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Power Fc Scale Tweaking For More Resolution


GTRNUR
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Hi everyone,

I've been making reasonable headway with the tune of my d-jetro on my new engine but have been having low speed stability issues. I have no doubt that part of it is due to the GTRS shuffle issue. But I think the other factor is that the engine makes boost below 2000 rpm in the taller gears and I just dont have enough resolution in the low end of the RPM scale to get the transitions right.

So I was thinking I could re-scale the RPM axis by sacrificing high end RPM load points, and then add more low resolution load points where I need them from 1500 to 3000. I figure if I set a 8500 RPM max map RPM and then drop the resolution to 500 RPM load bands down to 3000. So the RPM scale would look like this:

800

1200

1500

1750

2000

2250

2500

2750

3000

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000

8500

My questions are has anyone else done this? Am I on track here to sort out my issue, or am I going to cause more issues by lowering the resolution in the above 3000 rpm load bands... (I figure 100 rpm isnt a lot).

Suggestions appreciated.

Cheers,

Ian

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I did it with my Emanage Ultimate without issue.

I think the only potential problems is fine tuning any knock and or AFR's in the higher revs, so if you need to pull timing or add fuel at say 5200rpm you have to pull the timing for 500rpm so may show as a little dip in power.

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sounds reasonable to me and makes logical sense as far as tuning goes

trent would have a lot of experience here

i think for map sensor setups, particulary on ITB setups, the challenge is the transition and light load areas as you mentioned. once its on full boost and pressure is constant its fairly straight forward 1d tuning. the light load, transition from vacuum to boost is where it needs work / attention as you have found

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With the d-jetro look @ other settings too like inj vs accel etc... big gains to found there.

also tighten up your scale for better resoluton around peak torque.

Tip: inj vs accel will fix all your throttle (dead spots, jerks etc) transition issues.

Many times the base map is over adjusted which means the fuel economy sucks, set your main map to your desired target A/f's without a dyno or anything (@ this point values are arbitrary see attached rough target a/f map) then adjust /tune your base map injection values on the dyno with an A/F meter so that they give you the desired A/F you commanded in the main map... any hesitations can be dialed out via inj vs accel.

If you do it this way you can make changes on the fly to the main map without a A/f meter (say @ track day) because your changes in the main map are secondary to the base map.(providing the base map was setup on the dyno like i posted above)

post-34927-0-92013100-1292585104_thumb.jpg

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Thanks guys, thats the sort of thing I was hoping to hear.

Im guessing this is the sort of thing you mean Trent?

800

1200

1500 - )

1750 - )

2000 - ) Drivability/response area.

2250 - )

2500 - )

3000

3500

4000

4500

5000 - )

5250 - ) Peak torque area... cams are standard R34 vspec 2.

5500 - )

6000

6500

7000

7500

8000

8500

Thanks for the tip re TPS/Inj. Should be interesting to see the results I can get with it. Ive noticed the engine feels far more responsive when cold, and when it warms up it goes a little doey. I was guessing its the cold start enrichment topping up the transient enrichment a little. At the moment i've not delved too deeply into the rest of the ecu's settings.

Cheers,

Ian

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Thanks guys, thats the sort of thing I was hoping to hear.

Im guessing this is the sort of thing you mean Trent?

800

1200

1500 - )

1750 - )

2000 - ) Drivability/response area.

2250 - )

2500 - )

3000

3500

4000

4500

5000 - )

5250 - ) Peak torque area... cams are standard R34 vspec 2.

5500 - )

6000

6500

7000

7500

8000

8500

Thanks for the tip re TPS/Inj. Should be interesting to see the results I can get with it. Ive noticed the engine feels far more responsive when cold, and when it warms up it goes a little doey. I was guessing its the cold start enrichment topping up the transient enrichment a little. At the moment i've not delved too deeply into the rest of the ecu's settings.

Cheers,

Ian

yeah, its different for many cars so just find what works for you.

feel free to email me the file and im happy to look over it. [email protected] (im working on a few projects at home atm so have a few spare mins)

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So I was thinking I could re-scale the RPM axis by sacrificing high end RPM load points, and then add more low resolution load points where I need them :

Like you read my mind :cheers:

I was going to ask the same question as i think most ppl just leave it as default and tune from there

On the pfc it starts with Ne1 at 800 and goes up in 400 increments but when it reaches Ne13 it jumps 800 rpm to Ne14 ie. from 5600rpm to 6400rpm and then continues to go up in 400s again, jumps 800rpm again between Ne16 and Ne17 then 400s again to Ne20 which is 9200rpm.

I mean for a stock 26 none of us will rev over 8000rpm any way so those two points where it jumps 800 could be scaled down to 400 and still put Ne20 to 8400rpm

My concern also was if by doing this, will it affect any other settings that include rpm and will need to be changed also or will it affect just the inj and ign map?

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My concern also was if by doing this, will it affect any other settings that include rpm and will need to be changed also or will it affect just the inj and ign map?

no adverse effects.

i even re scale the load points around cruise and the high end load

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yes, it'll keep using the same values. but you shouldnt ever really have your limiter set higher than your last ne point

yeah, good point always keep a 500rpm header.

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Just about to rescale my map now, and then go for a test drive.

Regarding the settings 2 INJ vs TPS, im guessing adding a correction here works similar to a RPM vs TPS fuel map might? Whatever the current load/rpm point is, a correction factor is applied to that load point based on TPS. And with the default values being 1.000, it means entirely by map.

And then I might need to add more fuel progressively from low to the high end of the TPS scale, in order to prop up the AFR's.

I thought I had the tune pretty much dead on right for low end drivability until I drove up a nearby range yesterday. The extra load the engine was under had the afr's dipping into the 16's at 2000 rpm when cruising at 60km/h in 4th. That load wasn't being reflected in the MAP sensor as the engine produces really good vacuum and has good low end torque.

While thats still safe, the same cruise speed and gear on level ground was around 14.7:1. (at this stage im more concerned with completing a run in, so im not too woried about aiming for maximum fuel economy.)

I'll take you up on that offer too Trent, and will email you a copy of the map once ive finished my latest bunch of changes and re-tune.

Cheers,

Ian

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inj vs accel tps under setting 2 is throttle pump enrichment, that is enrichment from increases in tps voltages. so bascially, your cruising at 20% throttle, you move your foot to 50% throttle, the ecu adds fuel instantly according to these settings, as the map/afm takes a split second to respond.

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inj vs accel tps under setting 2 is throttle pump enrichment, that is enrichment from increases in tps voltages. so bascially, your cruising at 20% throttle, you move your foot to 50% throttle, the ecu adds fuel instantly according to these settings, as the map/afm takes a split second to respond.

I believe your confusing Accelerate Injector with INJ vs TPS. Accelerate injector tunes the equalivent of a throttle pump with RPM, Amount and decay rate for enrichment.

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theres 2 relevant settings under the 2nd tab. one is labelled Accelerate Injector (mS) and the other is INJ vs Accel TPS1. your talking about the latter one yer? or is there another one i'm not seeing on my version?

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theres 2 relevant settings under the 2nd tab. one is labelled Accelerate Injector (mS) and the other is INJ vs Accel TPS1. your talking about the latter one yer? or is there another one i'm not seeing on my version?

Yes the D-jetro has a bunch more settings on the settings 2 page. Check the screen shot, its plenty different to the l-jetro

Initial results with the re-scale are excellent. The car drives better and has less afr fluctuations at low speeds. Also the transition onto boost is MUCH smoother now that the afr's arent randomly dipping into the 10-11's.

Ive also cranked some ignition into the base map, still keeping the knock down and it has bought the turbo's on another 400rpm sooner. Full boost (0.8 bar) at 4000 rpm with a pair of GTRS's. Thats not bad for a 15 minute road tune. Ive got to do an oil and filter change before I do any more tuning now though.

One more question for Trent.... Do you know the minimum stable injector pulse width for delphi/sard 700cc injectors? It seems my idle afr's get flakey if I drop the pulse width below 1.8ms. It will randomly go lean. Above 1.85ms though its stable, though idle afr's get pretty rich. Closed loop currently turned off of course... turning it on pulls it back ok though.

post-26553-0-86024200-1292666375_thumb.jpg

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my bad then, was looking at a l jetro version which doesnt have inj vs tps or inj vs air temp.

just out of curiousity got a copy of your ignition map?

Not that it will do much for you but here it is. 14000 is the pim value for 0.8 bar boost. The scale is calibrated with a 3 bar map sensor. As you can see there is still plenty to do with the tune. The goal at the moment for me is keeping it safe.

post-26553-0-08240100-1292672692_thumb.jpg

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