Fuel cutout issue (possible free beer inside)

[rover346]

Hello,

I new to tuning things but not new to building engines and how engines work. I have a problem with what i think is the calibration on my computer where I'm having fuel cut out when the motor is being progressively loaded around 4k but I've seen it as low as 2500. This is while going down the free at speeds around 50-65. If I press the gas more during the cut out to downshift then fuel comes back. I'm including the tune so someone with more experienced eyes than I might be able to spot an simple oops that i'm not catching. I'm more than willing to buy someone a case of beer if they can help me get this figured out and I have no problem data logging if need be.

Thank you

[Jetmech442]

Hello,

I new to tuning things but not new to building engines and how engines work. I have a problem with what i think is the calibration on my computer where I'm having fuel cut out when the motor is being progressively loaded around 4k but I've seen it as low as 2500. This is while going down the free at speeds around 50-65. If I press the gas more during the cut out to downshift then fuel comes back. I'm including the tune so someone with more experienced eyes than I might be able to spot an simple oops that i'm not catching. I'm more than willing to buy someone a case of beer if they can help me get this figured out and I have no problem data logging if need be.

Thank youI'm not a pro either, but I'd be happy to look over the tune when I get home to see if anything might cause that. (unless someone gets to it before I do)

Sent from my Nexus 6P using Tapatalk

[rover346]

That would be much appreciated, and if anything needs to be logged let me know what pids need to be recorded. It might be abuse or torque management but I don't know what i'm looking at to be sure

[ScarabEpic22]

A0001 and A0002 are out of range, change these to 99, save the file, close V7, reopen and change back to 100.

Need to work on your VE tables, both Main and Boost. They are far too spikey. Spark looks a bit high in the High octane table as well.

For your fuel cutout issue, I bet it's because you have 64 in one cell and 92 in the next going from 4000 -> 4400rpm. Your fueling in row 3200rpm is way lower than 2800 or 3600, likely causing the PCM to think it's fueling properly, then over-fueling, then proper again.

I'd start by smoothing your VE tables out a bit, then logging again.

[rover346]

A0001 and A0002 are out of range, change these to 99, save the file, close V7, reopen and change back to 100.

Need to work on your VE tables, both Main and Boost. They are far too spikey. Spark looks a bit high in the High octane table as well.

For your fuel cutout issue, I bet it's because you have 64 in one cell and 92 in the next going from 4000 -> 4400rpm. Your fueling in row 3200rpm is way lower than 2800 or 3600, likely causing the PCM to think it's fueling properly, then over-fueling, then proper again.

I'd start by smoothing your VE tables out a bit, then logging again.

I did that which helped the weird spots but for some reason if I'm doing a WOT pull from zero, second gear hits about 70 which is around 4,200 and the ecm cuts fuel completely, like a governor fuel cut, its baffling me. The governor is set for 95.

Thank you for the help, hopefully my truck runs decent and someone gets a cold one. win win

[rover346]

I wanted to add that this is not in before a shift as it normally will go into third at 85, its just power then no power

[Jetmech442]

A0001 and A0002 are out of range, change these to 99, save the file, close V7, reopen and change back to 100.

Need to work on your VE tables, both Main and Boost. They are far too spikey. Spark looks a bit high in the High octane table as well.

For your fuel cutout issue, I bet it's because you have 64 in one cell and 92 in the next going from 4000 -> 4400rpm. Your fueling in row 3200rpm is way lower than 2800 or 3600, likely causing the PCM to think it's fueling properly, then over-fueling, then proper again.

I'd start by smoothing your VE tables out a bit, then logging again.

Beat me to it Scarab,lol.

Rover, how certain are you that it pulls fuel and not timing or throttle blade?I'll poke around now ans see what I see. Perhaps you should post the trans tune as well, and a description of mods to the car.

[rover346]

Beat me to it Scarab,lol.

Rover, how certain are you that it pulls fuel and not timing or throttle blade?I'll poke around now ans see what I see. Perhaps you should post the trans tune as well, and a description of mods to the car.

OK the truck is a 2002 silverado

Cable actuated Throttle
Iron block LS6 (5.3 bored to 3.898)
317 Heads
ZR1 Camshaft
Whipple
blower pushes right around 9 pounds at 3600 rpm and drops to 6 at 5600
I built the motor for longevity so if you guys have any suggestion as to make life easier on this motor through the tune, that would be much appreciated
I raised the amount of timing being pulled by psi based on scarabs suggestion

I was data logging injector duty cycle and it drops to almost nothing when it happens and my lambda value sky rockets, If I keep my foot on it when it cuts, you can hear the blower pulling air as rpm drops but no ignition.

Watching timing on the data log timing stays at 17 when the power disappears.


I've included my updated tune which has smoothed out VE tables

guys your help is much appreciated

[Jetmech442]

nm, trans tune already attached...

just some quick thoughts... 4000 RPPM is the threshold set to transition from the dynamic mode to pure MAF. Have you altered the stock MAF in any way?

Cat protection is still Enabled. Maybe a contributor?

Can you confirm you are running a 4 speed auto with 3.73 gears, and make sure your tire diameters are correct.

Last observation is that the max speed H0109, is set to 95 kph. thats really close (~60 mph) to your 70 mph issue. maybe if tires are off a bit, or converter is flashing higher...I dunno, but maybe worth looking into.

Other observations which will help for a better tune: Your Base spark in gear and PN need to match in the idle area for your High/Low octane tables. You have a large jump from 800 - 1000 rpm and different values in each one. matching them up will reduce surging off idle.

[rover346]

nm, trans tune already attached...

just some quick thoughts... 4000 RPPM is the threshold set to transition from the dynamic mode to pure MAF. Have you altered the stock MAF in any way?

Cat protection is still Enabled. Maybe a contributor?

Can you confirm you are running a 4 speed auto with 3.73 gears, and make sure your tire diameters are correct.

Last observation is that the max speed H0109, is set to 95 kph. thats really close (~60 mph) to your 70 mph issue. maybe if tires are off a bit, or converter is flashing higher...I dunno, but maybe worth looking into.

Other observations which will help for a better tune: Your Base spark in gear and PN need to match in the idle area for your High/Low octane tables. You have a large jump from 800 - 1000 rpm and different values in each one. matching them up will reduce surging off idle.


Jettmech if you have paypal pm me so I can send you a case of beer!!!!

Same for you scarab.


I paid for someone to do this for me and the guy gave me a base tune and walked. I paid in full to establish some sort of trust with the guy ��

Applying those changes now and will report

[joecar]

A0001, 2, 11, 12, 13 are out of range...

fix them by doing this:
- set them to max-1,
- save file,
- exit tune tool,
- restart tunetool,
- set them to max,
- save file.

[ScarabEpic22]

Jettmech if you have paypal pm me so I can send you a case of beer!!!!

Same for you scarab.


I paid for someone to do this for me and the guy gave me a base tune and walked. I paid in full to establish some fort of trust with the guy ��

Applying those changes now and will report

Sorry to hear about your tuner taking your money and walking, not cool at all. :(

As Jetmech mentioned, check you MAF crossover and make sure you're in SD only for now (switch back to MAF only later to calibrate the MAF, or use the Calc.VET procedure to calculate the MAF curve). I didnt even get into the trans stuff, was more concerned with keeping your engine alive with better VE tables! :)

[rover346]

Lesson learned and I justified the purchase of efi live as a scan tool. My top speed being 95 kph was my problem.Thank you very much for the help jetmech, spent quite a while on the side of the road trying to figure that out. I need to pay closer attention to measurements. I was making sure lambda was converting into the correct metric and missed the top speed.

I also spent more time with my VE tables as you suggested Scarab and got it dialed in. The truck gets the mail no problem now.

Is there a risk of the short term and long term fuel trims messing with the base tune of the engine or they only come into play during closed loop right?

Just double checking my bases.

[ScarabEpic22]

I'd shut STFT and LTFTs off while doing your VE and then MAF tuning, re-enable before calling it good so you can adjust for different quality fuels.

Glad you got it figure out and got the VE dialed in. Bet it pulls a LOT harder now!

[Jetmech442]

Lesson learned and I justified the purchase of efi live as a scan tool. My top speed being 95 kph was my problem.Thank you very much for the help jetmech, spent quite a while on the side of the road trying to figure that out. I need to pay closer attention to measurements. I was making sure lambda was converting into the correct metric and missed the top speed.

I also spent more time with my VE tables as you suggested Scarab and got it dialed in. The truck gets the mail no problem now.

Is there a risk of the short term and long term fuel trims messing with the base tune of the engine or they only come into play during closed loop right?

Just double checking my bases.Hey Rover, super happy that worked! No need for beer (the former Sailor in me would be disgusted to hear that), I'm just here trying to repay all the help I got years ago from great guys like scarab, Joecar, statesman... Etc.

If your doing Calc.vet, make sure units are in g*K/kPa. Your current displacement is 5.3 L (B0104) in the tune, so tuning or viewing %VE will be skewed until you update that.

Also, in between actually working, I briefly noticed that your Vee map only goes up to 105 kilopascals, I would think that with the vortec you would be running a 2 bar tune, again I made just not have seen the whole thing yet and I'm not accustomed to the two bar tune but just something to look at

Sent from my Nexus 6P using Tapatalk

[rover346]

Hey Rover, super happy that worked! No need for beer (the former Sailor in me would be disgusted to hear that), I'm just here trying to repay all the help I got years ago from great guys like scarab, Joecar, statesman... Etc.

If your doing Calc.vet, make sure units are in g*K/kPa. Your current displacement is 5.3 L (B0104) in the tune, so tuning or viewing %VE will be skewed until you update that.

Also, in between actually working, I briefly noticed that your Vee map only goes up to 105 kilopascals, I would think that with the vortec you would be running a 2 bar tune, again I made just not have seen the whole thing yet and I'm not accustomed to the two bar tune but just something to look at

Sent from my Nexus 6P using Tapatalk

Hey Jetmech,

The tune is running efi live custom OS so there is a main VE and The Boost VE as well. Somewhere in the tune I updated the Cylinder volume from a 5.3 to a 5.7 so that may be what your talking about but not sure. I went from 663 to 712 in that table for volume.

The Maf has been taken out completely and is a semi closed SD tune from what I've gathered. I'm not using PE and doing the commanded vs RPM. Once again I know enough to be dangerous so take it with a grain of salt.

[rover346]

Also is it normal to have some knock when snapping the throttle shut?? I have no knock while getting on it then when throttle shuts it pulls as much as 8 degrees for a split second

[joecar]

When throttle snaps shut, DFCO (decel fuel cut off) might enable, but it is not normal to get knock...

are you sure it's knock/detonation and not a loose bolt/crack allowing something to bang around...?

[joecar]

Without MAF, make sure you get a MAF DTC (otherwise it's not running from the VE tables).

While tuning, you might want to disable semi-open loop (beware: in COS, and stoich cell in B3647/B3649 will cause STFT-trimming).

Please use PE (set it up to provide sufficiently rich/safe fueling at load)(set it up to positively enable when you push down the throttle)...
it's ok to use PE since the commanded fueling due to PE shows up in the commanded fueling pids (GM.EQIVRATIO, GM.AFR)...
and you want to keep the engine safe in case the load/throttle increases.

[rover346]

Without MAF, make sure you get a MAF DTC (otherwise it's not running from the VE tables).

While tuning, you might want to disable semi-open loop (beware: in COS, and stoich cell in B3647/B3649 will cause STFT-trimming).

Please use PE (set it up to provide sufficiently rich/safe fueling at load)(set it up to positively enable when you push down the throttle)...
it's ok to use PE since the commanded fueling due to PE shows up in the commanded fueling pids (GM.EQIVRATIO, GM.AFR)...
and you want to keep the engine safe in case the load/throttle increases.

Hey Joe,

Its seems without PE the truck is fueling correctly all the way through the rev range. (only revving to 5800) Would you still recommend using PE. I have the transmission set to kick down somewhat easily from 4>3 3>2 as to not lug it. It could be the gear train in the blower making noise when the throttle gets shut being interpreted as knock. I'm requesting about 11.2 at wot. But I'm a green pea so just letting you know what I have going on, the motors been run out at least 50 times while tuning and i slowly but surely took fuel out till I arrived at 11.2:1.

I set the transmission up to kick down because it would start to bog if I tried to load the motor at too low an rpm ( Huge cam, 5 inches of mercury at idle and 8.26:1 dynamic compression ratio so I have to be on boost to make any power)

MAF is set to fail instantly and truck seems to drive pretty well. ( Of course its hard to see what your missing when you never had it)

Also with narrow band O2 sensor would the computer be able to trim 14.2 since its that much lower that 14.7 or would the computer be on a mission to keep pulling fuel?

Can the custom OS handle bosch 4.9s in place of the factory narrow bands?

Thank you for the help

[joecar]

Your B3647 is stoich everywhere until the 100 kPa column... you want to start increasing fueling earlier (i.e. engine load can still be quite significant at 80 kPa, for example);

also if you ever go closed loop, then on high load you want PE to provide fueling.

( ah, looking at your tune, PE is enabled already )


You don't really have to worry about lugging the engine in 3rd, it has plenty of torque to pull the vehicle smartly; same with 4th gear for a car, but not necessarily a truck.


You can fix the bogging by removing fuel (bump down the VE table in the low area)...
in the low area, unburnt fuel goes thru to the exhaust, this registers as lean (unburnt fuel = unburnt oxygen), so it makes you add too much fuel (by bumping up the VE table)...
so just remove some (by bumping down the VE table) just in that area.


If AFR 14.2 is due to you running E10, then yes the PCM will be able to trim to it (set B3601 to 14.2)...
your wideband reports AFR based on E00...
so you should use lambda (from the WB) and EQR from the PCM...
( the correction factor is then simply lambda x EQR ).

No, this family of PCM's is designed to handle only NB O2 sensors... the LSU4.2/LSU4.9 will not work with the PCM (they will only work with a WB controller, or an ECM designed specifically to use the LSU's, for example any of the self tuning aftermarket EFI kits, and some European vehicles).

[rover346]

Your B3647 is stoich everywhere until the 100 kPa column... you want to start increasing fueling earlier (i.e. engine load can still be quite significant at 80 kPa, for example);

also if you ever go closed loop, then on high load you want PE to provide fueling.

( ah, looking at your tune, PE is enabled already )


You don't really have to worry about lugging the engine in 3rd, it has plenty of torque to pull the vehicle smartly; same with 4th gear for a car, but not necessarily a truck.


You can fix the bogging by removing fuel (bump down the VE table in the low area)...
in the low area, unburnt fuel goes thru to the exhaust, this registers as lean (unburnt fuel = unburnt oxygen), so it makes you add too much fuel (by bumping up the VE table)...
so just remove some (by bumping down the VE table) just in that area.


If AFR 14.2 is due to you running E10, then yes the PCM will be able to trim to it (set B3601 to 14.2)...
your wideband reports AFR based on E00...
so you should use lambda (from the WB) and EQR from the PCM...
( the correction factor is then simply lambda x EQR ).

No, this family of PCM's is designed to handle only NB O2 sensors... the LSU4.2/LSU4.9 will not work with the PCM (they will only work with a WB controller, or an ECM designed specifically to use the LSU's, for example any of the self tuning aftermarket EFI kits, and some European vehicles).

Thank you Joe, Yeah the truck weighs roughly 5k with a factory stall converter since I wanted other drive train components to live. My issue now is the truck is taking 42 lb marine injectors to 88% duty cycle at full swing with 60-63 psi going through them. Far cry from the old 5.3 only being at 44%