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94 explorer code problems

garagedog369

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egan south dakota
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egan south dakota
Year, Model & Trim Level
94 explorer 4 wheel
94 explorer.it is a daily runner. 70 miles round trip. it always has been a good runner. never any real problems except for that dam check engine light. I've been chasing codes for the better part of a year now. when I first started among all the other codes I had #186 - injector pulse- width higher than expected. after replacing the throttle position sensor, both o2 sensors, the egr and tube , and the egr vacuum sensor. I am back to square one. and I don't know what to do. as of today my, not running, codes are.#181 -adaptive fuel rich limit reached at part throttle-right side. #186 - injector pulse width higher than expected. #188 -adaptive fuel lean limit reached- left side. any thoughts?
 



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Sounds like one side is getting all the fuel causing to rich and because that side is getting all the fuel the other is running to lean almost like the fuel rail or injector is clogged
 






Those codes indicate basically that the PCM is desperately trying to compensate for what it perceives as a constant rich condition on one bank and constant lean on the other. One side does not just "get all the fuel", there is plenty for both. Your O2 sensors are the main source of the PCM's visibility of downstream conditions. One possibility is that you still have an O2 sensor problem of some sort, perhaps a faulty sensor or bad wiring. Another is that the PCM itself may be faulty. Sometimes the O2 sensor heater circuits on the PC board actually burn out. Might be worth taking the PCM out (it's easy) and checking inside it for burns or water damage. You can also probe the sensors themselves with a multimeter while the engine runs; do a search on the forum for how.

I doubt that there's enough slack in the injector harness for the wires to be criss-crossed, but if the intake has been off and the injector connectors were swapped left to right, you could see a similar condition.
 






At part throttle it is to rich on one side and lean on the other if im correct could be opposite but fuel filter to left side fuel rail from left goes to right a clogged rail or bad injector would cause fuel to go more to one side whiche would be right side basically bypassing left side while the clogged rail or injector fights to get the right amount of fuel to the motor but cant causing lean
 






thanks for the help. i'll check the rail. pull it and clean it. I've already rechecked the o2 sensors. I was wondering about the pcm. if it's bad would one off a 91 work?it will be a few days. this my daily runner and its got to run to day.
 






It should but some of the wires might be different i would check both wiring diagrams.
 






A 91 won't have the CMP sensor, nor will it have EGR. Additionally, the 91 computer will use batch fire injection rather than sequential fuel injection so you may lose a little power and fuel economy assuming it works otherwise. I'd suggest doing forum searches to research whether this is a suitable interchange or not.

Rails don't generally clog. By design it just doesn't work that way. Injectors don't usually clog either, because the main fuel filter stops any debris. The exception would be if a fuel filter was punched through at any point, such as the redneck way of fixing a completely clogged filter with a screwdriver (bad idea). Injector filters (tiny, one in each injector) usually last for the life of the injector. If you want to pull the injector filters and check them you can; the easiest way is to clamp a screw into a vice grips, thread the screw into the soft brass ring of the filter, and yank it out. You'd want to install new filters, available in a rebuild kit, because the screw method often damages the filter. Additionally, the injectors themselves can be tested. You can check them for proper resistance with a multimeter. They will open with a pulse voltage; some people say no more than 5V, but I have used 12V without problems. I made a test harness using gator clips (for the battery), an injector connector, and a momentary pushbutton switch. You can give the injectors a (brief) pulse of voltage to open them and blow through them. Only a quick pulse though or the injector's coil may burn out. I soaked my injectors in injector cleaner overnight as well.
 






Theres different ways anything can fail just to say thats not how they work is wrong anything can happen in a car thats why you diagnos things injectors clog and it something people overlook they change pump filter and still have problems so anything can happen rails i agree dont gemerally get clogged but if the injectors are clogged not getting the fuel out fast enough its going to push it through the rail to the other side
 






No. If an injector is clogged or isn't operating for whatever reason (say it's unplugged for example) the "other side" won't neccessarily overfuel. There's 30-40PSI in the rail regardless, the regulator maintains that. There are no bursts of fuel from the tank to the rail that somehow coincide with injector duty cycle, it's a constant flow. One injector not firing doesn't make the other injectors overfuel because it doesn't raise pressure in the rail. The only way you're going to see overly high pressure in the rail is if the regulator itself malfunctions, and then it would be affecting every injector, not just one side.

Try punctuation too, and read up on return-style fuel systems.
 






I don't advocate throwing parts at a problem (Unless it's a cheap and easy part). If you feel you've exhausted all troubleshooting steps, and still have the problem, you may consider a PCM swap. I had an issue with a lean bank code. I went through everything at least a couple of times - all sensors, actuators, wiring, vacuum lines, and took apart the PCM to inspect inside for damaged components. Everything was either good or had been replaced. I found a PCM on Ebay. You will need the same part number and calibration code to keep compatibility.
 






40 psi on one 3 less wpking injector would cause excessive pressure have you put you finger infront of the hose on a water hose what happens more pressure causing water to go further DUH
and i am nott in english class so i dont care about punctuation this is not an essay so it doesnt matter to me
 






I don't advocate throwing parts at a problem (Unless it's a cheap and easy part). If you feel you've exhausted all troubleshooting steps, and still have the problem, you may consider a PCM swap. I had an issue with a lean bank code. I went through everything at least a couple of times - all sensors, actuators, wiring, vacuum lines, and took apart the PCM to inspect inside for damaged components. Everything was either good or had been replaced. I found a PCM on Ebay. You will need the same part number and calibration code to keep compatibility.

Agreed that PCM swap might be worth a try but look inside yours first and see if it looks or smells like it might be damaged. Maybe you can pull one from a junkyard that has a return policy like Pick-N-Pull.

Not sure of your calibration but the most common one I've seen for 94 is UMP1. Cali emissions would be different but otherwise UMP1 should work for all 94s.

Also, awood's suggestion not to throw parts at a problem is golden advice. Been there and done that and only had empty wallet to show for it. Throwing parts at a problem rarely ends well.
 






40 psi on one 3 less wpking injector would cause excessive pressure have you put you finger infront of the hose on a water hose what happens more pressure causing water to go further DUH
and i am nott in english class so i dont care about punctuation this is not an essay so it doesnt matter to me

How you conduct yourself on the this forum should matter to you, as proper punctuation and grammar show your professionalism and respect for other members. I don't see where you're going with "one 3 less wpking injector" or understand what you are trying to say, but the fact is that your hose analogy doesn't include a [water] pressure regulator. A return-style fuel injection system is not a garden hose, any more than a water hose is a good analogy for electricity.
 






I dont have to impress anyone over a Computer. Also respecr is given were its shown i get on here to read about explores and help tjrow out ideas when someone needs help no one knows everything but having ideas tossed around often leads to the problem being solved. Ive seen people stumped on the simplest things he sounds stumped o throwing ideas out there could help him solve the problem
 






Throwing ideas out is good, but you have to have the knowledge to back them up. Otherwise the original poster (OP) can get confused. I comment about the fuel system with some confidence because I've been through the fuel systems on both my Explorers more than once, and have done a lot of research on how they work.

I don't intend my posts toward you to antagonize, simply to say "you may want to do some more research before suggesting this". Your flawed hose analogy backs me up.

This forum's topics are not just a one time conversation. Each thread lives on for many years as a reference to future searchers. Therefore it's preferable to contribute the best info you can, and if you don't fully understand the topic, you might be better off letting other users give input.
 






Not sure of your calibration but the most common one I've seen for 94 is UMP1. Cali emissions would be different but otherwise UMP1 should work for all 94s.

As I recall, mine was a VET1, but it could be Cali emissions.
 






a week ago i went to a u-pull it. pulled a mass off another explorer. put it on just to see. ran it for a week and recheaked codes. down to one-injector band width higher than expected. what the hell. i'm at a lost here.is there any other sensor that i can replace, to get rid of this last code.
 






Pulse width higher than expected... still means the PCM is keeping the injectors open for way longer than necessary. Probably trying to compensate for something. Check for vacuum leaks and manifold leaks. Spraying carb cleaner in various spots around engine while it is running is one method. Also check fuel pressure is not faltering. It is worth monitoring the fuel pressure while driving, because if the fuel pump cannot deliver enough fuel (or clogged fuel filter), the PCM will be trying to compensate.
 






I will try it. never thought of a vacuum leek ,other than the hoses. which all have been replaced.
 



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