Rough running with no check engine light.

[Nikola718]

I just bought an 2000 Expedition last night that is in great shape but runs rough. As I backed off the accelerator, it started to pick up smoothly but when I accelerated it started to miss and buck. The check engine light is not on nor does it flicker on and off. Could this just be a bad fuel filter?

 

[Lane24]

You know, mine did this exact same thing the other day. Ran smooth unless I stepped on the gas, and then the truck shuddered like crazy. I was waiting on the CEL so I coud check codes, turnrd it around to take it home, then Bam... ran smooth as ever again. I was thinking maybe bad gas ( I'm on the last 8th of a tank). Not sure. I'm waiting on it happening again so I can better diagnose it. I'd rather it didn't though!!!

 

[Nikola718]

Is that your truck? That is nice! I am going to start with filling the tank and running some Seafoam through it and I will re-post the results here if it helps anyone else. I noticed tonight after starting and letting it idle, it started to idle a little rough and when I hit the accelerator it started to stumble. All of this happened after it warmed up. Other wise it starts right up and runs smooth at first.

 

[Nikola718]

I have an update. I replaced the PCV hose and the fuel vapor hose and the truck is running well. I didn't replace anything else yet. Thanks for the help and advice. I will continue using this forum.

 

[08HybridOK]

I think that's what mine's doing now; after I repalced the intake manifold a few weeks ago. Not sure if I have a bad coil, fouled plug; never thought of the PCV & hose leak. Starts fine, idles fine most of the time; it's when trying to maintain 45-50mph on flat ground it shakes & shudders! (Like big rumble stripps!) back off, or speed up & it's smooth. Occasionaly at idle it'll drop rpm real low for a split second; but recover.

 

[CaperCanadian]

Thats how mine started to go stumbling on the fuel but idle fine. ran like that 3 days than the #7 plug died. if it doesnt get better with sea foam, check the plugs and coils.

 

[08HybridOK]

Seafoamed it today; then went for a quick test run before changing the coils; it ran even worse! Scared me.
But finally got a CEL; 302 I think it threw, #2 coil. I was postive it was # 5 (driver front) as thats the one that got coolant dumped into it...

Swaped them all out (found a whole set on Amazon for like $50!)
{Oh yea, guess I should have posed the link to the coils http://www.amazon.com/gp/product/B0031ZDU62/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1}

Test run again, so far it seems better, no more shaking & shuddering!

 

[1997SCEBFEX]

fingers crossed that you got it remedied!

 

[Nikola718]

I ended up taking the number one coil off and found it had green on the electrode. I sprayed it with some electronic contact cleaner and it smoothed right out. I then replaced all of the plugs. I noticed that it would suddenly idle down for a second and the headlights and heater fan would pull down. I load tested the alternator in my driveway and found it had gone bad. Replaced it and the truck runs absolutely great! I have one more problem; I went to change oil and found white frothy looking substance on the oil filler neck and cap. There is no indication of water in the oil pan. I had it checked for blown headgasket but it came back inconclusive. Any ideas as to what is causing this? As I said, it runs great.

 

[FordandPolaris]

I ended up taking the number one coil off and found it had green on the electrode. I sprayed it with some electronic contact cleaner and it smoothed right out. I then replaced all of the plugs. I noticed that it would suddenly idle down for a second and the headlights and heater fan would pull down. I load tested the alternator in my driveway and found it had gone bad. Replaced it and the truck runs absolutely great! I have one more problem; I went to change oil and found white frothy looking substance on the oil filler neck and cap. There is no indication of water in the oil pan. I had it checked for blown headgasket but it came back inconclusive. Any ideas as to what is causing this? As I said, it runs great.

Cold temperatures and short trips. Basically it is the condensation in the motor rising to the highest point. If you don't see it in the oil, then it is nothing to worry about. My truck does the same thing all winter.

 

[Nikola718]

I bet your right. I bought this Expy for less than 2000 and put the parts in it I listed. so far it has been a great vehicle for my family. I guess we get lucky at least once.