NefMoto > Technical > Diagnostics > running lean....
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Author Topic: running lean....  (Read 6041 times)
lulu2003
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« on: November 01, 2013, 07:59:59 AM »
ME7.5 based 1.8T, closed loop lambda, is running lean after a +25% tune, though I know the stock fuel system can handle up to 40% more even into high revs.
5bar FPS did not change anything?!!
Fuel trims/adaption FRA are exactly at 100% not more than +/-2% even after changing KRKTE -15%, which makes me struggle a lot, wherer there is a hardware oder software problem.

duty cycle of injectors are 80-90% nearly from 4000rpm to 6800, and exceeding 100% with higher boost.
Lambda Setpoints over 6000rpm are 0.80 but sensor reads 0.9

next step would be putting a pressure gauge to the fuel rail and checking.

any further ideas to narrow down the cause?
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IamwhoIam
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« Reply #1 on: November 01, 2013, 10:08:31 AM »
check fuel pressure before even posting something like this, especially if you know injectors can handle loads more.
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I have no logs because I have a boost gauge (makes things easier)
lulu2003
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« Reply #2 on: November 02, 2013, 09:54:41 AM »
agree, but I had to check the software and logging only!

 why is fra_w and rkat_w  exacty 1 and 0?

here an Example:

if fuel pressure too low I would expect Inj_DC going over > 100% to match setpoint lambda.

Code:
time	nmot	te_w	lamsoni_w	lamsons_w	calc Inj DC
14:37:33.0781250	5047	19.6	0.89	0.83	82.4
14:37:33.1718750	5106	19.61	0.9	0.83	83.4
14:37:33.2968750	5126	19.32	0.89	0.83	82.5
14:37:33.4062500	5162	19.61	0.91	0.83	84.4
14:37:33.5156250	5215	19.43	0.9	0.83	84.4
14:37:33.6250000	5254	19.5	0.9	0.83	85.4
14:37:33.7343750	5301	19.24	0.91	0.83	85.0
14:37:33.8281250	5314	19.48	0.91	0.83	86.3
14:37:33.9531250	5358	19.24	0.91	0.83	85.9
14:37:34.0468750	5374	19.44	0.94	0.83	87.1
14:37:34.1718750	5423	19.36	0.93	0.83	87.5
14:37:34.2812500	5440	19.11	0.92	0.83	86.6
14:37:34.3906250	5479	19.02	0.93	0.83	86.8
14:37:34.5000000	5511	18.83	0.92	0.83	86.5
14:37:34.6093750	5576	19.14	0.94	0.82	88.9
14:37:34.7187500	5598	18.75	0.92	0.82	87.5
14:37:34.8281250	5624	18.75	0.93	0.83	87.9
14:37:34.9375000	5663	18.51	0.92	0.83	87.4
14:37:35.0468750	5675	18.69	0.92	0.83	88.4
14:37:35.1562500	5694	18.62	0.92	0.83	88.4
14:37:35.2656250	5746	18.75	0.93	0.83	89.8
14:37:35.3750000	5771	18.57	0.93	0.82	89.3
14:37:35.4843750	5807	18.42	0.92	0.82	89.1
14:37:35.5937500	5834	18.5	0.93	0.82	89.9
14:37:35.7031250	5875	18.49	0.95	0.81	90.5
14:37:35.8125000	5894	18.3	0.92	0.82	89.9
14:37:35.9218750	5930	18.45	0.93	0.82	91.2
14:37:36.0312500	5951	18.24	0.93	0.82	90.5
14:37:36.1406250	5984	18.13	0.93	0.82	90.4
14:37:36.2500000	6037	18.09	0.93	0.82	91.0
14:37:36.3593750	6053	17.88	0.93	0.82	90.2
14:37:36.4687500	6096	17.71	0.93	0.82	90.0
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oldcarguy85
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« Reply #3 on: November 08, 2013, 07:20:00 AM »
hey -- i just ran into an unexpected lean condition under boost on a 1.8T.  turns out i had a tear in an o-rin on the FPR.  I DID NOT see high injector duty cycles when i was experiencing the problem.  This also threw me off.  Maybe the ECU can only correct a small amount?  I'm not sure.
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Bi-turbo
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« Reply #4 on: November 08, 2013, 10:42:16 AM »
Quote from: lulu2003 on November 01, 2013, 07:59:59 AM
ME7.5 based 1.8T, closed loop lambda, is running lean after a +25% tune, though I know the stock fuel system can handle up to 40% more even into high revs.
5bar FPS did not change anything?!!
Fuel trims/adaption FRA are exactly at 100% not more than +/-2% even after changing KRKTE -15%, which makes me struggle a lot, wherer there is a hardware oder software problem.

duty cycle of injectors are 80-90% nearly from 4000rpm to 6800, and exceeding 100% with higher boost.
Lambda Setpoints over 6000rpm are 0.80 but sensor reads 0.9

next step would be putting a pressure gauge to the fuel rail and checking.

any further ideas to narrow down the cause?


If the injectors are getting to 100% DC then this could be the issue as there is no room for enrichment/further fueling?
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