I pulled 2 EGR soloniod fault codes/low flow EGR codes and one lean code on my 1990 6 cyl. The truck runs waek and stumbles hard when to step on the gas quickly.

Doe I need to change my EGR? How much is that? Can I just disable it?

Thanks!

 

Sounds like you might have a vacuum leak. I'm not sure bout the trucks, but on my Mustang there's a vacuum line that opens up the EGR valve. If I'm correct, that would explain the lean code and running rough symptoms. Like I said, I'm not sure bout it. It's just a suggestion.

 

I can not find any vacuum leaks, the truck runs just as crappy with the EGR disconennected too. I performed the voltage and resistance test prescribed in the manual and the EGR valve seems fine to me.

Thoughts??

 

The egr valve may be stuck open. How well does it idle? If it is stuck it wont matter whether it is disconnected or not. A stuck open egr will also cause the lean code since exhuast gas is being recirculated into the engine when the computer is not expecting it. You can try tapping on the valve lightly with a hammer to see if it will close back up then you can disconnect and plug the vacuum line for the time being. Otherwise you will have to replace the valve.

-Jon

 

Pull a vacuum on the EGR and see if it changes it. If not, the EGR is stuck open.

Adrianspeeder

 

The EGR seems to pass every test I can think of.

I took it to a good shop and they ran a fuel pressure test and determined that it is getting 75-80 PSI!

I ordered a new FPR per their instrustions and we shall see. I would have thought that it would be running pig rich not lean and falling on it's face but they said that the PSI is overwhelming the injectors and slmming them shut.

 

what a waste of time and money, still not working!!!

 

Wish I could help you. I'm getting insufficient EGR Flow codes myself.
It's tought when the questionable part costs $100+.
Hey; what size wrench did you need to detatch the air flow tube from the EGR?

 

Did you put a vacuum on the EGR at idle and see if it stubles worse???

Adrianspeeder

 

My truck runs fine except I get the error code and the air tube vibrates quite a bit here and there. I have a vacuum gate but no pump. I followed the repair book. I disconnected the Idle Air connector, removed the small vacuum line, and started the truck. The idle dropped way down. Books says if it doesn't idle, everything is fine or something.

I got 5V with my multimeter when testing the EGV wiring which is in line with that I should see.

If it weren't for the cost of the valve and the pain of replacing it, I'd just do it without a second thought.

Not trying to hijack your thread Fordman; but dialogue could help us both.

 

I can not believe that my shop has said nothing about the codes that the truck is pulling. I took it back to them and they want to change the fuel pump. Yeah I did all the EGR voltage, vacuum, ohms test and it seems to be OK to me. On my Mustangs I have often diable my EGR systems in various ways with NO ill effects like this.

They say the the 1990 has a "special" pump that is $249!!! That sounds like BS to me. How much should a 1990 fump pump really cost and why is is special? I was going to put a cheat BBK Mustang one on for $75

 

I dont know about the pump. Nappaonline shows them for $150.

So here's an image of my EGR


Red circle - Big nut. Caliper measures at like 1.10 inch.

Green circle - I assume this is the vacuum you're talking about? If I disconnect it and start the engine; I don't feel much more than a slight vacuum. It doesn't even register on my vacuum guage. Should I be getting more out of this?

 

EGR usually is connected to ported vacuum or controlled by a pulse width modulated vsv so no you wont feel much vacuum there at idle with the EGR off. I'm thinking that the nut might be a 24 or 26mm but i cant remember for sure. Unfortunately i'm not familier enough with the Ford egr systems without having the book to look at so i can't be of much help. However, If you have problems with a Toyota EGR system i'm all over it!

-Jon

 

If it idles cold, your EGR valve isn't stuck open.

If it stumbles off the line, try adding a couple bottles of injector cleaner to an almost empty gas tank, and then add 3 gallons of gas and drive around for 30 minutes. Let it sit overnight, and go for a test drive the next day. If you notice an improvement, have the injectors cleaned or replaced.

If you notice no improvement, you probably need to make and install a restrictor plate between the EGR valve and the intake. Buy a couple EGR gaskets, and use one to trace out a pattern on some 20 gauge sheetmetal. Drill out the mounting holes, and then drill out a 1/4" hole that lines up with the center of the valve, place a new gasket on both sides of the plate, and install it between the EGR valve and the intake.

Both are common fixes for the 4.9L.

If I remember correctly, a 1 1/16" works on the EGR tube nut, but you don't have much room to work with. Soak it with WD-40 (or whatever brand you like) first, and then put the wrench on and hit it hard. If you slowly apply pressure to the wrench, you'll strip the nut. A sharp rap on the end of the wrench will break it free.


If the stumble doesn't show up until freeway cruising speeds, it could be the AIRB/AIRD valve. If you need testing instructions, email me.