Greetings,

I had a CEL thrown on my 2000 V70 XC SE and pulled codes P1171 and P1174. I'se seen several different things listed online for those codes. The print out AutoZone gave me states "Fuel Adaption, bank 1" for both codes. I have also seen "cam position sensor" and "rotor sensor" listed for those codes. Which one is it?

It's looking like plugs, injectors, or MAF. Possibly fuel pump? Does that sound right? If it is the MAF, should I clean or just replace? I even saw a thread about someone who had these same two codes that said it was their battery. I also saw someone mention air leakage in the intake system - canister purge (CP) valve, the secondary air solenoid valve and power brake booster? Could it be as simple as the fuel pump relay?

My concern is that it is only showing for bank 1. That makes me think it is more likely plugs/injectors than the more system wide parts.

I've checked lines, and sprayed carb cleaner around to check for leaks. I haven't found anything. The car is hard to start especially below 1/4 tank but runs fine once started and doesn't seem to stumble or hesitate. It has never gotten good gas mileage. Any input?

Thanks.

 

those two codes point to short term and long term fuel trim. usual suspects are intake or exhaust leaks, fuel pressure issues or oxygen sensors. Usually plugs or injector issues show up as misfire codes so I'd be less inclined on those but its cheap enough to throw in some new OEM plugs. Your car is an I-5 so you don't have a bank 2 (a V6/V8 would) so no worries there. Given you say the car gets harder to start with 1/4 tank, I'd look inthe the evap system and purge valve as you noted - google/youtube "volvo j hose replacement" to see if that gives you any ideas.

 

All modern vehicles are built with what is called a "fuel map" in the basic software of the engine management system. Depending upon the manufacturer, there are slight differences. The goal is to keep the air/fuel ratio at 14.7 to 1.

In the case of Volvo, the mass airflow sensor tells the engine computer how much fuel to inject given the airflow across the mass airflow sensor. The oxygen sensor then has the actual oxygen content and it is reading lean. So, there is a discrepancy between what the computer is doing and the actual outcome. Of course, the computer adjusts the fuel flow to get the 14.7 to 1 air/fuel ratio and the percentage of adjustment is referred to "fuel trim". There is short-term fuel trim for what is happening at that moment and then there is long-term fuel trim, an average over say the last 20 miles of driving.

I have corrected two older 2001 and 2006 Volvo vehicles that had the same codes. Since I did a full service on each including cleaning the throttle body, I knew that there were no vacuum leaks anywhere. I confirmed same and found no problem.

By swapping in a known good mass airflow sensor, I saw on my scan tool that the air flow on the original sensor was showing about 20% less flow than the known good one. So, the conclusion was that with the computer seeing less airflow, it fed less fuel. However, the actual airflow was higher which created a lean condition.

Swapping in a new mass airflow sensor corrected the fuel trims and got rid of the code.

The code sets when your fuel trim (the computer's way of adjusting and adding fuel) reaches 25% or more of the calculated values.

PM me for more information. You will need access to a scan tool to test my theory on the mass airflow sensor.

 

So I swapped out the MAF and the fuel relay. It wasn't either of those. I have a new fuel pump and filter on the way. I read a bunch of stuff about similar symptoms (cranking strong, but taking a couple of tries to get it to start) pointing to the check valve built into the fuel pump going bad. If that doesn't fix it, then I'm going to check vacuum pressure to the the fuel pressure regulator and possibly the evap system.

 

I think that you are tossing parts at it without a thorough diagnosis. Did you test the fuel trims as suggested?