Bucking and surging w/ Check Engine Light

[Turkey]

I have been having this problem for a bout 8 months now. It started in December on a road trip. The check engine light comes on but doesn't stay on. The Explorer experiences a great deal of power loss and starts "bucking and surging". This only happens on the hwy. Higher speeds ie. more gas, seem to help the problem. Scan check in December showed MAF. Truck continually has lack of power and excessive gas consumption (more than usual). Replaced MAF (I had tried cleaning it) couple months ago and truck worked somewhat better for a while but the same problem is back. Its weird but its seems to happen more often when going against a strong wind. My best guess is some sort of vacuum problem causing rich/lean condition. Any ideas?

1994 XL 5spd.
30x9.5 BFG AT TA's
K&N Air
Hella FF Fog

 

[CADDYBILL]

I havn't been around in a while but know I'm back. My 94 has what sounds like the same problem. Only happens in OD over 50 mph. If I drop it into regular drive the surging goes away.
Could this be a tranny problem?

 

[JDraper]

Could be 02 sensors. They will definitely mess up your performance and gas mileage.

 

[Robert]

Any possibility that you have too much oil on your K&N? Over oiling it will cause the MAF to fail. Maybe the oil caused the first MAF to fail and it took some time for the new MAF to get the oily build up causing it to fail as well?

 

[Puck62]

check your FPR and O2 sensors. If your FPR is flooding your injectors ,the raw fuel will eat your O2 sensors up.

 

[85Dave]

I had the same problem, but no check engine light. The bucking and surging went away after I replaced the plugs and wires. I changed plugs first, the problem went away for a few hundred miles, then came back. Changing the wires seems to have fixed it.

 

[Turkey]

Thanks for the inputs

I was actually told to suspect the K&N air filter from a Ford Tech. I had put it in right out of the box and haven't re-oiled it yet. I even e-mailed K&N and they have never heard of this happening. However, I have noticed grease on the throttle body valves and inside air duct. I am probably going to take it out. My truck doesn't miss so I don't suspect the plugs. As for the FPR, I am not very familiar with it but shouldn't the problem happen all the time or does it stick? It doesn't look to hard to change though. How about O2 sensors?

 

[oahrens]

Checklist

OK...Here it is.

One Question though....
What happens if you gun it from a stop while shifting normally?

If MAF was replaced did you reset the computer?

Definetly check the O2 sensors....

The FPR can stick or clog up....and you're right it's easy to replace.

After similar symptoms and replacing all before mentioned parts....it ended up being clogged cats.

BTW...how about the fuel filter?

Keep us informed......

 

[todd_c]

I had a similar problem in my '95. The engine would surge/buck at around 40mph. Turned out to be a problem in the egr system: the PFE sensor was bad. If your check engine light comes on again, try to get the trouble codes.

 

[craigchams]

Have a 1994 XLT 4X4 and have what sounds like exactly the same problem. Had it to the Ford dealer 3 times and still have problem. Parts replaced so far: Mass airflow sensor, throttle position sensor, PCV (valve), fuel pump and filter..... $$$$$ HELP! Dealer says codes are inconclusive.

 

[CADDYBILL]

I have not had much time to ck the board in a while
Hears what Ive replaced,
FPR
Themostat
both O2 sensors
plugs
wires
Cleaned the MAS

I do have a K&N but Ive had it for about 5 years and the problem only started in the last year.

 

[my91explorer]

remember to check all the vacuum lines at the back of the intake. It looks like an octopus and has many lines running from it.

That happened with mine. Some of the caps get loose and they need replacing.

I also cleaning the throttle body butterfly which was filthy.

Good luck

 

[reconnell]

I had the same problem on my last car: an '89 Ford Escort. Happened only on interstate driving. It was the throttle position sensor. Don't know how to change them on the Explorer, but I heard of other Fords around that year that had similar problems because of the throttle position sensor.

 

[oahrens]

Again...

All those who have have similar probs....after replacing any parts in the fuel/exhaust make sure you reset the computer to learn the new fuel/air mixture.

Also, If you have over 70,000 miles start looking into exhaust (ie: clogged cats).

Keep posting....

 

[tallimeca]

bucking/surging-power loss

I'm having a similar problem with my 2000 sport......what motor do you have. I spoke with ford today and they are trying to arrange for a ford engineer to test my vehicle. Computer isn't storing codes.

 

[CADDYBILL]

Just to let everyone know I finally had my surging problem figured out. I brought it to the shop and they replaced the fuel filter and the EVP or is it ECP ( I don’t know) sensor. It's the thing that looks like a deck of cards and mounts just to the right of the throttle body.

 

[eguiyab]

got it

alright i got a 95 with the check engine light going on about a 15 to 20 mins of driving then blinks off. looks you guys solved the prob. i can change all the parts but how do i reset the computer ????

 

[Turkey]

I haven't done much highway driving after replacing the K&N with a cheapo brand filter and cleaning the MAF, however I do still notice the truck runs worse in high humidity and high heat. Another note - My manual tranny also shifts worse in higher temperatures. I had the fluid changed a couple years ago but I am thinking of putting in synthetic. Anyone ideas on this? Re: the CAT, how do you test if that is clogged? What kind of cost would a high-flow CAT be? The truck does surprise me the odd time and run almost perfect.

 

[drmoore71]

i think i'm in the same boat here. on my 95 xlt (122k miles), the other day, it started the bucking and snorting thing comming off a stoplight. i had just the night before replaced the plug wires and had a new tank of fuel. i immediately thought it was bad gas or a loose wire. got a bottle of fuel stabilizer and a can of b-12 chemtool and promptly dumped them in the tank. i also checked the plug wires for tightness, all good. i also picked up a cheapo code scanner. got egr high voltage and egr low voltage codes. disconnected the battery and retested, no codes other than normal. i still had the same bucking and snorting. then i replaced the fuel filter and cleaned the k&n last night. the problem seemed to be gone. tonight, i was driving the same stretch of road i had test driven the night before and, you guessed it, iit's back! WHAT DO I DO? i think i will try to replace the egr, but i don't want to keep spending good money after bad and not getting to the bottom of the problem. i am also curious as to how i could find out if my cat is clogged. please help me! i hate it when my truck isn't working right. thanks in advance.

 

[JT]

I had the same issue and just recently it came back, checked the codes, and found out the cam spark controller was bad? I think thats what my mechanic said. I will get clarification, since the installation of that, i have not had a problem since.