I have a 94 TD in a one ton dually. I recently went to get it smog tested to renew tabs and it blew a 65 with a legal limit of 40. The gal testing it didn't seem to know what she was doing so I drove across town, about fifteen miles and went through another station which then blew a 73. On my way to the other station I put in fresh fuel since she had been sitting three months.

The things I noticed...when doing the "snap" test I get a good amount of black smoke which seems to clear up when the rpm level off. I checked the turbo wastegate and the arm moves about 35 degrees, not sure how far it should move from engine off to engine running at idle, the air filter is slightly dirty but not very, the fuel filter has about 2500 miles on it, vacuum pump appears to be pulling good vacuum, engine runs smooth and I don't see any blowby from the dipstick tube.

I had my 93 smog tested two years ago just before buying this 94, the 93 has EXCESSIVE blowby due to a dead cylinder(any input on most likely causes of this will be greatly appreciated as well) and it blew a 43 so it's just odd that my smooth running truck won't pass and failed miserably and yet my worn out blown up rough running truck just barely failed!!!

Anyone with ideas on what to check on my 94 would be greatly appreciated! Also most likely causes of blowby on a 6.5TD. I did pickup a 95 long block to put in the 93 as well, anyone know what I will have to change to make it work? A lot of information to respond to I know but I try to cover it all at once! Thank you.

tie/clamp your wastegate shut REAL tight and try again. Don't romp on it until after you restore the wastegate motion, after the test.

You might have better *luck* if you can burn off all of that old fuel before having it tested again. Jim's FullTiltTurboTrick will probably help too, just be sure to baby it with the wastegate tied shut.
Any chance you're using some additive that's screwing up the test?

Nope, no additives! The thing is, I don't just want to "make it pass" because obviously it is dirty and not running properly. It only has 100k miles on it so it's not worn out. I'm trying to find a solution so I can also get better economy, seems to be low, my non dually 93 got 18 running rough and this one only about 15MPG. Thanks!

Some guys suggest pulling air filter for the test.Would need to make sure air box is clean to do that.
Give it a bunch of WOT,s at home or wherever in case soot trap has some particulates that need blowing or burning off.
Make sure no exhaust leaks ahead of turbo eg crossover.
My first test blew 20 plus .Blamed old lady type driving & leaky crossover . Last test was under 1 percent, but IP had been replaced just prior & I terorized the neighbourhood with WOTs for a week pror to the test to get rid of white smoke & black puffs.
Jim,s suggestion eclipses above but you might want to check further wastegate operation to see if black smoke can be reduced.in any case.

Nope, no additives! The thing is, I don't just want to "make it pass" because obviously it is dirty and not running properly. It only has 100k miles on it so it's not worn out. I'm trying to find a solution so I can also get better economy, seems to be low, my non dually 93 got 18 running rough and this one only about 15MPG. Thanks!

Could be due for injectors. They are usually good for 100K. Worn injectors will effect emissions and mileage.

Depending on the gear, 15mpg isn't too bad. I would consider it descent for a 4.10 gear.

Realize now from your post * 4 ,that as well as pass test you want to find out how to cure your black smoke problem. See" Waste Gate" ',WasteGate Solenoid" & related info in FAQs for starters.

CDR valve could be letting too much blow-by and oil threw. Clean tube and turbo inlet. Injectors could be main factor.

You are not going to improve your mileage by passing the test , most vehicles get terrible mileage and low emission output , go figure .

As above posters stated. Make sure your wastegate is working properly. Take it out and run it for an hour or so at highway speeds to clean out the cat(soot trap). The cat converter's on these are designed to store soot and then release it when the engine is run under load. Make sure your filter is clean for both the air and fuel. See if you can find some BIO diesel to run in it for the test. Injectors are definately a good possibility as a problem. Worn injectors won't atomize the diesel well and results in droplets of diesel making it into the combustion chamber and cause excess smoke. Also do you have the PMD/FSD on the pump or remote mounted? If it is remote mounted, did you put in a larger resistor?

And like an above poster said, just because your emissions test is cleaner DON'T mean the engine is running cleaner and getting better milage.

Good info so far.

I was wondering if pulling the ECT sensor connector (to show the ECU a -40 temperature) would advance the timing enough to overcome the smoke caused by the possibly worn injectors? Of course, this would depend on if you are the one in the cab running the throttle during the test AND if pulling the ECT connector results in a MIL lamp...

While we are talking about this, he may also have a stretched timing chain which would retard injection timing over time. If he performed a TDC offset on the engine (with a Tech II or other scanner) maybe that could clean up the exhaust enough to pass with the worn injectors...

Regards,

OK, so the PMD is still on the pump, I have been reading all around this site about the different resistors, what would happen if I put a lower resistor in? Could that help? I will probably have to pull the nozzles out and check them to see what popoff pressure is, should it be about 1700 with good chatter? Been a really long time since I've worked on these things!!! Also, if I did a TDC offset or timing adjustment what is the recommended TDC offset for lowest emissions and for best power? Thanks!!! OH, by the way, wastegate is working properly but I will try to wire it closed and see if I can burn some out of the exhaust!

The resistor won't do anything on the opacity.

My suggestion is to get a good fuel additive (Amsoil, Stanadyne or Schaeffer) and clean the injector first.

If you have access to BioDiesel, put B-100, drive it around for at least 100 miles. Change the fuel filter after that, should be good to go.

May be you can just use B-100 and pass it.

Cut a couple of quarter sized holes around the exhaust so not as much goes through the equipment and hope you get the same gal who doesn't know what she is doing and wont noticed anything.:D

Cut a couple of quarter sized holes around the exhaust so not as much goes through the equipment and hope you get the same gal who doesn't know what she is doing and wont noticed anything.:D
better to put stacks on, she won't be able to find the exhaust.:eek: and i'd think pulling the ect sensor would cause a ses light. here in bc they plug into the obd connector. my test was 1.95% in 2004, 2.59% in 2006 and last month it was 4.58 keeping in mind this last test was with the hp4 t/m and new HO injectors. Ed

Someone here in a thread not too long ago claimed they passed the test with a 25% kerosene fuel mixture. They were were having similar issues with opacity.

If you are getting ALOT of smoke the first thing I would do is pour in about 12 ounces of LUCAS INJECTOR CLEANER !!! It works !!!! Within 5 minutes you will notice about 90% of the smoke is gone.