Wont pass E-test

[KnuckleHead]

Ok need some help here. I went to do my emissions test and it wont pass. I have had the truck tested 2 times already. On the first one the HC reading read 6.13, limits are 5.00 - the CO reading was 78.31, limit of 55.00. As you can see from those it failed. So I did a tune up, plugs, wires, cap, rotor, pcv, air cleaner and adjusted the carb. Went today and sat in line for 2 hours to find out that again it failed. Readings are, HC 5.73 - limit still 5.00, CO 95.41 - limits still 55.00. Everything else passed. So again overall it failed. I really dont have the money to just keep replaceing parts to find out that they didn't work. So I'm woundering if anybody knows how or what to do to get it to pass? Or better yet yet someone that I can give $20 to that will make it pass, you know like in the old days.? Any help is always appreciated.

[Chris]

I've been told E85 or a couple cans of Heet in a tanks with a coule gallons will make it pass. After passing fill up w/ real gas.

[Jimmy]

With some research, you could generate a list of suspects based on your results.

How old is/are the catalytic converter(s) and oxygen sensor(s)? My '89 needed a new cat, sensor, and the A.I.R. pump cleaned to pass in CO.

Oh, one more thought... it might be time to suck it up and go to a garage to have it analyzed. I failed in my p/u twice as well, then finally to it to be checked out at a shop. There's a list of participating shops out there that are somehow tied to the emission program... I have forgotten the details. The list contains their pass rate after repair and such... I went with a shop that had a 100% pass rate, and it was worth it. The truck blew near zeros after the repair.

[Patrolman]

You have to understand what HC's and CO are to determine what the root cause of the fix should be.

HC is an unburnt fuel. Basically, anything ignition related (plugs, wires, cap, rotor, timing). A certain amount of HC's don't get burned in the engine. That is the job of the cat. It can't burn off too much, so if the engine isn't burning them completely, then the cat will miss too many and they come out the exhaust.

CO is fuel mixture. Simple thing that is often overlooked is the air filter. If the engine isn't getting enough air, then the mixture is off. That is a good place to start. Run it without the filter if you want. Also, if carb'd, check the float levels. Give the carb a good cleaning with a spray of carb cleaner. If EFI, there is a possibility that the injectors are dirty and dripping fuel rather than a full spray. This might be something to check since it would mess with the CO since the mixture is off, and also mess with the HC's since a lot of fuel is going in as a liquid rather than a mist and then being ejected as a liquid.

I have heard the same thing about E85 as well. I guess it can really dry out the tank and you don't want to leave it in there for long. Basically, put in a tank of E85, run it about 1/2 way, then test it. After the test, don't just park the truck. E85 draws in more moisture which can rust the tank out. Not that we have moisture to worry about this Summer!

Also, just in case others didn't know, they tightened up the emissions tests in April. They expect more vehicles to fail now which had previously just barely passed. There is also talk of the state "buying" vehicles that are repeat failures. Not sure how much $ they will be giving or when.

[Patrolman]

Almost forgot! Don't forget to check for any loose vacuum lines! Look, listen, feel! A vacuum line that is loose or cracked can create all sorts of e-test problems that wouldn't normally happen! If you have to, spray some starter fluid along the lines when the engine is running. If it is sucking in outside air, it should rev up a bit when it gets some starter fluid. That should indicate a bad or loose line.

[KnuckleHead]

Speaking of shops, I took the truck in today and had them do the testing. They recommended replaceing..... Throttle Postion Sensor, EGR valve, EGR valve sensor, and the o2 sensor. Total cost for parts plus labor....$551. That I don't have so I went to the junk yard today and pulled most of the parts plus a carb just incase. I also picked up a bank of sensors that controls alot of my vacum. The o2 sensor I will be buying new.
As for the air filter I replaced that and I also run with the top cover flipped to get more air and still protect it from anything big getting in to the carb.
The plan is to get everything on between Thursday and Friday and have a retest done on Saterday if they are open. Also I was thinking of taking the cat off and gutting i out then put it back on. I hope I get it this time or at least closer.

[Chris]

I suggest leaving the cat alone and see how you do with the other parts replaced. Good luck! :thunb:

[Patrolman]

I agree with the cat. A cat that isn't working up to par still works better than no cat at all. I would start by replacing the parts the shop recommended.

As for the O2 sensor, usually there is a test procedure to determine if it is actually bad. Sometimes the sensor isn't actually bad. Check to see if there is a way to test yours. Usually just requires a multi-meter and sometimes some heat (bbq grille) to make it kick on. You just measure the resistance. Easy to do if you can find the procedure.

If you HAVE to replace the O2 sensor, try this place
http://www.autobarn.com/
I believe that is where I got at least 1 sensor that I had to replace. MUCH cheaper than anywhere else. I also bought at least 1 O2 sensor off of Ebay. Got a really good deal on there for a brand new piece!

Hope all of that helps!

[Brody]

Contrary to popular belief, you can clean the O2 sensor and save yourself some $$...providing that the sensor is still good, of course.

Just undo the wiring harness connector,unbolt the sensor, and take some MAF or throttle body cleaner to it, using a light brush to get the harder residue off. Let dry, apply a goodly amount of anti sieze to the threads, and reinstall.

As far as e-tests go, you might also try that 'guaranteed to pass e-test' additive that you can get at Checkers, etc. Stuff really works and I have had some absolute beaters pass an e-test using it.

[KnuckleHead]

1st thanks for all the info. I replaced everything that was suggested from the junkyard and took the truck for a re-test on Saterday. 3rd time was a charm, it passed. The totals were very low so now I need to go and ajust somethings back up. Again thanks for all the info.

[Patrolman]

Glad it passed! Fairly simple fix! Have to adjust it back up?

[KnuckleHead]

Need to adjust the carb back up a little. When I give it gas it chokes abit, also when I'm holding 40mph you can feel the truck "chokeing". The results from the test were very low so I would imagine that the carb needs abit of tweeking.

[Patrolman]

If it is choking a bit, make sure that your timing is set correctly first. Also, if you make any adjustments, keep track of how many screw turns, etc. Then you can reset it if it doesn't work!

[KnuckleHead]

I hear you there. I'm only going 1/4 turn at a time then driveing it to see how it does. I had the same problem with te old carb and just kept ding it till it got better. I'm new to the 2.8 that I have in my truck. I was looking up info on it and foound out that it doesn't have a timeing chain nor belt. It uses 2 gears 1 big one at the top and a smaller one at the bottom. Good thing is I don't have to worry about the above stretching out or breaking but I do have to worry about the teeth on the gears. You can see a pic of what i am talking about on TheRangerStation.com web sit. Go to tech, then look for motor info and click on 2.8.

[Patrolman]

When I was in college I used to drive Subie's. Specifically early 1980's models. They had a EA81 motor. It was carb'd with a set of timing gears instead of a chain or belt. Super simple and never fail. Also had over head valves that were manually adjusted. Very few items motor wise to maintain. Plus in those models, almost all came with a 4wd and a low t-case. My Nissan Patrols also have a gear driven timing. If I remember right, so do the Scout V8's.