1994 Explorer Sport Stall

[blinden]

I've tried searching, but searching for Stall and Idle issues creates a LOT of results, and none of them that I saw after about 20 minutes really matches what I'm running into. I hope it's nothing too obvious, I don't know much about engines, but I'm learning, and trial by fire is the best motivation.

So, my situation is that the vehicle starts, and runs fine, but recently (and this happened about 15 miles after putting a tank of gas in, so I'm not ruling out 'bad gas', but I don't even know what that really means) the car will stall while idling. It kinda does and idle seek, revs up and down and eventually will fall too low and just die.

When under load in gear, it runs fine for the most part, but an almost sure way to get it to stall is if the car is sitting and you turn the wheel, as soon as the power steering starts working, it stalls. Is it an electrical issue? Mechanical? Any ideas

 

[MrShorty]

I would start with some basic diagnostics:

1) Check for vacuum leaks. My '92 gave me similar symptoms when one of the vacuum hoses came off.
2) Check fuel pressure. I've seen similar symptoms from inadequate fuel supply.
3) pull codes (CEL on or not) to see if the PCM is seeing any problems.

 

[blinden]

There HAS been a preexisting CEL, I forgot to mention, I don't think really related though. This is a CEL that will come on after about 5-10 minutes of driving, this has been months though, problem only started last week. I will look into finding the codes, have to do a little searching on how to actually do that though.

 

[MrShorty]

Go straight to the EEC-IV forum here and read the stickies.

 

[nitro71]

Fix what's wrong first before easter egg hunting!

 

[blinden]

okay!

(I don't even know what that means)

Printed out all the info I could find on the EEC-IV forum, will try and get code(s) when I get home from work tonight, that'll be a great start, thanks for the heading MrShorty

 

[nitro71]

Since you don't even know what code it's throwing that could be your answer to your problem you know.

 

[Masterd]

Maybe an IAC problem....

 

[blinden]

Think I got codes 157, 158, 172 (if I read them correctly, which, who knows)

157 R,C Mass Air Flow Sensor below minimum voltage
158 O,C,R Mass Air Flow Sensor above maximum voltage
172 R,C Heated Oxygen sensor indicates lean condition, right side

Okay, cleared codes, let the car run for about 5 minutes, checked codes again, the only one appearing is the 157. I'm going to try and replace this next week, between low and high voltage CELs, I think the MAF is running haywire. Anyone see anything flawed with that?

I think the O2 sensor error is one that has been going on for a while and I think this is the one that would cause the CEL orginally, but now I think the MAF is losing it and causing the stalling.

 

[MrShorty]

Is the 158 a KOEO code, CM code or both?

Recognize that codes point to problems in circuits, of which the sensor itself is only part. A bad connection, broken wire, bad power supply to the MAF, or bad ground to the MAF could also cause those codes. Just want to point out that you need to look at the whole circuit, not just the sensor.

Also note that the MAF and O2 sensor are both integral parts of calculating fuel mixture. If it does prove to be an MAF issue, fixing it might also fix the O2 sensor code.

 

[blinden]

great ponit. I'm goign to try the MAF first because I found one local for about $40, it will be the quickest and easiest thign to change.

as far as the KOEO and CM thing, I read through some posts, and had a hard time descerning the different types of codes, I got codes that read 111 and 111 and then 157, 158, 172. After I cleared it it went 111, 111, 157

 

[nitro71]

02 sensor is about a 100K replacement item anyways. How many does a 94 have? I should start scouring the junk yard for them.

 

[MrShorty]

great ponit. I'm goign to try the MAF first because I found one local for about $40, it will be the quickest and easiest thign to change.

as far as the KOEO and CM thing, I read through some posts, and had a hard time descerning the different types of codes, I got codes that read 111 and 111 and then 157, 158, 172. After I cleared it it went 111, 111, 157

The 1st 111's are the KOEO codes, meaning it passed the KOEO test, so all of your codes are CM codes. This means the computer doesn't see the fault until the engine is running. I would next be curious to see what you get from the kOER test.