P0171

[madpanfan]

Hi, a friends 2001 micra k11 with 106,000 miles has an engine light on with the code P0171 system too lean.

After clearing the code and driving, the longterm fuel trim increases to 25 and stays at 25.

There is a small pool of fluid in the inlet manifold.

Any hints of tips as to what the cause could be?

 

[Jorge_EETC]

Hi, a friends 2001 micra k11 with 106,000 miles has an engine light on with the code P0171 system too lean.

After clearing the code and driving, the longterm fuel trim increases to 25 and stays at 25.

There is a small pool of fluid in the inlet manifold.

Any hints of tips as to what the cause could be?

Could be alot of things, the fluid is gas? Could just be clogged injectors, fuel pump or pressure regulator

Enviado do meu MI 8 através do Tapatalk

 

[.Maarten]

Most of the time its a bad lmm or o2 sensor.

 

[madpanfan]

I think its gas (petrol) in the manifold.

I cannot hear the pump priming when I turn the key on. Is this normal, or should I hear the pump?

 

[Jorge_EETC]

I think its gas (petrol) in the manifold.

I cannot hear the pump priming when I turn the key on. Is this normal, or should I hear the pump?

If engines starts and runs the pump is running

Enviado do meu MI 8 através do Tapatalk

 

[madpanfan]

I'm wondering if the pump is supplying the recommended pressure though.
I thought I should be able to hear it, if the pump is weak it could cause a system lean code?

 

[.Maarten]

It can but if a pump cant supply the pressure you most likely also notice it when driving. So not likely. If i remember correctly i also dont hear the pump running when i turn the key on on my second facelift.

 

[madpanfan]

Cheers

 

[madpanfan]

Ok I must try full throttle up a hill and see how I get on

 

[madpanfan]

I unplugged the maf and it ran worse.
Here's a datastream with the maf plugged back in and the codes cleared

The engine was fully warmed up and was in Closed Loop but if I blip the accelerator it would go into OL-DRIVE


FUELSYS1 OL-DRIVE
ETC °C 80
SHRTFT1 -7.8
LONGFT1 0.0
RPM 640
SPARKADV 14
IAT °C 28
MAF g/s 1.57
TP % 8.6
O2B1S1 V 0.760
O2B1S2 V 0.735

 

[madpanfan]

Why would the reading for Load_pct be always reading 0.8 ?
Should it not fluctuate as the revs change?

 

[Rocket]

Hello. My 1.0 facelift has the same issue, P0171, LTFT is increasing untill 25%, STFT is negative when it is iddling, and the car is starting harder as the engine is hotter. I changed the MAF sensor untill now, and cleaned the TB, together with the IACV valve. Why the engine starts harder in hot condition? Thank you.