Hesitation at W.O.T

[89_Black_Beast]

I have a 89' with a 92 4.0L in it. Was out wheeling two weekends ago and the truck ran great all the way up there and when I was wheeling.

I got stuck in traffic on the way home all was good until the traffic broke up. I took off WOT (wide open throttle) and my truck hesitated.

It runs great until the pedal hits the floor.

I cleaned the air filter that night and it ran fine again so I didn't worry about it. Well it came back...

Was thinking maybe fuel filter? Prolly churned up a lot of junk in the tank when wheelin...

Don't have much time right now to full around with it. Just wanted to see if anyone else had this problem before I started to throw a couple cheap parts at it.

Plugs and wires are good only a month old...

 

[89_Black_Beast]

So I did the fuel filter and put a new air filter on...Still the same...

It doesn't seem like its bogging/running rich it doesn't pop, sputter, or gurgle... it seems like its getting starved for fuel. It feels to me like i'm pulling another car and they put the brakes on or the e-brake is on...and no the e-brake isn't stuck on.

The truck only hesitated when the pedal hits the floor.

Bad Mass air sensor?
Bad O2 sensor?

I'm not pulling any codes either...

 

[trhull]

Check the connetor for your MAF, I had that happen to me before. As it turns out i didn't get it clipped in all the way after cleaning it. I dont think the o2 sensor would make it hesitate like that. As I understand the EFI on these engines relies heavily on the MAF and the TPS to get the fuel mixture right.

Anyway check connectors on the MAF and TPS.

Good luck

 

[89_Black_Beast]

still need someone to shed some light on this dilly of a pickle I got goin on.

Not a fuel filter...
Found a nice crack in my intake, fixed it, still hesitates but not as bad...
I unhooked the o2 sensor to run in default mode and it ran decent, so its not fuel pump...
Cleaned my mass air also...still same

Any ideas will be much appreciated!!!!!!!!!!!!!!!!

 

[Bird]

check your TPS


Bird

 

[89_Black_Beast]

So I had about 25lbs of fuel pressure at idle so i replaced the fuel pump and nothing changed.

Ran a scan tool on my truck and it did the self test and I got nothing back. Test was good!!

Put a new TP sensor on and it helped but def didn't fix the issue...

Anybody... ideas?

 

[4x4Ranger]

I know I'm resurecting this thread from the dead...but did you ever find the problem?

I am having this same problem with my 94. Runs great except at full throttle it seems to bog. If I back off the pedal to just off the floor it's good to go. I have a cold air intake and I just cleaned the filter and the MAF. Seemed to help a little, but at 100% WOT it still bogs.

 

[rangerrager]

same exact problem here .
let me know if anyone knows

 

[slimchriz]

Check for Vac leaks I had a similar problem and it was a vac leak only discovered it when it got bad enough to throw a code and by then you could here it but previous owner complained of the problem entire time he had it. keep in mind though I have an SOHC if it matters

 

[91rangerxlt]

had this problem with my old ranger. put new plugs and wires in it ran like a charm. if you got new plugs though i dont have ny ideas