1994 explorer mis and hesitation.

[BigBlue302]

I gota 1994 explorer xlt thats running funky. it fires up an idles fine, but under slight throttle, it hesitates an misses. a mechanic shop said the coil and tps was bad. so i bought new parts an put them on but its still missing an hesitating. also put new MAF sensor, IAC, fuel pump and filter, and EGR valve. im freakin lost on what it could be. any help will be greatly appreciated.

 

[wood1]

I would have a look at the plugs and wires. As you add fuel and air the resistance increases (that the spark has to jump across the spark plug gap). Electricity is lazy and goes for the shortest route to ground. That can be a fouled plug or a plug wire that is grounding out. Wires can be checked by spraying salty water on the wires and running the truck at night. You will see any grounding out in the dark.

 

[BigBlue302]

i just put new plugs and wires on it about 6 months ago but ill check. i have heard that sticking a piece of tin between EGR valve and intake will cure this problem too. and also when i unplug the TPS, the hesitation and missing stops.

 

[Tbars4]

..Hesitation and misses could be several things so working with the limited info you supplied I would first suggest, Check for stored codes, then test your fuel pressure at idle and while revving it...

..If it is not that I would suspect the relays such as fuel/EEC, bad electrical connections even battery cables, as well as vacuum leaks while revving..

..I am thinking there is more info missing for what else was happening before and during the shop looking at it and for them to come up with TPS and coil...

 

[BigBlue302]

CEL is on but its not throwing any codes. i drove it probably 5 miles with no hesitation and miss an no CEL. after i stopped to get some oil, the light came back on an the hesitation an miss started again

 

[wood1]

Check your MAF, make sure it is plugged in properly. I'd even try the old one... if you saved it that is.

 

[Tbars4]

i drove it probably 5 miles with no hesitation and miss an no CEL.

..:scratch:..What did you do to get this result?

CEL is on but its not throwing any codes.

Whomever is checking the codes might be missing some important info during this check due to what they are using to scan the ODB-1.

..That light will have a code stored with it even if the computer has gone south..The computer going south itself is definitely another somewhat common item but getting the codes will tell if this or something else is the problem, along with more inclusive details..

..Until then, guessing and throwing parts at it will continue...

 

[BigBlue302]

it was after i replaced what the shop said was causing the hesitation and miss..whick was the coil and TPS

 

[Tbars4]

..The result would have been from disconnecting the battery then...

..Do you know how they come up with you needing either of those two items?

..Have you tried retrieving the codes yourself with a paperclip?
http://www.explorerforum.com/forums/showthread.php?t=255962&highlight=paperclip

 

[BigBlue302]

idk how they came up with it. im goin back tomorrow an telling them that there "Diagnotics" suck an it isnt fixed

 

[Tbars4]

..It would be more convincing if you used the paperclip, pulled the codes, and had them for reference when you went back to them..Heck, you may not want to even deal with them anymore if it works for ya and you hang around here for a while...

..Give it a try...It's totally free and painless..

 

[BigBlue302]

ok yeah i will...thanks for the link. this has been a real pain the ass for me. ill post the results i get.

 

[Tbars4]

..So how did this work out for ya..?..

 

[romy986]

know the pain, i have a 1994 Limited with 238K on it. I replaced the MAF, TPS, and EGR upon codes that it read, still no cure to CEL. now sounds like I have an exhaust leak from the EGR area.

 

[BigBlue302]

know the pain, i have a 1994 Limited with 238K on it. I replaced the MAF, TPS, and EGR upon codes that it read, still no cure to CEL. now sounds like I have an exhaust leak from the EGR area.

oh yeah i gotta leak around the egr too an i have kno idea where its at....i think now the IAC might be bad too

 

[JTH1972]

CEL is on but its not throwing any codes. i drove it probably 5 miles with no hesitation and miss an no CEL. after i stopped to get some oil, the light came back on an the hesitation an miss started again

Sounds like what mine was doing before the fuel pump went. I'd be checking the fuel pressure. As I was told, most of 1st gen issues are usually fuel related.

 

[cbach1997]

91 also in same boat perhaps

I gota 1994 explorer xlt thats running funky. it fires up an idles fine, but under slight throttle, it hesitates an misses. a mechanic shop said the coil and tps was bad. so i bought new parts an put them on but its still missing an hesitating. also put new MAF sensor, IAC, fuel pump and filter, and EGR valve. im freakin lost on what it could be. any help will be greatly appreciated.

This sounds familiar to me and my 91. Only when first starting, particularly when cold, and going from reverse into forward gear I get hesitation and some missing, and then we're off. This under real light throttle, heavy throttle and I worry it'll stall out. Did it on the original motor, and it's since been replaced with a factory crate long block, problem remains.

No codes, told the MAF is fine from the dealer, and have a new battery in it. Wires and plugs I think are next, I did the wires at 120,000 and now have 258,400. May have done the wires one time since then, can't remember so am playing it safe in case one is grounding out.

Am thinking it's got more to do with coils, however, since occasionally at operating temp (after I've been driving, then stopped somewhere only to restart) the same phenomenon occurs, but this time for a longer duration until I build some engine speed (above 2500). Doesn't feel like it's going to stall out, just missing and lower on power.

Very interested in what anyone else thinks on this.
BTW, it's a 4.0L 2WD A4LD setup in case anyone's wondering.

 

[smegun]

embarrasing exhaust noise a little smoke from y pipe drivers side

oh yeah i gotta leak around the egr too an i have kno idea where its at....i think now the IAC might be bad too

my truck had poor excelleration when I bought it but quiet enough .....after changing plugs and running some b12 ive got annoying exhaust noise and a little smoke from egr meets y pipe area been doing tuneups

usually all that gunk should burn up with good mixture and heat and turn into a powder looks like it still is upper egr appear to be clean lower ??? what are they prone for intake gunk or lower egr gunk ? bad mix clog cat ?

 

[429CJ-3X2]

Check the little Y pipe by the driver's side valve cover - probably the same one you referenced. Mine is broken where the tube going toward the front branches off the other tube. That tube is completely loose from the other tube which results in an exhaust leak as the lower/larger tube connects to the exhaust. It also causes the CEL to come on if the tube isn't positioned right in the resulting hole. Being connected directly to the exhaust, it gets too hot to "repair" with any sort of muffler repair product. The tube probably needs to be braised or soldered back together, on mine anyway.

Mine would have obviously been weak anyway, but I think it completely broke off the 1st time I changed plugs after I bought it.