Hey everyone, I'm new to the site but have been browsing awhile, recently my girlfriend picked up an S70 AWD B5254T this is the first Volvo I will be working on, but am more familiar with hondas. lol So here's my story

Car has 125,000 miles, I have done a "tune up" which just consisted of a tranny drain and refill, plugs, air filter, fuel filter, Oil change, coolant drain. The timing belt looks new but I have nothing to show it was done.

Now the problems, I have a check engine light on all the time, and service light that disappears in a few minutes. The car sometimes has some trouble starting, you need to crank it a few times, and sometimes it doesn't start at all, you need to wait hours sometimes. Last problem is randomly and intermittently, when slowing down, braking, midway through turns, the car will stall out, leaving her with no power steering or brakes. IT WILL USUALLY start back up first or second try.

I have all diagnostic codes from Volvo dealer:
[*]ECM-261A - Long-term fuel trim, bank 1 - upper limit
[*]ECM-280A - Front heated oxygen sensor (HO2S), bank 1 - faulty signal
[*]ECM-430D - Leak diagnostic, minor leak
[*]ECM-3100 - Engine speed (RPM) sensor - signal missing


I'm wondering where I should start. Thanks guys.

 

By quick search I found this
Service light is just oil change reminder.[*]ECM-261A - Long-term fuel trim, bank 1 - upper limit ( check MAF and Front heated oxygen sensor, air filter, )[*]ECM-280A - Front heated oxygen sensor (HO2S), bank 1 - faulty signal (check Front heated oxygen sensor )[*]ECM-430D - Leak diagnostic, minor leak (Possible Source
leaking fuel tank, filler pipe, fuel tank filler cap, EVAP canister, EVAP canister shut-off valve or lines between these components)[*]ECM-3100 - Engine speed (RPM) sensor - signal missing ( this could be also misfiring in one of cylinders)

 

The engine speed sensor code can be a fun one... had a customer bring a car to me after having some hillbilly replace the engine. it was running very badly, bucking and hesitating, not wanting to idle, and that was the main code... turned out that the idiot that changed the engine bent one of the teeth on the sensor ring on the flywheel. As this lady didn't have enough money to pay for a flywheel replacement, I straightened the tooth as best as I could through the starter hole. The car runs great now.

 

so what would you guys recommend me doing first?

Getting a replacement Crankshaft position sensor see if that helps the hard starts and stalling, then continue from there?

Also the car is getting HORRIBLE GAS mileage, less then 10mpg at times on PREMIUM. I just dont want to play the parts game, Could a faulty MAF bring up a code for a faulty O2 reading?

 

I'd try to clean MAF with maf cleaner, then change O2 sensor. That will improve gas mileage for sure. My main suspect is O2 sensor

 

sounds good, i'm going to order the rpm sensor let you know how it goes during the week.

 

Here's a reply from Tech in the other post:

I would start with the RPM sensor and front O2 sensor.

The 261 is a vacuum leak somewhere.

The 430D is a leak in the evaporative system.

The other post has been deleted.


JPN

 

thanks.

 

I just replaced the RPM sensor, and the check engine light is off for now, being that I disconnected the battery. I took it for a test drive, it feels smooth but like its missing power, being that the stalling and starting are intermediate I'll fill you in on that after more driving.

 

Okay I recently went over all the vacuum lines no leaks. The check engine light is once again on, and the car has a hard time starting as usual. It has stalled once since the crankshaft sensor installation.

My code is as follows: P1171

Running lean. Next question:

What should I do next or better yet what do you guys recommend?

Mass air meter?
Front o2?

 

bump bump

The O2 sensor is a pretty penny, so rather not replace it if its unnecessary.

 

I have just replaced all vacuum lines, and organized the whole intake system on the car, tightened everything down, etc. I also replaced the front 02 sensor, and MAF sensor, the car is still hard starting, no check engine light yet.

WTF??

 

I drove the car about 30 miles, no check engine light, however the car does still have a hard time starting. Could it possibly be an electrical problem? maybe the battery to starter, and a better ground? It sound like it is cranking normal. Last when it does start up, there is Zero Hesitation it starts right up as it should.

What do you guys think should be my next step?

 

Is it only hard start after it sits for a while?

 

It really depends I feel but more so when its cold. 2 Seconds ago it started up with just slight hesitation sitting for like 1.5 hours 2. Also just a quick dumb question, the fuel pump braket, is held on with like a torx screw that is all RUSTED and ****, how am I supposed to get that off without striping it???

 

Maybe the fuel pressure regulator is bad.

DO you mean fuel filter?

 

yeah my bad, the fuel filter bracket.

 

Soak it good with rust spray like PB Blaster.

 

I just tested the fuel pressure with the relay jumped it was 375kpa which is in spec. and the residual value was fine. But then when I used the relay it was 340-355 which is out of spec and residual value is fine. New Relay? or what?

 

That should still be close enough to not cause a problem. Maybe the relay is bad on why the pressure is a little lower.