What should Fuel pressure be & Trany no O.D.

[bruce119]

OK I am trouble shooting and fixing up a 93 XLT I got I do have another same truck to swap parts. So I am going to ask individual questions instead of a bunch.

1st off I got a fuel pressure gage. What should the pressure be. It pumps up with key on engine to about 38 psi with engine running it drops and holds about 29 psi engine stumbles from time to time and runs rough when it stumbles the pressure goes up about 2-3 psi then rite back down to 29 when it smooths out.

One more problem wile were here the trany will not go into overdrive. It works fine feels good shifts good just wont go into overdrive. I am hoping this mite be some type of sensor or something I can swap from my other truck.

Just those 2 for now.
Thanks
Bruce
Oh 93 XLT 4.0 2wd

 

[Deleted member 144197]

ok for the tranny question... im almost 100% sure that its the lock up in the trans which locks in overdrive (4th gear) im having my trans overhauled as we speak an that was one of the problems i had... also i was having a torque converter problem

 

[Deleted member 144197]

my ex is a 96 4x4 sport so idk if that makes a differance but fyi if you spend over $600 on any trans repair my advise is to jus go ahead an overhaul (rebuild) the whole thing!!! that way you know!!!!!!

 

[Deleted member 144197]

actually you live in holiday lol my ex is at discount transmissions in new port richey off grand blvd they are very knowledgable when it comes to the explorer tranny!!!

 

[bruce119]

yea I read about the torque lockup. But 96 and 93 I think are different animals. i also read something about about a PCM power control module I thought maybe that had something to do with it. A trany rebuild is pretty far down the list rite now. Still trouble shooting running issues. I would like to now what is a normal fuel PSI for a 93. I searched and found a 96 was something like 40-60 key on and 40 running. But I read 93 was different but couldn't fine the numbers I have manuals coming that should help me out.

That trany shop in N.P.R. is about 8 miles up 19 from me just across the river I know the place.

I think I mite take this truck to the dealer for a diagnostic. I don't mind spending $80.00 if they can give me a solid answer what is wrong.

Thanks

 

[Deleted member 144197]

yea i would spend the $80 too... do you plan on using your ex for a dd or wheelin? both maybe? lol... do you know anyone who'd be willing to instal my 3" body lift for somewhat on the cheaper side? i have cash!!!

 

[MrShorty]

KOEO fuel pressure should come up to near 40. KOER, pressure should drop in response to engine vacuum. 29 is still considered normal, and the fact that the pressure increases when it stumbles suggests to me that fuel delivery is not contributing to the stumble.

On your A4LD, 3-4 shift and TCC lockup are electronically controlled by the PCM. 1st step in diagnosing a no OD is to determine if the problem is electrical or not. I would probably start any diagnosis involving the engine management system by pulling codes from the computer to see if the computer has any input on what the problem might be.

The 3-4 shift solenoid and TCC lockup solenoid circuits are pretty basic DC circuits. With a wiring diagram and a voltmeter, it shouldn't be too difficult to check the circuits to see if they are intact.

 

[bruce119]

I got codes from auto zone. 124, 157, 158, 159, 172, & 177.

He wrote down some of the translation. I know the MAF came up but I have has that disconnected and I did replace with another (one year old from my other truck) with no change. The MAF was plugged in at the time of the codes read. But the truck runs much better with the MAF unplugged. It runs like crap when cold but OK when warm. It runs like crap with MAF plugged in but runs much better with MAF unplugged. I swapped out the IAC also no change. Any other ideas to swap out like I said I have another same truck sitting rite next to it. Were is the PCM would that be something easy to swap. I am not that good with a meter but can turn a wrench and have the good fortune of that spare truck for parts.

Thanks

 

[MrShorty]

The guy at Autozone didn't happen to mention which codes were KOEO and which were CM codes, did he (I'm also assuming he didn't perform the KOER test)? If you are unfamiliar with those acronyms, refer to my "notes on pulling EEC-IV codes" in the EEC-IV forum. My code list suggests that the 159 would have to be a KOEO code. Because KOEO codes are set with the engine off, they almost have to be electrical in nature, so we typically start by diagnosing the KOEO codes.

If we assume that you didn't have two bad MAF's, we might assume one of those MAF's is good and look elsewhere for the problem. Recognize that trouble codes point to problems in circuits of which the sensor is only one part. The next thing I might do would be to check for power and ground to the MAF and for continuity between the MAF and the PCM.

Another thing I might do, especially with a long list like that, is to clear CM (see test instructions), test drive, and repeat KOEO test to see which of those codes return.

The PCM is located in front of the passenger door, below the glove box, behind the kick panel next to the passenger's feet. It would be easy to swap, as long as you are certain the two PCM's are compatible. '93 is an interesting year for the engine management system. Some '93's have two O2 sensors, SEFI, and an EGR system, and some only have one sensor, batch fire, without an EGR system. If your parts truck is a '93 or a '94 with the same computer configuration, swapping PCM's may be a useful exercise. Anything else, and it probably won't be very useful. I would suggest that you pull codes from the donor PCM before removing it from the donor so you can see if it gives something different after swapping.

One interesting thing about that code list is that they all have to do with mixture control. I wouldn't be surprised if that entire list has a single cause. And, because MAF and TPS are important in the computer's decision to upshift, I wouldn't be surprised if resolving that list of codes also resolves the "no 4th gear" problem.

 

[bruce119]

Mr Shorty
Thanks for your replies and help. I am a newbie to this site and very old school so I have to research all the abbreviations used. Everything I used to work on was pre '90 so I didn't have all that computer stuff. I guess the old backyard mechanic mite as well be kindergarder. I am kind of lost with all these sensors and computers. But I can turn wrenches and change parts.

The codes were taken with the engine off from behind the fuse box under the hood. Keep in mind I do run the truck with the MAF disconnected (It runs much better) I did connect it before I drove to shop and got the codes. So that mite screw up codes don't know.

I compared the PCMs of both trucks. Number on PCM are

New truck
COW1
EEC-IV EFI-MA46G
F37F-12A650-AAB
63EMG 46A16 6623 -294 3E20

Old donor truck
same as above except last line last group of digits
63EMG 46A16 6623 -5 3E19

Are those last few digits just a manufacture serial # and date thing or is it a critical difference.

Thanks for the help
Bruce

 

[MrShorty]

I don't have any way of looking up those numbers, so I can't really say. Do both trucks have an EGR system? Do both trucks have 2 O2 sensors? Do both trucks have a CMP (camshaft position sensor where the distributor would normally be)? If so, then the PCM are probably close enough to the same.

The codes were taken with the engine off from behind the fuse box under the hood.

Two types of codes are output during the KOEO test: KOEO codes and CM codes. Did the Autozoner tell you which code(s) were which (assuming he knew how to distinguish them himself)?

 

[bruce119]

from the best I can tell neither truck has an ERG system. I used this thread as a reference to look and neither truck has what is in the photo.
http://www.explorerforum.com/forums//showthread.php?t=247568

Both trucks have the same O2 sensors just below the exhaust manifold. Both exhaust systems look the same.

I do not see a PCM

I haven't found anything different between the two engines. The only differences I can find is interior the new truck has power seats the old does not. Everything I can see is identical even the stickers the vehicle info. under the hood and the sticker on the driver door.

Would there be any chance of doing damage by swapping the PCM. Would anything need to be done to it going from one truck to the other some some sort of reset. Or maybe I guess just the act of disconnecting it will clear it out and reset it. I don't want to make things worse.

Here is what the guy from Autozone wrote on a slip.
124-TP sensor voltage higher than expected (91 on)
157/158- MAF sensor below, above minimum voltage/maximum voltage (91 on)
159- MAF sensor out of range doing self test (91 on)
172- HEGO sensor indicates lean condition, bank 1 (91 on)
177- HEGO sensor indicates rich condition bank 2 (91 on)

He just wrote them down out of a book that is all I know.

I don't mind taking the truck to a dealer to get an accurate diagnoses. I just can't afford to spend money I don't have a lot I don't work and am on disability. I was thinking taking to dealer and if they find something big $$ wrong then I could take it to the local garage to do the work a LOT less $$$. BUT I can do small jobs and swap parts myself, I just have limited tools and even worse I can't handle the heat.

thanks for your help

Thanks for your help