[solved] S40 T5 issues - Air leak between MAF and Throttle Body

azeng

Hi all, first post here.

I've recently started having some issues with my S40 T5. About 2 months ago, I got a reduced engine performance message followed by a CEL, accompanied by low power and rough idle. Codes pulled were P0300, P0301, P0302, P0303, which are all misfire codes, as well as P2281 (Air leak between MAF and throttle body) and P2177(System too lean off Idle Bank 1). After taking to my mechanic (Savvas), the MAF was replaced and all was fine, until 2 weeks ago, the Reduced Engine Performance message appeared again, with similar symptoms (rough idle/loss of power), but no CEL. Codes pulled were pretty much the same, where P2281 appears first. However after I cleared the codes, the car seemed to perform normally again for another week (unlike the first time where it would almost immediately throw codes again). Cleared codes again, performed well for another few days until today.

Any ideas what the issue is? I've read the post with similar symptoms that were fixed by changing the PCV check valve. However in my case, why would changing the MAF solve the issue temporarily, or are they 2 separate issues with the same symptoms?

So my 2nd problem is more minor, where none of the interior roof lights are working probably, exhibiting the symptoms described here: http://volvoforums.com/forum/volvo-s...problem-55760/
I tried replacing the #47 fuse but it blew immediately, so there's probably a short somewhere. I'm attributing this to the replacement of my roof lining a few weeks ago, where the wires probably weren't reconnected properly (I didn't do it). Where should I start looking for the source of this short, or should I just take it to an electrician?

Any advice is appreciated, thanks!

Philia_Bear

What's the long term fuel trim sitting at?

You might be due for a fuel pressure sensor
(recall in usa but not in aus as usual)

azeng

Philia_Bear;69562 wroteWhat's the long term fuel trim sitting at?

You might be due for a fuel pressure sensor
(recall in usa but not in aus as usual)

Haven't really looked into this, didn't think fuel pressure would cause an Air Leak code. I'll check on the next few drives and report back.

Ex850R

Unless you use a proper Volvo scan tool the codes you pull are just vague.....

timbo

It depends on how many kms you drive daily. The ecu diagnoses these faults via long term fuel trim. If youre only doing short trips its probably not going to code straight away. It will most likely be pcv valve or fuel pressure sensor. Fuel system issues are never clearly diagnosed via fault codes. The misfire codes are the clearest sign of a fuel issue

Philia_Bear

azeng;69598 wrote
Philia_Bear;69562 wroteWhat's the long term fuel trim sitting at?

You might be due for a fuel pressure sensor
(recall in usa but not in aus as usual)
Haven't really looked into this, didn't think fuel pressure would cause an Air Leak code. I'll check on the next few drives and report back.

Yes it does,frequently

Also the translation of codes via a standard obd2 reader is frequently wrong

Thus plug in Vida And see what the real issue is

azeng

Thanks, I've booked in with Lupica to check the issue. Also I drove it 100kms in the city today without any problems...long term fuel trim on bank 1 is about -10%.
As for the light issue, it was due to the wire to the sunvisor lights being pinched by a screw. It is fixed now.

Philia_Bear

Ok... so this is how it works...

Unlike most cars that have a fuel pressure regulator with a fuel return line, the P1 cars maintain fuel pressure by using a variable speed fuel pump in combination with a fuel pressure sensor in the rail
When the fuel pressure sensor in the rail starts failing it will read off quite a bit like reading 40psi when its 60psi or the other way round.
There was a recall on the sensor in the USA, but this did not happen in Australia
The sensor is however dirt cheap at sub $100usd for the BOSCH sensor

When the sensor reads high the engine will be getting too little fuel (pump is slowed and actual fuel pressure is less than desired), this causes it to be running lean based off the combination reading of the AMM and fuel pressure and so the engine things its got an air leak causing unmetered air to enter the engine.. when its really just the fuel pressure sensor....

A long term fuel trim thats off more than 3% is a sign that something is failing in the P1 cars
Healthy cars run 0-1% in general

So... solution is to
1. Replace the sensor
2. Reset the adaption
3. Drive normal

I'm happy to plug my vida unit into the car for free if you ever want to take a ride out to Blacktown one evening or weekend. Just PM me for address etc...

azeng

Thanks for the explanation, PMed.

azeng

So 1 week without issues since clearing codes (I expected them to come back sooner), except I feel like there is a slight stutter when I put my foot on the throttle. LT Fuel trim is sitting at ~3.5% (10% written in earlier post was a mistake). I might just change the FPS and see if it affects anything. Where's the best place to get one?
Thanks

Philia_Bear

Fcp euro or ipd or Rockauto.com

What's the adaption % on the amm?
(dice will read this)

Also consider new wideband o2 as well if the lambda reading changes slowly

azeng

So this issue has been resolved by replacing the PCV->turbo check valve, as detailed here: forums.swedespeed.com/showthread.php?163933-Unsolved-problem-getting-expensive-2005-S40-T5&highlight=unsolved

Philia_Bear

BTW... what year was your S40?

azeng

Philia_Bear;100275 wroteBTW... what year was your S40?

2004