rom tuning for pops and backfires

[Xero-Limit]

Originally Posted by shiv@vishnu

I'm quite sure it's possible to do by just remapping the active ignition table and by playing around with the duration for throttle enrichment.

Any alteration to the main ignition and fueling tables will make for a rough transition from on/off throttle. With RaceROM we can make a custom map that is only active in a certain range, only for a certain time, and only when desired. That is why we can enable this without messing up cruise and low load operation and trims. Otherwise if you tweak the primary fueling and timing tables (or enrichment) you get sideffects that make for a lousy ride. Been there done that with the MX5 where we don't have custom maps (yet....), so this is a FT86/GTR only feature.

[DJCarbine]

The next time I send in logs I'm going to request this... for science and stuff.

[Grip Ronin]

Originally Posted by shiv@vishnu

I'm quite sure it's possible to do by just remapping the active ignition table and by playing around with the duration for throttle enrichment.

i only see the ignition tables go to .15 and theres no way to adjust the break points on it. closed loop goes ~.08 always a steady 32 degrees. how would i go about changing closed loop timing?

[Shiv@Openflash]

Originally Posted by Grip Ronin

i only see the ignition tables go to .15 and theres no way to adjust the break points on it. closed loop goes ~.08 always a steady 32 degrees. how would i go about changing closed loop timing?

You can adjust load and rpm breakpoints in Rom Raider. In Tuner Pro, I never bothered to defined them individually since it didn't seem necessary or useful at the time. For maximum pop-age, you'd want to run negative timing during over-run and try to delay deccel-triggered fuel cut. Basically making the ECU control fuel/spark like ECUs did 10 years ago before emissions required them to get clean. It's all do-able and shouldn't require any custom maps.

[Grip Ronin]

Originally Posted by shiv@vishnu

You can adjust load and rpm breakpoints in Rom Raider. In Tuner Pro, I never bothered to defined them individually since it didn't seem necessary or useful at the time. For maximum pop-age, you'd want to run negative timing during over-run and try to delay deccel-triggered fuel cut. Basically making the ECU control fuel/spark like ECUs did 10 years ago before emissions required them to get clean. It's all do-able and shouldn't require any custom maps.

im gonna give it a shot and get back to you thanks.

[Malt]

Have any of you guys seen an muffler burst from backfires or had to replace a muffler due to the packing being ruined from constant over fueling? I'm honestly surprised a tuner would intentionally tune this into a tune as it serves no practical purpose other than wasting fuel and potentially causing exhaust damage.

[mad_sb]

Originally Posted by Grip Ronin

im gonna give it a shot and get back to you thanks. for the fuel delay id change which cl,ol timer?

No, not the timers, there are some beta tables for overrun fueling, but they look like they are all related to the resume normal fueling cutover point. I assume if you raised the overrun fueling rpm resume threshold you could get it to do what you want, or possibly just change the RPM delta value.

As for the timing.. you will need to setup the map with the first load column being a little uder the decel load you see and the next column just over the decel load so you can run negative values in the first column and normal values in the second so your not trying to cruise at low load with retarded timing values.

Just had another thought, you might run into some idle / low fuel trim issues if you turn off decel fuel cut.. keep an eye on them and see. You could always force open loop at decel load values and that might allow you to play around with how much fuel etc you have during decel, you will need to modify the load axis of the fuel tables as well as the closed loop fueling target compensation A&B tables (set them to 14.7 where you want open loop). But that might require you to zero out the cl-ol timers and transition based on fuel map values.

[s2d4]

Wouldn't this also increase EGT? Increased potential of burning/melting cats?

[Grip Ronin]

Originally Posted by s2d4

Wouldn't this also increase EGT? Increased potential of burning/melting cats?

what cats? lol

[DJCarbine]

Originally Posted by Malt

Have any of you guys seen an muffler burst from backfires or had to replace a muffler due to the packing being ruined from constant over fueling? I'm honestly surprised a tuner would intentionally tune this into a tune as it serves no practical purpose other than wasting fuel and potentially causing exhaust damage.

Never had a muffler explode due to overrun popping. Maybe if it was overdone.... but the popping in the video was extremely subtle. Ive had cars that popped/banged twice as aggressive on a stock tune with only exhaust mods

[DJCarbine]

Originally Posted by s2d4

Wouldn't this also increase EGT? Increased potential of burning/melting cats?

Im a dog person myself....

[Grip Ronin]

Originally Posted by mad_sb

No, not the timers, there are some beta tables for overrun fueling, but they look like they are all related to the resume normal fueling cutover point. I assume if you raised the overrun fueling rpm resume threshold you could get it to do what you want, or possibly just change the RPM delta value.

As for the timing.. you will need to setup the map with the first load column being a little uder the decel load you see and the next column just over the decel load so you can run negative values in the first column and normal values in the second so your not trying to cruise at low load with retarded timing values.

Just had another thought, you might run into some idle / low fuel trim issues if you turn off decel fuel cut.. keep an eye on them and see. You could always force open loop at decel load values and that might allow you to play around with how much fuel etc you have during decel, you will need to modify the load axis of the fuel tables as well as the closed loop fueling target compensation A&B tables (set them to 14.7 where you want open loop). But that might require you to zero out the cl-ol timers and transition based on fuel map values.

ive tried zeroing timers, it didnt do much but i did find that messing wit the front o2 ratio changes the 20.3 ratio when in closed loop off throttle but i havnt found the timing control for it. i dont know if the primary igniton table would do that

[andrew5826]

wow. great discussion going on. did some testing. I changed the ignition advance base timing A map to neg 10 degrees on the first column (,15) and the base idle (above speed threshold) to negative timing. lots of pops at partial throttle. lots on downshift and a couple on hard shifts. I'm gonna fine tune it a bit more so I don't have to play with the throttle so much to get the pops.

Sent from my SGH-I337M using Tapatalk

[DJCarbine]

Originally Posted by andrew5826

wow. great discussion going on. did some testing. I changed the ignition advance base timing A map to neg 10 degrees on the first column (,15) and the base idle (above speed threshold) to negative timing. lots of pops at partial throttle. lots on downshift and a couple on hard shifts. I'm gonna fine tune it a bit more so I don't have to play with the throttle so much to get the pops.

Sent from my SGH-I337M using Tapatalk

I would try to get the partial throttle popping resolved.... is it fun though? I miss the overrun popping/crackle on my e36