Ugh... 92 Explorer Hell..

[MistahYebba]

On the other hand, when I got it to actually run with the IAC valve plugged in and ALL of the vacuum lines connected..

Here's what happened.



Check out how much smoother it idles when I unplug it.

 

[natenkiki2004]

Have you unplugged the MAF and ran the engine? You still could have a vacuum leak, most likely spot would be upper intake gaskets. Aside from that, it's either a computer issue or you're not getting enough fuel (bad/clogged injector?).

It's been so long in this thread... have you pulled codes? Does the Check Engine light come on before you crank the engine? If there's no codes, do a KOER test, that should tell you if there's faulty sensors.

 

[MistahYebba]

How can I check upper intake gasket leaks and do they normally work one day and then not the next? And would plugging in the IAC make an upper intake leak stall the car or?

I tried pulling the codes today but the car seems to stall at idle in Park... Seems like I'll have to try in neutral?

I did pull the MAF and it does make a difference but it doesn't stop the problem

 

[MistahYebba]

I think my RPM meter (tachometer?) is bad cause it always says 3000 rpms.

Unless I rev... it goes higher than 3000RPMS but no lower when the engine is running?

 

[natenkiki2004]

Park & Neutral are the same but you can try it, just remember to apply the emergency brakes.

You don't need the engine running to pull codes but you do need it running for the KOER test (obviously).

Upper intake gasket is easy to test, spray something around the gasket area. Brake cleaner, WD40, starter fluid, even water. Any change in the RPM and the gasket is faulty.

Is your tach at 3,000 RPM with the key on or only with the engine running? If it's only that high with the engine running... that could easily be your problem.

 

[MistahYebba]

When I turn the engine off my tach drops all the way down to nothing..

When I turn the engine on, however, my tach is always on the 3 mark (3000). Even when I can hear the RPMs nearly stalling, etc, my tach is always on the 3 mark..

However, if I actually rev higher than 3000 RPM, it does climb accordingly.

Why would it display correctly anything higher than 3000RPM, but nothing lower?

It's not revving at 3000RPMs, I know that much...



I tried to do the self test again just now but nothing was happening.. I have a feeling the paper clip I'm trying to use is either too small or not made of metal lmao.. but I couldn't get it working.

I lost the large paperclip I used before Have to get one from work tomorrow.

 

[MistahYebba]

This problem is really frustrating for me... :/

As you can probably imagine.

So thank you for your patience. If you think the length of this thread is annoying, just imagine how annoying it is for me that I bought a used car that hasn't stopped having problems since I got it..

The first day I drove it, it overheated after like 15 miles and was smoking.. I can't tell you the problems I've had to fix since that day just over a month ago....

It only gets better

 

[natenkiki2004]

So, let me get this straight...

Key on, engine off... what are the RPMs at?

Engine & key off, tach shows 0?
Engine running at idle, tach shows 3,000 unless you rev higher?



I understand your frustration, I really do. I just wish we could help narrow this down. It's kind of stumping me so far.

 

[MistahYebba]

Yes, you got that right.

Key on, engine off = 0 rpms.

Only time tach moves is Engine on... in which case it goes to 3000RPM unless I rev higher.

but when I hear it nearly stalling, the tach isn't showing the RPMS accordingly.

 

[MistahYebba]

We should just start from the very beginning and look at it this way..

When everything is hooked up properly the way it should be; my truck either stalls right after starting, or starts and idles very terribly until it stalls soon after.

Then we can test each possibility..

Vacuum Leak?: I capped every port on the tree at the same time.. same results. Vacuum leak disproven.

Dirty/faulty MAF?: Disconnecting the MAF doesn't help the problem.

Dirty/faulty IAC?: Disconnecting the IAC fixes the stalling after startup, but I still have bad idle and will stall occassionally.

Any other "straight-to-the-point" ones you can think of?

 

[natenkiki2004]

While waiting for your reply, I was going over that in my head.

I was thinking that maybe your computer thinks the engine is actually at 3,000 RPM at idle. However, I think your engine is running too well for that to happen. If the computer thought that RPM was at 3,000, it would throw the timing off. It would likely backfire at the very least. It couldn't stay running if that was the case.

Though, I'm curious, do you have access to a timing light or clip-on tachometer? It'd be nice to verify that the spark is occurring at true engine speed, not 3,000 RPM. If the computer knows the true RPM and you have a gauge issue, you can write that one off entirely for later. It is possible to have gauge issues. There's been 2-3 times that my tachometer dropped to 0 for 5 or so seconds then back to normal but there was no change at all in RPM.


I'd like to see you get a water spray bottle and spray around the upper intake gasket then spray around the coil pack and all the spark plug wires. Free, quick and worth a shot.

 

[MistahYebba]

I don't have access to a timing light or clip-on tach unfortunately, but I want to say that the engine has always told me 3000RPM since I got this used car.. I just never thought it was a problem til reading posts on here about people idling in the hundreds and I thought that was crazy!

I did spray MAF cleaner everywhere all over the lines and stuff today and found no differences. I will focus more on the upper intake gasket when I get another chance tomorrow along with pulling the codes if I can manage to do that.

One thing I can say, I did put new plugs and wires on about a week before this starting happening..

A wire could be loose, but I doubt it would be doing all this just over a loose wire? And furthermore it wouldn't explain why unplugging the IAC changes a loose plug wire, would it?

Finally.... would an O2 sensor cause stuff like this?? Don't forget about the whole unplugging the IAC part.. I feel like that's a really important thing... maybe I emphasize it too much, but I really feel like the fact that plugging in my IAC while the car is running makes it stall is the dead giveaway of a certain problem.

Also.. I did notice some loss in power on the windows.. they go up much slower and the motor seems to not spin as fast? Could be unrelated :/

 

[Number4]

I'm going to lean with [MENTION=241671]natenkiki2004[/MENTION], seems like you have a computer issue.

 

[MistahYebba]

Do you have any examples of how a computer issue could just arise out of no where? Working fine one day and then all of these problems progressively worsening over the span of a few days?

It all started because my car stalled when I turned the AC off. That was the only real problem I had.

I cleaned my IAC and put fuel injector cleaner in.. Drove it home with the IAC plugged in and everything seemed to be okay...except the "ac off" stalling problem didn't change a bit... parked it and went to bed...

and suddenly the next morning, the car wouldn't stay running if the IAC was plugged in. Of course, even with the IAC unplugged I am still feeling the symptoms of whatever is wrong (which is most likely unrelated to the IAC completely).

What would make it get so much progressively worse over night??

It's quite boggling..

The only thing I could imagine is maybe unplugging the IAC initially... now my car needs to re-learn idle, bla bla bla... could disconnecting the battery help with that?

Let's say that helps it re-learn idle and that fixes that whole aspect of it.. I'd imagine I'd still be at square 1 with turning off my AC at a stop causing my car to stall or drop RPMs massively.

If it's not the IAC or a vacuum leak, what else could even cause that?

 

[Number4]

Im going with the computer thinking the vehicle is at a wrong rpm all/most of the time.

 

[MistahYebba]

What would cause that?

 

[MistahYebba]

And why would it just become a problem??

Since I got this car a month ago it's always shown 3000RPM until I rev greater than 3000RPM to my knowledge..

This whole stalling/rough idle/IACV being plugged in causing instant stall stuff only started happening a week ago. :/

 

[MistahYebba]

Check it out..

http://www.explorerforum.com/forums/showthread.php?t=275462

Apparently the 3000RPM thing is common. So I'm gonna go ahead and rule that out too.

Gonna fix that later.

So.... any ideas?

 

[natenkiki2004]

I don't think it's a computer issue with the tach. If the computer thought it was at 3,000 RPM all the time, you would have to run the engine at 1,500 RPM to even have a chance of it to stay running and then you would be overly rich, it may not even run on that merit alone. Besides, the crank sensor picks up distortions in a magnetic field, it can't just magically say that the distortions are happening faster than they actually are.

Yebba, have you been able to pull codes? If the engine doesn't stay running long enough, disconnect the battery for 10 minutes. Hook it back up, run the engine a few minutes and do the KOER. The engine should run long enough to get KOER codes. The computer has to be in closed loop status, meaning that the O2 sensor has to be warm enough to start switching. This may give you an indication of where to go; if there's a sensor problem or...

 

[MistahYebba]

Tachometer is working great now. I re-soldered the points as illustrated in that post that I linked... so that is ruled out.

I want to say vacuum leaks are ruled out... (I guess it wouldn't hurt to spray water around the intake manifold gasket like Natenkiki just said? but I have a feeling the vacuum system is nice and sealed.

I want to say a faulty IAC is ruled out... considered I tried 2 replacements and both did the same thing.

I would guess that the MAF is ruled out? Because I cleaned it pretty well.. even though it wasn't really "dirty" to begin with? (probably microscopic pollution). I guess the only way to know that for sure is to replace it, but I highly doubt a faulty MAF would be causing all of this to happen. I don't think it has anything to do with AC turning off causing a stall..

-------------

As for the check engine light... I just tried over and over again to get the dang EEC self test to work. I know how to do it, I've done it before... but I can't get it to enter test mode or whatever.

I put a paper clip in the correct slots, and the first time I started it up, it did that weird "barely visible" check engine light blink that tells you it's working.. but a couple seconds later, instead of blinking 3 times (v6) to tell you how many cylinders your engine has, and then 1 time to tell you to initiate the goose test; it just went straight to telling me codes.. it gave me "998"... (wtf?); and then a few others.

I mostly disregarded all these codes though because I want it to ask me to do the goose test before I trust anything it's saying..

Any ideas on that?

And furthermore, any other possibilites yall can think of that would make a truck with everything hooked up correctly (included the IAC) stall shortly after startup?

Someone mentioned fuel injectors... that's a pretty good one.. especially considering I put fuel injector cleaner in the night before it started stalling with the IAC plugged in..but then explain why it works with the IAC unplugged?

Open to suggestions.. one day at a time