Hello, I have a question about EGR failure and gas mileage. I've read a few threads, but am looking for an answer. Check this out.
True Senario: 1989 Camaro Rs 305 TBI 700r4

Code 32 has been off and on for a while

Car used to get great fuel mileage but now it has gone terriblly bad. Only engine mods are:

Hypertech 180* thermo and fan switch
Hypertech underdrive crank and alternator pulley
Open element K&N filter
Magnaflow High flow cat
Magnaflow 3" exhaust W/ muffler

Please help me, prices at the pump are killing me.

 

Did you notice poor mileage before or after you added those mods? I would go back to the stock chip and thermostat setting. The hypertech stuff just adds fuel and timing where it is not needed. That alone can cause serious mileage changes. A poorly functioning EGR can reduce your mileage as you suspect.

The best recipe for TBI fuel mileage is to keep the car as near to stock as possible with simple intake and exhaust mods. Custom chip work to dial it all in will give you even better results on top of that.

 

Other threads to ponder:

https://www.thirdgen.org/techbb2/sho...hreadid=319262

http://impalassforum.com/noncgi/ulti...;f=33;t=007360

 

When you get a code 32 (SES light on) the comp will retard timing back to 25* (bad for milage) When it is off (SES light) timing will advace fully (good for milage!). I think I have the same problem. I started having intermitant SES light after the same mod's you have execpt for the chip change. My symtoms are 1. I can start the car, let it warm up or take off cold and drive 41 miles to work with no SES light. 2. I can start the car after work and head back 41 mi. home, and the SES light will come on within 5 mi. after I hit the interstate and stay on untill I get off then the light will go off after a couple of mi. and a couple of traffic lights. I hooked up a vacuum guage and monitored it for a few days and the results were, normal operation on the way to work. On the way home, right after I got on the freeway, the EGR solinoid would shut off vacuum to the EGR for about 3 sec. and come back on. The second time (about 10 sec. later) it would do it again causing the SES light to come on.
I still haven't figured it out even after replacing the EGR control solinoid, all the vacuum lines, the EGR valve, and checked the passages (had good flow). Now I have read that the EGR valves on the Lo3 are of the positive backpressure type and wonder if the 3" cat back has something to do with the problem? (less back pressure, = poor operation)
I've even pondered sticking a tater in one of my exaust pipes to see if it helps! (not really) but I'm out of idea's! So I'm going to be monitoring your post and all others on this subject .

 

I finally replaced the EGR valve. While I was at it I replaced the distributor cap, rotor cap, and plugs and wires. NO Service Engine for a week now. The car runs great too.

One more thing, before I swaped out the EGR valve, my heater would "hiss" when you select heater functions. Since the heater works off a vacuum and the new EGR is in place, the heater works great! No more hiss like a loose vacuum line or something, and it warms up alot faster!

No more SES light for me!!! Thanks guys for your help!

 

Is there a chance that one could be kinda clogged or bad and the SES light doesnt come on, cause mu heat hisses too?

 

When I took my EGR off it was almost totally clogged with black greasy gunk. The vacuum function still worked but, it looked pretty bad. Heater works great with new EGR though!!