Nissan Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
78 Posts
Discussion Starter #1
Code:
Test/RPM/%CO2meas/%02meas/HC_Max/HC_Avg/HC_meas/CO_Max/CO_avg/CO_meas/NOx_Max/NOx_avg/NOx_meas
15mph/2063/14.6/0.2/92/21/101F/0.55/0.06/0.57F/716/150/484/FAIL
25mph/1997/14.7/0.3/57/13/93F/0.54/0.05/0.37/764/136/403/FAIL
So I am high on HC and on CO. Me thinks me running too rich. Any ideas on what controls how rich she runs? The O2 sensor is brand new, along with the spark plugs, distributor, timing chain, wires, temp sensor.

Fuel pressure is normal. Could a leaky injector cause this? What about a faulty temp sensor? I've got no engine lights on, so, hmmmmm.

BTW I'm getting between 28-31 mpg with mostly fwy driving.
 

·
Registered
Joined
·
450 Posts
I failed emission after running some Bosch plugs. They fouled out quickly. I had injector cleaning service done, and it cleaned things out so I passed. Also, I put stock NGK plugs in and have not had a fouling problem since. A thermostat stuck open will also cause a car to run rich. Are you sure your timing is OK? If it is retarded it could cause problems (lower fuel economy/incomplete combustion). It may be a good idea to run some injector cleaner for a tank or two, and do some highway driving, opening the throttle when possible. That may clean some of the deposits/carbon. Then, be sure to change your oil, before you retest. I would check the timing if there is any doubt it could be off. Also, if you did not warm your car up before testing? Make sure it is very warm. You did not mention the air filter? Is it new, clean? Good luck!
 

·
Registered
Joined
·
78 Posts
Discussion Starter #3
Thanks for the suggestions, unfortunately, they are pretty much all covered.

I am using properly gapped NGK plugs, new o2 sensor, I ran "seafoam" through it to remove all the carbon. (This stuff you suck in through a vacuum line, it's much more concentrated than tank based cleaners). Anyway, it smoked like crazy afterward (It's supposed to) and then I drove the car for a week afterwards, back and forth to work. I'm getting between 31 and 28mpg. This tank will be alot lower, because I have been less than nice with her. Let's just say I spend a lot of time above 5k :)

She was warm, as a matter of fact the smog tech let it run while he did other checks before putting it on the rollers first. The smog tech did check the timing and said it was at 8*. I told him how the cat would get reddish in color after driving sometimes and he said that's why it's rich. Now I'm just trying to figure out why.

I am going to clean the fuel injectors myself, takeing them out and running them in an ultrasonic cleaner, and then trying to blast some fuel injector cleaner through them at 50-120psi (I have an air compressor). I figure between that, they should hopefully spray correctly. It's got a brand new air filter in it. The car feels way low on power though, but I have nothing to go by because I didn't drive it when it ran correct. I am tempted to advance the timing some more past 8*, but I don't want to use premium. The air in the tires was at max pressure, and it was in the 60's when I tried to smog it.

hmmmmm.......
 

·
Registered
Joined
·
450 Posts
I figured you probably did some of the basic things, so that is covered. To me, your timing is a little low. On my car it is 10 degrees +/- 2 degrees. You could safely go to 10 degrees, maybe 12 before going to a higher grade of gas. Plus, you could adjust it back, if it is a problem. I never have changed my timing. The car runs better now then it did 100,000 miles ago. I have a feeling when the timing chain was changed, the timing was set a little lower than when it came from the factory. I am just amazed at how peppy and responsive my 1.6 is. Changing the timing may get rid of the low power feeling also. Good luck!
 

·
Registered
Joined
·
1,014 Posts
1. use the consult on the engine first to eliminate any issues, you will be able to see the engine running rich/lean. the consult shows this on the meter.
2. Look into it being a weak coil.
3. Your CAT may be too old. my CAT was starting to get worse every year starting at 80,000 even with my engine in tune. it was not clogged, but starting to become blacker and blacker. what happens is the carbon shuts closes the contact areas and the tailpipe shoots carbon more and more especially at WOT.
 

·
Mofo
Joined
·
2,225 Posts
sunnysentra said:
.
3. Your CAT may be too old. my CAT was starting to get worse every year starting at 80,000 even with my engine in tune. it was not clogged, but starting to become blacker and blacker. what happens is the carbon shuts closes the contact areas and the tailpipe shoots carbon more and more especially at WOT.
That would be my suggestion. Take it into the muffler shop and see if they can check out the cat for you. I think you have gone over just about everything else......lol
 

·
Registered
Joined
·
78 Posts
Discussion Starter #7
Ok, well I checked the timing again today...It came up 15* (wow) considering I was using 87 octane. I played around with it until I brought it back down to 7-8*. I then took it for a spin and it did feel like it pulled harder. I poped the hood and also saw the cat was not as red as before, so more than likely more fuel is being burned because I was probably having serious misfire with it at 15*.

I also found this, for those that are interested:
linky

Interestingly enough, they say #1, make sure ignition is not too advanced. They also say to run premium, especially if the NOx is high. The Smog guy (A nice dude) told me that as well. He suggested getting the fuel injectors cleaned, checking the vacuum hoses for leaks. He said the cat is working because the numbers would be way higher than what I am getting if it wasn't working.

Because of the rich condition, I may try a different clt temp sensor just for the hell of it.
 

·
Registered
Joined
·
450 Posts
Looks like you are making progress! I went from failing to having stellar readings. I think having the injectors cleaned made the difference in my case. I have 172,000 miles on my cat (knock on wood). It will be interesting to see if it will pass emissions this fall. Good luck!
 

·
Registered
Joined
·
78 Posts
Discussion Starter #9
Found another good link for those trying to pass :)

http://www.mr2.com/TEXT/SmogCheck.html

Looks like adding Drygas to a nearly empty tank of Premium fuel will help as well. Just as long as the drygas has isopropyl alcahol in it.

I just dumped a bnch of the pass smog stuff in the tank, I also used Chevron Premium fuel, which is what the "big 3" use when they smog their cars. When I run this tankful through, then I can try and smog it. I bought an ultrasonic cleaner and I plan to ultrasonically clean the injectors out of the vehicle (In a bath of Techron fuel injection cleaner). Let's hope all this helps.

I did notice the car is much more fun to drive, it pulls way harder (With the timing closer to where it should be). A tank of hard driving still gave me 30mpg, so I'm pretty happy.

One last thing, I am going to bleed the cooling system because I forgot to do that when I did my timing chain. I'm thinking that maybe there is an air bubble sitting right next to the coolant sensor, somewhat isolating it from the real temp of the coolant.
 

·
Registered
Joined
·
11 Posts
I would like to suggest a couple of things about injector cleaning.

1. You will need to remove the screens or filters.
2. Don't use a harsh chemical for cleaning, let the ultrasonics do all the work. undulted injector cleaners are hard on internal seals.
3. You will need to cycle the injector while cleaning them. Our setup actually forces the contaminates out the top while cleaning.

Good luck... If you need them professionaly done, we only charge $12 each and you get before and after test data.

Gordon
WitchHunter Performance
Fuel Injector cleaning & flow testing service
 

·
Registered
Joined
·
303 Posts
I had some of the same concerns about passing emmisions that people are talking about. Here are the details of my car
Had a full tune up at 85K miles (filters, plugs, wires)
Timing is at 15 degrees.
Engine had 98K miles on it at the time of testing.
Oil had 6300 miles on it, same filter, mobil 1 oil.

40 degree day outside, car sat for 15 mins (not running) before it was tested.

Passed with no problems.
 
1 - 11 of 11 Posts
Top