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Old 08-22-2012, 01:26 AM   #1
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Default Running lean at partial throttle and WOT around 4k RPM

I recently built and installed a DIYPNP into my 92 Miata in preparation for the turbo install. I am using an AEM wideband and GM IAT. I am running lean at very light throttle, if I give it a little less or a little more throttle it is no longer lean, but will run 16+ AFRs while cruising. It also goes lean at WOT around 4k RPM. At idle the AFRs are around 14.7. I have tried adjusting the VE table around 4k rpm and its a little less lean but still approaching 14 AFR at WOT. Here is a screen shot from the log viewer. Any ideas what is causing this?
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Running lean at partial throttle and WOT around 4k RPM-mslog.jpg  
Attached Files
File Type: msl 2012-08-21_16.56.04.msl (1,023.7 KB, 94 views)
File Type: msq CurrentTune.msq (83.9 KB, 93 views)

Last edited by codices; 08-22-2012 at 01:46 AM.
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Old 08-22-2012, 01:37 AM   #2
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upload the data log and tune
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Old 08-22-2012, 01:50 AM   #3
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Added the files to the original post. Another thing about this, I had to set req fuel to 17.6 to get it to idle properly. This seems too high. Does that indicate a problem? The motor is currently completely stock.
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Old 08-22-2012, 01:52 AM   #4
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You're obviously using MegaLog Viewer. Use the tuning console. Fill your AFR target table with decent values and let MegaLog tune your fuel for you. It's easy and it works.
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Old 08-22-2012, 02:08 AM   #5
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yea 17.6 seems odd
stock 1.6 injectors? should be ariound 12 or 13 iirc, I would make sure fuel pressure at the rail is to spec.
9-7% of the fuel is being taken out by gair

I would look at reducing the effect of gair on the tune, disabling closed loop operation, disabling any acceleration enrichments, get a variable TPS, while dialing in the tune.
Also in project properties switch it from narrowband to wideband


Also if stock 1.6 injectors 1.2ms is too much dead time for them I would start at around .8 and go lower, the closer you get the flatter the VE table will become
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Old 08-22-2012, 12:14 PM   #6
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I will try these today to see if it helps. Does anyone know why the PW is drooping right after the cursor in the log screen shot? If that drop in PW wasn't there I don't think I would be leaning out at WOT around 4k rpm.
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Old 08-22-2012, 02:01 PM   #7
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Quote:
Originally Posted by codices View Post
I will try these today to see if it helps. Does anyone know why the PW is drooping right after the cursor in the log screen shot? If that drop in PW wasn't there I don't think I would be leaning out at WOT around 4k rpm.
Because between math and your tune the ecu thinks the car needs less fuel there.
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Old 08-23-2012, 01:12 AM   #8
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Quote:
Originally Posted by Techsalvager View Post
yea 17.6 seems odd
stock 1.6 injectors? should be ariound 12 or 13 iirc, I would make sure fuel pressure at the rail is to spec.
9-7% of the fuel is being taken out by gair

I would look at reducing the effect of gair on the tune, disabling closed loop operation, disabling any acceleration enrichments, get a variable TPS, while dialing in the tune.
Also in project properties switch it from narrowband to wideband


Also if stock 1.6 injectors 1.2ms is too much dead time for them I would start at around .8 and go lower, the closer you get the flatter the VE table will become
Yes it is the stock injectors. I'm thinking there might be a problem with them. I managed to fix the lean spot at 4k rpm by adjusting the ve table a lot higher in that range than the default tune. Req fuel is now set to 15.5. I tried lowering the injector dead time to .8 but the car ran much worse. By increasing it to 1.6, I was able to lower the req fuel to 15.5 from 17.6. Any thoughts? The FM kit is being delivered today.

Could you elaborate on disabling closed loop, disabling acceleration enrichment?
Attached Thumbnails
Running lean at partial throttle and WOT around 4k RPM-tune.jpg  
Attached Files
File Type: msq CurrentTune.msq (83.6 KB, 89 views)
File Type: msl 2012-08-22_15.06.15.msl (657.1 KB, 86 views)
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Old 08-25-2012, 12:49 AM   #9
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MSPNP default uses:

Required Fuel = 13.4
Opening Time = 1ms

Why on earth are you adjusting your VE table yourself? Use VE Analyze.

Set your required fuel based upon the calculation. Tune with VE, not with required fuel. What you said about adjusting required fuel to get it to idle is pure gibberish. You may have caused a side effect, but you're doing it wrong. I've posted extensively on tuning idle. Others have too. Try a search.

Also, check your fuel pressure and make sure it is up to snuff. You've bought bigger injectors for your FM kit, right? The stock 1.6 injectors don't have enough.
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Old 08-25-2012, 09:44 PM   #10
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I am running stock injectors for the time being. I actually have it running pretty well by adjusting the req fuel, injector dead time and adjusting the VE table for cruising and for WOT at 4k RPM. Honestly, I don't want to mess with it any more until I get the turbo installed.

I am adjusting the VE table manually because I do not have the full version of the software.

I plan on running the stock injectors at wastegate pressure. FM sells the voodoo kit for use with the stock injectors and says that they are good for about 160whp. This winter comes clutch, differential, injectors and exhaust for big boost.
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Old 08-26-2012, 12:38 AM   #11
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You can use VE Analyze in the demo version. That said, the full MegaLog software is worth way more than the licensing fee.
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