Ok I am trying to figure out exactly how EGR works and would work with aluminum head instead of the iron smog heads on the car now..

Just for FYI I have a superram upper and lower already on the car.

With the original Iron heads I understand the egr is routed inside the heads into the exhaust ports to the exhaust manifold, using the egr valve right under my Superram plenum.

If I switch to aluminum heads, I will just have to connect the pipe to the rear EGR location on the accel lower intake manifold, and have it welded to the header I am installing. I could even use my stock egr valve sitting pretty under the superram plenum right?

 

You should be able to use your current EGR valve so long as it just bolts up to the new base.

Atop the new EGR tube, just near the intake base, is the EGR Temp Switch. This switch closes when exhaust gasses providing feedback to the ECM. I don't know where this switch is located on your '85 but it will be needed on the new setup to avoid throwing the dreaded "code 32" (I'm assuming your ECM also has this EGR feedback element).

On the #113 head setup this switch connector comes out of a large harness located behind and just to the left of the distributor. It is very difficult to access with the base & dist installed so I suggest you find this connector and splice in little wire to bring the connector up to the right of the dist for easy access.

Check out the discussion of EGR components & funciton on my site.

Also, on L98 with external EGR tube there are two sheet matal heat shields covering the ignition wires that pass along side the cylinder head under the EGR tube. It would be a good idea to fab up a set of these even though the tube has an insulative sleeve.

 

Thanks for all the info. I am reading through tonns of topics right now about this.. I have my stock '85 egr valve and switch running everything perfect in the superram upper and lower setup, so I was thinking hwo simple really it would be to upgrade to a good aluminum set of heads.. The EGR switch on my '85 is located at the place you described, to the right of the distributor, and the EGR temp sensor is mounted ON the egr valve for the '85 engines. I am curious if I could use that stock location for the egr temp sensor or would I still have to relocate it to the egr pipe I'll connect between the intake and the header pipe..

 

I'm not sure if the Temp Switch would come up to temp with the new setup but it would be worth a try.

You might just try a plug in the sensor position of the new EGR tube to see if the sensor in the current location works.

 

Sounds good

 

Jim,

I swear you should work for GM! :yesnod:

 

Well I'm no threat to Gordon Killebrew, but what is the going rate at the local GM diagnostic center. :lol:

Jay thanks, I just feel it's a nice change when "goes around, comes around" is a good thing.

 

"EGR Temp Switch", hmm that I have never seen. Is that supposed to be enar the oil pressure unit at the rear??

 

He meant to say EGR Temp sensor.. the EGR Temp sensor on my '85 is plugged into the EGR valve under the plenum, and on later L98's is plugged into the EGR pipe on the passenger side..

 

Some good info in this thread. Went to read the article at the web site mentioned above. It is really good, thanks!

Question; is there any downside to just bolting a plate in place of the EGR and just blocking it off? (We don't have emission inspections here)

 

I don't think it would do much performance difference, as during WOT it is not active..


By the way I guess I am scratching teh D-port 113 heads, as the deal fell through.. :sad:

 

you mean the EGR pipe that is coming from the passenger side exhaust system to the intake maifold? I dont have any censor on that pipe?

 

Yea... Some years had them (I've seen) and some don't..
On my '85 is actually is threaded into teh egr valve itself..

 

You should have an temperature sensor almost all the way up the pipe. 85's is in the EGR unit itself because of the internal routing.

 

hugh..? I cant find any censor there? Should the censor be in the intake base just where the pipe is going in? Or? hmmm

 

anyone else? Im just about to disable my egr , and I need to unplug all the egr stuff :/

 

Hi.
I have learned very much on the EGR side the last weeks as I have had the 32 code coming.
The so called EGR diagnostic switch is placed on the 85 at least at the EGR valve itself. It is a bimetall switch that is on (grounding)the ECM input when the temp is high enough. If something is wrong with the switch and it is "on" when you start the engine the check engine light will be on. If you stop the engine when it is warm and restart it the check engine light will not come on.

This switch is, as I have understood more or less there to give the ECM a message to send or not to send the vode 32.
The EGR system itself is the EGR valve and the solenoid. The EGR valve opens when it get vacuum and the bleeder valve internal in the EGR valve make the EGR valve close when exhaust back pressure occurs. The solenoid control the vacuum and gives no vacuum when on idle and wot. In between the ECM controls the solenoid and the vacuum to the EGR valve by taking into account the temp, the rpm, the TPS reading etc. So closing the EGR function you can only take away the vacuum to the EGR valve if the valve is ok. You just have to ensure that you do not have any vacuum leakage through the solenoid and then ground the EGR diagnostic switch cable to avoid check engine light.

Just remember that the EGR decreases the combustion temp in the cylinder. So it is possible that you will get ignition knocks by taking the EGR away. Especially with cast iron heads. Aluminium heads conduct heat much better so that there will be a chance that you will not get the ignition knocks.

I have an 85 and had slightly raised compression ratio by .5. I had a tendency to knocks. When I got long tube headers on the knocks disappeared. I don't know why but it might be that they emptied the cylinders faster with exhaust gas.

Hope you got some usable info

If there any comments please do not hesitate to do so

 

where is the "EGR diagnostic switch " located on my 91. Som people say its right where the pipe from the exhuast enters the intake manifold. But I have NO censor/switch there?
So to take off the EGR i take off the vaccume tube from the eger valve ( under the plenum ). Then I seal the vaccume tube from the solenoid ( tha was going in to the vavle before i took it of )
And then ground the EGR diagnostic switch ( witch i cant find )

ok ?

so thats it?

 

The EGR switch itself on you r'91 should be towards the front of your plenum. Close to your ThrottleBody.. On my '85 it sits next to the distributor, but I have seen an 87 and a 90 where they are by the front of the engine..

 

ahh, now it starts to make sence