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MAP slope or injector scaling


Milanski
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I've put myself in a corner.  Built custom intake and exhaust system for twin turbo 5.4.  So lots of heavy mods.  Should have kept the stock fuel system to see whatbthe MAP slope and intercept tables (auf0056 and 61) looked like after the build.  But alas i didnt.  Now i dont know if its the map zero or map slope tables (56 / 61) that need changing along with the the new id1050x injector data.  For now i am keeping the MAP tables stock and dialling in the low slope and offset for the  injectors.  The i.d. data is have thus far to give me a goodnidle are like 20% different to theirnrecommendation.  This would auggest to me that the Map tables need a looking at.

The question is, should i continue to tune the slopes in against stock map zero and slope tables OR install the original fuel system along with oem ford bosch injectors and confirm the MAP tables are correct for speed density calculations.  This will ensure i have the air mass system functional against good known injector curves.  Buy this is a lot of work to revert back and forth....

Ive noted a few tunes going around, mainly supercharger type where the map tables are stock.  I get the feeling im playing with a chicken and egg scenario.  A point in the right direction is appreciated.

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Put the entire base table and cold table to 0.8. Turn off the O2 sensor/force open loop. At operating temp note the idle afr. Adjust the low slope so idle afr matches 0.8. Stall it up on the brake and note afr. Adjust high slope until it matches 0.8.

Revert tables back to desired figures.

This will dial the slopes in and you don't even have to leave the driveway.

Leave the breakpoint where the id data suggests.

Go for a drive and see how far out the high slope is, this will give you an idea if the airflow tables need touching up.

Anyhow hope that helps.

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Thanks Mate.

I will leave the MAP table stock then.  I have got the low slope almost there which i found i need to adjust the battery offset.

Have you any experience with widebands? When the car was idling in closed loop i had ltft around 2%, my wide band afr's were showing 16. But the o2 narrowband was happily oscillating as required, hence stoich happy. The widebands are dg1-2 by innovate.  Ive checked for leaks and flanges, no leaks. Eveb wrapped them up to see difference.  I tried a third party afr by plx shows the same.  Its just before the cats.  So i have been using 16 as the baseline for stoich, weird i know. 

 

 

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Is there an O2 bias happening in the tune? Apart from exhaust leaks and possible ground issues I can't think of why it'd be doing that.

I've only tuned one boss motor and I can't remember it idling that lean, but it was ages ago so yerp.

Edited by Puffwagon
Stupid autocorrect
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My WB AFR are sitting about 50mm before the cats.   As a test I moved bank 1 (drivers side) upstream to the location of the Ford Narrowband.  On bank 2 the O2 sensor remains 50mm before the Cats.  Interesting observation -->  Bank 1 now read 14.8 or there abouts and bank 2 reads 15.8. Its as if though the Cats are having some sort of effect in that area.  It could also mean I have minor leaks on the 2 v-bands between the narrowband and wideband. 

I have also made a rookie mistake with the turbo set up, i should have welded the O2 bung position on the header before the turbo to take the narrowband.   I'm looking at the amount of sources of air ingress between the header collector and narrowband and there are 4 V-Bands...   Next engine swap will have the O2 fitted at the headers. 

As for the injector calibrations, I set the MAP slopes to stock.  Set up the fuel tables at 0.9lambda.  Adjusted the offset and low slope and honed it in so that under idle I had 13.3AFR (0.9xLambda) and under handbrake+ foot to the brake up to 1500 i had 13.4AFR.  (I dont really want to risk going through the garage walls!). I think should be a good starting point. Injector pulsewidth was showing 0.8ms at 1500, only 0.3ms from idle. I am not sure if I am logging the true pulse width, seems very short.  Many Thanks   

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Seems like a good starting point with the slopes, it'll get you in the ballpark. You might be onto something with the vbands. I have 6 in my system and they don't always seal up perfectly, so I wouldn't be surprised to see an issue even after one or two. Whether or not it is the problem, it doesn't hurt to check it off the list.

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  • 1 month later...

Hi there, quick update and now I am stuck.  

I have spent weeks getting the ID1050x data dialed in and I think I have made some good progress.  Ex-tuners data simply was wrong and InjectorDynamics data doesnt work either, couldnt even get the engine to crank and start properly with ID Data. 

I am able to idle at 3 to 4 % STFT and less than 1% LTFT.  On light cruise the LTFT seem to be less than 2%.  STFT move +/-5% (some cases as high as 10% after decel). 

On zero foot pedal and coasting I have LTFT at 0.9 or -10% @ 1500RPM for example.  Should I just leave it or continue to make changes.  Further background information, heavily modified intake, twin turbo 5.4 set up with custom plenum, stock 260 whilst building my engine, some scavenging around the v-bands.  I want to get the ID data correct before putting in the new 1000HP engine.  For now im thinking of using the VE corrections around 1500rpm / 0-20% load to "work around" the -10%LTFT.   Or should I just leave it! 

Is there anything more I can do to the injector offsets and low slope to fix this, as it seems like im going in circles moving the offsets and slopes.  Is there something else to look at? - not sure what accelerator pump is...  or hack the speed density tables.  I am operating in the smallest range of Injectors capability and understand this area to be hard to dial in, (about 1.4ms PW).  I wasting my time?  Should I just call it a day?  The data below has minimum 100 cell count and tried to keep it in the low slope.  

Cruise Data:

  image.thumb.png.31ae1e1a119d9e10ceedf9bb17581736.png

 

 

Off throttle data, the flat line is showing OL - Accel/Decl TQ Req. Lean which is net on the list to sort out.

image.thumb.png.3aca56df2fc249c81dd7b109a36641a6.png

 

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