seeking guidance ..0300 code ( kitchen sink code)

[Carlo]

my 2002 c70 2,3,, was running all smiles for a year now, 1 month ago, started it, ran a little rough, shut it down and checked the plugs.. looked a little overly gapped, so installed new Bosch plugs, Volvo coils, and Bosch MAF. no improvement. Car now starts, goes into high idle for 15 seconds then slows down to a fumble, gas pedal does VERY little seems dead, then dies. Checked the fuel rail on 2 different days; key on 58/ running 52/ key off 50/ hour sitting 43. Day two, key on 43/ start 50/ off 50/ sitting hour 35...my little angel meter says p0300, yes, it's a multiple cylinder misfire, I know that, not any help. I looked everyplace for the fuel pressure regulator, on the lift, I don't see it , and not sure its the culprit.. I have a smoke machine and vacuum gauge, I have been pouring over these posts, and the possible causes are leading me to surmise, throttle ETM, vacuum leak, .... is there a systematic write up on procedurally how to approach this? it has 125k on it, any stories of similar problems and remedies would offer some direction, Thanks

[scot850]

Try disconnecting the MAF and see if it starts and runs. If it does the MAF is bad or dirty. You can try cleaning it and the connector for it to see if that helps. If it still does the same, clean the MAF (only use MAF cleaner) and connector and put it back in.

Smoke testing is worthwhile and looking for leaks in the turbo intercooler system and the vacuum pipework.

I'm assuming with the 2.3 it is a turbo.

Throttle body (ETM) in these cars are a common failure at this age. They are a pain to remove, but worth it to clean the throttle plate in the ETM. Don't soak it! Use throttle cleaner and cloths and soft brushes to clean it.

P0300 is not a very helpful code. It can be fuel, timing or sensor like cam/crank sensors.

There is a fuel pressure regulator on these as well as a fuel filter and pump. Borrow if you can a fuel pressure tester and connect it at the injector rail at the Schraeder valve. For your car year you are looking ideally for 55-58psi when static and not running with the ignition on. It may drop from that if it starts, but if it drops below mid-40's psi the pump is likely on the way out.

The fuel regulator can have different locations. I am happy to be corrected, but on a FWD ca I believe it is near the rear of the car near the fuel tank and carbon filter. Check this drawing. Not totally helpful but may help recognise it. It is item #7.

https://www.volvocarstorontoparts.ca/a/ ... 78648.html

Neil.

[Carlo]

Neil, thank you ! studying now, some good thoughts.