IDLE issue revisited

[killerbee]

This is a prayer for help for a known problem that exists on every LLY. This one had a more prominent set of symptoms, while all LLY trucks have this issue to some extent. It has been discussed in other threads. This screen shot shows the fully warmed up idling truck, first in gear, then in Park/Neutral. The ONLY commanded change is main timing. The first half of the chart (-5.0 timing) is characterized by:

1. chugging white cold-smoke
2. idle rpm instability (lope)
3. 50-70% more fuel consumption
4. Failed emission test (8X opacity)
5. LOTS of dirty looks.
6. More "what's that exhaust smell in traffic" threads.

As soon as the truck is put in park (-1.0 timing), all these problems resolve, and smooth, clean, efficient, and economical operation resumes. As I see it, this problem is more prevalent in the winter and with EGR blocked. Multiple sources have confirmed the same observation. Specifically, the -5.0 timing has trouble maintaining auto-ignition with the cooler air. The simple fix to this, is to adjust main timing during in-gear idle. To date we have no adjustabilty, except for P/N. I have been using a workaround that I will avoid discusing, in hopes of addressing this properly (if possible). I know we can really improve economy with this one issue solved.

[DirtyMax03]

KillerBee,
I have just encountered this LLY issue. I have tuned a few LB7s (including mine) and a few LBZs. Started working on an LLY and have really been thrown for a loop. The truck I am working on has an intake, exhaust, EGR blocker plate, and a fingerstick on the MAF sensor. Used to be tuned with an Edge fooler box.
Anyhow, I drafted up a tune with more pulsewidth on the big end, around 50/50 timing, turbo brake, less boost at cruising, and opened VG veins at idle for a LB7 idle. The customer had experienced an intermittent issue with rough / lopey idle along with light smoking previously but it was very intermittent and it had been taken to a local dealer for diagnostics and all they did was replace the fuel filter as a 'fix'. As it was an intermittent issue they probably couldn't get it to replicate the problem.
I loaded my tune to it and after a test drive I noticed a lopey idle with fairly heavy white smoking at idle when in gear on the brakes. As you stated, I noticed that when in gear the timing goes to -5 degrees. Along with that, I noticed that the commanded mm3 was bouncing between 20-25 mm3 which seemed like a lot. For comparison, I reloaded the stock file. Below are the differences.

Stock
NOT in Gear
Commanded Fueling - 8 mm3
Timing: -1 degrees

IN Gear
Commanded Fueling - 15 mm3
Timing: -5 degrees

Modified
NOT in Gear
Commanded Fueling - 14 mm3
Timing: -1 degrees

IN Gear
Commanded Fueling - 22 mm3
Timing: -5 degrees

So I looked at the base timing tables and idle timing tables and realized that neither should be commanding -5 degrees timing. The -5 degrees timing is coming from the MINIMUM timing 'at idle' table. It appears that surprisingly it also references this table with a stock tune.

Next I modified my tune to not effect the turbo veins at idle so that my modified tune should be NO different at idle than the stock tune. While this made the loping and smoke slightly less extreme it was still commanding higher commanded fuel (mm3) than the stock tune.

Along with all of this, I was trying to determine if there was a Fuel Pressure Regulator or Injector problem on this truck. FPR seems good as the Desired and Actual Rail Pressures match pretty well. On a stock tune, the #2 injector was reading +5 in Park and +5 in gear, so 'out of spec' for Park but 'in spec' for in gear. +/-4 and +/-6 for the specs respectively. With the modified tune in, the balance rate on #2 went up to +9 and a couple other injectors were around +5, but knowing how the balance rates are figured by the ECM, I feel that this change for the worst between stock and modified is due to the rough idle.

This truck does have a slight miss at idle on a stock tune, but does NOT throw any codes. On a separate note, with my modified tune the timing rattle was much more than expected. I was around 5 degrees BTDC at cruising 1600 rpm / 40 mm3, so not very advanced at all. So I still think that I may be dealing with a bad injector, but it is good to know that this is a common problem. How is everyone else getting around this issue? Seems like the best fix would be to increase the "MINIMUM" timing table to (0) or so from the current (-5), which I might add is ONLY at 190 deg F ECT.

I have another LLY 'test truck' that is more stock and a different Operating System, so I plan to load this tune to that truck to see if I have the same issue.

I would love to discuss this topic further and I am pretty baffled at this point. I can't figure out why my 'modified' tune would be any different than the 'stock' tune once I reset the turbo vane maps back to stock.

[DirtyMax03]

Also, checked the truck for the harness rub on alternator bracket - did not appear to be an issue, but wrapped with radiator hose for fun.
And did the ice pick trick on #2 and #7, but did not help. Plus, if it was a bad connection on any of the injectors, I would expect a code and it would be running poorly under more operating conditions than just idle.

[DirtyMax03]

huh, my long post isn't showing up, said the site moderator had to approve it. Sure hope I don't have to type it out again, but it will make the previous post make more sense.

[DirtyMax03]

Killerbee,
Well, looks like I am going to have to retype my book again.
First off, I have tuned a few LB7s (including mine) and LBZs but just recently had a customer with an LLY. So I drafted up a tune for an LLY with more pulsewidth on the big end, roughly 50/50 timing, turbo brake, LB7 idle, and slightly lower boost at cruising. The modifications on the truck are intake, exhaust, EGR blocker plate, and fingerstick on MAF sensor. The truck was previously tuned with an Edge fooler box and has been completely removed.
I was unaware of this LLY idle issue and have really been thrown for a loop. I loaded the tune and after a test drive it began to lope and white smoke significantly at idle in gear. The customer had experienced a rough idle with white smoke on the STOCK tune in the past a couple of times but only a couple of times. The dealer inspected it and ended up just replacing the fuel filter. However, even with the stock tune loaded the truck does idle a little rough (misses) and lopes slightly.
Logging desired vs actual fuel pressure it seems that the Fuel Pressure Regulator is fine.
Logging injector balance rates shows the #2 injector at +5 in park and +5.5 in gear, so out of spec in Park but passes in gear. Another interesting fact is that with the modified tune loaded, I was getting a lot more timing rattle than expected (maybe an injector not closing properly).

Regarding the jump to -5 degrees timing at idle when in park, it seemed to do that with the stock tune as well!!! Looking at the tables, it would appear that when the truck is put in gear at idle the calibration is reading from the MINIMUM idle timing table NOT the normal idle timing table or the main timing table which specs -3.2 degrees at idle. With compensations, this usually works out to -1 degrees timing at idle with the truck not in gear. I do not know why it references the MINIMUM table but I also don't think that the shift in timing from -1 to -5 is causing the problem. What I also noticed was that with a MODIFIED tune the commanded fueling (mm3) at idle increases both in gear and out of gear even if the modified tune doesn't change anything at idle conditions. I am going to post this before I lose it again and then add additional findings:

[DirtyMax03]

STOCK TUNE
Out of Gear
Fueling: 8 mm3
Timing: -1 deg

In Gear
Fueling: 15 mm3
Timing: -5 deg

MODIFIED TUNE
Out of Gear
Fueling: 13 mm3
Timing: -1 deg

In Gear
Fueling: 20-25 mm3 (bouncing all over the place)
Timing: -5 deg

I plan to try my tune on a different stock '05 LLY to see if it has the same issues to determine if it is my tune or a combination of my tune with a mechanical issue on this '04.5 LLY. Oh, also I changed the turbo vane tables back to stock (not LB7 idle) and made sure that my timing and fueling at idle were the same as the stock table. With this modified tune loaded, I got the above results, but putting the turbo vanes back to stock reduced the white smoke and lope a little I assume because it would move more air into the engine and increase the A/F.
1. Has anyone else noticed this bump in fueling with a modified tune?
2. Does anyone know why it references the MINIMUM timing table when in gear? Along with this, is the best way to help mask this issue to just increase the -5 vale to 0 or so? Interestingly, it is ONLY -5 in this table when the ECT is 190 degF. At all other cells it is more like 0 or so.
3. Is this issue worse on EGR blocked LLYs? Worse on certain OS's?
4. Has anyone else noticed the fueling issue? Is this something that I have missed in my tune or an issue with EFI Live? I am surprised that I haven't seen more threads talking about this issue if it is widespread.
5. Do you think this truck has an injector issue? Only 80,000 miles. Also, with a modified tune and the rough idle, the balance rate on #2 was at +9 but like I said with stock tune was +5. I think the rough idle is causing the poor balance rates, but it could be a bad injector causing a poor idle instead???

Would love to hear KillerBee's or others' thoughts.

[killerbee]

It is a known issue, several years old, all your timing and idle observations are consistent with many I have seen...timing is too retarded in gear and causes roughness after warmup. It becomes worse if you reduce pilot qty or play with pilot timing. You may find that increasing pilot qty will help, that is one workaround. This has the effect of advancing overall timing. Another is experiment with increased rail ressure at idle, but this can have other consequences. The better route is to just disable the idle timing values (lower B0940 an example) then focus on just the main timing tables.

I doubt that you have an injector issue. Blocking the EGR may make it worse, at least in theory. There may be others with different ideas/conclusions.

[DirtyMax03]

Based on my findings, it doesn't seem that the idle timing is any different between the stock tune and modified tune (at least the timing that EFI Live is logging). For me, it seems that the increase in fuel quantity is what is causing the lope and smoke.
Similar to creating a lope tune (on purpose) it is increasing the commanded fueling, but trying to maintain a desired idle speed. In doing so, it goes into a lope condition where it commands excessive fuel, then backs off to maintain idle speed, then more fuel again, etc.

Maybe I have another issue with the tune if nobody else notices the increased fueling with a modified tune loaded, but I am almost certain that the tables that would affect idle are completely stock even on my modified tune.

I will try out some of these work-arounds and see where I get. Seems to me that the best work-around would be to bring the -5 degrees in the MINIMUM idle timing table at 190 ECT to 0 to keep it from becoming so retarded. I will try that first and see where that gets me.

[killerbee]

Consistent with my experience. Keep plugging away.

[DirtyMax03]

Tried changing the -5 in the "Idle Mode" Timing table, but it didn't do anything. This is probably for 2 reasons: 1. The parameters for the "idle mode" timing, the very last parameter only allows it to reference this table for 0.02 seconds (so it never uses it) 2. The description from EFI Live says it is only used in P/N, so wouldn't be any help at idle in gear anyway.

Guess I am going to have to try the pilot injection work-around. I could set the parameter to use this "Idle Timing Table" but if it only works in P/N than it isn't going to do me any good. I assume that Killerbee and everyone else has already figured this out.

On a side note, I still have a lot of light load timing rattle on a tune that isn't commanding very much timing at all (<50% from timing calculator) and basically the same timing values as stock at light loads. Maybe this is due to dropping the desired boost pressure at light loads, but I would think that this would actually make the burn slower and effectively reduce timing. Gonna have to play with timing and boost independently to figure out how to get rid of this light load rattle. A real head scratcher as I run much more timing on my LB7 and LBZ tunes with no rattle, so doesn't make sense, but when I log timing I am getting what I think I should be getting, so no modifier tables causing me problems.