Denatured Alcohol and Emissions

[AHall]

I wanted to provide some information on my actual experience on this subject. I found a lot of people talking about this on the internet but no actual results were ever posted. I have an all stock 1993 Nissan 240SX and live in the Dallas Texas area. I have battled with these emissions tests for the last 5+ years.

Anyways this year my inspection was due in August of 2011. I took the car in and failed. I did not do a whole lot to the vehicle as I had a new catalytic converter installed the year before, my second in two years. Last year I failed, had the new catalytic converter installed and after two retest, I managed to just squeak by.

My numbers in August were as follows:

25 mph Test 15 mph Test
Max Actual Max Actual
HC (PPM) 132 208 136 206
CO(%) 0.73 0.62 0.76 0.43
NOx 945 3275 1045 3607

I have been able to learn a lot about emissions over the years after getting screwed by a state certified repair facility. So I knew the EGR system was a problem after this test. I also need to replace my valve seals. Although I have heard different opinions on whether or not bad valve seals will effect emissions. No I do have an alternate vehicle so I took my time with this repair.

I removed the intake manifold and the passages the gas from the EGR system is circulated through was completely plugged with carbon. So again I took my time taking it apart, thoroughly cleaning it and replacing it along with knock sensor, oil breather and gaskets. I also took off the EGR valve recirculation tube and made sure all was clear. It was.

I took the car back and failed again. Now at the time I was unsure on how much the EGR valve should lift and when it should lift when you rev the engine. When I rev’ed the engine, the valve seemed to move a little, but not very noticeable. I read some information that the EGR valve only moves when the car is in motion or can not be noticed. My experience based on test results is the valve should move when you rev the engine and it should be very noticeable.

I could go on and on about my repairs, but ultimately I repaired the EGR problem and returned for a test January 2, 2012.

My results were as follows:

25 mph Test 15 mph Test
Max Actual Max Actual
HC (PPM) 132 193 136 219
CO(%) 0.73 0.45 0.76 0.41
NOx 945 310 1045 321

Wow look at the change in NOx, only about 10% of what it was before the EGR repair.

The HC is supposed to be due to unburned fuel in the exhaust, and at this point I think the cause is my MAF sensor. I have ordered new spark plug wires, a distributor cap and rotor and fuel filter because I have noticed some sluggish acceleration and hesitation. Also my idle would sometimes be unstable and a little high (1000 rpm) after warm up. Once when the idle was unstable I moved the MAF connector and the idle smooth out and has not been rough for about a week now. So maybe it needs to be replaced. That will probably be my next move if the problem is not resolved by the parts I have coming in.

Not wanting to wait any longer because I have only 15 days for a free retest and not really having anything to loose, I decided to try the denatured alcohol trick. I purchased a gallon from Home Depot for about $15. Here there are a few stations that will do a trial run before the retest so that you do not loose your free retest if you have not resolve the problems causing you to fail the emissions test. I drove to the emissions test after work, about 30 minutes on the highway which ran may car down pretty low on gas to where the fuel needle was on E. I pulled into a parking lot next to the emissions test station and poured about 1/3 of the gallon directly into the fuel tank using a funnel. There was no one waiting so my car was put directly on the dyno.

The trial test results were as follows:

25 mph Test 15 mph Test
Max Actual Max Actual
HC (PPM) 132 103 136 74
CO(%) 0.73 0.23 0.76 0.07
NOx 945 149 1045 267

This is amazing right??

So they did the retest and my numbers were as follows:

25 mph Test 15 mph Test
Max Actual Max Actual
HC (PPM) 132 116 136 136
CO(%) 0.73 0.27 0.76 0.19
NOx 945 251 1045 445

I was surprised at the increase. Maybe most of the alcohol was used up during the trial test. But I did pass!!!!

I then went directly to a gas station and filled up with gas. I do still plan to make the repairs, but I needed to get the inspection done given the time constraints and already being four months pass due. Anyways I want to provide real life results. I hope this helps someone with similar problems.

[compactfean]

This is why nico nico is the best nissan forum!!!! Great job man! Very detailed. What section in lowes do I find this denature alcohol?

[AHall]

I got it at Home Depot in the section with paints and wood stains.

[180sx91]

That's pretty awesome, I also live in the Dallas fort worth area

[zer0c123]

How did you fix the EGR problem?

When I was trying to pass smog 2 years ago, I made the same observation about the ege valves movement. I have 2 EGR-BPT valves at my disposal. One old one that was repaired by a smog tech and the other purchased new back in 04 from nissan dealer.

What I noticed is that during revs, the egr valve's diaphram displaced more when the OLD EGR-BPT was installed. To make a long story short, I basically failed smog with high Nox using the new EGR-BPT Valve, but passed on the 2nd try after reinstalling the old EGR-BPT valve.

Your passing Nox's #'s are similar to my last smog check. Although you passed, those Nox #'s are still pretty high. Have checked for an exhaust or vacuum leak?

[compactfean]

Just for a little info. We tried this on my buddys car and he was only 35 hc off from passing. he has less than 1/4 tank and we used the 32 oz can of denatured alcohol and it only changed his results by 1 hc! So if you are going to do this, do it on a near empty tank.

[zer0c123]

Just for a little info. We tried this on my buddys car and he was only 35 hc off from passing. he has less than 1/4 tank and we used the 32 oz can of denatured alcohol and it only changed his results by 1 hc! So if you are going to do this, do it on a near empty tank.

Try it again with 2 gallons at 1/4 tank of gas. That's the typical instruction that you will see floating around the web.

[compactfean]

Didn't know that thanks man. As far as the egr problem, there is a bung on the front and back of the intake manifold. You have to remove those bungs and clean the egr passage.

[AHall]

Yes I took my entire intake off and cleaned everything. I did make sure that all of my vacuum lines were connected and were able to pass air and vacuum. I have not investigate an exhaust leak. One thing I should mention is that while trying to remove the exhaust manifold, I was unable to separate the manifold from the pipe that leads to the muffler. So I only was able to pull the manifold away from the head enough to change the gaskets. I should not have an exhaust leak and there re no obvious signs of one such as smell or loud noise.

What I noticed about the EGR system is that the EGR-BPT valve was not passing the vacuum on from the EGR solenoid to the EGR valve. I did a couple of test to confirm that the EGR-BPT valve was the problem. What I did was first determine at what point I was getting vacuum. I confirmed that vacuum was coming out of the solenoid and entering the EGR-BPT valve, but it was not passing on the the EGR valve under any conditions. I then disconnected the hose on the bottom of the EGR-BPT valve to confirm that back pressure from the exhaust was present, and it was. Keep in mind that all other vacuum lines were connected correctly. I then connected a long hose to the port coming out of the bottom of the EGR-BPT valve and blew air into the hose to simulate the exhaust back pressure with the car running. When I would rev the engine and the EGR valve would raise as it should. So for some reason the back pressure from the exhuast was not sufficient to allow the vacuum to travel through the EGR-BPT on to the EGR valve. I believe the EGR-BPT valve is the problem and needs to be replace. However, not wanting to send more money on parts, what I did for the test was purchase a long piece of vacuum hose and run the hose from the "Y" connection the feeds the vacuum from the EGR solenoid valve into the EGR-BPT and connected it directly into the EGR valve. I basically removed the EGR-BPT valve from the loop. Not what I wanted long-term, but I needed to go ahead and pass the test and again I do have another vehicle that I have been driving since I passed the test.

Also, I noticed that during the second portion of my retest, I noticed that the technician performing the test switch the thing they clip on the spark plug wires from the #2 wire to the #4 wire. I do not know why the NOx jumped during the second test, but I figure the numbers are pretty low even during the second test, but maybe not. I checked my records back to 2006 and I could not find a reading less than 719 on NOx at 15 mph, so I will take 445 any day. I have a new distributor cap and rotor as well as spark plug wires and a fuel filter that I purchased from Nissan so hopefully that will resolve my problem of high HC. I will likely spend the extra $50-$60 to get the EGR-BPT valve in the next few weeks. I will let you know if this solves my problem. Hopefully so. Who has $50-$60 to blow on parts that are not needed? Good luck to everyone, for me emissions are the worst part of the year.