CamaroX84

I am going to burn my own PROM and was wondering if I should keep it enabled or if I should disable it. I am wondering if it will affect performance or gas milage. Thanks.

Rosco the Iroc

Yes it would hurt MPG and the comp uses it so removing it cause a check light. EGR does not really hurt performance. The comp uses it to get a good A/F ratio.

Beast5spdGTA

anyone know where that temp sensor? wire coming from the EGR valve goes to, I can't find the plug on my wiring harness after a cam swap. '89 305 5 speed.

rhuarc30

The temp sensor should plug into the wiring harness, the temp is how the computer knows that the egr is working. But yes the egr does hurt performance, it dilutes the mixture with an unburnable gas, of course that hurts performance. Just not at wide open throttle because the egr is not active then. However your current chip is optimized for it so you might actually lower performance if you don't optimize your programming to run without it. You might also get some detonation since the spark and fuel tables won't be properly set up in the range the egr valve is active. Then your knock sensor will take out a bunch of timing and hurt your performance even worse. Optimize the chip though and you'll see an improvement in part throttle performance.

Omar

Removing it will NOT cause a SES to go off. The EGR valve is *supposed* to lower combustion temps. In my opinion, the gains, if any, are not worth removing it.

Beast5spdGTA

Does anyone know where on the wiring harness that single wire connector is??? I can't find it after my cam swap, just been driving with it unplugged?

Guest

Its in the main harness from the ECM, I am pretty sure it goes into the plastic harness covering right where everything else does where the AC unit is.

Disconnecting the EGR on MAF cars in my experience doesnt set a code. I've done quite a few and it never happened, but I have heard of it happening to other people. I always read that the SD cars set a code rather reliably with it disconnected. I have never tried that so I'm not positive if its possible to bypass it on those without setting a code.

Grim Reaper

If the ECM "thinks" the EGR is functioning (though it may be diisconnected and/or "diagnostics" are turned off), it will affect the fuel mixture. If you want to truly disable the EGR, you should set the "EGR Minimum Temp to Enable" to a very high number (x254 or 150*C). Then the ECM will properly calculate the fuel mixture as it will know the EGR is not functioning.

Most "EGR Errors" are set by a variety of parameters where the ECM "believes" the EGR is not functioning. There is no "direct feedback" to the ECM to let it know the EGR is (or is not) working to my knowledge for either MAF or MAP.

Ditto on the CCP Purge and AIR - the ECM "expects" them to be functioning when commanded to function, but gets no feedback that they are. Also, much like the EGR, the do affect the calculations within the ECM and should be disabled by setting their "enabling constraints" to a value that will never occur. I forget exactly what the ECM looks at to determine whether or not to "enable" the CCP or AIR, but there is an "enabling parameter".

As for costing HP, as mentioned above, the EGR is disabled in WOT (actually MAP value on SD) and you can adjust that value. The EGR on operates in part-throttle and "not in idle". When in part-throttle (i.e. crusing down the highway), you are NOT getting full HP anyway - so it really doesn't matter.

The best reasons to disable the EGR are: 1) your system does not support an EGR (i.e. Miniram) or 2) You are getting EGR errors and want to stop it. On a properly operating engine, there will not be any power difference because (as mentioned above) it is disabled anyway in WOT, and you'll never notice the difference in part-throttle since you are only making part of the HP due to "incomplete cylinder filling" when in part-throttle.

Beast5spdGTA

Thanks for the info madmax, I looked there before i put everything back together but I'll check again, at least i have an idea where to look now, that wire could reach anywhere. Thanks