Poor acceleration on a 94 Explorer

[ps2man32]

Hi all. This is my first post here. My gf has a 94 Explorer 4X4 with the 4.0L V6 auto. For a while she has said her truck has had poor acceleration. I didn't think much of it until I drove it. Poor acceleration was a understatement. With the accel pedal floored, the car would accel slowly and would shift gears at 2200-2300 rpm on the tach. The first thing I thought was a misadjusted throttle cable. I checked that and with the pedal floored, the throttle plate was at WOT. ( I was not able to pull the intake tube off to check the butterfly. After loosening the clamps i tried pulling the intake tube off to no avail. I checked on the arm the cables attach to, when the pedal was down the arm hit its stop on the body of the throttle body.) I also checked the cables at the pedal and there was no slack in one cable which was connected to the throttle butterfly, but the other cable was very loose, like when the pedal was floored, it would barely pull on the other cable. Is this loose cable causing the poor acceleration, or what else might be the problem?

 

[boggs1227]

dunknow hard to say , but when i got mine it was kinda sluggish imo , so then later on i read about the gas pedal mod / fix ,did that and it was like a night and day differance.your takeing the slack out of the cable on the pedal side of the cable .right where the cable hooks onto the pedal you get some tie wraps and fix it . i do know that other cable is the kick down for the transmission don't know if that would make the truck slow seeing as i have not had to mess with that after getting the transmission rebuilt ( maybe someone can comment on that ) .
also to get the intake tube off the throttle body try some wd-40 and spray it in and around the tube that will break it free if it's never been removed .

hope this helps if any . . . .

 

[MrShorty]

It sounds like the cable going to the pedal is mostly working. The other cable should be the transmission "kickdown" cable, which forces the transmission to downshift. If that cable is out of adjustment or not attached correctly, the transmission may not always downshift when you want to accelerate, so it seems sluggish because it's still in 3rd gear (or 2nd gear at slower speeds). I would investigate what is up with that cable to start with.

 

[ps2man32]

Well, its slow even from a dead stop. Say, I am at a light and I floor it, it has slow acceleration and will upshift from first to second at 2200-2400 rpm, well short of where it should be shifting at WOT.

 

[MrShorty]

I would try a few other diagnostics (pull codes, test fuel pressure, any brakes dragging, etc).

 

[ps2man32]

But would any of those cause it to short shift while the vehicle is at WOT?

Edit: Forgot to mention that there are no lights on and teh brakes are not dragging.

 

[MrShorty]

In addition to the kickdown cable, the 1-2 and 2-3 shifts are controlled by the vacuum modulator. Is the vacuum line clear to the modulator?

I don't know enough about the transmission internals to know exactly how the kickdown interacts with normal control of the shift points at WOT, but I still wonder if the broken kickdown cable isn't still contributing to the problem.

 

[Blacksheep Josh]

Drop about 2000 pounds off the body... that'll help acceleration

 

[ps2man32]

Hmm, this weekend i will tighen up the kickdown cable this weekend. I will also try to test the vaccuum line. The other thing I was wondering was about the TPS sensor. If this is giving a bad read, the ecu may not be providing enough fuel.

 

[boggs1227]

Hmm, this weekend i will tighen up the kickdown cable this weekend. I will also try to test the vaccuum line. The other thing I was wondering was about the TPS sensor. If this is giving a bad read, the ecu may not be providing enough fuel.

when you check the vac line going to the modulator on the intake ...see if there is any red fluid in the vac line (should be dry ...just a harmless check since you have to undo that line anyways) second ...is the cel on ? or has it been on latelly then goes out ?? your right about the tps sensor. it tells the computer how much the injectors need to spray ...if bad then it would activate the cel light in the dash.

another thing i forgot to ask ...when you turn on the key and you hear the fuel pump prime does it give you a good solid "whirr" sound or is it garbled and or a slow "whirr" sound ???

 

[ps2man32]

There were no lights on. Would it be possible to post a pic of the vac line going to the intake? I will check for the fuel pump sound this Saturday. I won't be able to work on it until then. So this Saturday I will get the slack out of the kickdown cable and check the vac line and report back. Thanks for the help.

 

[ryoungo2]

I found a dirty MAF sensor, but by that time we also had a code for "rich adaptive limit"
Made all the diff in the world.

 

[boggs1227]

the modulator vac line is the one on top of the upper intake and is nearest the firewall ...it's the one thats a metal line and has a rubber vac hose connected running back to the vac tree .

 

[Verno]

WOW Boggs, did you clean that baby up for te photo shoot, or does she always stay that nice lookin?

 

[boggs1227]

thanks, no it always stays like that a lot of the time .the iac is semi new off of a junked 93 xlt ( i did polish it tho with brasso : ) but other than that i spray "meguiars isane wet tire shine" all over the engine ...keeps dirt off and all you have to do is hose it down with a water hose.

 

[ps2man32]

Hey all. Thanks for the advice. I checked everything and it checked out fine, though I feel a bit well stupid after one of the things I found. When I drove it, the floor mat slid up and kept the pedal from going to WOT. With the floor mat removed, it accelerates like it should but still short shifts. The only thing left is to adjust the kick down cable which I will do. Sorry for the delay in my response, but thanks for the advice.

 

[boggs1227]

...yeah ,those floor mats are a performance killer for sure .good to hear everything is ok now .

 

[Masterd]

Weird that it would be short shifting.

 

[Pdwight]

Revive an old thread

I have a 94 4X4 that had the same problem with terrible acceleration. I mean I have a cop buddy that often says if I get a speeding ticket I must have been dropped out of a cargo plane. Here is what I found

1 the floor mat was under the pedal, that was an easy fix

2 the cable had about 1/2 inch of slop in it, the pedal moved and inch of it's already short throw before it did anything and while it was floored the throttle body was less than 3/4 open....not good. I did the cable tie trick and used two cable ties on the end of the cable to take out some slop or play in the cable, the result was amazing.

3 the other shift cable that goes to the transmission (according to this thread) has over an inch of slack, I mean the pedal has to go 80% down before it even tightens up and goes into effect.

My question is how much slack should there be in this cable ?? should it be tight or tighter or what ??

Thanks
Dwight

 

[smegun]

slow overall excelleration she get up to 75 and she dosnt have any shift problems to me it seems a little vibral rough though i take it easy im wondering if after 200k its the timing chain a little out and loosen too much timing sweets to sloppy chain it does everything though just slow getten there

its a simple design it could probobly run without the guide or tensioner a little popcorn i heard could of been valves but was a little random getn a little juice under the pan too ???