ketchup

iTrader: (3)

Ok so this car didn't pass smog due to high nox. SO I did a valve job, reset timing within spec, and replaced the DC header with a stock header (O2 sensor location). Now I found the exhaust leak which is at the cat conv. connection from the stock header.

NOW I can replace the stock exhaust clamping springs with a plain bolt and nut to tighten up the connection that's leaking. Will THIS reduce my NOX emissions??

traxxasx

i always run a bolt with nut its a for sure secure seal, the spring bolt crap is junk. You might be missing your donut gasket make sure you have that if you do put some bolts and tighten down on them see if it seals the leak.

thesmogman

I would keep the OG stuff on it. This is designed to flex a bit and that flex will save the other pipes/welds from cracking. You can add washers to the springs tighten it up.

Yes, a new donut gasket would help too

Yes, a leak there will affect the cat's reduction big time.

ketchup

iTrader: (3)

I might have a set of springs in better condition than the current ones on the car, I'll try that washer idea too.

I can't believe the leak caused that high of an NOX output. After I get the gasket on and ensure that there are no more leaks I'll re-smog the car and see if she passes maybe today(fingerscrossed).

ketchup

iTrader: (3)

Problem solved. I didn't realize the DC exhaust manifold had the donut gasket on it, took it off and put it on the stock manifold.

So this leaves me to believe that there was NO exhaust leak when the DC manifold was on when the car filed the first smog test.

The car has not been tested again yet, looks like it'll be Monday. I hope it passes, all I did was replace the O2 sensor, stock manifold, reset the timing belt and ign. timing.

With the last NOX result at 1913/15mph and 2413/25mph, will what I've done to the car thus far enough to reduce the NOX output by 1600?

Targa250R

Doubtful that you've reduced it at all.

What engine is this?

4drEF

If your O2 was bad before then maybe.
Old DC manifods were notorious for not keeping exhaust gasses hot enough to give a good smog check.

Do you have the old O2 still? I have failed REALLY bad before and did a trick that cleaned up the numbers really well. My friend did the same thing when his truck failed and tested with flying colors next try.
I took a bottle of injector cleaner and some spare vacuum line. After a nice drive to warm up the engine, I hooked the spare vacuum line up on the intake manifold pinched the open end off and then restarted the car. Open the pinch and dip it into the bottle of injector cleaner and it will start sucking it through. You will have to manually keep the car idling by giving it throttle. Your exhaust will smoke an insane not even funny amount.

It killed the O2 sensor, had to reset the ECU to clear codes, and probably made the entire neighborhood mad with all the smoke, but the smog check numbers were awesome!

This completely cleaned my intake valves, piston tops, exhaust valves and whatever else.

ketchup

iTrader: (3)

D15b7 with a D16z6 head

I still have the old O2 and the previous owner used some sort of Octane Booster and engine treatment which didn't help it pass. He even got a new Catalytic Converter and O2 sensor.

Will the stock manifold and new O2 sensor do the trick? Should I try to smog it Monday?

ketchup

iTrader: (3)

Well I went ahead and got a pre-test for $27 bucks.

Smog2 Results:

15mph
HC failed @ 156 (134 max)
NO failed @ 1177 (847 max)

25mph
NOX PASSED @ 293 (Smog1 was 2413)
HC barely PASSED @ 105 (108 max)

17 BTDC

Fuel cap failed.

Tank was originally filled with 91 octane but was low and almost empty, I filled with 2.5 gals of 87 octane. I heard 87 is better but the tech told me that 91 burns cleaner.


Looking back at the numbers, looks like the O2 sensor was dead on the first GPOL fail, maybe has to do with the previous owners use of "Octane Booster and engine treatment".

What is causing the fail at 15mph now? also the increase in HC? and why is there a change in max allowable?!

Targa250R

For your purposes, you are right. The tech is wrong.

ketchup

iTrader: (3)

and you passed smog? I thought that stuff would have killed your catalytic converter along with the O2.

matt_honda95

NOX is present when the engine is at 2500 degreese F or more and to have that many thats crazy. I have a D15B7 and i did a test up at school and when the engine was warmed up i had only 3 PPM's of NOX.

ketchup

iTrader: (3)

Yea but this D15b7 has a D16z6 vtec head/obd1/p28 ecu.

matt_honda95

This is true, mine is also an OBD1, but would the D16z6 make that much more heat causing more NOX? I'm not saying your wrong by any means I'm just wondering.

ketchup

iTrader: (3)

I believe it has to do with the higher compression ratio from swapping the head. 11:1 maybe?

Would changing the type of spark plugs help lower the 15mph NOX numbers? I have a set of NGK ZFR6J11 (1 step colder) that I've yet to put in.

matt_honda95

That makes sense, and holy **** that CR is nuts for a single cam. You have a step colder so that might be helping out, when the guy was doing 15 mph what gear was he in and what were the RPM's, it might not be much but every little bit helps. i can ask around in class tomorrow and see what would help lower the temp. Ill let you know tomorrow.

ketchup

iTrader: (3)

Could be lower, depends on the head gasket and I don't know which head gasket is on there. Also since the motor is higher compression, shouldn't I be using 91 octane? Maybe using 87 was the reason it failed the 15mph HC and Nox?

If 91 would give a more complete burn, there would be less HC in the mix allowing NOx to be reduced even more by the cat.

4drEF

Nope.
the idea was to clean off all the valves, piston tops, and combustion chamber.
Old engines are dirty inside and the cabon build adds to bad fuel flow and hotter internal temps.

ketchup

iTrader: (3)

There's got to be some easy fix for this. If the car is good enough to pass at 25mph, it should be able to pass the 15mph with some changes. Maybe retard the ign. timing to 16, run 1 step colder spark plugs with new wires and put in some Chevron 91 octane for a more efficient burn?

Remember we're talking about a d15b7 block with a d16z6 vtec head = high compression.

matt_honda95

i couldnt get anything or you today. sorry man good luck, i will still keep askin around though.

Targa250R

Z6 head on a B7 bottom end is something like 10.1:1 or 10.2:1 compression ratio when used with a standard head gasket. Not all that extreme. Shouldn't require 91. Retard the base timing 2 degrees and run 89, or 87 if it doesn't knock.

OneBadTurboCRV

Incorrect on all aspects, besides not being extreme. When you retard a motor it does not increase/promote knock it reduces the chances of it.

With a D15B7 block/rotating assembly and a D16Z6 head with a D15B7 head gasket it will yield a compression of about 9.84:1 and with that combination and a D16Z6 head gasket it yields 10.58:1 so what head gasket you are running could be the balance between 89 or 87 octane.

Choosing what octane to run really depends on what you are doing with your car. The truth behind it is really what is the basic requirements of the octane needed. Running too high of an octane can actually hurt motor more than you realize. This usually only comes into play when you start getting into 97 and up/race gas in a stock motor.

Look at these links if you really want to get into octane and its requirements...
http://dnr.louisiana.gov/sec/execdiv.../trans/b/b.htm
http://chevron.com/products/ourfuels...&aID=50&cID=22
(These just scratch the surface for beginners.)

Also lowering the heat range on the spark plug is a bad idea considering you are not in the compression range to have to worry about that even with 87~89 octane. Honda motors have a much more efficient quench area in the head so they can take less octane with a slight increase in compression.

Also what spark plugs are you running? 5's? The reason is NGK is one of the few plugs that actually get hotter when you go down in numbers.

ketchup

iTrader: (3)

5's are in the motor. I have a new set of 6's sitting pretty.