I'd like to see the results at each step, it's always good knowledge to see what changes do to data! You have an AutoProm like me so should be able to tell pretty fast!
CK5
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Tuning a GMPP 383
- Thread starter cuervo
- Start date
I'd like to see the results at each step, it's always good knowledge to see what changes do to data! You have an AutoProm like me so should be able to tell pretty fast!
I assume I should be tuning for long term.
This is at 113 BPW
Also, what is the correct way to turn off the EGR?
This is at 113 BPW
Also, what is the correct way to turn off the EGR?
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dave w
1/2 ton status
I turn off the EGR by setting the the Minimum Speed for EGR ON to 255 MPH, and Minimum Speed for EGR OFF to 248 MPH. I also set the temperature EGR ON to Max 151 C, and Temperature EGR OFF to 146C.
If I had a histogram look like the ones posted, I would INCREASE the Injector Flow +2 lb / hr. Example old Injector Flow =61 lb / hr. ~ new Injector Flow =63 lb / hr.
dave w
dave w
1/2 ton status
Ok, I looked back at the thread and now see the definition file is $85.
To disable the EGR with $85 set EGR on engine speed to 6375 RPM or max. EGR off with engine speed of 6100 RPM.
I'd also try a lower BPW of -2.
dave w
I never even thought of doing that! 
Told you there is more than one way to skin a cat!
Just looked at a $85 and didn't see that paremeter, kind of weird being a newer PCM for a 4l80E. What exactly was this used in?
When you disable EGR then also turn off/uncheck Error 32
You could also disable EGR by raising Enable EGR coolant temp to 151.25 C
Well, the strangeness continues.
Was driving to the lake on Sunday and started to hear some backfiring, mostly through the exhaust a couple of times from the TBI. Nothing had changed in the chip other then dropping the BPW by 3.
I was extremely low on fuel so I stopped and filled up, $100 worth. About 10 miles into the drive the backfiring started. It was consistent at any RPM or load. I thought just to be on the safe side I'd put the old chip back in and see if that was the issue. It was still backfiring and running the same.
I'm hoping its a bad tank of gas. I did check the knock wire to make sure it was on and not burnt. I guess next is the distributor, wires and what not.
Also, I tried finding some 63 lb injectors a while back but had no luck. Does anyone know where to source some?
Was driving to the lake on Sunday and started to hear some backfiring, mostly through the exhaust a couple of times from the TBI. Nothing had changed in the chip other then dropping the BPW by 3.
I was extremely low on fuel so I stopped and filled up, $100 worth. About 10 miles into the drive the backfiring started. It was consistent at any RPM or load. I thought just to be on the safe side I'd put the old chip back in and see if that was the issue. It was still backfiring and running the same.
I'm hoping its a bad tank of gas. I did check the knock wire to make sure it was on and not burnt. I guess next is the distributor, wires and what not.
Also, I tried finding some 63 lb injectors a while back but had no luck. Does anyone know where to source some?
Well, turned out to be bad gas and a worn distributor cap.
I kept logging and lowering the BPW. It ended up 98 was to low and WOT went lean, just a bit. I went upto 95.5 and have good WOT numbers now.
Time to start working on the VE tables.
I kept logging and lowering the BPW. It ended up 98 was to low and WOT went lean, just a bit. I went upto 95.5 and have good WOT numbers now.
Time to start working on the VE tables.
dave w
1/2 ton status
Would it be possible to see a screen shot post of the VE tables?
Ideally, VE numbers should be more than 45 and less than 95.
dave w
Ideally, VE numbers should be more than 45 and less than 95.
dave w
I just got back from a 20 minute log after the first VE table ajdustments. Looks like I need to move the BPW up to 100 or 101 and check the tables again.
Right now the table is between 45.70 and 83ish but I leaned out on WOT after changing the table.
How long is LongTerm and how short is ShortTerm? Do they affect each other?
dave w
1/2 ton status
You probably already know this, but for someone new to tuning it's worth mentioning. The BPW is a course adjustment, and the VE table is a fine adjustment.
I tend to adjust the BPW so that the histogram shows some cells rich, and some cells lean.
dave w
I tend to adjust the BPW so that the histogram shows some cells rich, and some cells lean.
dave w
Copied from this page, has lots of good information to read:
http://www.noid.org/~lj/PCM%20Tutori...reviations.htm
BLM: The block learn multiplier, aka long term fuel trim, is a value the PCM stores to adjust the injector pulsewidth based on accumulated (or "learned") oxygen sensor feedback. BLM's usually change fairly slowly, if at all. The PCM limits the range of BLM from 108 to 160. Here's a frequent source of confusion: A BLM of 128 means that the PCM is calculating the right injector pulsewidth. A BLM below 128 means that the PCM has to take out fuel to get the mixture right (the PCM calibration is too rich). A BLM above 128 means that the PCM has to add fuel to get the mixture right (the PCM calibration is too lean).
One way to remember which is rich and which is lean requires that you can remember that 128 is ideal. You get numbers less than 128 by subtracting - when the BLM is less than 128, the PCM is subtracting fuel. You get numbers above 128 by adding - when the BLM is above 128 the PCM is adding fuel.
Another misconception: In general there is nothing wrong with the BLMs not being 128. As long as they don't reach their limits of 108 or 160, the PCM will be able to get the fuel mixture just right. The exception to this is covered on the Split BLM page. All that said, many of us like to tinker with the PCM until we gat the BLMs as close to 128 as we can, just cuz...
INT: integrator, aka short term fuel trim, is a value the PCM uses to adjust the injector pulsewidth based on the current oxygen sensor feedback. INTs usually change very rapidly, as in many times per second. Here's that same source of confusion mentioned in the BLM section : an INT of 128 means that the PCM is calculating the right injector pulsewidth for the current conditions. An INT below 128 means that the PCM has to take out fuel to get the mixture right (the PCM calibration is too rich). An INT above 128 means that the PCM has to add fuel to get the mixture right (the PCM calibration is too lean).
http://www.noid.org/~lj/PCM%20Tutori...reviations.htm
BLM: The block learn multiplier, aka long term fuel trim, is a value the PCM stores to adjust the injector pulsewidth based on accumulated (or "learned") oxygen sensor feedback. BLM's usually change fairly slowly, if at all. The PCM limits the range of BLM from 108 to 160. Here's a frequent source of confusion: A BLM of 128 means that the PCM is calculating the right injector pulsewidth. A BLM below 128 means that the PCM has to take out fuel to get the mixture right (the PCM calibration is too rich). A BLM above 128 means that the PCM has to add fuel to get the mixture right (the PCM calibration is too lean).
One way to remember which is rich and which is lean requires that you can remember that 128 is ideal. You get numbers less than 128 by subtracting - when the BLM is less than 128, the PCM is subtracting fuel. You get numbers above 128 by adding - when the BLM is above 128 the PCM is adding fuel.
Another misconception: In general there is nothing wrong with the BLMs not being 128. As long as they don't reach their limits of 108 or 160, the PCM will be able to get the fuel mixture just right. The exception to this is covered on the Split BLM page. All that said, many of us like to tinker with the PCM until we gat the BLMs as close to 128 as we can, just cuz...
INT: integrator, aka short term fuel trim, is a value the PCM uses to adjust the injector pulsewidth based on the current oxygen sensor feedback. INTs usually change very rapidly, as in many times per second. Here's that same source of confusion mentioned in the BLM section : an INT of 128 means that the PCM is calculating the right injector pulsewidth for the current conditions. An INT below 128 means that the PCM has to take out fuel to get the mixture right (the PCM calibration is too rich). An INT above 128 means that the PCM has to add fuel to get the mixture right (the PCM calibration is too lean).
Yeah, I was ok with that until saw WOT go lean. I'm under the assumption that the BPW should not go so low that it allows lean at WOT.
I didn't see dav w post when I did must have been the same time.
He is right except for one issue with cammed built engines. At WOT if they are the cells that are lean? Is there enough VE left to adjust? Goal is 95 total or under, some say 85. If you take out to much BPW and can not add enough VE to upper RPM lower MAP table then FAIL! Start all over with more BPW and lower VE in lower cells in low load low RPM cells. It's a balencing act. But to low a BPW and you will never get WOT cells correct.
BTW Having WOT cells a liitle rich will give more HP and run cooler at WOT because the richer AFR will run cooler then a 14.7 to 1 which is 128. I tend to do built engines to 122... Widband O2 has proved this to be correct. Since the o2 sensor is ignored in PE... it takes last BLM and adds whatever PE is set to.
What does more HP need? More fuel. When does it need it? WOT! Larger cams produce less vacuum. What does this do to idle? Makes the MAP think there is a load and adds more fuel. Thenn idle is pig rich, but do you have enough fuel WOT?
dave w
1/2 ton status
I define lean as BLM's over 135. Usually the ECM has enough INT to correct for a 135 lean. A BLM of 150 makes me nervous
. I usually wait on WOT tuning till I get the majority of the VE Table figured out.
dave w
. I usually wait on WOT tuning till I get the majority of the VE Table figured out.dave w
More than one way to skin a cat!
I try to get injector size and fuel pressure set for estimated HP (since finding the injector sizing speadsheet has saved tons of time increasing fuel pressure), then get engine to run to warm up and always have to reduce VE in idle along with more base timing to get it to idle, then work on BLMs. One out of ten has not had enough fuel WOT this way...
I try to get injector size and fuel pressure set for estimated HP (since finding the injector sizing speadsheet has saved tons of time increasing fuel pressure), then get engine to run to warm up and always have to reduce VE in idle along with more base timing to get it to idle, then work on BLMs. One out of ten has not had enough fuel WOT this way...
Exactly! You could raise WOT cells to 95 and if it does not go lean your OK with BPW you came up with.Yeah, I was ok with that until saw WOT go lean. I'm under the assumption that the BPW should not go so low that it allows lean at WOT.
The last log you showed a picture of seems OK at WOT? Rich everywhere else. If this is correct then VE needs work. Very typical of what I have seen.
Well, I do have a lot of room at the top and not so much at the bottom. Seems it would be better at this point to go back to the lower BPW and work on the WOT cells. It will give me more room to work on the rich cells at lower RPM.
Thanks for the input guys. The suburban is running better then it ever has.
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right now my min BLM is set to 105, what would be the affect of moving that to 108? I ask because I read a document that 108 should be the lowest setting.
I think I'm going to lower the BPW 97 and do another log. At 98 my lean cell is 132 and the corresponding VE cell is only 71.09 so there is a lot of room to move that up. I hope this will help lower the rich tables a little more before going into the VE table.
/edit
Thanks for the input guys. The suburban is running better then it ever has.
edit
right now my min BLM is set to 105, what would be the affect of moving that to 108? I ask because I read a document that 108 should be the lowest setting.
I think I'm going to lower the BPW 97 and do another log. At 98 my lean cell is 132 and the corresponding VE cell is only 71.09 so there is a lot of room to move that up. I hope this will help lower the rich tables a little more before going into the VE table.
/edit
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Dave w said you can change BLM to lower numbers. I never have and read the same thing years agao it should not be touched and never have, ultimatly I would work with what was there to begin with. If it hits bottom (rich) it will still run, I have taken out VE and still hit bottom, take out more VE and BLM starts to come up.
All your doing in TP or TC or whatever tuner program is using the mask to change bits and bytes in hex. If you add BLMs like going lower than 108 where does that go in in hex? Did it add bits and bytes? did it push down other information in hex so now the address changes for other changes done in the mask? I don't know? That may be a question for THirdgen guys that have been doing this in hex before mask programs.
All your doing in TP or TC or whatever tuner program is using the mask to change bits and bytes in hex. If you add BLMs like going lower than 108 where does that go in in hex? Did it add bits and bytes? did it push down other information in hex so now the address changes for other changes done in the mask? I don't know? That may be a question for THirdgen guys that have been doing this in hex before mask programs.
Well 105 in hex is 0x69 and 108 is 0x6C so it wont change the byte location or file size. It may not have the affect that I think it would, IE move some of the lower RPM rich cells to a less rich condition.
I was looking at the lower rich cells were the numbers were min, max, ave of 106, 112, 110.3 respectively.
My thinking is if the 106 is forced to 108 the average across the board on those cells would go up and lean out a few of the lower RPM cells.
I was looking at the lower rich cells were the numbers were min, max, ave of 106, 112, 110.3 respectively.
My thinking is if the 106 is forced to 108 the average across the board on those cells would go up and lean out a few of the lower RPM cells.
I was so curious, even though I have never done this I asked on Thirdgen and yes it can be done. reason not to is motor could go so low on fuel it will not run.
http://www.thirdgen.org/techboard/diy-prom/629533-can-you-change-blm.html#post5055976
I just don't see any point in it...
If your max rich at 108 why change to 100? Just fix VE!
http://www.thirdgen.org/techboard/diy-prom/629533-can-you-change-blm.html#post5055976
I just don't see any point in it...
If your max rich at 108 why change to 100? Just fix VE!
