OFT Dead Spot 1000-1700

[trueno86power]

Originally Posted by Shiv@Openflash

I have seen some combinations of ethanol formulations and cars run quite rich at low RPM full load. I suspect it may be caused by some combination of header design, MAF turbulance and lower Ethanol %. All that you need to do to fix it is adjust the primary fuel table. The OTS AFR values will be in the mid-12:1 range down like this:


I fixed the issue by just tweaking it as such:


You can confirm by just datalogging a few low rpm/high gear pulls. The nice thing is that the engine will happily accept a pretty wide range of AFR at that low engine speed. Anything result from an actual 12.5:1 to 13.5:1 will work fine.

@Shiv@Openflash, with the K&N intake I still can feel the drop in 1st gear at 1500-1800 rpm. I don't run on E85, but on gas 93 Octage stage 1 tune. For now my LTFT and my STFT don't indicate me that I need to rescale my MAF (App 0.8 to 4% of adaptation)

Is there a way to limit the % of the throttle body on this zone?

[steve99]

Originally Posted by trueno86power

@Shiv@Openflash, with the K&N intake I still can feel the drop in 1st gear at 1500-1800 rpm. I don't run on E85, but on gas 93 Octage stage 1 tune. For now my LTFT and my STFT don't indicate me that I need to rescale my MAF (App 0.8 to 4% of adaptation)

Is there a way to limit the % of the throttle body on this zone?

Yes you need to fix the load limits even on petrol tunes.

on C & D series oft roms the load limits are set to 1.6 across whole rpm range.

if you look at other roms load limits are about 0.9 at low rpm rising to 1.3 at higher rpm.

With load limits set to 1.6 at low rpm when you stomp on the accelerator the load rises rapidly and ecu looks up timing and fueling for 1.4 (max in tables) load this results in very rich fueling and minimal or retarded ignition timing and car will bog below 2000 rpm.

with loads limited to arround 1 at lower rpm the ecu is then looking up fueling and timing for load 1 even if load calculated is way above that, so it stops the engine bogging at low rpm.

the load limits are ok in other rom calids only the usa/canada roms have the issue

either copy the load limits from and equivalent G or I series rom they are same or use wayno's load limit tables below note he has rescaled axis so copy that as well

Their are two load limit tables make sure both are set to same values

if you dont have both load limit tables in your definitions grab waynos defs attached to his tuning post
http://www.ft86club.com/forums/showthread.php?t=94822

[PantsDants]

An alternative to limiting the load is to scale back the GDI pressure for these conditions. If you can verify that your AFR is going crazy rich when the "dead spot" happens, you can give this a try as well. Your numbers may vary, make sure you're not leaning it out, etc.

http://www.ft86club.com/forums/showp...5&postcount=15

[steve99]

Originally Posted by PantsDants

An alternative to limiting the load is to scale back the GDI pressure for these conditions. If you can verify that your AFR is going crazy rich when the "dead spot" happens, you can give this a try as well. Your numbers may vary, make sure you're not leaning it out, etc.

http://www.ft86club.com/forums/showp...5&postcount=15

thats might be necessary for ESC

with correct load limits (we never had the problem on G roms (its only C&D)
you can stomp on the throttle in any gear even 6th at 1500 rpm and it won't die or bog, just slowly pull away.

its the ignition timing that an issue as well
2000 rpm with load limited to 0.9 as per normal your timing will be about +10 degrees if load not limited ie limits set to 1.6 as per C&D roms the timing used by ECU will be about -2 (retarded) combined with a rich mix and it bogs.

[PantsDants]

Originally Posted by steve99

thats might be necessary for ESC

with correct load limits (we never had the problem on G roms (its only C&D)
you can stomp on the throttle in any gear even 6th at 1500 rpm and it won't die or bog, just slowly pull away.

its the ignition timing that an issue as well
2000 rpm with load limited to 0.9 as per normal your timing will be about +10 degrees if load not limited ie limits set to 1.6 as per C&D roms the timing used by ECU will be about -2 (retarded) combined with a rich mix and it bogs.

You're absolutely right that timing plays a part in the bogging. I'd be concerned that running +10 degrees at low RPM when engine load exceeds 1.5 g/rev is a recipe for knock, but that may not be a concern when naturally aspirated. You'd know that better than I do.

[steve99]

Originally Posted by PantsDants

You're absolutely right that timing plays a part in the bogging. I'd be concerned that running +10 degrees at low RPM when engine load exceeds 1.5 g/rev is a recipe for knock, but that may not be a concern when naturally aspirated. You'd know that better than I do.

that's what the stock load limit table does (as per all stock roms and all oft NA roms except USA roms), its just for some reason the oft guys changed the load limit tables in the C & D roms only. All the other NA oft roms have the standard load limit tables. People did not see them as the load limits were not defined in the oft defs. I think the oft guys were testing something and just forgot to put the load limit tables back to stock.

load limits are going to need to be adjusted for FI ESC but on NA cars having the load limits flat at 1.6 does not make sense to me and its only in usa OFT NA roms , weird, i think its just a mistake.

[thambu19]

@Steve does OFT tune for E85 have changes made to fuel density or Pulsewidth to mass table to correct for the longer PWs of E85? Or are they just letting the ECU adapt with higher fuel trims? I know most ECUs only allow for 33% excess fuelling using adaptions so wondering how the 45% extra fuel for E85 is accomodated. Now I am not sure the limit for Long term adapt but I do know the short term is usually clipped to 33%

[Wayno]

Originally Posted by thambu19

@Steve does OFT tune for E85 have changes made to fuel density or Pulsewidth to mass table to correct for the longer PWs of E85? Or are they just letting the ECU adapt with higher fuel trims? I know most ECUs only allow for 33% excess fuelling using adaptions so wondering how the 45% extra fuel for E85 is accomodated. Now I am not sure the limit for Long term adapt but I do know the short term is usually clipped to 33%

Why don't you just download them and look for yourself?

[steve99]

Originally Posted by thambu19

@Steve does OFT tune for E85 have changes made to fuel density or Pulsewidth to mass table to correct for the longer PWs of E85? Or are they just letting the ECU adapt with higher fuel trims? I know most ECUs only allow for 33% excess fuelling using adaptions so wondering how the 45% extra fuel for E85 is accomodated. Now I am not sure the limit for Long term adapt but I do know the short term is usually clipped to 33%

I am not faliliar with the tables you are talking about , not sure they exist in definitions ?

the fueling adjustments for e85 were achieved by altering the port injector scalar and the direct injector pressure multiplier tables by about 33%

maf scaling is slightly different on e85

this get fueling in the ballbark then the fuel trims adapt for variations in E% from different fuel outlets.

you usually dont see ltft over 6% if you maf scaling is ok and done for average e% in your local area

[thambu19]

Thanks @steve99. Most OEMs model fuel temperature at the rails and hence the fuel density so I thought perhaps the E85 cal fudged the fuel temp/density cal to make ECU think it should use more PW to get to same mass.
The fuel mass to PW cal is usually the injector characterization done mostly by injector supplier who formulates the injection offset/delay and the PW to mass surface. Once again we could cheat the ECU by fudging that surface. I guess many ways to skin the cat.
I took a look at the DI pressure mult change. I am guessing they made the ECU think it was either getting a lower pressure or making ECU think the flow is lower for the same pressure to adjust for E85.
I will spend more time looking at stuff meanwhile I ask questions so I dont have to spend the next 6months understanding things before I can actually start contributing. With knowledge sharing we can bring people upto speed quickly and improve the collective understanding of the group

I was assuming the E85 cal would have used 100% PFI injection since the knock relief given by DI was no longer needed with E85 and Ethanol need more time/energy to fully vaporize and mix.

I am guessing Toyota did not go full DI at low speeds due to Soot and we should be able to go 100% DI for petrol only cal and make use of of it ignoring soot. On the other hand I think they went 100% DI at 2400rpm because that is where scavenging peaks in this engine? Going DI will avoid fuel shortcircuiting and hence lower HC emissions.
Just trying to decipher why they did things this way so we can maximise gains

[steve99]

Originally Posted by thambu19

Thanks @steve99. Most OEMs model fuel temperature at the rails and hence the fuel density so I thought perhaps the E85 cal fudged the fuel temp/density cal to make ECU think it should use more PW to get to same mass.
The fuel mass to PW cal is usually the injector characterization done mostly by injector supplier who formulates the injection offset/delay and the PW to mass surface. Once again we could cheat the ECU by fudging that surface. I guess many ways to skin the cat.
I took a look at the DI pressure mult change. I am guessing they made the ECU think it was either getting a lower pressure or making ECU think the flow is lower for the same pressure to adjust for E85.
I will spend more time looking at stuff meanwhile I ask questions so I dont have to spend the next 6months understanding things before I can actually start contributing. With knowledge sharing we can bring people upto speed quickly and improve the collective understanding of the group

I was assuming the E85 cal would have used 100% PFI injection since the knock relief given by DI was no longer needed with E85 and Ethanol need more time/energy to fully vaporize and mix.

I am guessing Toyota did not go full DI at low speeds due to Soot and we should be able to go 100% DI for petrol only cal and make use of of it ignoring soot. On the other hand I think they went 100% DI at 2400rpm because that is where scavenging peaks in this engine? Going DI will avoid fuel shortcircuiting and hence lower HC emissions.
Just trying to decipher why they did things this way so we can maximise gains

The easiest way to see the changes is grab a OFT Stage 2 petrol say UEL rom and compare it Stage 2 E85 UEL rom from same calid using rom compare function in Romraider editor software.

they do run more DI on the E85 rom, but we found it was also beneficial to run same increased DI fueling on poor quality petrol for better knock resistance. Yes think the PI fueling is primarily for intake valve deposit reduction.

their was some good discussion here
http://www.ft86club.com/forums/showthread.php?t=71506

[thambu19]

Thanks Steve for the link. I will do the compare in romraider today.