Stalling 1992 ranger 4.0 automatic transmission four-wheel-drive

[Fast Doc]

Good afternoon gentlemen. Thank you in advance for your help. I have been a member of this form for many years, but have not been active. I have a 1992 ranger 4.0 V6 four-wheel-drive. As of late, on cold mornings (still above freezing) it will Idle eratically, and sometimes high. When I put it in gear, it will stall, sometimes multiple times. Once I get going it is fine. Once it is warmed up it also operates fine.

The truck has 110,000 miles on it. I have only owned it for 20,000 miles, and it has been well taken care of in that time at least. It has new air filter oil change oil filter coolant fuel filter and spark plugs. I just cleaned the throttlebody and the mass airflow sensor, but to be honest, they did not look to be too dirty.

Any ideas would be helpful. I could bring into the shop, but if this is something simple I'd rather do it myself. Could this be my oxygen sensor? Should I just replace the airflow sensor? It was hard to tell if it was clean or dirty

Best I could tell, I don't have any vacuum leaks, although I have to say that the symptoms are similar to if I did. I checked my vacuum connections with some starting fluid, no change in Idol. Currently, after cleaning these things, it runs perfectly, but recall the problem only occurs when it is cold.

 

[SenorNoob]

'Scribed cause this sounds familiar.

 

[Fast Doc]

So, I checked again for vacuum leaks. I couldn't find anything, but I did find some loose hose connections at the servo for the cruise control. I fixed the connections, and put on hose clamps (it was just a friction fit before). Also, the truck seems to run normal now. Not sure if it is anything I did, or just a coincidence. Hopefully this information helps somebody.

 

[Fast Doc]

I'm at square one. Truck acted up again last night after work. Stalled when put in gear a few times, then, in a hundred yards of driving ran normal.

When it was acting up with high irregular idle I pulled the IAC wires and idle dropped but did not stall. As I understand that it means vacuum leak.

Then it ran fine going home but had CEL on pulling into garage.

This morning it runs fine, no CEL. WTH?!

I used a whole can of carb cleaner can't find a vacuum leak. I cleaned the PCV valve but it rattled normally.

It seems to me the way the valve is that it itself is a vacuum leak, but rather than atmosphere from the air under the valve cover and rest of the engine, no?

Any help guys would be appreciated.

Thanks.

 

[Fast Doc]

Also when I pulled the IAC wires this morning when it was running fine it stalled which I understand is normal indicating no vacuum leak. Again, WTH!?

Intermittent vacuum leak only for first minutes sometimes after cold start? What could do that?

 

[Fast Doc]

I can still use some help guys if anyone out there knows what's wrong.

I was thinking about cleaning the IAC if that would help, otherwise I'll have to bring it in and I don't have time. I don't like to be without the truck in January as although we ahve mild winters here in the desert, snow is possible, and my other vehicles can't go in the snow.

 

[SenorNoob]

Is it hard to start after it stalls? Have you considered the possibility of lacking fuel or spark in cold weather?

 

[downer]

i'm not too familiar with 92s, but a bad egr valve could cause similar symptoms if it is not opening on start up. or possibly the dpfe sensor.

 

[Fast Doc]

Thanks for helping/asking.

The 92's don't have an EGR valve.

What is the DPFE sensor?

It starts right up after it stalls, will seem to idle fine until I put in in gear and it stalls. Once I get it going (using a little gas when putting it in gear) it operates normally almost immediatley.

 

[downer]

if you don't have an egr valve then there won't be a dpfe sensor. the dpfe sensor (differential pressure flow element, or something like that) basically measures egr valve operation.

 

[Fast Doc]

OK.

FWIW the truck is operating normally. I don't know if I fixed it, its a miracle, or just waiting to screw up another day.