All,

Sorry to go back to the well so soon....again. I drove my 1986 F-150 to work today. It has a 5.0 EFI and about 150K miles on it.
I noticed today that the idle was rough when stopped at a light. When it is in reverse the idle is rough too. When in park or in neutral it seems fine.

I pulled the codes performing a key on engine off test when I got home. I pulled a 31O and a 31C. This is either EGR valve control sensor fault or EVAP system below minimum voltage. I did test the electrical connection on the top of the EGR using my volt meter last weekend and if I recall correctly it was 5 volts - which I think was normal. Today after taking the codes I turned the truck on and pulled the green vacuum line off. There was no suction - which I think is not a good sign.

Could this be the issue with my fluttering engine and rough idle?

I have not yet checked for vacuum leaks but I think that I will do that later this weekend using the propane torch test as opposed to using starting fluid.

Recently I pulled the intake hoses off and cleaned the throttle plate with throttle plate/intake cleaner and at the same time I took off and cleaned the idle air control. Not sure if that "did" anything to the truck. I also replaced the PCV valve and put it back into the manifold (it was out) last weekend.

More history:
The PO did the following - the spark plugs, spark plug wires were changed out by the PO in 2012 . The alternator and starter were replaced in 2013

The picture shows my EGR. Do I clean it? Would that solve the problem? The rusty pipe below makes me worry that if I try to loosen it that it will snap. What do you all recommend?

What do I do next? Any help is appreciated. Have a nice weekend.


Do I replace this? Look at the rusty pipe? Ugh. Looks like problems.

 

You won't get vacuum on the green line, the EGR cannot open unless the engine is above idle. You may get some vacuum on it if you rev the engine for a little bit. If you soak that fitting in PB blaster, it will probably come loose.

 

Franklin,

You were right. PB Blaster for a couple days on the pipe and I got it off easily.
I took off the top sensor and shot Carb and choke cleaner in it and then let it sit for a couple of hours. Inside it looked like a coal mine shaft. I took an old toothbrush and swirled it around the hole and black carbon crud came out. The pindle moves but since I do not have a vacuum tester I cannot be sure that the diaphragm is sticking open or closed.

Do you think that I should just go buy a new EGR?

When I do finally put this back on the truck should I use anti-sieze on the bolts that go back into the engine behind the throttle body or is that a no-no?

Thanks for your help. I do appreciate it.

 

It never hurts to use anti-seize on bolts like this. If you are unsure if the EGR is leaking at idle, you can temp make a solid gasket out of a pop can and block it off and see if it makes any difference in idle quality.

 

Franklin2,

I was amazed at how much carbon was in there. Probably 33 years worth!

I will give the pop can a try as you instruct. Maybe this will solve the issue.


Thanks again for your help!

 

So what's the update on this? I may have a leaking/sticking EGR as well.

Ken

 

Well... I blocked off the EGR with aluminized tape... Still stumbles.
Check for intake manifold leak on inside and outside... Pinched off pcv hose got the nice pulsation-back and forth on the paper I placed on the fresh air intake hose to the valve cover. No leaks found with car spray or using a 3/8" gas hose to the ear trick.
IAC sounds constant at idle via TBI hoses.
I also pulled the PCM and the circuit board looks normal with no capacitor leaks.... I'll post some pics.
Still has the same stumble when the fuel regulator is disconnect... has good vacuum signal to it.
Did not make any difference when I shorted out each spark plug wire.
Compression was consistent at 145/150 dry. Good strong first pump on all holes.
Has fresh premium gas... Timing set at 10BTDC with gray spout disconnected and tested on a restart... Timing reading remains constant at idle even with stumble.

Has new premium wires and Autolite copper plugs... Fuel filter is new and recheck it... Ok.

I can't find my fuel pressure test kit so I may have to buy one...
Will test the fuel pressures soon. May also have an injector issue?

Ah, I forgot to attach my vacuum gauge.... Will do that in a bit and report back.... Maybe video it.

 

I am guessing you have a 1985 or 1986 f150 with the 302 fuel injected engine?

 

Sorry, I need to add a profile.

1994 Ford E350 with 7.5L

 

Guys over at the iRV2 Forums told me to post here as trucks are similar...

Many there suspect my capacitors are starting to leak if you zoom in.... I found a $15 repair kit on Bay which has over 30 sales with 100% feedback... I might go that route.

 

Well, even if you are using a truck forum, this is the wrong one, we stop at 1986. But as a general rule, I would pull the codes before doing anything else.

 

Yeah, I need to move it over to the other forum... Sorry, my bad.