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Old 04-10-2014, 01:25 AM   #1 (permalink)
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1986 CRX VX Failed Smog

Hello Ecomodder! I recently swapped the D15Z1 into my 1986 CRX SI and took it out to the referee. Passed inspection but failed smog.
My build thread: http://crxcommunity.com/viewtopic.php?f=36&t=15743

I got the idea of swapping in the VX thanks to all the other VX mods on this forum. I'm hoping someone can help me figure out what is causing me to fail HC and CO.

Here are the results for reference:


(Typed out due to inability to post pictures)
--------------------
Smog Test 1
15MPH - 2363RPM
Max - Measured
HC 121 - 868
CO .7 - 5.27
NO 1297 - 82
O2 1.1
CO2 11.3
-------------------
25MPH - 2260RPM
HC 104 - 762
CO .56 - 5.12
NO 1127 - 53
O2 0.6
CO2 11.7
============
Smog Test 2
15MPH - 2369RPM
Max - Measured
HC 121 - 517
CO .7 - 1.3
NO 1297 - 988
O2 1.2
CO2 13.6
-------------------
25MPH - 2189RPM
HC 104 - 460
CO .56 - .67
NO 1127 - 525
O2 0.6
CO2 14.4


The difference between test 1 & 2 is that I fixed my EGR. Results were improved a bit since the EGR was no longer stuck open. The EGR was stuck open initially because the vacuum lines were run incorrectly between the EGR valve, EGR solenoid, and EGR Controller, which is now corrected in test 2. Since the EGR is not stuck open, it appears the NOx went up but I didn't fail because of it.

Things that I've done or tested prior to the smog tests above:
1. Installed new O2 sensor (4 Wire)
2. Tested EGR Valve by applying vacuum to the valve. The car dies during idle if I apply vacuum to the EGR valve. This should handle NOx but I'm uncertain if it causes HC or CO.
3. New Sparkplugs, spark plug cables, and distributor cap & rotor

Possible things I plan to check
1. Coolant Temperature Switch
My coolant temperature switch is rigged right now to always be on. Given that there is a connection for the ECU to know if the switch is grounded, I'm not certain if it impacts HC or CO but it is possible that it could trick the engine into thinking it is running too hot and therefore not run as hot as it needs to be. Just a theory. Please chime in with your thinking and advice.

2. Fuel Injectors
The high HC means I'm running rich. Could it be possible that there is too much fuel or if it isn't atomizing?

3. Figure out if there is a misfire
There is a possibility that the engine is misfiring as there is HC and O2. Fuel and oxygen with spark should result in combustion but there is left over air and fuel so is there a possible misfire occuring? How to check if my engine has a misfire? I tried pulling spark plug cables but the car runs as I didn't pull anything. This happens on all cylinders. Only upon removing 2 spark plug cables in any combination will the engine stagger.

4. Change the CAT?
Theres a good possibility I might need to change the Catalytic converter but if I do so before fixing the cause of running rich, the CAT will simply be destroyed by the excess fuel.

5. Find out if double CAT is causing an issue
I have both CRX Cat and VX cat on the car. Is there a possibility that due to double CAT, the car has back pressure, misfires and is resulting in high HC and CO? I initially thought having double CAT should instead help the HC and CO issue as it would burn the extra fuel.

Your guidance is welcome. Thanks!


Last edited by windraver; 04-10-2014 at 06:19 PM..
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Old 04-10-2014, 03:20 AM   #2 (permalink)
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I assume there are no CEL's?

Since you are running a CA ECU lean burn should not be an issue, and technically the car should pass the emissions test. You mentioned the possibility of a misfire. You would be able to tell if there was a misfire. It shakes the car, doesn't sound or feel right at all. However, it is possible one or more of your cylinders is leaking compression, creating inefficient combustion and therefore higher emissions.

I didn't read through your whole build, so you might have already done this. But rent a compression tester and test each cylinder. If that checks out I would replace your CAT. 2 CATs is not really helping. The CAT is expecting a certain mixture of gases that will react inside, and produce different gases as exhaust. When you are feeding exhaust from one CAT into another, who knows what goes on inside the other one. This topic is interesting because lean burn engines actually emit lower NO2 and CO2 than a normal burn engine out of the exhaust ports. But due to the reaction inside the CAT, which is designed for normal burn exhaust, the emissions from the normal burn engine actually come out cleaner. Lean burn engines need special CATs to handle the different mixture of exhaust gases to efficiently react with them.

The compression test is where I would start, it's free and easy. If indeed compression is low it's plausible that is the cause of your emissions failure.
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Old 04-10-2014, 04:45 AM   #3 (permalink)
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Quote:
Originally Posted by cbaber View Post
I assume there are no CEL's?

You mentioned the possibility of a misfire.

The compression test is where I would start
Thanks cbaber for the response.

No check engine lights. I did a compression test a month due to prior rough idle and all cylinders are good. I rebuilt the engine prior to dropping it in so compression should still be good.

The reason I have difficulty knowing if there is a misfire is due to the fact the engine barely reacts if I disconnect a fuel injector plug. it takes two unplugged injectors to make a difference and even so the ecu simply adjusts.

My query into misfire is due to the high HC leading me to wonder if the car is running rich. The other key to the guess is the O2 level should be closer to 0 if it simply lacked the oxygen to burn.

Some theories I've come up with. please tell me if it makes any sense...
HC means theres unburnt fuel. Maybe fuel injector is not atomizing? Maybe the Cat still burns the some of the fuel(HC) but it ends up being left as CO so high CO?

Would the fuel regulator play any role in excess fuel?

Double cat could means less exhaust outflow. Would that impact the intake vacuum pressure and therefore confuse the MAP sensor to think there is less vacuum... which would mean more speed and so more fuel so I would run too rich?

Actually that last one seems very plausible. Ill try and get a pipe in place of that 2nd cat. Please let me know if you have any other ideas.
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Old 04-10-2014, 12:14 PM   #4 (permalink)
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The only other thing that caught my attention was the O2 sensor situation and stalling while driving. I had a lot of problems with my HX O2 sensor, and still have problems with the EGR valve. The symptoms you described before you fixed the EGR where exactly what I was going through with the O2 sensor.

The EGR system is responsible for controlling HC's, but I thought that was only during lean burn operation. Unlike the VX, the HX EGR is electronically controlled. In fact, I have it unplugged and the car still runs fine, unlike your car which seemed to not like when the vacuum line was switched or pinched. So maybe there is still an EGR issue and that could possibly explain the high HC's. Your second test improved when you fixed the EGR, but have all the problems gone away?

Could you possibly borrow or find a wideband O2 sensor + gauge? This would allow you to read the A/F mixture and know for sure if it is within spec. Until then we are just speculating on what the engine is doing, it might be helpful to know the exact mixture that is going into the cylinders, maybe that will shed some light on the situation.
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Old 04-10-2014, 02:52 PM   #5 (permalink)
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Quote:
Originally Posted by cbaber View Post
The only other thing that caught my attention was the O2 sensor situation and stalling while driving. I had a lot of problems with my HX O2 sensor, and still have problems with the EGR valve. The symptoms you described before you fixed the EGR where exactly what I was going through with the O2 sensor.

The EGR system is responsible for controlling HC's, but I thought that was only during lean burn operation. Unlike the VX, the HX EGR is electronically controlled. In fact, I have it unplugged and the car still runs fine, unlike your car which seemed to not like when the vacuum line was switched or pinched. So maybe there is still an EGR issue and that could possibly explain the high HC's. Your second test improved when you fixed the EGR, but have all the problems gone away?

Could you possibly borrow or find a wideband O2 sensor + gauge? This would allow you to read the A/F mixture and know for sure if it is within spec. Until then we are just speculating on what the engine is doing, it might be helpful to know the exact mixture that is going into the cylinders, maybe that will shed some light on the situation.
Hmmm good idea. I'll see if I can find a wideband O2 sensor + gauge.

The EGR system vacuum lines were connected wrong initially which caused the EGR system to stay stuck open one the EGR engaged. It turns out that my idle screw was also set wrong as it was fully closed. This forced the ECU to compensate using the EACV. Once I corrected the idle and egr system the engine no longer stalled and ran much better. That was done between test 1 & test 2. Removing the EGR does allow the engine to run much smoother but I imagine it would increase my NOx.

I'll try to get something to check my A/F ratio and remove the 2nd Cat.
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Old 04-10-2014, 05:44 PM   #6 (permalink)
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It is possible that one or more injectors are not atomizing well. This could be due to fuel pressure out of spec, or blockage inside the injector.

If the fuel pressure regulator is borked, the fuel pressure could be bad. Too much pressure will usually mean too much fuel (the injector opens an orifice, the pressure pushes fuel out through that orifice). Too low a pressure will mean too little fuel, or possibly fuel that does not atomize well, and just dribbles instead of spraying.

Do you have access to a gauge that can check the pressure? Do you have a spec for the pressure? Most of the time, the pressure is referenced to manifold pressure, so the fuel rail pressure would be 3 bar (or whatever measurement) above manifold pressure. There would be a vacuum line from the manifold to the FPR in that case.

I'm not sure how you'd test the injectors for flow and/or pattern except by building up a test rig with pressurized fuel and a battery (3V? 9V?) to open the injector...

-soD
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Old 04-10-2014, 06:18 PM   #7 (permalink)
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Thanks for the reply soD.

I was wondering the fuel pressure as well since the fuel pump is for the CRX SI and the engine is for the Civic VX.

I don't have a gauge to test the fuel pressure but I'll if I can borrow one. Never tested fuel pressure before though so I'll need to find some info on how.

(which on a quick note I'm still trying to figure out how to test my air fuel ratio...)
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Old 04-10-2014, 07:43 PM   #8 (permalink)
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On the fuel pressure, I just used a oil pressure gauge. It seemed to work fine.
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Old 04-10-2014, 08:28 PM   #9 (permalink)
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Also be sure to double check for vacuum leaks. I know you believe the car is running rich, but at this point we are just speculating based on the emissions test. I took my EGR plate off to clean the passages, and the car ran like crap afterwards. I tried everything I could think of, and then I traced down everything I touched when I clean the EGR ports.

The fuel injector seals were allowing extra air into the intake manifold, creating a lean condition. The seals looked fine, but sure enough a new set of seals solved my problem. Just something else to look into.
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Old 04-10-2014, 11:06 PM   #10 (permalink)
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Retard your timing run 1/3 E85 to gas and make sure you do a tune up ..you can check for vacuum leaks use break part cleaner spray around manifold if you have a leak your idle will change when you spray good luck

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