DPF Filter Load - What do the numbers mean?

[Dale_K]

I don't know what it means. I just thought it was cool, lol. I think the link does include the actual units of measurement the original poster asked about. I believe the soot load is in grams per liter.

[spoolin'up]

This is a really great thread.

Someone else mentioned that there must be a time related regen, I'd have to agree this is the case. I started driving a pea-shooter to work, and now I notice if the truck has sat for a while mileage will be horrible for the 1st half hour. If it hasn't run for a while, it will try to regen every time.

Now someone else mentioned that the ECU is calculating 'estimated soot output' and forcing a regen 'because it thinks it's time'.

So here's my question: Knowing that there are (or at least might be) situations like this, how can the guys selling fooler boxes be claiming that their boxes eliminate all regens? I can see how using sensor input they might be able to reduce or eliminate some of the regens, but if some of the stuff I read on this thread is true (you guys sure sound like you know what you're talking about,) it seems there would be no way to eliminate all regens, especially if the computer is trying to be that sneaky about it. The estimated soot buildup I'm not sure of, but I'm fairly certain (just from watching the over head MPG readout) that a time based regen does exist.

Do any of the 'black box' guys have any comments?

[slagburn]

The 1st gen DPF delete kits keep the ECM supplied with high EGT data which probably prevents regens due to either the ECM thinking that passive regen is occurring or that the EGTs are simply too high for a regen cycle to run safely.

[spoolin'up]

Originally Posted by slagburn

The 1st gen DPF delete kits keep the ECM supplied with high EGT data which probably prevents regens due to either the ECM thinking that passive regen is occurring or that the EGTs are simply too high for a regen cycle to run safely.

The second part of what you said makes sense. If there's some sort of 'time based' or 'soot counter' that triggers a regen no matter what the sensors say, the ECU might want to regen, but if there's a safety feature to try and prevent 'china syndrome' then maybe excessive EGTs will prevent it no matter what.

[LSmith]

1st Gen DPF delete kits will also throw a soft code every now and then too...they are not "Code Free". The time based Regen may be the culprit causing the code. The ECM wants to regen, but can't "safely" (or so it thinks) and sets a code. Make sense to me.....but then again if it makes sense, that probably isn't how it works!!

[rbisch]

Installed 4" H@S TBE back in February along with Insight. Have now driven 12,000 miles with this system. LST regen now reads 1,423,751 and RG filter is at 43.4.
If I do not clear codes before start up the check engine light comes on within a few minutes and the stupid useless dinger will ding about every 5-10 minutes. Most of the time I drive with the CEL on and listen to the dinger. Seldom check to see what codes have been activated. Just not interested.
Have come to the conclusion that all these sensors and wires to them cause more problems and create more aggravation then they do any good.
Improved MPG has now paid for the H@S system.

[circ1977]

Originally Posted by spoolin'up

This is a really great thread.

Someone else mentioned that there must be a time related regen, I'd have to agree this is the case. I started driving a pea-shooter to work, and now I notice if the truck has sat for a while mileage will be horrible for the 1st half hour. If it hasn't run for a while, it will try to regen every time.

Now someone else mentioned that the ECU is calculating 'estimated soot output' and forcing a regen 'because it thinks it's time'.

So here's my question: Knowing that there are (or at least might be) situations like this, how can the guys selling fooler boxes be claiming that their boxes eliminate all regens? I can see how using sensor input they might be able to reduce or eliminate some of the regens, but if some of the stuff I read on this thread is true (you guys sure sound like you know what you're talking about,) it seems there would be no way to eliminate all regens, especially if the computer is trying to be that sneaky about it. The estimated soot buildup I'm not sure of, but I'm fairly certain (just from watching the over head MPG readout) that a time based regen does exist.

Do any of the 'black box' guys have any comments?

well, there is ways to prevent active regens, if you read thru this thread i said how this can be done. the reason disabling temp sensor 3 prevents active regens is to prevent damage to the catalyst's and dpf if a excessive temp condition were to arise.bill, we do not always replace the doc/nac they are supposed to be visually inspected before replacement. but in the real world alot of tech's just throw both on at the same time reason being when the dpf gets full enough to cause a no start condition sometimes the soot will start backing it's way up into the nac as well.

[BillG]

So we just need to wire a switch into the EGT3 sensor to lock out regens. Works for me.

I've been on a long road trip across the country, and the info has been interesting. I'm used to being at low altitudes on the east coast, and the EGR is almost always at 94.9% when the truck is not under load. However, I noticed that at altitudes >7000ft, it will restrict it to less than 10% EGR even at idle. That creates more ideas for electronic limitation. Wonder if that's just a lower O2 level?

My truck got broken into on the road. Stole my edge and elm based scan tool. Got about $1600 worth of stuff! My kid thinks he was hurt worse, though, because they took all is Nintendo DS games. ;(

[LSmith]

Sorry for the loss there Bill. Might have been better off if they took the whole truck!!

As for your observations on the amount of EGR -- so if the O2 sensor "thought" there were less oxygen, it would limit the flow though the EGR valve??!! That seems way too easy, but it may work and it makes perfect sense. The engine has to have a minimum amount of oxygen to run. Wonder what would happen if you just unplugged the O2 sensor in the intake? Better yet, put a resistor in series with the O2 sensor and allow it to function with the the varying conditions, but basically it exaggerates what the ECM sees as EGR (or lies about the actual amount of oxygen -- take your pick!).

[BillG]

Definitely worth experimenting. What would be the drawback of the ECU thinking there was less O2 than there really is? A too lean mix?

Something else of interest. Up to the point where my monitoring equipment was stollen, I would always drop to 55mph during a regen, and I never let my filter_load get over 4. After a good regen, the soot pressure delta would be 0.1 at idle.

But, when my stuff was stolen, I had to drive 900 miles over two days with no idea about regens. I just drove 75-80mph steady. Then, I got another Elm based device to work with the software I'm working on, and when I first hooked it up, I was horrified. My filter_load was 5! And my soot differential was 0.3 at idle. The first successful regen (at 55mph) brought everything back to normal, but it shows me that without knowing what the truck is doing, you don't have a chance at keeping it happy unless you just drive 55mph on the hwy all the time!

[LSmith]

What would be the drawback of the ECU thinking there was less O2 than there really is? A too lean mix?

Possibly. So what may actually happen is the ECM tries to adjust the amount of fuel to match the amount of "measured" oxygen. Low oxygen measured so we get less fuel. In your case in high altitudes, the EGR was lowered to allow more oxygen in a less dense environment, but the measurement was accurate so the actual Fuel/Air ratio was correct.

But when these guys remove the EGR and butterfly, the engine seems to respond with enough fuel to run properly -- but the O2 measurement is still accurate. So it may not be a feasible work around.....

[Dale_K]

From a tech article on Bosch diesel engine controls... Link to full article..

http://autospeed.com/cms/A_108105/article.html

"As with petrol management systems, diesel management system use oxygen sensor closed loop control. However, in diesel systems a broadband oxygen sensor is used that is capable of measuring air/fuel ratios as lean as 60:1. This Universal Lambda Sensor (abbreviation in German: LSU) comprises a combination of a Nernst concentration cell and an oxygen pump cell.

Because the LSU signal output is a function of exhaust gas oxygen concentration and exhaust gas pressure, the sensor output is compensated for variations in exhaust gas pressure. The LSU sensor output also changes over time and to compensate for this, when the engine is in over-run conditions, comparison is made between the measured oxygen concentration of the exhaust gas and the expected output of the sensor if it were sensing fresh air. Any difference is applied as a learned correction value.

Closed loop oxygen control is used for short- and long-term adaptation learning of the injected fuel quantity. This is especially important in limiting smoke output, where the measured exhaust gas oxygen is compared with a target value on a smoke limitation map. Oxygen sensor feedback is also used to determine whether the target exhaust gas recirculation is being achieved. "