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View Full Version : LMM timing limiter and pilot issue



camcojb
April 2nd, 2009, 12:24 PM
I've got the MPI twins on my LMM. Fantastic kit. I got the tuning from Rob and he's been great, but there's an issue that neither of us have solved yet.

We turn the pilots off in the tune above 70% tp or so and 2500 rpm up. But you datalog and the pilot is not off, sitting at about 240 US and 3.5 mm3. So you go into fuel pressure, and set the max number of pulses from 13 volts and 2500 rpm up to 1 (only allows the main pulse). Great, pilot is now off, but it now activates a timing limiter. On my truck it stops at 22 degrees max, no matter what is commanded, max allowed, etc. One interesting thing is that from a roll on in second gear I will shut the pilot off and get my desired 26-27 degrees, but once it upshifts and loads the motor it sets on 22 degrees and will not move regardless of rpm.

So it seems I can either have the pilot on and timing, or shut it off and lose timing. Thing is I want the timing and the pilot off, makes a big difference. I am guessing that there's a timing limiting table that references boost, and we do not yet have access to adjust it. We have the max desired boost set to 400 kpa, the most EFI Live allows. The truck is making 50-55 psi of boost on a run.

Any thoughts, Ross, or anyone?

Jody

bballer182
April 2nd, 2009, 12:48 PM
A buddy over next to me had the exact same issue. however he had his resolved with a new tune from Rob. The thing about LMM's is that there are so many timing tables that its just ridiculous, and it makes it hard to find a timing issue. OSUBeaver is his name on dieselplace. I don't think he ever posted anything about it though, just a few PM to me... PM him about it...

GMPX
April 2nd, 2009, 01:09 PM
Does seem rather odd.
But if you enter in 0mm3 for B9101 in the area's you want the pilot off, does it still command something other than 0mm3 for the pilot?
Maybe restore B1021 back to stock and set the B9101 table as I suggested above and see what happens?

Cheers,
Ross

GMPX
April 2nd, 2009, 01:10 PM
The thing about LMM's is that there are so many timing tables that its just ridiculousIt is totally over the top, imagine being the poor guys at GM having to tune every one of those tables to ensure emissions etc are met. No wonder there is not too many updates to these ECM's.

Cheers,
Ross

camcojb
April 2nd, 2009, 01:55 PM
Does seem rather odd.
But if you enter in 0mm3 for B9101 in the area's you want the pilot off, does it still command something other than 0mm3 for the pilot?
Maybe restore B1021 back to stock and set the B9101 table as I suggested above and see what happens?

Cheers,
Ross

yes, with B9101 zeroed from 2500 rpms up and 70mm3 (or whatever you choose as we've moved it around) it still commands a pilot UNLESS you put "1"'s in the B1021 table for those areas. But then you lose your timing. Put B1021 back to stock and it always shows a pilot, in my case 3.5 mm3 and 240 US.

Jody

camcojb
April 2nd, 2009, 01:56 PM
A buddy over next to me had the exact same issue. however he had his resolved with a new tune from Rob. The thing about LMM's is that there are so many timing tables that its just ridiculous, and it makes it hard to find a timing issue. OSUBeaver is his name on dieselplace. I don't think he ever posted anything about it though, just a few PM to me... PM him about it...

yeah, Rob is as confused as I, we've tried everything, even a new OS full flash. Still does it.

Jody

camcojb
April 2nd, 2009, 02:35 PM
A buddy over next to me had the exact same issue. however he had his resolved with a new tune from Rob. The thing about LMM's is that there are so many timing tables that its just ridiculous, and it makes it hard to find a timing issue. OSUBeaver is his name on dieselplace. I don't think he ever posted anything about it though, just a few PM to me... PM him about it...

well, apparently his is not resolved either. If the pulse shuts off he can't get more than 15 degrees of timing; that's worse than me, but still the exact same issue. With the pilot on he can get his timing where it should be.

Ross, that makes at least two of us with the exact same issue. Find that boost vs timing limiter table.............. :)

Jody

OSUBeaver
April 2nd, 2009, 02:51 PM
Yep....something is wrong I would say, but I'm no tuner.

I'm the guy that lives by Bballer btw.

camcojb
April 2nd, 2009, 02:52 PM
Yep....something is wrong I would say, but I'm no tuner.

I'm the guy that lives by Bballer btw.

it's a table we can't see yet. Hopefully it will be discovered in the future. Frickin' LMM's........................... :hihi:

IdahoRob
April 2nd, 2009, 03:18 PM
This one is kicking my rear.

Works perfect on the LBZ. I can command pilot off and get the timing I desire.

At first I didn't believe it was boost related, now I'm not so sure. This is a major limiter for the LMM.

camcojb
April 2nd, 2009, 03:20 PM
This one is kicking my rear.

Works perfect on the LBZ. I can command pilot off and get the timing I desire.

At first I didn't believe it was boost related, now I'm not so sure. This is a major limiter for the LMM.

I'm not positive it is either, that was just my hunch. Especially after seeing my roll-on wot datalog where in second gear I initially got full timing with the pilot off, then as soon as it shifted gears, loaded the truck to full boost it dropped back to 22 degrees and locked, never moving from there for the rest of the run.

I'm trying a couple changes now, and I'll datalog tomorrow. If it changes things I'll let you know, but I think we need Ross to find a table we're missing.


Jody

camcojb
April 3rd, 2009, 08:33 AM
ok, went out and tried 12-15 different tune changes today. Here are the results.

The pilot off and limited timing deal doesn't appear to be boost related, at least if it is, it's at a pretty low boost (under 35 psi for sure). If you put a 1 in the fuel pressure max pulses map (B1021) the pilot is off, but timing is limited to (in my case) 22 degrees no matter what you put in the timing tables. If you put a 2 in the fuel pressure or anything larger, the timing control comes back, but the pilot is back on at 3.5 mm3 and 240 US. Also, although you get more timing, you still cannot get more than 26.3 degrees on my truck. That may be a boost related table as I could get 38-39 before with the single turbo, but that only made 35-38 psi. I tried lowering boost down to 40 psi with the same results.

I tried every combo on the pilots I could think of. If you zero out the pilot tables from 70% tp up and from 2400 rpms and up and then go into the pilot 1 B9117 table and zero out the 180 and 190 mpa rows top to bottom, the pulse drops to 150 US. This is the change I made before on the single turbo that netted me the 2-3 tenths gain. I never did get the pilot completely off before, but never knew about the fuel pressure max pulses table, not sure it was even available in January 08. A quick datalog into a 20-30 mph headwind confirmed the power difference as even with the big headwind it matched my best ever 60-80 mph runs at wot with the old combo; I'm sure it'd beat it easily without the wind. Before dropping the pulse to 150US and with no headwind I could not match my old combo. I did not do any full passes, just wot partial runs due to the wind.

So zeroing out the pilot 1 in the wot fuel pressure area does pick the truck up, yet according to the table it shouldn't do a thing as it is only listed up to 30 mm3..........:confused: No idea why but it'll help an LMM.

So there's still two issues; one, zeroing the pilot tables does not shut them off on an LMM. Setting the fuel pressure max pulses to 1 will shut off the pilot, but then limits timing to 22 degrees total. Also, that 22 degrees locks there, even on the shift when the rpms drop to 2500 or so and you're commanding several degrees less. So more than you want at the shift, and less from there up.

The second issue is that even with the pilot on at 240 US or the new 150 US you cannot get over 26.3 degrees; I raised the tables to ramp up to 29 degrees with a 30 degree max, still the same 26.3 degrees. It ramps up nicely on the shift as it should, but stops there, won't go higher. This was not an issue with the old stock single turbo combo and 35 psi of boost, so it seems the higher boost levels of the twins are causing it.

So I think there's some table or limiter in the LMM's that when you pick 1 pulse to help fuel pressure the timing maxes and sticks to 22 degrees, at least at my boost level on my truck (I tried between 40 and 52 psi, still the same 22 degrees). Then, the second thing is the 26.3 degree limit which I think may be related to boost, as I could get almost 40 degrees before at a lower boost level.

Jody

LBZoom
April 3rd, 2009, 09:21 AM
I've got a question... what is the benefit of shutting the pilot off at higher TPS? Just curious is all

camcojb
April 3rd, 2009, 09:26 AM
I've got a question... what is the benefit of shutting the pilot off at higher TPS? Just curious is all

more power. It was worth 2 to 3 tenths in et on my old combo. That was pretty much a race tune, so it would likely affect things differently on a milder tune.

Jody

OSUBeaver
April 3rd, 2009, 10:35 AM
Nice write-up Jody. Thanks for taking the time to do that.

camcojb
April 3rd, 2009, 10:38 AM
Nice write-up Jody. Thanks for taking the time to do that.

you're welcome. Baby steps man, at least we can now improve the situation. Ideally Ross would have a ton of time on his hands and would locate these missing tables limiters............................. :cucumber:

Jody

GMPX
April 3rd, 2009, 10:44 AM
Next week I will look in to it, I was actually adding in some MAF tables for the Bosch ECM this week, so while I'm running hot!

Interesting it's an LMM thing only, but at least you have given me some numbers to go on.

Cheers,
Ross

camcojb
April 3rd, 2009, 10:46 AM
Next week I will look in to it, I was actually adding in some MAF tables for the Bosch ECM this week, so while I'm running hot!

Interesting it's an LMM thing only, but at least you have given me some numbers to go on.

Cheers,
Ross

I'm not positive it's LMM only, but Rob said the LBZ's do not have this issue; pilot completely off, and any timing he wants.

Jody

IdahoRob
April 3rd, 2009, 11:09 AM
Nice job Jody.

Jody, did log mm3 and make sure you are getting where you want to be in the mm3 table for timing? In the past I've seem LMM's only go to 79mm3 max even though should be in the 110mm3 range, just a thought on the timing limitation.

camcojb
April 3rd, 2009, 11:10 AM
Nice job Jody.

Jody, did log mm3 and make sure you are getting where you want to be in the mm3 table for timing? In the past I've seem LMM's only go to 79mm3 max even though should be in the 110mm3 range, just a thought on the timing limitation.

my logs have been in the 100-110 mm3 range at wot.

Jody

bballer182
April 3rd, 2009, 12:23 PM
What would happen if you left the pilot on and commanded the pulse width down to 1 uS which is virtually off. so you could use the pilot on timing table to get the timing desired? Would that work as a work around?

camcojb
April 3rd, 2009, 12:33 PM
What would happen if you left the pilot on and commanded the pulse width down to 1 uS which is virtually off. so you could use the pilot on timing table to get the timing desired? Would that work as a work around?

You can zero out the pilot tables and it still shows 240 US and 3.5 mm3. I tried going down to .1 and it still had 240 US and 3.5 mm3. When you zero out even the 0-30 mm3 pilot and pilot 2 tables (which shouldn't even be working at 105 mm3 and wot) then you can get the US down to 150, still at 3.5 mm3 pilot. There is no way I can find to get it down below that, other than to not allow more than 1 pulse in the fuel pressure area, but then you lose your timing.

Oh, I also tried negative pilot since 0 didn't work and I noticed it was available in the limits. That doesn't work at all, cut my timing back to 6.5 degrees total at wot.

Jody

vortecfcar
April 3rd, 2009, 04:16 PM
Jody,

I don't know how Rob has scaled your boost tables, or if you're still using the desired boost tables, but you might try rescaling your boost sensor if you think the timing limit is boost related. Of course this is only a 'solution' if Rob isn't using the desired boost tables.

Nick

camcojb
April 3rd, 2009, 04:23 PM
Jody,

I don't know how Rob has scaled your boost tables, or if you're still using the desired boost tables, but you might try rescaling your boost sensor if you think the timing limit is boost related. Of course this is only a 'solution' if Rob isn't using the desired boost tables.

Nick

thanks for your input Nick. He has the sensor max voltage set as high as EFI Live allows (5.10 volts). Is that what you meant? Looks like he still uses the desired boost tables.

Jody

vortecfcar
April 3rd, 2009, 05:57 PM
My thought was that if he were only using the vane tables to tune the turbo, he could rescale the MAP sensor so that it reports a lower manifold pressure than actual. This under reporting could potentially help avoid a boost related timing limit (which I thought you were alluding to).

On second read through, it looks like you struck out on a boost related timing retard.

Have you tried setting the timing on the pilot to coincide with the main pulse? You might also try setting the main pulse table to 0uS from 0-10mm3 when fuel pressure exceeds 150 MPa. I suggest this simply to eliminate the pulsewidth tables we have access to with regard to possible usage for the pilot PW calc.


Nick

camcojb
April 4th, 2009, 02:58 AM
My thought was that if he were only using the vane tables to tune the turbo, he could rescale the MAP sensor so that it reports a lower manifold pressure than actual. This under reporting could potentially help avoid a boost related timing limit (which I thought you were alluding to).

On second read through, it looks like you struck out on a boost related timing retard.

Have you tried setting the timing on the pilot to coincide with the main pulse? You might also try setting the main pulse table to 0uS from 0-10mm3 when fuel pressure exceeds 150 MPa. I suggest this simply to eliminate the pulsewidth tables we have access to with regard to possible usage for the pilot PW calc.


Nick

I have not moved the pilot timing (didn't know you could), but I have zeroed out all the pilots from 160 mpa up. This does change the pilot from 240 US to 150 US, and picks up 2-3 tenths in et, but still does not shut the pilot off.

Have you ever got the pilot to go off on an LMM without changing the fuel pressure max pulses allowed table (B1021) to 1? I zeroed everything on my old combo and could only get it to 150US and 3.5 mm3. I can get the pilot to 0 with the B1021 table, but then lose my timing.

Then again, maybe the 150US is a glitch in the software and it really is off, as the truck definitely picks up; you would think going from 240US to 150US would help much if at all. This still means there's another timing limiter at the high boost ranges a twin runs, because even with it at 150 or 240US it won't go past 26.3 degrees on my truck. We also did a full flash of another OS, same results.

Jody

OSUBeaver
April 4th, 2009, 04:41 AM
Have you ran it at the track Jody? What were your times and trap speeds? Just curious if they are congruent with mine.

bballer182
April 4th, 2009, 05:46 AM
My thought was that if he were only using the vane tables to tune the turbo, he could rescale the MAP sensor so that it reports a lower manifold pressure than actual. This under reporting could potentially help avoid a boost related timing limit (which I thought you were alluding to).

On second read through, it looks like you struck out on a boost related timing retard.

Have you tried setting the timing on the pilot to coincide with the main pulse? You might also try setting the main pulse table to 0uS from 0-10mm3 when fuel pressure exceeds 150 MPa. I suggest this simply to eliminate the pulsewidth tables we have access to with regard to possible usage for the pilot PW calc.



Nick


That's what i was trying to say.. while the ecm can still command a certain mm3 for the pilot the actual pulse width would be zero so that the ecm thinks it's using the pilot but there is not pulse for the pilot in actuality?!?

camcojb
April 4th, 2009, 06:02 AM
That's what i was trying to say.. while the ecm can still command a certain mm3 for the pilot the actual pulse width would be zero so that the ecm thinks it's using the pilot but there is not pulse for the pilot in actuality?!?

setting the pilot pulse to 0 doesn't zero out the pulse; it still shows a 150US pulse width. The only way to get the pilot to be zero is shut off the extra pulses in the fuel pressure section; but then it won't go over 22 degrees of timing.

camcojb
April 4th, 2009, 06:10 AM
Have you ran it at the track Jody? What were your times and trap speeds? Just curious if they are congruent with mine.

no, but it's not going to run with my old combo yet. My old stock turbo went 12.75 at 108.4 with 70 psi in the tires and no track prep at all. That same combo datalogged 0 to 100 mph in 11 flat. It also showed 0-108 mph at 12.7, so pretty much dead on with what it did at the track.

I use a dead end road for datalogging, starting at the same spot and going the same direction every time to eliminate variables. So far the twin setup is .6 to .8 of a second slower from 0-100 mph than my old combo, so I'd bet on it not being equal to what I had.......... yet.

I did get the timing up to 28 degrees by asking for 30 and raising the max limits. But the pilot is still on at 150US (then again it was the same with the old combo datalogs). I'm running 3100-3200 pulse like the old combo. The difference is the old combo had water/meth and 8-9 degrees more timing, but a lot less boost (35-38 vs 50-55). And again, the old combo lost a piston after 15000 miles on that tune.

This is not to bag on the twins, just that I do not have it sorted out enough to equal or beat my stock single combo. Plus, there are still some minor defuels going on and on this last datalog my mm3 dropped to 85 for a while, which it has never done before. And to top it off, I heard a pfttttttt sound at 85 mph or so and aborted the run. Now if the boost hits 48 psi or so the sound comes back and stays until the boost drops. Sounds like a split boot or possibly intercooler, but a quick look didn't show anything. Won't make any noise at 45 psi though, seems like a split anything would do it under just about any boost. I hope it's not a head gasket...................... :) The good news, the last datalog went 11.74 0-100 mph with me pulling my foot out of the throttle for a full half second, when I thought I heard the noise. So once I figure out the noise, figure out why the mm3 dropped for a second or so, and can make a full run I should be close.

EDIT: It appears after looking at the logs closer that either my trans is slipping or the converter is not staying locked and slipping. My speedo settings are the same from a year ago with my old combination logs, but the rpms vs mph do not line up. At the top of each gear they're the same, but after the shift the rpms are 300 or so higher now than they used to be. It would drop down to just over 2500 rpms after an upshift at wot, no it's over 2800 rpms after an upshift, yet the rpms just before the shift and the mph at the shift line up still. That's too big of a difference, either the converter is not locking or the trans has an issue. So never mkind about the power, because if it's that close with the converter not locking/slipping trans then it's making big power now.

I still would like to be able to shut the pilot off and control the timing, so hopefully Ross can figure that out.

Jody

rcr1978
April 4th, 2009, 12:32 PM
Might as well ask while you are getting some attention for the proper pids to see the convertor apply percentage so you can see if your trans is actualy slipping. The slip pid works now but we don't know apply percentage to tell if the damn thing is at full lock/unlock I have asked a few times but I must not be buffing the right helmet and never get even a grumble of a answer. :pokey: :wave: :cheers:

camcojb
April 4th, 2009, 12:34 PM
Might as well ask while you are getting some attention for the proper pids to see the convertor apply percentage so you can see if your trans is actualy slipping. The slip pid works now but we don't know apply percentage to tell if the damn thing is at full lock/unlock I have asked a few times but I must not be buffing the right helmet and never get even a grumble of a answer. :pokey: :wave: :cheers:


yeah, Mike L mentioned watching the tcc, so I was going to add that to my pids and see what it says.

Jody

rcr1978
April 4th, 2009, 12:57 PM
That bad thing is you can't watch your convertor yet unless I'm missing something.

camcojb
April 4th, 2009, 02:48 PM
That bad thing is you can't watch your convertor yet unless I'm missing something.

I don't think you're missing something, I couldn't get it to work either.

I did figure out my converter lock though.................... :doh2: I had re-done the wot lock/unlock tables and got them reversed for both tow/haul and normal driving. So anything under 97% throttle was fine, converter locked correctly. But at wot the unlock tables were a couple mph higher than the lock tables; should have been the opposite. Stupid mistake on my part, just glad I figured it out.:cucumber: Thanks to Mike L for telling me to re-check the tune........... :cheers:

Jody