1.6d no boost on motorway!

[mlmcelligott]

hi - I accidentally posted this in the diesel d5 section but just realised its the PSA Hdi engine, sorry Mods!

I have a vacuum issue on my 2007 v50 1.6d

Around town the car pulls like a train and never misses a beat. After about an hour on the motorway the car will loose boost. When that happens I can put the car in third and keep the foot flat to the floor and after thirty seconds or so it'll boost fine for ten seconds and then it'll loose boost again and the car will slow down. Again, after about thirty seconds it'll boost again and it'll repeat this cycle until I get off the motorway and then after a few minutes the boost will come back again and it'll drive fine until i get on the motorway again.

Ive made the assumption thats its got nothing to do with the turbo since it works fine on the back roads and in town. It only happens at high speed and only after about an hours driving so it has to be heat related. Im thinking its either a vacuum leak on a hose that only presents itself when it gets hot and expands or the vacuum control solenoid thats getting stuck

no codes

Any ideas?

[Clan]

Originally Posted by mlmcelligott

hi - I accidentally posted this in the diesel d5 section but just realised its the PSA Hdi engine, sorry Mods!

I have a vacuum issue on my 2007 v50 1.6d

Around town the car pulls like a train and never misses a beat. After about an hour on the motorway the car will loose boost. When that happens I can put the car in third and keep the foot flat to the floor and after thirty seconds or so it'll boost fine for ten seconds and then it'll loose boost again and the car will slow down. Again, after about thirty seconds it'll boost again and it'll repeat this cycle until I get off the motorway and then after a few minutes the boost will come back again and it'll drive fine until i get on the motorway again.

Ive made the assumption thats its got nothing to do with the turbo since it works fine on the back roads and in town. It only happens at high speed and only after about an hours driving so it has to be heat related. Im thinking its either a vacuum leak on a hose that only presents itself when it gets hot and expands or the vacuum control solenoid thats getting stuck

no codes

Any ideas?

The first thing to do is change the fuel filter then try it ....

[mlmcelligott]

Originally Posted by Clan

The first thing to do is change the fuel filter then try it ....

Thanks

I'll try that and let you know how it goes.

[mlmcelligott]

Just replaced the boost control valve, map sensor and a new fuel filter. I also found the MAF sensor had a lot of oil gunk on it so i cleaned it with some card cleaner. I havent taken the car for a test drive yet but after leaving it idle for 20 minutes its running much smoother. Ill give an update after a long motorway journey.

[rippedoffagain]

Originally Posted by mlmcelligott

Just replaced the boost control valve, map sensor and a new fuel filter. I also found the MAF sensor had a lot of oil gunk on it so i cleaned it with some card cleaner. I havent taken the car for a test drive yet but after leaving it idle for 20 minutes its running much smoother. Ill give an update after a long motorway journey.

Does you car have both MAP and MAF sensors? I thought engines just had one or the other but not both (but then my knowledge of such things is quite out of date and not that comprehensive anyway).

How come the MAF was full of gunk? Its after the air filter so it should pretty much stay clean forever, unless there is a problem with your air filter or maybe a split somewhere allowing unfiltered air in, which would be a recipe for disaster (I used to be into off road motorbikes. I once discovered by chance that the engine performed better without an air filter so I left it off. Expensive mistake. It worked better for about an hour before making all the wrong noises before dying. When I opened the engine up to see why, filth had got in and with the pistons popping up and down as they do, they'd effectively ground big grooves into the cylinder linings and completely destroyed the piston heads).

[mlmcelligott]

Yip, the car has both MAP and MAF sensors. The MAF had some oil residue gunk on it so i just blasted it off with carb cleaner and its running much smoother now.

[rippedoffagain]

Originally Posted by mlmcelligott

The MAF had some oil residue gunk on it

On the outside casing or on the inside?

If it was on the inside, I'd be digging about to find out why.

[mlmcelligott]

yip it was on the inside. The MAP sensor was faulty and the turbo actuator was faulty also so the car wasn't running well for a while so i wasn't surprised to see some oil in the MAF.

I also have a BMW 320d e46 so I'm used to cleaning out the MAF at least once a year.