I took my truck to the dealership to put it on a scanner (because my engine light was going on, going off, going on..etc) so I could be some codes. They said it had no codes. But under further testing they did. They said the EGR valve solenoid was not opening(something like that and also the valve or something not dumping...). Just wondering what you guys think of this. What exactly does the EGR do??

Ohh my truck was kinda stumpling once and a while during idle, But not all the time, and the service engine soon light would only come on once and a while.
Thanks guys

The EGR is a vlave that opens and allows exhaust gas to fill the intake instead of just air. That is why they say S= soot and F = fun. The egr will crud up an intake in a few years use.

So just replace the valve and be done with it.. Can you remove the EGR system at all? And if you can, any gains?

Ohh. I just looked my 8th Digit on my VIN is 'P'
so what does that mean?

With a 94, I *think* you can eliminate that EGR stuff without your computer throwing a fit.

Elky, you said your 8th digit is a "p". Does that even exist?

Vin P is N/A just like his signature says.

My 1994 can't do without the EGR system at least hooked up to the solenoids and the sensor on the firewall right next to the brake master cylinder.

If you get an F prom or an aftermarket prom from an F vin code engine, it doesn't look at the EGR system. :ro)

Well I replaced the EGR valve solenoid and it did absolutely nothing.. If I wiggle the wire connectors slightly there then the engine stumples around and the egr would sometimes work, and sometimes not. So I ordered the wiring harness for those EGR solenoids..
Also.. what would happen, other than a ses light comming on if i run my truck without those hooked up??

You can disable it easier than anything.

Pull the vac line off the EGR and put a scew in the end of the line. Nothing in the system will notice on a '94.

If by-passing or replacing your EGR dosen't change your problems, you might have blown out the EGR "mystery gasket" between the upper and lower intake manifold. Like QM said pull the vacuum line to the EGR and plug it, the computer won't know.

Just plug the EGR vacuum line?... what about the EGR, do i plug that, or just leave it?
Will there be any difference with running a functioning EGR, compared to not running the EGR when it is suposed to be??

Just plug the EGR vacuum line if that takes care of the problem then forget about it.

As for " What exactly does the EGR do??"

A short chemistry lesson is in order here. It was discovered way back when, that high combustion chamber peak temperatures (the really short duration high temperatures near the end of the combustion process) caused oxygen and nitrogen to combine chemically and form these oxides of nitrogen mentioned above. Most of the anti-pollution devices of the day (early 70's) did a pretty good job of reducing the other bad by-products of combustion, namely excessive hydrocarbons and carbon monoxide, however they tended to induce the formation of oxides of nitrogen. Something had to be done else we would all die of smog diseases.
The automotive engineers figured that they needed to do something to lower the peak combustion temperatures which only occurred under certain high load driving conditions. They figured they could do so at the expense of power and fuel economy but what the heck, ya can't have everything! If they could only add something to the combustion chamber that would act like sort of a fire extinguisher to cool the combustion temperatures that would do it.

So they invented a way to allow some very inert gas to get back into the combustion chamber only when needed. They needed a source of this gas - it wasn't air, cuz that contains oxygen and nitrogen which caused the problem in the first place. So they chose carbon dioxide. Where to get a supply of carbon dioxide . . . ??? Hmmmm, how about the exhaust system? That is mainly carbon dioxide and water (plus a zillion other noxious chemicals) Suppose we allow some of the exhaust gas to get back into the intake manifold under strict control and only when we need it? That would cool the combustion chamber and prevent the formation of the NoX.

Now we understand why it is there. And we understand what it does. So what can go wrong with it and what are the symptoms??
It's really pretty simple - it can be open when it isn't supposed to be, or it can be closed when it is supposed to be open. Not rocket science, but it is science. If it is open when it is not supposed to be open, at idle for instance, It will act like one monster vacuum leak and the engine will not idle or will idle really roughly. If it doesn't open when it is supposed to open you will probably experience a symptom of "pinging" or "knocking" since the combustion chamber temperature will be higher than normal (one of the main causes of pinging in an engine).

There are a zillion different types of EGR valves some of which work strictly on vacuum, and some which work on a combination of vacuum and pressure. Some have electronic controls, some have mechanical controls. I won't go into detail here about all the different types but suffice it to say that most can be checked by looking inside to see if the plunger shaft is stuck open or doesn't move when the engine is revved up (after it is warmed up). Replacement is probably the easiest part since most are held in by two small bolts and have a vacuum line connected to it.

welcome viking thanks for the detailed explanation of this turd that i thankfully don't have on my truck!

-brian

Thanks for the welcome Bagalac, yeah I got used to dealing with em on gas burners, now with my first oil burner I find out they're here too, Censored

Viking , welcome to the site; just cause you got one does not mean it has to work always, I have some helpful ideas, for "offroad" modification of a K1500 that gives you a little more power, or you could go all out depending on your power needs, time & money are main factors, but PM me and I can give you a few low cost options to consider.

Thanks TD, you've got mail.

Exhaust gas soot mixes with crankcase vapors and builds up on the intake manifold partially clogging it over time. 150,000-200,000 mi is enough to require cleaning the crud out of the manifold.

Welcome Viking!

Thanks QM