Timing vs Power

[6.5L]

I have been wondering if I am not running a slight amount of too much advance on my motor. Right now, I am about 3ish ticks mark advance on my DB2-4911. Isn't every tick mark width about 2 degree's? So like maybe 6* or so advance. Would going to about 3-4* advance help my turbo spool any sooner/quicker and reduce smoke levels? Just wondering?

 

[Slim Shady]

I have been talking (actually asking questions) with some people that do some professional (factory tuners) tunning for diesel trucks, They have a lot of experience with tunning for power and they tell me that just dumping fuel to a diesel doesn't constitute tunning, however they did say that unless you had some type of altitude compensation and fuel feed back system to let your PCM know that you are over fueling all diesels will smoke with the fuel turned up. Also told me that the smaller turbos tend to mask the smoke. I don't really know but seems that without some type of feedback from the intake and exhaust stream we are not much better off with a DS4 pump and probably a little better off with a manual pump.

If you mash the pedal on the gm obd 1 and obd 2 do you get fuel fuel the max the pump will put out the minute the APP sees full throttle.? Is there a way to tune the truck to not smoke? I suggest that the tuners can make any truck smoke and that just giving it more fuel does not make power, hence some tuners that don't know or never have run a set up can make the truck run poorly just by tunning it improperly, from not knowing or make the truck run poorly just because they may not recommend a set up. I know KOJO has obd 1 and obd 2 tunes that smoke less and have power because he has run and tested the truck and made adjustments to the tune while driving the truck for a particular set up. There are others that tune well also but some tuner's tunes seem to smoke more than others, is this a tuner issue?

Speaking with a tuner for GM regarding the 6.5 diesel he stated that data logging over many months and then running computer simulations with that data is how they get a good starting point for a tune. One that gives drive-ability and fuel economy with good emissions. I know for a fact the fuel delivery systems on these systems are not just a progressive linear fuel line, they have hills valleys and peaks that make the fuel curve. Any programmer thoughts on this?

Sorry Big T don't mean to derail your thread but if there was tunning that limited fuel to just enough to make power but not smoke wouldn't that be the way to tune? I guess the Dodge guys didn't get the note because I see them laying down big smoke a lot. Most of them don't find it offensive, at least I don't think so.

 

[Slim Shady]

I know advance gives more power at lower rpm but is there a fine balance between to much advance and to little power. Example, generator set 6.2 diesel rpm regulated electronically to 1800 rpm no matter what the load is. Fuel is given to manual pump by electronic solenoid that cycles faster than the eye can see. So rpm is regulated by fuel only. now at 0 degrees TDC the engine had plenty of power and any load applied did not make much of a change in the rpm. same load same fuel setting advancing the timing to 2 degree BTDC gave better response and fuel economy. Same settings advance now at 4 degree and fuel economy went up slightly but any big load and the engine labored more and smoked. Advance to 6 degree and any big load made the motor slow and labor noticeably. So best setting for power and fuel ended up being three degree before TDC at 1800 rpm. The timing was measured with a MT 480 luminosity probe.

Also finding that what is called timing on the DS$ pump is not necessarily what is being seen correspondingly with a Luminosity probe.

 

[6.5L]

So what you are saying is maybe turning it back to 2ish tick marks advance would be a little better?

 

[great white]

I'm interested in any and all conversations you have had with factory programmers....

 

[WarWagon]

How does it Sound? Do you "Feel" the cold advance kick off under light throttle as a loss of power? Does the black smoke go down with the Cold advance off?

Heath's blog or calls to em say at 45 MPH with no to little throttle bring on throttle and heat to the precups. The diesel clatter should quiet down. This is proper timing by ear.

Advance = Black Smoke.
Retarded timing = White smoke.

Common to retard timing for high altitude. Or was for 6.2 NA engines in Colorado to cut black smoke. Overdoing this would smoke white a common complaint back in the day in Colorado after timing was reset.

A good read about 6.2 timing including your 1993.

http://www.oliverdiesel.com/tech/timing.htm

FWIW the tick marks mean nothing for timing as you can loosen the nuts and re-tighten them to get a different reading without moving the pump. Line to line timing and the sticker mean line of IP to Line on cover. It isn't very accurate.

 

[6.2 turbo]

Less timing makes a huge difference in turbo drive pressure. I'm trying very hard to get my timing right ,through the entire rpm range. Not happening.

 

[great white]

..... Also told me that the smaller turbos tend to mask the smoke....

I would say it has to do with the transient response of a smaller unit. I guess in a round about way it can mask too much fuel by providing enough mass at the throttle setting demanded.

Bigger or stock turbo choices depend on what your goals are......

If you mash the pedal on the gm obd 1 and obd 2 do you get fuel fuel the max the pump will put out the minute the APP sees full throttle.?

Maybe, maybe not. It's not as simple as dumping in fuel. Depends on what variable fall into what position on the tables that come into play. So, while you may call for WOT, you may not get the maximum 79.9 mm3 the programming is limited to. Chuck in timing, temperatures, pulse width, etc and things get even more complex.

I've dialed timing out as boost comes up. I've yanked out fuel in some cases. There's general rules, but there's just no substitute for a data logging run in actual conditions.

Is there a way to tune the truck to not smoke?

Yup. Mine doesn't smoke anywhere except a puff at start. The most I see with either my own program of the Heath PCM I have is a barely perceptible haze and I have to be on it really hard and heavy to get that. You can deal with "smoke" with more than just the fuel variable.

I suggest that the tuners can make any truck smoke and that just giving it more fuel does not make power, hence some tuners that don't know or never have run a set up can make the truck run poorly just by tunning it improperly, from not knowing or make the truck run poorly just because they may not recommend a set up.

Agree.

In extreme cases, they can damage the engine.

I know KOJO has obd 1 and obd 2 tunes that smoke less and have power because he has run and tested the truck and made adjustments to the tune while driving the truck for a particular set up.

That's the way to do it. Unfortunately, "tune in a can" is what you get unless you can have the truck on the spot tuned. Most "tuners" get close enough that the last little bit isn't really needed. That goes for all the EFI/duramax guys running around out there too. There's some really good guys and some guys that should step away from the laptop....

Now, if you have something really custom.....well, you need a guy local or learn to do it yourself.

There are others that tune well also but some tuner's tunes seem to smoke more than others, is this a tuner issue?

Pretty much, barring a mechanical failure of some sort.

Speaking with a tuner for GM regarding the 6.5 diesel he stated that data logging over many months and then running computer simulations with that data is how they get a good starting point for a tune. One that gives drive-ability and fuel economy with good emissions. I know for a fact the fuel delivery systems on these systems are not just a progressive linear fuel line, they have hills valleys and peaks that make the fuel curve. Any programmer thoughts on this?

Nothing other than; "correct on all points".

Where power is often found is the "good emissions" point the OE's achieve in conjunction with power and fuel economy.

NOx is often traded off for hotter burns. Many other hydrocarbon emissions are also mucked around with.

Not that they all do this, but it's difficult and expensive to work up a tune to make more power and maintain fuel economy/emissions.

It's all a trade off, that's why OE's programs come out of the factory the way they do.

There's so many factors to consider: crank angle, burn time, propagation, throttling losses, etc, etc......the more I learn, the more I can't believe they ever find a point to even start from...far better at it than I am (OE's that is).

The other trade off is longevity.

Gotta make it last until the warranty runs out.......

That's just my opinion/outlook, I sure don't have all the answers so I'll sum up with a standard "YMMV" and check it out real good before you drink that Kool aid......

 

[6.5L]

Well witht he cold advance on it sounds pretty clanky. With the cold advance on, there is a barely noticable haze when I first start it cold then it goes away as it warms up, then the cold advance kicks off. It is pretty responsive but still, I think it is just slightly too advance? What do you guys think I should do. I live every summer at 5000ft and work at 6000ft.

 

[WarWagon]

Advance = Black Smoke.
Retarded timing = White smoke.

Common to retard timing for high altitude. Or was for 6.2 NA engines in Colorado to cut black smoke. Overdoing this would smoke white a common complaint back in the day in Colorado after timing was reset.

I am going to correct myself here as my memory from 1991 is backwards. The timing is advanced for high altitude.

Reference timing numbers that are hard to come by:
http://www.gm-diesel.com/vbull/non-turbo-charged-diesels/20692-5-7-4-3-olds-diesel-faq-13.html

 

[buddy]

I absolutely dont like normal driving with a whole lot of advance, as I dont like the extra engine noise that sounds like strain to me. It can hurt turbo performance and with high IAT cause too much combustion before TDC and you start working against yourself. But a good amount of advance helps at low RPM with no boost. There is a big difference on a DS4 programmed around 5 degrees (cam referenced) and 8 degrees at and around idle. The more advance from there has less return, but still get a little more punch from 9-11 degrees, and it also helps low idle fuel rates to go down a tad, better idle AC performance. Those are programmed numbers.

I would be interested in knowing how a timing measurement device compared to the scanner reported timing. I would guess somewhere between whats reported and double that, to correlate to crank timing versus cam timing that is reported.

 

[6.2 turbo]

Whats the highest total advance you ever tried ? I think what your seeing on the scanner is crank degrees,because 8-11 will give me a nice idle. That's using a gas timing light,and an adapter on #1 injector line.

 

[buddy]

I know its cam referenced, its defined that way in the code, and the scanner also gives an actual IP injection pump timing which does report 28 degrees and up. The actual IP timing is always at least what it was set at with TDCO, and goes past that once the stepper motor takes it higher. So actual IP timing doesnt decrease when the stepper retards injection, but increases when stepper brings it over. That is also why people think setting the TDCO around -1.94 is advancing base timing from 3.5 to 8 degrees. Because youre really just advacing it from 7 crank reference (3.5x2) to about 8 crank reference (~4ishx2). On the scanner its a change from 3.5 to 4. Actual IP timing at idle is -25.7 degrees + TDCO value. The TDCO value is a crank degree value of how far it is physically set away from 25.7 degrees advance.

 

[6.2 turbo]

So 8 at idle is crank degrees,and already taken x2.

 

[buddy]

Oh no, sorry, if you havent ever had to do a TDCO learn it might not be clear. The TDCO learn is when stepper is told to step as low as it can and timing is measured for a "base" timing. Idle timing is set in the program based on RPM and fuel rate, so when I set it to 8 its actually 16 crank degrees. When base timing is at 8 crank degrees in "Time Set" of the timing procedure then the scanner will display 4 degrees, which is right in the TDCO area of -1.94 to -2.18 or so. The TDCO and base timing has nothing to do with idle timing, because we can program it to advance to whatever we want it to be.

But our programmed timing may not compensate for time to send the command from PCM through the PMD, the metering valve close and pressure build to pop the injector. Thats where if someone has measured timing with a device and compared it, that info could be useful in this discussion.

 

[Big T]

I have been talking (actually asking questions) with some people that do some professional (factory tuners) tunning for diesel trucks, They have a lot of experience with tunning for power and they tell me that just dumping fuel to a diesel doesn't constitute tunning, however they did say that unless you had some type of altitude compensation and fuel feed back system to let your PCM know that you are over fueling all diesels will smoke with the fuel turned up. Also told me that the smaller turbos tend to mask the smoke. I don't really know but seems that without some type of feedback from the intake and exhaust stream we are not much better off with a DS4 pump and probably a little better off with a manual pump.

If you mash the pedal on the gm obd 1 and obd 2 do you get fuel fuel the max the pump will put out the minute the APP sees full throttle.? Is there a way to tune the truck to not smoke? I suggest that the tuners can make any truck smoke and that just giving it more fuel does not make power, hence some tuners that don't know or never have run a set up can make the truck run poorly just by tunning it improperly, from not knowing or make the truck run poorly just because they may not recommend a set up. I know KOJO has obd 1 and obd 2 tunes that smoke less and have power because he has run and tested the truck and made adjustments to the tune while driving the truck for a particular set up. There are others that tune well also but some tuner's tunes seem to smoke more than others, is this a tuner issue?

Speaking with a tuner for GM regarding the 6.5 diesel he stated that data logging over many months and then running computer simulations with that data is how they get a good starting point for a tune. One that gives drive-ability and fuel economy with good emissions. I know for a fact the fuel delivery systems on these systems are not just a progressive linear fuel line, they have hills valleys and peaks that make the fuel curve. Any programmer thoughts on this?

Sorry Big T don't mean to derail your thread but if there was tunning that limited fuel to just enough to make power but not smoke wouldn't that be the way to tune? I guess the Dodge guys didn't get the note because I see them laying down big smoke a lot. Most of them don't find it offensive, at least I don't think so.

No worries Slim. I'm all ears on the tune discussion. The PCM in the '99 was custom tuned by Heath for the ATT.

As noted, both the '95 and the '99 in my signature smoked at altitude on low rpm acclerations. Certainly the '99 with the ATT smoked noticeably more, but the performance is so much better. The '99 will let out a puff of smoke on hard acceleration at sea level, but not a big deal at all. So far, it has always passed smog.

 

[Slim Shady]

Buddy, I have not gotten enough hard data on the discrepancies between the electronic IP in regards to the indicated timing noted on the scanner verses the actual start of combustion as noted on a luminosity probe timing meter.

I want to make sure it is not my configuration that is or could be causing the anomaly I noted, while checking the timing on my truck with the luminosity probe timing meter. I am also not sure how I am going to get the MT480 timing meter to ride in my truck and still be able to use the meter while driving. Leads are not long enough for that and time is something I don't have a lot of lately.

I would be interested in the reference you made to the map sensor and altitude compensation that may be available in the tuning program for the DS pumps. I think that is very interesting that gm put it in there but never used it. What else is in there?