HELP needed , engine running to lean .
#1
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HELP needed , engine running to lean .
Hey ;
I have a stock impreza wrx 02 from a client that is running way to lean .
Also getting the faultcode p0171 . ( system to lean )
First off corse checked all the vacuumhoses and even blocked them off compleet . Stays the same . Car even starts cold at 17 AFR .
fuel trim go's directly to the max of 25% and even then it come's to a afr of 15.5 - 16 .
Things done :
- New fuelpump
- New lamdasonde ( first one )
- Other tmic
- AF sensor changed from a car that run's fine ( even from 2 different cars already )
- Changet the complete intake manifold incl injectors and fpr )with other one inc new gaskets and intakehose
- Checked timing belt ( is correct )
- Swapt ecu from other bugeye
Nothing that even chaged a bit the afr .
I'm realy with my back against the wall now....
Is it possible with let us say bad closing valve's you get a lean afr ?
I have no more idea's for the moment to look at .
I have a stock impreza wrx 02 from a client that is running way to lean .
Also getting the faultcode p0171 . ( system to lean )
First off corse checked all the vacuumhoses and even blocked them off compleet . Stays the same . Car even starts cold at 17 AFR .
fuel trim go's directly to the max of 25% and even then it come's to a afr of 15.5 - 16 .
Things done :
- New fuelpump
- New lamdasonde ( first one )
- Other tmic
- AF sensor changed from a car that run's fine ( even from 2 different cars already )
- Changet the complete intake manifold incl injectors and fpr )with other one inc new gaskets and intakehose
- Checked timing belt ( is correct )
- Swapt ecu from other bugeye
Nothing that even chaged a bit the afr .
I'm realy with my back against the wall now....
Is it possible with let us say bad closing valve's you get a lean afr ?
I have no more idea's for the moment to look at .
Last edited by ducske916; 12 September 2017 at 12:58 PM.
#3
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Denso .
But can't believe even it as somting to do with the lamda sensor because it runs even lean at cold startup ( so still in open loop and not using the lamda sensor )
But can't believe even it as somting to do with the lamda sensor because it runs even lean at cold startup ( so still in open loop and not using the lamda sensor )
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i checked all above items .
Now i did get the tip to disconect the maf , then the afr go's to 14.8 .
So maybe a problem in the maf wire's to the ecu . will check this first now .
Now i did get the tip to disconect the maf , then the afr go's to 14.8 .
So maybe a problem in the maf wire's to the ecu . will check this first now .
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checkt the maf sensor, 12v ok - ground ok and signal wire i put a wire direct to the ecu but still the same problem .
Maf is already bin changed with 2 other one's from fine running wrx'es ( and cleaned also with maf cleaner )
Maf is already bin changed with 2 other one's from fine running wrx'es ( and cleaned also with maf cleaner )
Last edited by ducske916; 13 September 2017 at 06:17 PM.
#13
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Possibly a pre-turbo air leak. The standard turbo inlet pipe is prone to splitting where it joins the turbo compressor cover.
This would cause a maxed out fuel trim and 'system too lean' fault code to be generated.
A smoke/pressure test on the inlet would be a good idea.
This would cause a maxed out fuel trim and 'system too lean' fault code to be generated.
A smoke/pressure test on the inlet would be a good idea.
Last edited by little'un; 13 September 2017 at 08:17 PM.
#16
Manifold, upipe leak? Allowing oxygen into the exhaust and making sensor think it is too lean? The pulsing nature of the exhaust can pull air in as well as leak exhaust out.
Measured the actual fuel pressure in the rail?
Can you not read live sensor values using SSM? That would probably give a clue.
Is it misfiring? Running lean could cause a misfire, but a continual misfire may show lean on the O2 sensor, because of the excess of oxygen now in the exhaust.
Measured the actual fuel pressure in the rail?
Can you not read live sensor values using SSM? That would probably give a clue.
Is it misfiring? Running lean could cause a misfire, but a continual misfire may show lean on the O2 sensor, because of the excess of oxygen now in the exhaust.
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Up-pipe is new
fuel pressure with running engine 2.5bar @ rail
and like said, it does this even at cold start so then the lamdasensor even doesn't work ( open loop) so a exhaust leak can not be the problem
fuel pressure with running engine 2.5bar @ rail
and like said, it does this even at cold start so then the lamdasensor even doesn't work ( open loop) so a exhaust leak can not be the problem
#21
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If it runs OK with the MAF disconnected then your most likely going to be chasing a faulty maf sensor or an air leak somewhere. If you can smoke/pressure test the intake/intercooler/manifold it may give you a clue. Also check the IACV operation and gasket orientation as that can give you bother.