Explorer stalls out on high loads.

[kbsmith_48]

My 94 sport will hesitate from idle to wide open. But when driving down the road the truck will rev to about 3000 rpm and then it is like you shut the truck off. It will drop from 3000 to about 1500 with out ever shifting or letting up on the gas. But if I take my foot off the gas it will rev right back up them repeat the same process again.

 

[arco777]

Please run a KOEO test and give us any KOEO or CM codes. Also, please run a KOER test and report any codes.

Also, check the TPS - check that the voltage is moving in a linear fashion from idle to WOT.

 

[kbsmith_48]

I checked the tps .75 at closed throttle and 3.92 at wot. From what I have read this means a bad tps.

 

[arco777]

I wouldn't say it is necessarily bad - but .75 at idle would be out of adjustment. Sounds like you should do the TPS adjustment modification and try to get the idle number closer to .96/.97v.

When you actuate the throttle and watch the voltage, does the voltage rise smoothly with the throttle position, or are there dead spots or spots that the voltage jumps? Those would be signs of a bad TPS.

 

[kbsmith_48]

It went up smoothly but like I said it only goes up to 3.92 and from what I've read it should be 4.5-4.6 and up but not over 5.0

 

[kbsmith_48]

Update I changed the tps And now the readings are good but it still does the same thing it did. Could I have a vacuumm leak will try and pull codes tonight

 

[Big_Stig352]

In My Experience, You Might Be In The Beginning Of Having Your Engine Control Module Fail, Happened To Me, If It Dont Start One Day, Spray A Little Bit Of Engine Starting Fluid In The Intake.

 

[arco777]

Update I changed the tps And now the readings are good but it still does the same thing it did. Could I have a vacuumm leak will try and pull codes tonight

Usually you'll hear a vac leak. You can spray carb cleaner at various points in the engine bay and if it's getting sucked in somewhere your engine will slow down.

Let us know what you find for codes.

 

[kbsmith_48]

I got home today and didnt have time to check codes before it got dark. But i did unplug the maf and the truck started good and would rev up instantly. while the maf was unplugged it was smoking though. We then unplugged the iac and idle dropped like a rock upon plugging the iac back in revs returned to normal. after plugging the maf back in the truck started to hesitate again.

 

[arco777]

Bad MAF. Had the exact same thing happen on mine - erratic driving issues, but ran fine with MAF unplugged. New MAF cured all problems.

 

[kbsmith_48]

I will get one and replace it. But what would have been causing it to smoke. It was a white smoke.

 

[arco777]

White smoke is usually coolant on these cars from a cracked head. But yours could be unrelated. Put your hand under the exhaust stream with engine running and smoking. If after 30 seconds your hand is wet/damp, that white smoke is coolant.

Smoke can be produced from the engine running far too rich but usually that's black smoke I think...

The only other source of smoke I can think of would be if your trans vacuum modulator is bad - if the internal diaphram was bad it would suck trans fluid up the vac tubing into the intake and then be burning trans fluid.

 

[kbsmith_48]

It only smokes when unplugging the maf and the modulator valve is new. I pulled codes tonight. My first time but checked it over and over.

So here is what i got.
KOEO

335

CM

56
58
72
76

KOER

536 Because i forgot to press the brake pedal
rechecked and it didnt appear

111

 

[arco777]

335 is DPFE sensor fault. Common issue on cars with EGR, the DPFE sensor goes bad. Usually causes minor driving issues and nothing major. The sensor is about $50 online and is a 2 minute job to replace.

56 is MAF out of range, too high.
58, 72 and 76... well, those don't make any sense to me. You sure on those ones? Were you using a code reader or counting blinks?

536, ok.
111 is a pass.

 

[kbsmith_48]

We were counting blinks and that is what we got after counting them three times KOEO test and thats what showed up in continuous memory.

 

[kbsmith_48]

Those may have been 158 172 and 177. Is there a separating blink or not? These actually make more sense seeing as we cut the exhaust when changing tranny and put a piece of flexpipe back instead of taking and getting the exhaust put back on.

 

[arco777]

Those may have been 158 172 and 177. Is there a separating blink or not? These actually make more sense seeing as we cut the exhaust when changing tranny and put a piece of flexpipe back instead of taking and getting the exhaust put back on.

Those make more sense. Those are another MAF fault, system lean and system rich. Sounds more and more like a bad MAF.

No separator blink between individual codes, just a pause.

Exhaust shouln't throw any codes unless you messed with the y-pipe. First gen PCMs don't care much what you do with the exhaust.

I personally lost power when I put a straight-through Magnaflow on and got my power back when I re-installed a stock muffler, but no codes were ever thrown and the engine ran fine. Just a side note.

 

[kbsmith_48]

We cut out right after the o2 sensors on each side so that why it's throwing those codes.
I will order a new Maf and replace it.
Thank you arco777 for all your help I really really appreciate it.
I also want to thank you for serving our country. I really appreciate it.

 

[arco777]

Good luck, hope that does the trick. I see a new MAF on RockAuto starts at $82-87. Might be able to find a cheaper price elsewhere, just a heads up though.