughts as to which route would be the best for me to take?

 

[ahodges]

It's Fixed!... I think

Well I decided on getting that computer from the junk yard last weekend. I installed it and have been driving it a lot over this past week and weekend, even pulling a trailer at times, and it has yet to act up. I'm crossing my fingers that I fixed the problem but it seems promising!

I hope this helps others out and saves them money, time, and a lot of headaches..

I only spent $45 on a used computer from an explorer with more miles on it than mine and it worked!