EGR CODE, EGR CODE, It comes on, It goes off, ect...ect....ect.
When exactly does this effect the timing retard control from the computer. When the CE light is on, or from the first time it registers a code? When the light is off, do I still get full adv?
Here's one for the genius's out there!
Ever heard of a sloppy timing chain that causes irratic valve timing that in turn is picked up by the knock sensor (false knock right?) would the computer try to compensate with a little EGR action? Of course, that ain't going to work because of the timing chain. Sooo.... the computer thinks the EGR valve isn't working and then what? EEEGGGRRR code!


The valve and control module have been changed, code erased,
and still get CE light on and off for a few miles every time I drive it.
I thought it might be a back-presure thing for a while with the cat gutted and 3" cat back, but no one else has had that problem.

I'm at a loss for what to do next!

 

The EGR passages themselves may be clogged up. A cheap low-buck way to clean them out is to remove the EGR valve from the intake and then briefly start the engine up. It'll rev up pretty high when you do this (becuase of the huge vacuum leak you have without the EGR valve being present) but it'll also blow all the crap out of the passages. A few seconds of running is all it takes. Might work, might not. I've had modest success with this technique.

The ECM stores intermittent codes for some number of restarts after the CE light goes out but it only takes corrective action (retarding timing, etc.) when the light is actually lit.

Never heard of a loose timing chain causing false knock. More likely that the combustion chambers and intake ports are gummed up/carboned up like the EGR system, allowing detonation to happen much more easily. Also, if the EGR system isn't working correctly that will definitely give the engine a greater tendency to experience ACTUAL spark knock under part throttle conditions. Might want to invest in a regular regimen of fuel system additives. Use them double strength for a few weeks in a row and I suspect your false knock problem will be reduced or maybe even eliminated, in conjunction with repairing whatever is wrong with the EGR system.

 

In addition, make sure the PCV valve is clean, operating, and the correct part for your engine. An incorrectly calibrated PCV can cause incorrect MAP readings, and st a false EGR error code (among other problems). I had it happen on a 262 V-6 TBI installation.

 

The computer will add addl. advance and remove fuel when the EGR is active and a code has not been set.

 

Thanks for the quick reply! I'll try that EGR removal thing and see if that works. Anyway, if it doesn't, I believe I can erase the code before I run the autocross next week and still get performance in the bottom end. The only time it ever comes on (CE) is cruising down the highway at part throttle. So, if I don't get it fixed by race day, I've still got an option! Thanks again!