Hi guys was hoping someone could give me a direction to go in with this problem.
I have a 1990 F250 4x4 5.6L v8 automatic transmission
When the engine is cold there is no problem. When it gets up to operating temperature the engine light comes on. This has been happening for a year without any stalling problem though so I don't know if its related. The stalling started a couple days ago. It idles no problem and drives no problem, but when I'm stopped and it's in drive it will stall. It seems to stall right when I let off the brake and touch the gas.
Any ideas?

 

I'd begin by getting a read on the error codes.They're held in the vehicles computer...a code reader is fairly cheap,although I think it's possible to pull them up without one.Sorry,I don't recall the exact procedure.....

 

I got the codes. 33 (egr not closing or egr valve opening not detected) I removed the egr and gave it a good cleaning, tested the sensor ok, resealed the gasket and did not see any obvious vacuum leaks.

Code 41 (no ho2s switching detected) I tested power going to the oxygen sensor 12 volts not sure if the sensor is bad...I intend to replace it tomorrow unless someone can tell me how to test the sensor itself...

Code 67 (Park/Neutral Position (PNP) switch circuit open - A/C on during Self-Test.) I don't have a/c. not sure what this one means or if it might be related.

Your thoughts anyone?

 

Today I replaced both the egr valve and the oxygen sensor. The problem persists and the error codes 33 and 41 have returned after I had cleared them from memory.

Help?

 

the emissions system on my '91 5.8L E350 is pretty similar,and I've had to change the MAP sensor ,but nothing else that I recall.That alone would affect the O2 codes...not sure about the EGR valve,which has a vacuum diaphram that sends readings to the computer regarding the EGR valve position.A vacuum leak could still be at play here..two ways to check are to use either carb cleaner,or 'brake clean' on a suspected component or area in question.You may have an intake manifold leak at he plenum.With the engine running,'brake clean' will cause it to stall,whereas carb cleaner will cause the rpm to pick up,What do your plugs and tail pipe show? Rich/lean? It may not be possible to get a totally accurate picture from their condition,but their color could hold some clues...these emissions control problems can make you nuts.

 

Having an issue when engine is warmed up....if I step on the gas peddle the engine dies....Any Ideas??? I have a 2004 F350 deisel