comegetme

This is a follow-up on another thread about the VX catalytics configuration, but I want to start a new thread to discuss the smog test results specifically.
Background: 49-state 1992 Civic VX, 190k miles, almost all original stock parts. no oil leaks. No check engine error code.
I need to smog it in CA (ouch!)
Failed on HC at 25mph of ca. 280, many times the maximum allowed value. All other values, including all 15mph values, are withing allowable range. Although %CO and %O2 seem to be off at 25mph.
I am realizing that I am not the only VX owner having this problem.
Already done: New rotor / new spark plugs / new spark plug wires / new throttle body / new EGR valve / new O2 sensor / new PCV valve. Mechanic said cap, distributor, and catalytic don't need replacing (opinion to be verified).

Other symptoms: Significantly less power accelerating, compared to other VX's. But, somewhat paradoxically, very high gas mileage of ca. 55 mpg with conservative driving.

One smog station stated something to the effect that the EGR system, while not throwing an error code, is somehow not engaging, or coming into effect. They finally gave up on this car.

I hear that changing the ecu to another 49-state, or a CA ECU, somtimes resolves issues that are otherwise inexplicable.

I am attaching my values. Any input on most probably root causes, and proposed course of action, is very appreciated.

comegetme

On another note, what I'm not understanding is I have another VX where the same 15 mph and 25 mph tests were performed two years ago at about half the RPMs. I assume they used another gear. So which of the two is the "right" way to test the VX? (Note: This was for a completely different VX.)

eghatch9295

iTrader: (1)

remove and clean egr valve and passages. cant do anything but help

mk378

Cruising at 1350 rpm is wrong. The engine makes basically no power below 2000.

Double check the spark timing. If spark timing doesn't come in near the center of the adjustment range, consider the cam timing may be off.

comegetme

Our friends at ecomodder and gassavers shift at about 1000 rpm. I can shift at about 1000 while slowly accelerating (or cruising) and without bucking the engine of course. However, the driving style is a completely different topic. The important question here is whether the smog test officer has a choice which gear to use, and how it might affect my chances of passing vs. failing.

TomCat39

Actually, this is a special breed honda motor, the vtec-e produces more torque down low than it does up high.

1992 VX project "sipper" dynograph after maximizing the car for fuel efficency aka "sipper":

http://www.superstreetonline.com/how...lery/#photo-31

Please notice how torque drops as RPM goes up. That is the beauty of the vtec-e engine and why the 3 stage D15B is such a marvelous 1.5 liter that has serious oomph all the way around when done right.

Relic1

the second sheet shows the exact same RPM for two different speeds. I don't think that the tech sat there and dialed it in to read that way..... I'm betting they faked the tach reading cause something wasn't working on their side.

as far as your results, EGR is likely the cause. Yank the intake manifold and clean out the passage. It's not a fun job but your car will thank you.

comegetme

Already done: New rotor / new spark plugs / new spark plug wires / new throttle body / new EGR valve / new O2 sensor / new PCV / new air intake temperature valve / new idle air control valve. Mechanic said cap, distributor, and catalytic don't need replacing (opinion to be verified).

If you mean that "intake manifold" is separate from EGR and might need cleaning to make EGR work, I will have someone do that. The car is currently at a Honda dealership for diagnosis ($300 !!!), so I hope they would catch that, if that was the root cause.

mk378

The EGR system is mainly to reduce NO. Your NO numbers look pretty good, so either the EGR is working or it is running rich, in which case you get HC and CO instead of NO.

Cleaning the EGR involves removing the fuel rail, EGR valve, and the EGR passage plate on top of the intake manifold (under the fuel rail). The manifold does not need to be removed from the engine.

EGR can be somewhat tested by forcing the EGR valve open at idle, which it normally does not do. The unexpected gas recirculation should cause the engine to stumble or stall.

comegetme

Dropped the car off at the Honda dealer this morning. They just informed me that they need more time. They are swapping in another "mass airflow sensor" to test if this fixes the problems.

I didn't know that such a thing existed, and not sure why it doesn't send an error code.

TomCat39

If you read the article, they were doing a complete tune on it including modding cam angles with adjustable cams. So yes, I'm sure the tech did many passes.

I tend to think the second line (dotted) may have to do with the low cam (vetc-e) portion of the run. They used external vtec controllers through Hondata S300 so they could do runs without disengaging vtec-e and then with etc.

Also if you look at the pic, it's a split screen software, the left panel is rpm to torque while the right panel is the same pull, rpm to hp. The software then captures the peak points for each, peak torque usually is not at the same rpm as peak hp.

Relic1

sorry was referring to the OP's first and second pic. (I should have stated that)
I got what they were doing with the pulls.

I peaked at 62mpg with my VX with the stock ECU with no where near the stuff they did. (50-55mpg mixed daily driving)
I never tried to tune with that engine, went for more power before tuning was in my vocabulary.

After reading the article I had to scroll back up to check the date on it, for 2013 there are a few of things that read like it was written in 2005 or earlier.
Ehh, none the less an interesting project. Makes me miss my Z1 a little more.

94eg!

iTrader: (2)

[QUOTE=TomCat39;51508997...peak torque usually is not at the same rpm as peak hp.[/QUOTE]

That only happens when peak torque occurs at 5252rpm. Just how the torque to hp conversion is calculated.