93 LX smogging...but great mileage
 

Hi to all in the group....I hope you can help.


I have a 93 LX non-vtec 1.5 which is smogging and failing the HC badly and the CO miserably.

The short version...I've done alot. New thermostat, O2 sensor, PCV,plugs, timing to 16BTC,new temp sensor, new CAT (it needed it), new valve seals to stop some oil consumption.

Here's the oddity of the car...I think it has a vtec ECU. I found that the previous owner had disabled the CEL and when I hooked it up I got two codes for Vtec variable valve timing issues and one code for an O2 sensor heater. I'm not giving too much merrit to the codes as it must be confusing for the VTEC ECU. I am concerned that the VTEC ECU may be dumping fuel in its confusion causing the smogging.

HERES THE QUESTION: Recently discovered that it runs clean after a hard run....but after 5 minutes in park it starts smoking/smogging out of the back...right up until the radiator cooling fan cuts on...then it STOPS!....until it cuts off...then it starts smoking again.

Does anyone know the corrolation of what is happening between when teh cooling fan cuts on and what the ECU is telling the fuel injectors at that point....or any generalization of why this occurs?

I'd hate to chage out the ECU at this point as the car has 180+psi across all cylinders, performs like a dream, and gets 40+mpg.

I failed a lot of retests in between all of my attempts.

Any advice would be greatly appreciated.

I'll post later to tell you what I did to go from 32mpg to 26mpg to 42mpg along the way of trying to solve this smog problem.

Jamie

If your ECU is set up for a 1.6 liter engine, but actually connected to a 1.5, it's going to run rich no matter what you do. You need to replace it. A 1.5 VTEC ECU on your 1.5 non-VTEC should be OK, but I'm not absolutely sure of that.

Another thing you could consider is a bad fuel injector. Let it idle making visible smoke for a while, then turn it off. After it cools, remove the spark plugs to inspect. If one plug is darker than the others, that cylinder may have a dirty or sticky injector.

The cooling fan runs independent of the ECU usually, though some cars (not sure if yours is one of them) have the ECU detect the engine overheating via the ECT and go into overheat mode where (among other things) they force the fan on. This should not happen in normal operation. Normally the fan is activated by rising temperature in the lower radiator hose, through the switch on the thermostat housing. It comes on before the engine temperature increases above normal.

Thanks MK,

I'll check the injectors...but agree that I need to get a fix on what this ECU really is. Is there any reference you know that tells either what the ECU is by part # or what ECU should be attached to a certain engine #?

Pull your ECU out. It will have a sticker like the one pictured below. Give us the code from it. The one below is a P28.

http://i97.photobucket.com/albums/l2...82885_4240.jpg

Thanks....

I found that I had a P07 computer which lists as a VX vtec version. The original was in the trunk of the car and was a P06 but was burnt out. By pure grace of God, I found one on e-bay that was a pullout and was the same P06 rev01 that was in the car originally. As a matter of fact, the seller listed the car model and engine associated with the computer (D15B7 non-vtec) and it was a perfect match. Purchase price -$41. Somebody likes me. :)

I found this link on an australian Honda tech forum...we may have it here somewhere....I'm new. But it shows most all of the computer types OBD 1 2 etc by connector type as well as a listing of all of the P#'s and revs and their assoiated model car. I tried to capture this to a JPEG as I'm not sure the link will be there forever...but my software didn't work...so here's the link for now:

http://www.hondatech.com.au/forum/showthread.php?t=105