Emissions failure - Opacity too high. HELP!

[MarkMorissette]

Hey everyone. Well, I took my trusty 6.5TD in for it's emissions test today and it failed.

Allowable opacity is 30% for a pass and it blew 47, 49, and 51 respectively on the snap tests.

Of course the first thing that came to mind was the IP, but I called Kennedy Diesel (where I bought my injectors from a few months back) and spoke to one of the guys there. He doubted that this was the problem (it's not setting a code and runs perfect otherwise) and suggested a few options including a boost controller to max the boost for the test itself.

So, first, what's causing it?

- My air filter was cleaned only a few months ago. Perhaps it could use a cleaning again (it's a K&N Cone) but I can't immagine that's the root cause for such a major blow-over.

- My turbo is making lots of boost. On hard acceleration (onramp, for example) I routinely see 13-15 PSI of boost on the gauge before the waste-gate opens (noticeably) and it drops back to a sustained 8-9'ish PSI of boost. At cruise it maintains about 3-6 PSI of boost with no problems.

- Wastegate is functional (see above).

- Engine has 8 brand new AC Delco injectors that were just installed a month or so back.

- Oil has about 3000 Kilometers (1800 miles) of mixed city and highway driving on it. Not terribly old, but would it make that much of a difference?

- It was up to temperature (well, as much as it will get up to no load in this mornings cool weather) before I took it in.

- Fuel filter is anyones guess...I've never done it, and I don't know when the previous owner did, so it's at *least* a year old, potentially more...however, this wouldn't cause an overfueling/opacity issue, would it? Logic would seem (to me) that this would result in an under-fueling condition, not over fueling.

Now, admittedly, I drive this thing like an old fart, especially with todays diesel prices. Not since last summer have I ever "matted it", and even towing I rarely exceed 2100RPM or so, letting the torque do the work instead. Even highway onramps are usually dealt with gently.

A few week ago while towing the engine temps came up a bit, but still not even 1/4 of the way up the guage....so it's been a long while since it was hot.

Any guesses based on that info?

Now, as for a band-aid solution, Googling things today I came up with:

1/ Provide full-time vacuum to the wastegate solenoid for the test so that the gate stays firmly closed. Extra boost for the E-test should help?

2/ Run #1 diesel. (Tough to get in my neck of the woods based on todays phone calls).

3/ Bring the fuel level down and put in 10 gallons of kerosene along with lots of lubricity additive. Run E-test, then refill with regular diesel.

4/ Remove/gut the cat. (It must be present for the Ontario E-Test, so I'd have to gut it or put in a dummy, not just remove it...)

Thoughts anyone? We're 15 days away from a 10,000 Kilometer trip with our RV and this is the absolute last thing I needed to deal with right now! Ahhhhhhhhh! :(

Thanks!
Mark

[More Power]

Make sure the engine and drivetrain are at operating temperature right before the test is performed.

If you have a remote mounted PMD, you could install a #1 resistor then do a re-learn.

If you're using a custom programmed PCM, get a stock programmed PCM to swap into it for the tests.

Jim

[MarkMorissette]

Make sure the engine and drivetrain are at operating temperature right before the test is performed.

If you have a remote mounted PMD, you could install a #1 resistor then do a re-learn.

If you're using a custom programmed PCM, get a stock programmed PCM to swap into it for the tests.

Jim

Hi Jim;

Getting the drivetrain up to temperature is tough, especially the engine - my 6.5 is tough to get warm, much less hot - it's always been a cool runner. Short of hooking up my 5th wheel and blasting around town with plenty of WOT stops and starts I'm not sure how I'd get it much hotter then it was at the time of the test.

I do have a remote PMD and had considered the resistor issue - I've no idea what's in it currently - is it easy to tell? What's the easiest/quickest place to source a #1 from?

As for the PCM, I've no idea at all - I've no reason to believe it's anything other then stock, but again, I can't confirm it's not aftermarket either - what's the best way to tell?

THanks
Mark

[Hubert]

Fuel additive cetane booster. Brand new paper air filter.

Healthy injectors? 4 new are 4 old? For the snap test you don't build a bunch of boost I don't think. Its a snap test to see how much soot you puff on zero to max throttle. If turbo waste gate and control is working you should be ok.

Injector spray pattern, timing, fuel quality, and air are most important to snap test. So the technician can affect test if they floor it really fast.

Gutted cat would help. Drive it hard to get EGT high and clean the soot trap out some might help with better air flow.

[MarkMorissette]

Fuel additive cetane booster. Brand new paper air filter.

Healthy injectors? 4 new are 4 old? For the snap test you don't build a bunch of boost I don't think. Its a snap test to see how much soot you puff on zero to max throttle. If turbo waste gate and control is working you should be ok.

Injector spray pattern, timing, fuel quality, and air are most important to snap test. So the technician can affect test if they floor it really fast.

Gutted cat would help. Drive it hard to get EGT high and clean the soot trap out some might help with better air flow.

All 8 injectors are brand new - sorry, that was a mistype on my original post.

I don't have the original airbox so putting a stock paper filter isn't possible short of going to the scrapyard and buying an airbox - and scrapyard 6.5's are tough to non-existant to find. Versus a K&N that breathes freer then a paper filter, is this really going to be beneficial though?

Thanks
Mark

[DmaxMaverick]

Or.......

A discrete throttle stopper under the pedal. It would limit your WOT to whatever you desire. If it sounds like WOT, that's what it'll be on the snap test. The results may depend on where in the range you are getting the bulk of the opacity.

I've also hear the biodiesel helps, but I can't confirm it.

[MarkMorissette]

Or.......

A discrete throttle stopper under the pedal. It would limit your WOT to whatever you desire. If it sounds like WOT, that's what it'll be on the snap test. The results may depend on where in the range you are getting the bulk of the opacity.

My truck classifies as a medium duty truck (over 4500 Kilograms triggers this in Canada) so I'm forced to get the test done at a heavy duty truck center that normally deals with class 8 and down.

They're wise to that sorta thing and I don't think it would fly very far. :-)

[Kennedy]

Fuel filter is a must do. It can cause smoke.

Take it out for a flog with the trailer on. Since you drive like an old fart, it's probably pretty sooted up.


I still say that there has got to be someone with #1 diesel around...


What year was this again? 8th digit of the VIN F or S?

[DennisG01]

Getting the drivetrain up to temperature is tough, especially the engine - my 6.5 is tough to get warm, much less hot - it's always been a cool runner.

Change your stats. It sounds like your running too much on the cool side, anyway.

[MarkMorissette]

Fuel filter is a must do. It can cause smoke.

Bought a new one today, will replace before the test again.


Take it out for a flog with the trailer on. Since you drive like an old fart, it's probably pretty sooted up.

I think I'll go pickup the trailer and haul it around town just before the test..this is the only way I have any chance of getting the engine hot as just driving around town just doesn't build up much heat.

I did get two new T-stats today and will get them in before the retest, but I'm still not confident I'll be able to get it really *hot* without a load.


I still say that there has got to be someone with #1 diesel around...

I picked up 20 Litres (5 gallons) of #1 diesel today. Tough to find, but found some.


What year was this again? 8th digit of the VIN F or S?

Vin F. (Why out of curiosity?)

So, here's the plan - Install new thermostats, replace fuel filter, mix the 5 gallons of #1 with about 5 gallons of regular #2 diesel, bypass wastegate with full-time vacuum for the duration of the emissions re-test, get it as hot as I can, and get the test done. Am I home free with this plan?

Thanks for everyones help!

[MarkMorissette]

I went out this evening and confirmed operation of the wastegate. Disconnected from vacuum line the actuator lever is very free (no signs of obstruction in the turbo) and once reconnected to vacuum it's impossible to move again so the actuator (and vacuum) seem perfect.

I'll assume that the wastegate is *closed* when vacuum is applied and the plunger is pulled upwards, correct? If I simply wanted to wire the wastegate open (avoiding bothering with replacing vacuum lines temporarily for the E-test) I should just wire it so that the wastegate actuator stays in the UP position, right?

Will a few wraps of mechanics wire do the trick?

[a5150nut]

Will a few wraps of mechanics wire do the trick?

I'm sure it would. But I doubt it would pass inspection. Even crosssing the vacume line is risky. don't they check for these things? :eek:

[JohnC]

OK, I'll bite. Why would you want to wire it open? Just pull the vacuum line off and the exhaust gasses will blow it open. That's how it opens normally. This will give you nearly no boost.

The turbo has little to do with a snap test anyhow as the test is over before the turbo has a chance to spool up.

An EFI truck that fails a snap test has something else going on, unless it's chipped to the max (maybe).

[MarkMorissette]

OK, I'll bite. Why would you want to wire it open? Just pull the vacuum line off and the exhaust gasses will blow it open. That's how it opens normally. This will give you nearly no boost.

The turbo has little to do with a snap test anyhow as the test is over before the turbo has a chance to spool up.

Er, I meant to say "Hold it closed", not open.

The actual snap is maintained for about 5 seconds so there's plenty of time for the turbo to spool. I believe that the actual test metering is averaged over the duration of the actual snap so if the turbo spools dramatically (due to the forced closed wastegate) and signifigantly decreases opacity at that point it would be beneficial.


An EFI truck that fails a snap test has something else going on, unless it's chipped to the max (maybe).

And your suggestion would be? I'd love to have one thing to point the finger at but am coming up empty so far besides what's been discussed in this thread to date.

[MrDiesel]

You say you have to take it a shop that does larger trucks to get yours done? If so try taking it to a different shop, I have worked at Highway truck shop for a while now and have heard many stories of drivers taking their trucks to one dealership and failing the test then taking it to another where they pass no problem. Depending on how bad your truck smokes it may just be a shop trying to get an engine job out of the deal. Try taking it to another shop and see if you get the same result. Just a suggestion.

[JohnC]

When you stomp on the throttle with no load on the engine, the fuel rate is at maximum only until the engin reaches the governor speed, at which time the fuel rate drops dramatically, to neat the idle rate, since it doesn;'t take much fuel to run an unloaded engine at 3400 RPM. At that point the turbo is moot; normal aspiration provides way more than enough air. If you can't pass at this point I'd look at the air filter, the injectors or EGR if equipped.

If it fails because of a puff of smoke in the brief moment between stomping on the pedal and reaching governor speed, and it's not overfueled because of a chip, it could be the same things, or you can try to mash the pedal a little more slowly.

Either way, but the time the turbo spins up it's too late...

[jggiedeman]

My father-in-law drives his 93 C3500 like an old fart also. He is one but a pretty cool guy. He failed his emission test in Boise last year. The dealership wanted to replace injectors, the IP, etc. I told him to run it down the highway in 4th and keep it there around 2800 rpm for at least 15 minutes before the re-test. Worked like a champ and his levels were back down to to 93 levels. Can't baby a creature that likes heat to operate porperly.

[MarkMorissette]

If it fails because of a puff of smoke in the brief moment between stomping on the pedal and reaching governor speed, and it's not overfueled because of a chip, it could be the same things, or you can try to mash the pedal a little more slowly.

Having observed the exhaust during the test (and having experimented since) I've noticed that the smoke seems fairly consistent at high throttle when under load.

For example, when I was driving home last night coming up a moderate hill I floored it and there was a noticably steady stream of black smoke. Not heavy, not even moderate IMHO, but present enough to see it.

I've done a few unloaded snaps since (man, I hate revving that high) and still observe smoke, but again, not terribly heavy IMHO.

Thinking back to the test there was some pretty signifigant plumes of smoke on the snaps (that's when my heart dropped as I suspected I was in for a failure before I even got the test results), but that was the first time it was run to the governer (or even much above 2300RPM, as I mentioned earlier) in over 6+ months. It's very likely that this was a ton of carbon and such simply blowing out, something that I didn't expect.

The new fuel filter and two new thermostats are going in tommorow. We're taking the 5er camping on the weekend and I'll get things hot and drive the snot out of it. When I get home I'll see how it behaves then.

The only thing I haven't checked at this point is the ECM...I've no reason to believe it's chipped (horribly expensive on the 97's I've learned since it's a non-removable PROM) but I will admit I haven't checked it - where is it located on the 97's? I'll take a look at the PROM and see.

[MarkMorissette]

Can't baby a creature that likes heat to operate porperly.

With Diesel having been as high as $1.46/Litre recently ($5.40/Gallon for the Americans here) you may reconsider that statement. I drive it like an old fart because I'm trying to squeeze every possible MPG out of it, not because I wouldn't rather honk on it at every intersection. :-)

Diesel is dropping now (about $1.36/L, or $5.10/Gallon) but it still hurts for a while after a fill up.

[AKMark]

I paid $5.29 the other day here in California, I have been taking it as easy as possible as well.

However, I do try to find the proper time to romp on it once in a great while to clear the engine out. It does seem to appreciate it, although I wish it wasn't as painful at the pump.

[JohnC]

The convertor may be full of soot. A good hot run will help here.

There's no physical change to the ODB II PCM's; it's all software. If you have a scanner, see what it gives you for a maximum fuel rate. Also, just for grins, see what it gives you for a fuel rate when it's running against the governor without a load.

[MarkMorissette]

Well, following up.. Got the 2 new thermostats and the new fuel filter installed today - dramatic difference already.

The engine is now running at a much higher temperature even just around town. I think I had significantly underestimated how bad the old thermostats were (Clearly one or both were stuck open) and how cool the engine was actually running as a result. With the new Tstats it now runs routinely at temperatures I was only seeing before when pulling our 5th wheel.

Also, the new fuel filter has seemingly also contributed towards an improvement.

A few snaps this evening and I noted:

1/ Much less smoke at the beginning of the snap, just a small puff before WOT is reached.

2/ No smoke at WOT.

3/ Again, a small puff of black smoke when going from WOT to idle again.

I'm going to do quite allot of driving tomorrow with the AC on (weather is forecasted to get miserably hot so things will get heated up) and then observe the exhaust again through the day.

Could it be that these two simple things were the largest root of my issues?

[AKMark]

Yes, and it's the simple things that give the most grief from time to time.

[MarkMorissette]

Ok, got it hot this morning and checked things out some more.

Still get a decent puff of black smoke at the beginning of the snap but then the exhaust clears up to only the occasion noticable whiff of black smoke while it's held at the governor.

Does this sound normal to everyone, or should I still not be getting the puff of black at the onset of the snap?

[Hubert]

A little diesel puff of black smoke just on initial pedal punch is normal and varies with age and health. Its hard to quantify visually over the internet. Sounds normal. Post up your new snap test opacity numbers when you retest.

[Kennedy]

I think you'll be in good shape come the next test attempt.

[MarkMorissette]

OK, Following up! Retested it this evening. Engine was hot, prepared as best as I could and crossed my fingers.

Good news: It passed.

Bad news: It passed by only .1 of a percent. Yeow! Allowable was 30 percent, and the average of 6 snaps was 29.9. Yes, a pass, but not a great one.

There was a decent swing between snaps...the highest was 32, I saw one as low as 20, and most were in the high 20's on average. Still a big improvement versus the 50's averages I blew last time, but 29.9 average is still up there.

I never did put in the #1 diesel as I figured I wouldn't need it, and I had just filled the tank on the truck a few days earlier before Diesel was scheduled to go up by 10c/Litre (.39/gallon) overnight. I had ran it down close to empty in preparation for adding the #1 and doing the retest, but with the prospect of a fill up costing $15 more (>$155!) the next day (and not figuring I'd need to bother with the #1 after having seen a vast improvement) I figured I'd skip it. Turns out I could have used it after all.

Anyhow, the good thing is that it passed and I'm good for another year. The bad is that apparently there's still an underlying issue somewhere causing these marginal opacity numbers and I'm going to be fighting the same fight this time next year.

[Hubert]

Has the numbers been creaping up over the last few years? I'd say just age issues the soot trap is probably getting restrictive and one of biggest contributors then timing chain wear (and timing variance) maybe.

I saw a pretty big improvement (reduction) in smoke on acceration and pedal punch with my new exhaust then performance declined slowly. I saw another big improvement when I did my injectors but now my diesel puff is again slowly getting worse. I am pretty sure its the timing chain and some IP wear and precise fuel metering performance decay in my case.

Now can't remember your earlier posts but a good regular dose of fuel injector cleaner as a maintenance thing at least (along with good fuel practices ) and with regular filter changes also helps keep smoke to a minimum.

[Kennedy]

I think you will find that a good free flowing exhaust with a "ghost cat" will work better yet.

[damork]

I give my vote to the timing chain being a bit stretched. I ordered the DSG gearset from Kennedy and installed them in my Yukon when it had 160,000 miles and it would smoke from time to time before I did that. After the gears were installed I could never get it to smoke unless I really pulled it hard, and I mean hard. It also had a BD "Race" chip in it at the time which usually made it easy to make smoke but the gears really made it burn that fuel. It was still running super clean when I sold it at 258,000 miles.