court76wi

I was wondering if anyone knows what CEL codes for OBD2 are considered "soft codes", or don't affect engine performance at all. CEL codes that won't put the engine in backup, fail safe, or limp mode.

I have a '97 GSR that I'm building for competition use, so removing some of the emissions would reduce a touch of weight, but mostly eliminate the amount of hoses snaking around under the hood. Plus, they're just not required for off-road use.

I know a tuned/untuned OBD1 would be ultimate regarding this. But I don't care if an OBD2 computer throws a CEL light, espeically if it doesn't affect engine performance.

Does anyone know what you can all pull or remove off an OBD2 vehicle without affecting the motor performance??

Thanks.

RC000E

Your plan is not a good one.

court76wi

Are you referring to the point that it's just not correct to remove emissions equipment. Or is the ECU just too finicky?

RC000E

I'm referring to the fact that trying to drive your car with "non imperative" cel's while attempting to "compete" is a recipe for failure.

Go with a standalone, build an OBD1 car for competition, or leave the car alone.

court76wi

You'd be surprised how many competition cars throw CELs. Honda and non-Honda vehicles, even those from professional racing or training institutions. I've seen and even drove the vehicles myself. Some just pull the CEL light so they don't have to look at it - if they even still have the OEM instrument cluster installed.

Depends upon the builder. You can disagree with that practice, but it's not uncommon.

court76wi

FYI: I just got my car running again after 8 months. I only had a header pipe and neither O2 sensor was hooked up.

The ECU might be running the car "conservatively", but these specific CELs it didn't affect the VTEC engagement or rev limiter...

technine

I wonder if it effects timing and by how many degrees does it pull if any and I'm guess since you don't have the O2 sensor plugged in it is going off the other sensors like MAP, ECT and TPS to determine the fuel map? I also wonder how much does the ECU try to richen up the fuel mixture from stock.

court76wi

Well, if I'm reading the service manual correctly. The primary O2 sensor is used only at idle to trim the mixture. Maybe at part throttle too, but I'd have to reconfirm.

I know definately that WOT is an open-loop, and part throttle might be as well. Meaning that the ECU doesn't use any O2 sensor feedback and bases the fuel mixture on other inputs.

So the idle will be rich for sure, how the ECU affects other operation is unknown. It could make the motor more "conservative" in order to motivate the owner to check the CEL. A CEL from the primary O2 sensor doesn't affect the rev limit, VTEC engagement, and IAB valve actuation though...

technine

Hmm... I thought part throttle was closed loop when it the car is at operational temp.

I wonder if the timing is effected at all.

court76wi

Just an FYI. I removed all the emissions equipment under the hood that dealt with the carbon canister. Left the line from the fuel tank vented into the engine compartment. Removed the solenoid valve, etc. For the CAT converter, we're faking the computer out with an O2 extension. Works like a charm.

Various road / break-in miles and 2 events so far and no CEL light for the OBD2 ECU. At least for my car it doesn't seem to be that picky...