Stalling at idle...driving me crazy.

[Joelzme]

My 91 2.3L (manual) has an intermittent problem of alomst stalling out at idle. She runs fine on the highway. It comes and goes and has recently come back. So far I have:

Replaced the DPFE sensor. (had thrown this code)
Checked all vacume lines, no leaks.
Cleaned EGR. Verified it is working properly.
Replaced all spark plugs and wires.
Replaced ICM. (Was bad, verified at autozone)
New oil.
Replaced fuel pump/sending unit.
In the process cleared out all computer codes. She is code free.

I am leaning to the fuel pressure regulator (FPR) because the truck is not throwing a code. When I pull the vac lines it runs better immediately. When pulling the vac line to the FPR, I see no fuel so I don't think it is bad.

It was running well up until this weekend when I did a brake service. I replaced the RABS valve trying to clear a code for that system. After starting it back up, she was running rough and then ok. I don't think it is the bake booster because it's not stalling out when I hit the brakes, only when at a dead idle.

What is the normal idle for this truck anyhow? Usually she is at about 700-800 but when this problem happens she dips down to about 400 and when I give her gas she stalls out. I am so frustrated right now, but I need her to work. Any ideas?

Thanks,
Joel

 

[scotts90ranger]

back in the day when my idle was misadjusted on my '90 it would randomly die on me at idle without a code. if you have a tach, start the engine with the IAC (passenger side of intake, to the rear of the throttle body opening) unplugged start the engine and set the idle to 500rpm with the idle adjustment screw, when you reconnect the IAC it should idle around 900rpm, if it doesn't change, or is sluggish, the IAC is either dirty or bad

 

[Loanranger]

Have you checked timing? I had this same problem, granted it was on my 2.9, but it would do the same thing, idle waaay down, and sometimes stall from idle. I tried just about everything before checking the timing, and it was off, turns out the distributor bolt was a little loose, and it had just walked itself out of time after awhile. Put it back in time, and it hasn't done it since.

 

[scotts90ranger]

no distributor on the 2.3 '89 and up...

 

[Joelzme]

Yea, no distributor on this thing. Forgive me for being stupid, but what is the IAC?

Thanks for the replies tho!

 

[scotts90ranger]

Idle Air Control Solenoid, it's a cylinder about 1.5" diameter and about 2" long with a 2 wire connector coming out the back of it either straight or at a 90* angle, held onto the intake manifold by two philips head screws, one on top and one on bottom. if you look at the intake manifold where the ducting meets the throttle body and look directly between there and the firewall, that's where it will be

 

[Loanranger]

Ahh. Well, worth a mention at least. Hope you find the problem.

 

[Joelzme]

Thanks will check it asap. If it was going bad would it throw a check engine code?

Will let you know what I find.

 

[scotts90ranger]

sometimes it does, sometimes it doesn't, if they're just sluggish (dirty) they don't all the time...

when mine died on me years ago it was usually when I didn't let the engine idle down after startup, just started and went on my way, it'd usually die by the first stop light I got to... never had a check engine light

 

[Joelzme]

Scott,

Thanks. I pulled it off and checked it out. Has a lot of carbonation inside so sprayed it with carb cleaner. Waiting for it to dry nd we'll see what happens.

When I pulled the sensor off she idled down to almost nothing. I was going to set the idle screw, but don't know where that is. Is that the spring loaded screw under the throttle body cover? I did not think you could set the idle on this truck.

Thanks!
Joel

 

[jdm90]

What is ICM ?

 

[scotts90ranger]

ignition control module, it's mounted to the drivers side of the intake manifold facing forward, I think it says DIS in big letters on it...

 

[fireguy12117]

just to throw it out there, i had my mass air flow sensor go bad without throwing a CEL. i could start the truck all day long, but as soon as i tried to come off of idle it would stall out, and it did this intermittenly. i randomly had a spare 4.0 MAF and tried it and it worked with a little pinging until i put the proper 2.5 MAF in.

 

[Joelzme]

Going to try cleaning mine out and see if it helps. Keep you updated.

 

[Mark_88]

When the MAF sensor on my Tempo went south the engine would die at idle...but it also would rev up for no reason and would die on the highway at times...I was going to suggest that but you didn't have all the symptoms...