rough idle on 93 4.0

[rainfly]

my daughters explorer started running rough and chundered so she pulled it over..i went and got it and on the way home it wanted to die at stops and run rough, unless i kept a foot on the gas. then every once and a while, it would start running fine for short periods and the cel would go out. i replaced the fuel pump, relay and filter a year ago. i also replaced the lower intake man gasket (coolent leak) a few weeks ago, but it ran fine after. i see by the alt guage, it is on the high side of normal, almost over. i replaced the fuel filter again just to make sure as she runs it low on fuel and put in good fuel and seafoam. i did a koeo test with a jumper this morning and got codes (122) tps sensor voltage, (513) internal voltage fail in pcm, (565) canister purge circuit fail, (556) primary fuel pump fail and a koeo code of (998) hard fault. i hooked up a fuel pressure guage and with the koeo the fuel pump and relay work and i get almost 40lbs of pressure, i repeated this several times and always after starting it kept the pressure. i can smell a 'raw' or unburned fuel smell but see no drips or leaks. my daughter says she always smells this and goes through a lot of fuel. the oil also has the faint smell of this..any clues to start my trouble shooting would be greatly appreciated. thanks,

 

[Roadrunner777]

40 PSI is really a bit high. A failure of the fuel pressure regulator can cause fuel to be sucked back through a vacuum line into the intake, causing such smells and problems. Otherwise, an issue with the return line? I probably should not have replied, I am going to be away from my computer for a few days, but that's where I would go, search on fuel pressure regulator.

 

[Nedwreck]

I've seen some really weird stuff with TPS problems.

Fortunately, they are the easiest thing to replace.

I'd give that a try, since a failed TPS can cause a very rich idle if it sends a part-throttle signal when at idle.

It could be that 122 and 513 are related (bad signal from the TPS).

565 canister purge solenoid is usually not a serious problem, but I'd inspect it. that may add to your MPG woes, but I'm not sure.

I'd also inspect the vacuum line to the fuel pressure regulator, if it's broken or disconnected that may be running your pressure up (as well as roadrunner's thoughts.. look for evidence of raw fuel in the line).

 

[MrShorty]

According to my code list, KOEO 513 indicates some kind of internal PCM failure. Because, the PCM is responsible for mixture control and other things related to keeping the engine running right, I'd probably replace the PCM before chasing any of the other codes/symptoms you describe.

I don't know if you saw this thread http://www.explorerforum.com/forums/showthread.php?t=342313, but he and I just went through something similar with a KOEO 513.

 

[rainfly]

thank you mr. shorty..i did not see this thread and i spent a great deal of time last night, searching..it is good to have friends in forums. his code list and mine are very similer and from the sound of it, similer symptoms. i will look to a wrecking yard this week. do i re-use the chips in my pcm? should i seek a 91-94 or a 93 only?

 

[Turdle]

Mismatching the PCM to the incorrect harness will be a big mistake and might cause further damage--so be careful

There are 3 different wire harness --pcm combinations for 93. It is very important you get the correct PCM

Does your truck have EGR?

Another quick check is the color of the wires going to the fuel injectors--

check one injector on each bank--are the wires common colors(s) on each bank, or do you see different colors on each injector wire?


There is also a single 02 sensor system, and a dual 02 sensor system possible for non egr

single 02 is after the y pipe, dual 02 sensors will be found in the down pipe on each side.

 

[rainfly]

my explorer has no EGR and the wires going to the injectors are different, three have red and white, three have red and tan. i will slide under later to count my O2's

 

[Turdle]

OK, you do have a batch fire injection system. Sequential fire have ALL wires color coded. Batch fire has coding only for each bank, like yours.

If you pul the PCM, look for a 4 digit code printed in larger charaters then the rest. I am assuming it will say BAT1

 

[rainfly]

i'm about to go and pull the pcm..i have been lazy this beautiful sunday morning..if so, do i just need a 'BAT1' pcm and use my same chips? is my problem in the chips themselves or in the main brain?

 

[rainfly]

Bat1..so now do i need to find an F37F-ZB? or will any of the fed ones work?

 

[Turdle]

No, I would scour the junkyards for a 93 with a BAT1 coded pcm. Others will not work well, if at all as the pin configurations are different.

 

[rainfly]

yes a BAT1, F37F-12A650-ZB..i am not sure what a CARDONE-78-5512 means, but i believe they are compatable..

 

[rainfly]

That was exactly the problem..the PCM..! i picked one up from a local wrecker for $75. and she started and runs like a champ! THANK YOU, THANK YOU ALL!! you guys are the best!!
Fly~

 

[tmosesjr]

fuel pressure regulator

Where is this located on a 93 explorer 4.0 pushrod 4X4?