The still image is my last test results. The video was taken from a "retest".

Details: 1990 civic si. D16A vtec jdm engine, essentially a D16Z6 running off a D15B P08 ECU (HMO sent me this ecu, saying it will run the engine without issue, but now I wonder if that is the problem.) No internal mods. DC header and AEM intake. New distributor, timing set to 16 degrees. New NGK plugs (.041). OBD1 injectors, eliminated the resistor box. New CAT, 500 miles. New O2 sensor. PVC fine, charcoal canister fine, no vac leaks... The intake and throttle body have been cleaned. I also calibrated the TPS. The CAT was hot for the test.

Around the 5 second mark in the video it is plane to see when the HC are high, running rich, the NOx is low. And as soon as the HC drop the Nox rises... What is happening?

The car runs great and gets good mileage, over 300 a tank.


http://www.youtube.com/watch?v=udN8v...ature=youtu.be

 

HC is raw fuel. It keeps the engine cool internally if it runs a little rich.
If you run lean, the internal temps rise and you run the risk of detonation.

NoX is the result of high internal temps.
So if your raw fuel is dropping off then it's not really a surprise that your NoX rises.

Maybe not the right map for your engine?
P08 is for a 1.5 liter economy motor whereas you are running a 1.6 liter with a little pep for performance.

Other causes might be defective fuel supply components, too low octane fuel, carbon build-up in the engine, ignition timing too advanced, inefficient cooling system.

 

The engine is clearly running very lean, which in turn leads to high NOx. Have you measured the fuel pressure or replaced the fuel filter?

 

Hey 4dr, thanks for your ideas. I too am beginning to think it is a map issue. I'm tempted to get a P28 off craigslist.

I forgot to mention i put in a new fuel filter, and was running 91 for the test. I also have a new thermostat in and everything seems to be working perfect with the coolant system.

Do the FITV and or IACV come into play?

 

Have you measured the fuel pressure and tested the FPR?

 

Plan to visit harbor freight tomorrow and pick up a fuel pressure gauge.

 

This test was done COLD.

Just tested the fuel pressure, connected to the filter service connection.

35 with the vac line connected to the FPR

45 with the FPR vac line disconnected

 

I don't see a problem with the fuel pressure.

I would follow 4drEF's suggestion that you may not be using the right ECU.

 

I also tried to test after the fuel rail but am not confident with my results, which resulted in 0 pressure. The test was done with the car running.

Perhaps I set it up wrong. Please see photo. I connected a line off the FPR and conjoined it to the return line using a male to male barb connector, which provided a mount point for the gauge.

Should I connect the gauge to the return line as a terminus?

(On second thought, this sounds like a really bad idea. Naturally the pressure would continue to rise.)

 

I believe the first psi numbers you posted. The later 0 psi reading doesn't make much sense given that the engine runs, albeit lean.

Beside the ECU, you also may want to look into the possibility that you are using incorrect fuel injectors for your set up (supplying insufficient fuel).

 

My girlfriends car failed nox, turned out to be a leak in the exhaust system... right where the header conects to the downpipe or whatever its called. I lathered that **** up with gasket maker and it passed lol. It obviously didnt last, but it worked.

 

Agreed.

The injectors have been on my list, however, they came with the engine. In regard to the ECU, would you recommend using a P28?

THANKS Ron and 4dr!!!!!!

 

Just to put this to rest, I passed. Running the wrong ecu was the problem. Hooked up the p28 wired in the 4 wire o2 sensor and that was it.

Thanks for the help peeps.