OT Volvo V40 Diesel Woes
Turbo Mini Forums

Bit of a long shot, but I hope somebody on here can help with this as there isn't much help coming out of the Volvo community. Basically, bought a 2003 V40 1.9 diesel last week and it quickly became apparent that it was lacking in power and the mpg was lower than the generally accepted norm (43mpg cruising at 70, instead over 50mpg). This is a Renault common rail diesel lump running at 115bhp. Common fault on these is a blocked EGR valve, and I removed mine and cleaned it up (it was chocka with oily sludge) but it made no difference. Air filter is like new, changed fuel filter which made no difference.

It was in at a Renault specialist yesterday for a cambelt change, and asked them to take a look at the power and mpg problem. They noticed that a hose was disconnected on the boost solenoid that is part of the wastegate control (I actually think it is just a variable vane turbo without a wategate, but I could be wrong). There are three hoses on the solenoid, vacuum in, vacuum out and this third hose that wasn't connected. They said that on Renaults the solenoid only has the vacuum in and out, so they blanked off the third connection and the car goes like it should (although the mpg is still the same). The boost solenoid and where the hose should connect are shown in this photo (I nicked this picture off the net, and the two left hand hoses are not connected to the solenoid in this picture)



I had a go at reconnecting the hose to the air intake hose as it is supposed to be, but the car went back to gutless. Does anybody know what the purpose of this extra hose is? Blocking the hose has obviously made the car much more drivable, but I'd like to fix the fault rather than mask it and also not just start changing everything until it works.

There isn't a Haynes manual available for the Renault engine in the Volvo. There are Haynes manuals for the diesel engine as fitted to Renaults, but as this solenoid is different on Renaults they won't be of any help.

best to BLOCK the EGR mate, they only lead to trouble.

your "fix" by blocking the hose is most likely keepign the vanes in the almost-closed position so turbo is boosting its wee brains out, been a while since i have had the pleasure of working on one of these engines so cant say how it ought to be plumbed in, but if i were you i would test the solenoid and feevourishly google till you find a vacuum routing diagram :)

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

You are right that variable vein turbos don't have wastegates, but they do have actuators to change the vein positions.

My old Xsara had a similar control. It was a Bosch unit with two connections, one to the vacuum pump and the other to the actuator. When it failed the car was slow, so I swapped it for the same unit controlling the EGR valve, all power was restored.

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You got me thinking evolution, so I went out for a drive with my cheapo OBD and laptop. You are right, it was boosting its arse off. Couple of graphs for comparison, the first one is with the boost solenoid connected properly (but possibly not working correctly), and the second one is with the third port blocked off. Any thought about the boost curve on the first one? I think my first port of call is to check all the vacuum hoses and then get a boost solenoid from the scrappers to try out.

I would give your solenoid valve a good clean out first, it takes hardly any gunk at all to restrict the amount they can bleed off or flow.

I had a similar issue on my 205 recently after the head gasket let go, it got mayo in the boost control valve and it was down to about 50% of normal boost pressure. Cleaned it out it was OK for a day, then had to do it again. Since then no problem.

hmm :S your average diesel runs 15-20psi of boost, thats 30-35psi absolute so not totally out of the quesiton, assuming your obd readout is accurate!

EDIT on over-run the MAP signal flat lines at 14.5 ish so would appear to be accurate

woudl electrically test the solenoid, clean it out, and try your best to get a nosey around a working car for the pipe routing.

Edited by evolotion on 27th Jan, 2011.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Hi metroturbo.
I also own a 2003 Volvo V40 1.9 TD and I'm having similar issues.
Unfortunately, my cheap OBD reader only reads RPM.
Can you tell me what's your OBD reader brand and model so I can get one?
Thanks!

The car has long since gone, and I'm afraid I've no idea what OBD reader I used. What I can tell you is that the fault was with the boost solenoid being stuck open. Fitting a new solenoid fixed it straight away.