Vacuum to EGR (solenoid, delay valve,etc)?

[PHOENIX]

I have a new EGR and it is the correct one.
It is working properly, but it is working too early.
I have it hooked to the port specified by Edelbrock on my Edelbrock Q-Jet 1904 carb.
I have stumble off idle and purchased and install vacuum delay valve from GM as noted in Edelbrocks instructions.
The valve helped, but the stumble is still there.
The GM dealers tell me the valve is for automatic transmissions and they dont understand why Edelbrock would say to use it with the EGR. This doesnt matter much, because I catch the dealers being wrong about something every so often.
Checker and Autozone say that they show nothing in their computer for this and cant help me unless I know a part number or something.

I NEED SOMETHING TO INSTALL BETWEEN THE THERMAL VACUUM SWITCH AND THE EGR VALVE. IT NEEDS TO LIMIT THE AMOUNT OF VACUUM ALLOWED TO THE EGR SO THE EGR DOESNT OPEN TO EARLY. WHAT CAN I DO ABOUT THIS?

Thanks!

[swervin ervin]

Eddie,

first, what EGR valve are you using? Mine is number 17113439. It has a N stamped on top. There are also valves with a P. One is for negative and the other positive. I'm not a EGR valve expert, but it does make a difference somehow.

Next, I have my EGR on the same port Edelbrock shows to use (D port) going through a 4 port TVS to my EGR. The other side of the TVS is for the distributor. I don't have a delay valve in the vacuum hose to the EGR. I've never had a flat spot off idle with this setup but of course I have a strongly modified 1904.

The delay valve you are using is normally used on the vacuum line going to the vacuum switch for the tranny. I bought a new one for my tranny from GM number 14020691, same valve as recommended by Edelbrock for the EGR.

Does the stumble happen all the time, even when it's cold or just after the engine has come up to temp? I seem to remember there being a delay valve in the vacuum hose when it was stock but can't remember what it was hooked to.

Have you tried Edelbrocks instructions and unhooking the EGR to see if your flat spot goes away? Are you sure the EGR is causing the flat spot and not some other adjustment on the carb?

[PHOENIX]

Mike,

Ill check the EGR part number when I get home. I brought my old EGR to the dealer and got the new one that way. Pretty sure its correct, but I think I remember it being a different number then yours.

I have mine going to a (2) port switch with a T in there somewhere that may be the problem. I need to play with that alittle more. On my emissions sticker is shows some sort of delay valve in the line between the TVS and EGR.
I am going to try and heat the truck up and run the EGR direct from the carb with nothing in between and see what happens.

It happens all the time, cold or hot.
If the EGR is hooked up it stumbles off idle.

Yes I have had it unhooked for awhile now, but I want to get it right.
When the EGR is hooked up without the vacuum delay valve it stumbles a lot. When the valve is in the line its not as bad, but still not correct.

I know the carb needs some tuning and I am going to take it in to have someone tune the carb and distributor. I dont want to buy a bunch of jets, metering rods, etc. and play with it. For now I need to get emissions test and registered so I am going to pay someone to do that work. But before I take it in I want this egr problem solved.

[swervin ervin]

If it's doing it cold, the TVS is probably bad. It's not supposed to let any vacuum through until it reaches around 160 to 170 degrees.

Try a different port on the carb, as long as it's a ported source it will work. The D port location is ported though. Like I say, I don't use a delay valve in mine and have never felt a flat spot. I'm inclined to think your EGR might be causing it. Of course they are too expensive to try a different one.

Do you still have the EGR solenoid thing hooked up too? It's the little solenoid mounted at the rear of the passenger valve cover.

[PHOENIX]

I didnt think about the TVS being bad until I got home today and was getting the EGR part number. The switch is not old at all either.
The EGR valve I have is:
Rochester Products - GM
17084818 S
347 01N

If the TVS is bad and letting vacuum in when cold, then why does it still do it when warm, unless the EGR is wrong?
This EGR is the one they gave me based on the one I brought them. The part numbers did not match, but apparently their computer said this was the proper replacement for trucks with the EGR that I had (they ran my part number and came up with a newer one).

Also I was mistaken on my emissions sticker showing the delay vavle. It shows one for the distributor not the EGR. I have the EGR hooked up exactly as shown in the emissions sticker. The T in the line going to the canister and everything is correct.
I bet I have the wrong EGR valve.

Damn this pisses me off, these things arent cheap.
I also checked the EGR valve p/n you provided and that seems to be correct for my truck also.

Anyone know what this EGR:
Rochester Products - GM
17084818 S
347 01N
will fit so I can try and sell it to someone for cheap?

[swervin ervin]

The one you have is a negative backpressure also. I couldn't begin to tell you is different between part numbers. I'm guessing the hole for vacuum or the exhaust port on it is a different size. There is some reason they are different part numbers and I can only guess it has to do with the way they work.

I am in no way telling you to buy another valve cause I know they are expensive. All I can tell you is I have never had any problems with the one I have. I don't remember where I found the info on it, but some article on the net recommended it to work good and it does.

[PHOENIX]

Well on gmpartsdirect.com it lists that part number (ONLY) for my truck.
Because I have the crate motor I am going to try and get a number off of it and contact the dealer and a few others with that and see where it gets me.
Where can I find numbers on this crate motor, on fron passenger side head?

Thanks

[greg0380]

My past experience :The original EGR I had was for a 350 and when I tried it on my 305, I had mid throttle surging. Disconnecting the vac line solved that. When I bought the universal replacement (the one with the washer orifices), it didn't close all the way and I had idle problems. Brought it back and the new one works fine. By the way, the original units were designed to move the needle with vacuum only. you can see it by applying vac to the valve and the valve will operate. The newer styles you buy today (but the dealer may sell you the original style) require backpressure to operate. You can tell these by applying vacuum with no back pressure (engine idling) and the valve will not operate. These are said to be more accurate in regulating ehaust gas when needed. If you have this style, look at the end that sits in the exhaust port, it should have a small hole that allows exhaust pressure to be applied to the underside of the diaphram. I read that to truly test these you need a special setup. That is the difference between the N and P and negative and positive backpressure. I forget which is which though.

[greg0380]

by the way, the TOMCO website is a good source of cross reference info on emission parts including EGRs.

[PHOENIX]

http://www.tomco.com/ ?

[greg0380]

www.tomco-inc.com

[PHOENIX]

Mike,

I went down to a local dealer (Sands Chevrolet) with the part number 17113439.
In the box the EGR is stamped 17084818.
17084818 is the one I have on the truck now.
The lady told me that this is correct, but she doesnt know why the number on the EGR itself is different but thats how they all are.

Does your EGR have 17113439 stamped on it or does your receipt say 17113439?
I guess I have the right EGR after all, must be the ported vacuum on the carb is coming on too early and I need a different port or a better/different delay valve.

I am going to try and get the truck in a shop tomorrow to tune the carb and distr, maybe Ill have them figure it out while they are at it.

I contacted two other dealers and both of them told me that the number on the EGR is a casting/production number and is not a part number.

So does your EGR have 17113439 stamped on it?

thanks

[swervin ervin]

I never really paid any attention to the EGR number but it is like yours. The part number I bought was 17113439 but it's stamped as follows:

17084818 S
300 91N

Strange. I always thought and was pretty sure any number stamped on a GM part was the part number.

Well, anyway, it saves you some money. Now just to figure out what is causing the problem.

Mike

[PHOENIX]

I know its strange, I could not figure out why the EGR part number didnt exist
Well this is good news!
Thanks for taking the time to check for me.

[C&C Chevy]

Hey Eddie and Mike, sorry to jump this thread, but do you guys have a pic of what the EGR valve looks like and where it is?

[PHOENIX]

I can get you a picture later tonight.

[C&C Chevy]

Gracias!

[swervin ervin]

Here's an old pic of mine.

It's the gold piece in middle.

[C&C Chevy]

Thanks Mike. I'm pretty sure mine is different then that. Is the TBI EGR unit different?

[swervin ervin]

It will look close to the same. A different part number I'm sure.