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sprinkles08, ASE Certified Technician
Category: Volvo
Satisfied Customers: 21947
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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Volvo s40 turbo: i have a 2001 volvo s40 that has a p0171 lean

Customer Question

i have a 2001 volvo s40 that has a p0171 lean code and misfire codes on all cylinders on cold start ups. both long term and short term fuel trim seem high. i recently changed a frozen turbo, and did the timming belt and cam seals. was running fine before. also the car sat for a year but always started good the few times i did start it. i also swapped out the airbag module because i got a code from changing the seat belt.
Submitted: 1 year ago.
Category: Volvo
Expert:  sprinkles08 replied 1 year ago.
Hello and welcome to JustAnswer!
If it's setting a fuel system lean code and missing when cold then a fuel issue is very likely. Low fuel pressure would definitely be the most likely cause for what you're having. I would recommend checking fuel pressure under the conditions where it acts up, if pressure is low and the ump's power and ground are good then replace the pump.
Customer: replied 1 year ago.
I checked pressure 45psi when turn to on position. running is 35psi. goes up to 40psi when i turn it off and holds pressure. also changed pressure regulator. I changed the pump and filter also. pump was from a good running s40.
Expert:  sprinkles08 replied 1 year ago.
Did you check under a load while driving?
Customer: replied 1 year ago.
No. How would i do that?
Customer: replied 1 year ago.
Scan tool?
Expert:  sprinkles08 replied 1 year ago.
You would check with a fuel pressure gauge.
Customer: replied 1 year ago.
So like on the open road? How would you close the hood and see the gauge?
Expert:  sprinkles08 replied 1 year ago.
You would use a gauge that has a hose long enough to run out of the engine compartment and secure it in a place that can be seen from the driver's seat.
Customer: replied 1 year ago.
Ahh ok will try that. What am i looking for as far as pressure?
Expert:  sprinkles08 replied 1 year ago.
It should stay steady and not drop lower under a load.
Customer: replied 1 year ago.
when I give it gas the pressure doesnt go down. any ideas?
Expert:  sprinkles08 replied 1 year ago.
Have you checked the ambient, intake and coolant temperature sensors with a scan tool while the engine is cold to see if they all agree and show the correct temperature?
Customer: replied 1 year ago.
The coolant temp looks normal. I changed the coolant temp sensor anyway with volvo sensor. How do you check the intake temp sensor?
Expert:  sprinkles08 replied 1 year ago.
A scan tool would be needed to check these sensors.
Customer: replied 1 year ago.
I have a scan tool with like 300 pids?
Expert:  sprinkles08 replied 1 year ago.
You'll need to look at intake, ambient and coolant temperature with the vehicle cold and see if all the sensors agree and are correct.