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First, let me say you are doing an excellent job with your graphing. Lots of detail, the proper scales, easy to read lines, etc.... Top-notch work.
Second.... Holy carp! The system is defueling in a big way! I don't get that. Was the engine fully warmed up when you did this? I know a low EOT will stifle the fueling, to protect the pistons.
First, let me say you are doing an excellent job with your graphing. Lots of detail, the proper scales, easy to read lines, etc.... Top-notch work.
Thank you.
Originally Posted by Tugly
Second.... Holy carp! The system is defueling in a big way! I don't get that. Was the engine fully warmed up when you did this? I know a low EOT will stifle the fueling, to protect the pistons.
EOT at the time of the test was 194.
I've been bugged by my inability to generate black smoke under any conditions for a long time.
It seems as if the defueling is related to RPM. The first one from sample 5-15 seems to be faster than the one from 35 to 50. The RPM rise is faster in the first one as well.
Also the pulse width seems to cross back over at about the same point 2875 RPMs. I don't know if this means anything....
Hopefully my super zoomed in Y axis scales aren't confusing the issue....
Could the de-fueling simply be that the since the RPM are rising fast the CPU doesn't see a need for as much fuel per cycle?
Maybe I need a real load (tow the 8,000 lb trailer) in order to see what's really going on?
What are the the chances that the ECU was programmed for bigger injectors by the previous owner - are there any obvious signs I can look for to determine that?
Could the de-fueling simply be that the since the RPM are rising fast the CPU doesn't see a need for as much fuel per cycle?.... ...What are the the chances that the ECU was programmed for bigger injectors by the previous owner - are there any obvious signs I can look for to determine that?
If the truck had bigger nozzles at one time, the injectors drain in xyz milliseconds with zyx ICP - no matter the RPM. You have a defueling, but it's using a different method than I'm familiar with. When my stock tune defueled, it lowered the ICP - not the FIPW. This is a weird one, but maybe your stock tune is older/newer than mine.
After having a look at the MAP, I noticed this happened after you crossed "the line of death" for boost (not MAP) - 27 PSI. That's where one gets the SES light and an overboost code. A clue. If your BARO reads zero, this will happen. If a previous owner had a programmer and left the teenager tune in there, that could explain it too.
After having a look at the MAP, I noticed this happened after you crossed "the line of death" for boost (not MAP) - 27 PSI. That's where one gets the SES light and an overboost code. A clue. If your BARO reads zero, this will happen. If a previous owner had a programmer and left the teenager tune in there, that could explain it too.
The BARO looks good. I looked for drop outs to zero and didn't see any captured. The max boost using MAP-BARO is 15.73.
I did try calling the dealer to see if the computer has been flashed, but they were no help. It's only been there for recalls and to get a key programmed.
For recalls I think it was the CPS and the Brakes.
I'm not sure if the MAP value is the trigger. I marked up the chart in the two places where the pulse width started its dive. I would think that if the MAP value was the trigger that it would have stayed in defuel mode from the first dive. Does that make sense?
It's interesting that the defuel turned off with the shift. I also had OD off, so the 2nd defuel could be around where it would have shifted into OD if it wasn't off.
It seemed as if there might be some relationship between RPM and defueling. The chart below is interesting. I don't know if it's helpful. The chart seems to be saying that the CPU is trying to maintain a hard upper limit on the fuel usage. So as RPM goes up, the fuel available goes down:
f you look closely at the Injection Pulsewidth table, you'll see that by 70 mg/stroke of fuel mass that you are well over 3.00ms. Now take a close look at the Mass Fuel Desired tables and you'll notice something funny... the mass fuel desired DROPS as the RPMs increase. Hmmm, I wonder why? Maybe because as you get over 3000 RPM bad things start happening by commanding too much pulsewidth.
I can't claim to fully understand the details but it does seem to be consistent with what I'm seeing.
I need to rifle through my logs and look for this more closely. With the amplified scale, we may be seeing I haven't tagged before - or your tune is doing something unusual.
Here's another chart - towing. The red box is show the 1800-2800 RPM range. The red line at the bottom is showing a MAP of 30, for a boost reference. I REALLY wanted to get EGTs here but I had to send my PLX device back for repairs.
I made the red box because this is a more practical range for driving in 3rd gear.
Does anything interesting jump out in this chart?
I realize that ideally my max MAP should be closer to 31.5. I'm not yet sure how to get there. Maybe a combination of tired turbo and injectors or simply a missed leak.....
EOT was 212-214 for this test.
Also, still no smoke, no matter how hard I try. I should be able to at least get puff when I go to WOT right?
No smoke makes a missed exhaust or cac leak less likely right?
I dont know enough to interpret the graphs but am curious in your seat of the pants.
If it's defueling at high rpm, when pulling trailer have you noticed more power with TC locked up in OD vs. a downshift and high revs?
am curious in your seat of the pants.
If it's defueling at high rpm, when pulling trailer have you noticed more power with TC locked up in OD vs. a downshift and high revs?
I see more power above 2,000 RPM for sure.
I can't say that I've seen a power increase when going down from 3200 to 2700 or so.
The last time that I had a good opportunity to see something like that (long steep hills), I was driving by EGT gauge and could not really run with the RPMS above about 2200 for any length of time.
I don't (yet) know if my injector o-ring replacement has helped with the EGT issues or not.
I looked at some stock WOT logs with a tighter resolution, and I'm finding defueling at about 2700-2800 RPM. I think we can call it - revving high (above 2800 RPM) on a stock tune will rob you of power. I never saw that coming.
