tuning egr

[pstrbrc]

OK, I'm squirting one of those cars that had an absolute rat's nest of vacuum lines, etc. to control emissions, including the exhaust gas recirculation valve. Now, I know it's not cool to talk about emissions control devices like they were GOOD, but, heck, a well-functioning egr valve makes performance and economy sense! It's not like I'm planning on re-installing the air pump and cat con!
So, anyhoo...
I was busy yanking out all the emission stuff from undr my hood (1981 AMC, 258 six). I'm going to be using a GM TBI, which has a fitting for egr that is clearly superior to the manifold port, so I'm on the road to re-engineering my egr, and I think, "what's the best way to control this?"
The most important part of the egr system is making sure it only funtions at full engine temperature. My car had the teperature-sensitive vacuum switch (beats the heck out of me what the technical name for this thing is!) imbedded in a coolant passage in the intake manifold, which was heated because AMC insisted on using just about the crappiest carburator I've ever had to work on. (Obviously, I've never had to tune an English car! I've heard horror stories about your SU's and Strombergs!) With the TBI I'm working under the assumption that heating the manifold will not be necessary, which means I need to deal with the egr vacuum switch some other way.
So, here's what I'm thinking.
The FIdle solenoid signal!
Would it work to get a Normally Open solenoid to put in the vacuum line to the EGR? I've seen a couple of them in the Grange catalog that might work. Has anybody played around with this?
Any feedback to anything I've rambled on about will be appreciated!
Bruce

[Matt Dupuis]

Now, I know it's not cool to talk about emissions control devices like they were GOOD, but, heck, a well-functioning egr valve makes performance and economy sense! It's not like I'm planning on re-installing the air pump and cat con!

Now I've heard everything.

My car had the teperature-sensitive vacuum switch (beats the heck out of me what the technical name for this thing is!)

Ported thermal vacuum valve

With the TBI I'm working under the assumption that heating the manifold will not be necessary, which means I need to deal with the egr vacuum switch some other way.

Doubtful. The carb probably had little to do with the need for heat in the intake - keeping mixture distribution even required absolutely vapourized fuel to get to #1 and #6 cylinders. You could ditch the heat if you went port injection, but if you're running TBI I'd probably keep it.

Would it work to get a Normally Open solenoid to put in the vacuum line to the EGR? I've seen a couple of them in the Grange catalog that might work. Has anybody played around with this?
Any feedback to anything I've rambled on about will be appreciated!
Bruce

You can get them from your local junkyard too - Turbo Dodges had a bank of three or four two-way valves. One normally open, one normally closed. Block off the port of the valve you choose not to use, and you're done. You'd be amazed at all the things you can think of doing with these valves...

[dsleepy47]

You probably don't want your EGR valve open at idle unless you are modulating the flow rate. if you have just open and closed and you have enough flow to do any good, it will probably run pretty crappy at idle. a lot of cars won't open the EGR below 1500 RPM and some use a PWM solenoid to regulate flow.

Deems

[JeepGuy24]

Sorry to dredge this out again. I've got an AMC 360, and it's got to get better mpg and be legal. So, need to keep EGR. Mine works with a CTO to tell it when to let gases back in.

I'm puting on a GM Rochester TBI (from 350) and going to be running the MS-extra so that I can use EDIS.

My question is:
GM made solenoid activated EGR for some of their vehicles. Is there some way to use the extra outputs to control the solenoid at specific RPMs, Temp, and MAP values? Simple on off type thing. Don't need to really modulate flow (at least I hopw not).

Also, what did you mean about "TBI with an EGR port" instead of the manifold one? Sorry, I'm ignorant on this one. Is there a way to run EGR "through" the TBI? I would guess it's possible, but not sure how. I would also love to avoid the manifold port, cause then I could buy a better intake manifold and not worry about the EGR port. Ok, done being clueless. Thanks for reading over this.

-Nick

[pstrbrc]

My rochester TBI has an egr port right at the base, rear right side. Mine came off of a Cadillac 4.5 v-8, but from what I have seen of others, I vaguely remember others having this same port. Are you sure that you don't have one on your unit?
Bruce

[JeepGuy24]

I'm sorry, I wasn't specific enough. My TBI has a ported vacuum port to connect to the EGR valve. I was just wondering if there was some way to bring the exhuast gas from the EGR valve into the TBI, under the throttle blades. I remember seeing this ring with a tube on top of some TBI vehicles in the junkyard, but I have no idea what it is used for. The reason I'm asking this is because most of the 4 bbl manifolds i'm looking at do not have EGR provisions. I was thinking if there was some way to bring the gasses in through the TBI, everything would work out. I'm also tempted by a computer controlled EGR valve. It would be nice to dump a bunch of the vacuum lines that are prone to eventually leaking. If you have any ideas, I'd greatly appreciate it. Thanks

[typhoontx]

I have 85 Pontiac Fiero v6 it has a egr valve that mounts on the exhaust pipe and has a 8" to 9" long corrugated stainless steel hose that is connected to the intake manifold just after the TB you might be able to adapt one of those to your setup.

Regards, Robert

[JeepGuy24]

That's a good idea. Guess it's time to head to the junkyard to start scavenging. Have you just left EGR control to vacuum or is your's electronically controlled. I've been thinking about the GM EGR solenoids and ways to control them with MS, but haven't seen much about it. More searching to do. Thanks