Surging and "Bucking"

[AirbossGordo]

Hey all,

Gordo here. New to the site.

My 98 Explorer XLT has 135,000 miles and still looks great considering it's black. I love this thing and I've had since it was new. It's my daily driver while the Z28 sits in the garage waiting for next spring for cruising and racing season.

Recently, like for the past 30K miles or so, the thing "bucks" and surges when it's turning between 1500 and 2500 RPM and you give some gas. It acts like it's bogging down, but it doesn't stay bogged down. It just jerks. Tranny feels like it's in overdrive and it's choking and won't downshift. Sometimes it jerks pretty hard. When I over ride the overdrive and the RPM's come up a little, the surging/bucking stops.

Thinking about having a Blue Oval tech run a diagnostic and possibly flash the computer for starters.

Any other ideas or clues?

 

[drivetrain]

Is this when you first get the vehicle moving or is it when you're up to speed? Does it do it first thing in the morning but get better when the vehicle is warmed up?

 

[ZBlackBeast]

and what motor do you have?

 

[AirbossGordo]

Hot or cold...Doesn't matter and only between 1500 and 2500 rpm.

 

[AirbossGordo]

and what motor do you have?

4.0 SOHC

 

[FexplorerV8]

have you replaced the spark plugs and wires? sounds like an ignition problem, do a full tune up if you havent done so already.

 

[FexplorerV8]

also does it miss or buck when sitting on drive at a light or stop? if it does I'm sure is the cables and spark plugs.

 

[AirbossGordo]

New plugs, wires, coil. Idles like it's brand new...smooooth. Runs strong when you put your foot in it, but bogs, jerks and surges at low speed and low rpm. New fuel filter, fuel pressure good, clean air inlet path.

 

[bosoxfan1]

Had nearly The Same

Spent a lot of time and aggravation, and even after new plugs, wires and testing coils, no luck. Had a Svc manager from Ford ride with me and asked about wires. Said they were new from Autozone. He said replace them, it's a misfire under load.

I went home and put my OEM wires back on. It was gone!

Bad wire out of the box.

 

[AirbossGordo]

Spent a lot of time and aggravation, and even after new plugs, wires and testing coils, no luck. Had a Svc manager from Ford ride with me and asked about wires. Said they were new from Autozone. He said replace them, it's a misfire under load.

I went home and put my OEM wires back on. It was gone!

Bad wire out of the box.

Still did it with the OEM's, a set of aftermarkets, and a set of Taylors.

 

[FexplorerV8]

what brand sparkplugs did u install?

 

[aj20045]

ok, im not sure what your problem is, but is the transmission shaking between shifts?

my old blazer used to get caught going into over drive and buck and stuff. Put new tranny filter and lucas oil in her and she was all better.

 

[AirbossGordo]

ok, im not sure what your problem is, but is the transmission shaking between shifts?

my old blazer used to get caught going into over drive and buck and stuff. Put new tranny filter and lucas oil in her and she was all better.

No shaking. Brand new transmission, installed by the Blue Oval themselves. Did it with the old tranny, does it with the new tranny.

I'm still thinking the PCM has something to do with it. With the new and old tranny, it upshifts into overdrive at 30-35 mph. Then when in OD at 30-35 mph at @ 2000-2500 RPM, it falls on its face so hard it jerks your neck. When the RPM's finally come up, it smooths out. Idles great, good power, but it's driving me nuts.

 

[puzzell]

i have the same kind of prob when acc from 1500rpm to 2000 once its doing over 80kmh normaly done plugs and leads to and it dose it all the time if hot or cold makes no differnce and it 97 x 4.0 sohc done 175,000km

 

[AirbossGordo]

what brand spark plugs did u install?

Motorcraft

 

[ZBlackBeast]

Try reseting the computer maby.... unplug the battery for about a half hour then plug it back in and take it for a drive so it can reteach itself.

 

[AirbossGordo]

Try reseting the computer maby.... unplug the battery for about a half hour then plug it back in and take it for a drive so it can reteach itself.

As a matter of fact, I did that today.

While I was waiting, I pulled the plugs for a look. All were in great shape and showed no signs of any other trouble until....... I pulled #3.

Of course, the LAST FREAKING plug I pull (no, it couldn't have been the first one, it had to be the last one....RANT), looked like the insulator was cracked although only a hairline crack (that's all it takes).

Inspection of the plug wire showed evidence of some arcing and possible burning in the boot. So I pull all the other 5 plugs again (to replace them all) and put a new wire on #3.

SO FAR SO GOOD AND NO BUCKING, surging, jerking, BUT I HAVE NOT taken it out for a good trashing run.

Stay tuned.......

 

[ZBlackBeast]

Will do!!

 

[Ryanca]

Is this when you first get the vehicle moving or is it when you're up to speed? Does it do it first thing in the morning but get better when the vehicle is warmed up?

Having the same problem exactly on 98 mountaineer 5L AWD. Surging at 1500-1800 rpm and OD shifting. No problem at higher rpm’s. Changed all sensors on fuel input, gas filter, flushed transmission. No debris. Thought it maybe torque converter or trans solenoid. Idles well. Accelerates well as long as not sitting at 1500rpm. Have driven many miles with this problem and no worse over time. Great SUV with 218000miles.

 

[EB4X]

/\ You did replace your MAF ? I had surging on mine in that RPM range / during shifting (felt similar to trans slipping / re-engaging) and it turned out to be a poor o2 sensor....NO CODES..... sometimes they wont generate a code.... unplug all of them and your system will run off factory presets as if the o2 sensors are all fine...... if the surging then goes away bingo....of course plug back in one at a time to see which one is the culprit.