No Boost - C5 2003 110 HDI 8V

[MattCyclone]

Hi all,

Found this excellent forum through some google searches when trying to diagnose some issues with my wifes C5...

I was hoping I could pick a few brains about what the issues could be:-

Symptoms:-

Car drives as though there is no boost what so ever. We had to drive 300 miles last weekend and it was like being back in my old (F Reg!) 1.0l carb'ed fiesta - no power at all! There is a little more history though, my wife mentioned that the car seemed not to pull as well - I had recently changed the air filter and oil (which it uses a little of, though it has done 170k miles and I don't think that you could consider that it has a complete service history) and hence I also put a new fuel filter on it (infact, after leaning on a small pipe on the filter housing I had to buy brand new filter and housing! But that is a another story!).

This didn't change the issue, when driving it seemed like the boost was happening much higher up the rev range (3k plus), this got a little worse and then (when we had to drive the 150 miles north there was little boost till about 100 miles into the journey when the car came alive again (well, at least for the rest of the journey). Parked up and the next morning it was worse (no boost at all and a K light with limp home mode active.

As we were away at my parents for a birthday I had a small tool kit but managed to whip the air filter out, it was 4/5th's soaked through - dripping wet! The filter box was full of water too - further pulling of bits off revealed that the intake hose cover which goes up into the inner wing is full of tears and holes, which I presume over a period has been sucking up water if going through puddles or if there is water on the top of the plastic floor of the inner wing, which as there is no undertray on this car I imagine can get wet... I look at the MAF, it seems intact but there is some green corrosion on not the wires but the other metal sensors.

So, new air filter, system drained of as much water as possible and put back together, no change at all - though the K light and limp home mode cancelled so we could at least drive home! Got back, economy is bad as you would imagine but the car sounds fine!

Checks tonight:-

1. Engine idles fine, revs up quickly to over 5k and you can hear the turbo whistle as always. Hence I am assuming that there isn't a blocked exhaust/cat
2. Removed the intercooler top hose, can feel the turbo pushing air through which increases as the engine revs increase.
3. The intercooler has a leak (oil and gunk at the bottom) but when you blow into it with one end blocked it seems airtight, so I am assuming a pinhole or something.
4. The 2 rubber hoses at top and bottom of the intercooler look ok, will take then off and inspect once I get some time look at them in daylight.
5. I have blanked off the EGR and I have blocked the vacuum supply line to the solenoid.
6. Due to working in cold temps (and some muppetry on my part) I managed to snap off a spigot from my spare solenoid - hence I don't have an extra one! When sucking the wastegate vacuum like you can pull some vacuum and when released you can hear a slight noise from the turbo.
7. I jacked it up and tried to look at the turbo and wastegate area but you cannot see a thing, though it does have a film of oil over most of the areas, the drive shaft etc.

Questions:-

1. MAF's - I understand you can't check them, I tried driving without it plugged in and it made no difference, though as it didn't then produce boost I assume that is not the problem (though could be contributing...). Anyway, I assume I need a new one, is there a link to a decently priced one? Not the £100 plus it seems for OEm!
2. Intercooler - a small leak couldn't loose all the boost?
3. Wastegate operation - I understand from this forum that the turbo requires vacuum to hold the wastegate shut? Any reduction (or loss of) vacuum reducing the boost - would an open wastegate mean that you wouldn't feel air coming out of the intercooler when reving the engine whilst stationary?
4. Vacuum solenoids - Can these be tested at all? I blew back ino the vacuum system and it seemed to be airtight.
5. Oily film round the turbo area - is this normal? I would imagine not but the car is 10 years old with 170k miles... So who knows that has happened in that time! We've only had it 1.5 years. What could be blowing off, I will need to check the solid pipe that goes from the turbo to the intercooler and the short piece of hose that connects it to the turbo - apart from those, anything else that could cause this?
6. What does the butteryfly valve do on the inlet manifold, when does it operate? I want to put a mirror round the back to see if the actuator is actually moving!

Finally - I have emailed MikeT who is my closest Lexia expert to see if it would be possible to get the engine tested, if not I will see if the local dealer will do one - any idea what these normally cost?

Sorry for the lengthly post, I know that diagnosis via words is almost impossible but any ideas or thoughts would be most appreciated - funds are tight and I can't justify just buying loads of things to see if that fixes the problem.

Many thanks in advance!

Cheers,

Matt

[Northern_Mike]

Whereabouts are you Matt?

[MattCyclone]

In Southampton Mike.

[myglaren]

Your symptoms are indicative of MAF failure.

The guy who had my car before me* bought an original Siemens MAF from eBay, for around £80 IIRC and it has been fine. Some of the cheaper ones fail early.

A wet air filter indicates water being drawn in to the induction system, which was what ruined my first replacement (£135 from Citroen).
My nearside wheel arch liner had blown out and allowed water and grit/salt to be drawn into the induction system as the 'snorkel' from the air box ends up behind that liner. As that side is in the ditch most of the time it is very exposed to spray from the front wheel.

*Deano1970 of this forum.

[MattCyclone]

A wet air filter indicates water being drawn in to the induction system, which was what ruined my first replacement (£135 from Citroen).
My nearside wheel arch liner had blown out and allowed water and grit/salt to be drawn into the induction system as the 'snorkel' from the air box ends up behind that liner. As that side is in the ditch most of the time it is very exposed to spray from the front wheel.

*Deano1970 of this forum.

Hi Myglaren,

Many thanks for that, I was thinking it maybe - regarding the liner you mention - there is an ill fitting inner cover for the wing area which seems as though it screws into place which has a cutout for the intake pipe to pass through - this has 2 empty holes in it and just seems wedged in place... Is this what you were missing? We have no undertray anymore and a bolt or 2 were missing from the bumper/wheelarch liner so I will replace them to try and make sure its as watertight as possible - could you suggest if there is anywhere online which shows a diagram of all the bits - as it may not have had them all when we got the car!

Also - I have 'repaired' the cover of the tube by wrapping it in a bin bag and taping the ends but I don't imagine this is a long lasting repair! I will look for a replacement one - do you think (keeping in mind where the inlet is) that even a small amount of water in the bottom of the arch would make its way into the trumpet?

I will also look for a MAF - shopping list is thus:-

1. MAF
2. Intercooler
3. New intake pipe

Missing anything else?

[SaabC5]

I will also look for a MAF - shopping list is thus:-

1. MAF
2. Intercooler
3. New intake pipe

Missing anything else?

How about an undertray? If you can't get a used one try eBay, i got a pattern one from Poland for £40. Its surprisingly good quality.

[MattCyclone]

I was hoping not to need one, or without one will we just trash MAF's again?

[myglaren]

I was hoping not to need one, or without one will we just trash MAF's again?

Yes, fairly quickly in this weather too. The liner was £53.10 but worth it to protect the MAF.

My wheel arch liner went missing due to no undertray - it exploded in a shower of little bits of black plastic that appeared as a cloud in my rear view mirror.

I'm having difficulty visualising what you describe (no imagination) but it doesn't tally with my recollection of the wheel arch as I remember it - although it was a couple of years ago now.
I can't recall any holes/cut outs in it - the 'snorkel' thing just drapes behind the plastic liner.

I found on removing the air filter that the airbox was full of grit, very wet and there is a kind of 'well' that was full of water - drilled a small hole in the bottom of that, can't see what it is good for anyway.

The MAF looked like this:

click for larger image.
Didn't respond to attempts to clean it.

[MattCyclone]

I was hoping not to need one, or without one will we just trash MAF's again?

Yes, fairly quickly in this weather too. The liner was £53.10 but worth it to protect the MAF.

My wheel arch liner went missing due to no undertray - it exploded in a shower of little bits of black plastic that appeared as a cloud in my rear view mirror.

I'm having difficulty visualising what you describe (no imagination) but it doesn't tally with my recollection of the wheel arch as I remember it - although it was a couple of years ago now.
I can't recall any holes/cut outs in it - the 'snorkel' thing just drapes behind the plastic liner.

I found on removing the air filter that the airbox was full of grit, very wet and there is a kind of 'well' that was full of water - drilled a small hole in the bottom of that, can't see what it is good for anyway.

The MAF looked like this:

click for larger image.
Didn't respond to attempts to clean it.

I have the wheel arch liner intact, it is just the undertray I am missing - I will check again this weekend about if there are any holes etc in it. I am also going to take the snorkel out and dry the gauze off inside so at least I can start with a dry tube while waiting for my new one.

I have my new MAF ready to go in, its dry down here so a quick swap and I'll check it out round the block.

Thanks for all the help, I will update the thread if this helps and add photos of the old MAF for reference.

[MattCyclone]

It works! The short answer is that it was the MAF... Mine looked very similar to myglaren, just without the leaves on the mesh!

So, works done is removing the snorkel off, peeling the plastic cover off and drying it out, repairing the cover with copious amounts of Gaffa tape and wrapping in clear plastic whilst awaiting the new one. I put a decent MAF (Lucas from a good motor factors in Southampton) in and a totally dry air filter. Started her up and its like having a new car (the extra inch and bit of throttle travel is helping no doubt too!).

I need to put a couple of extra bolts through between the inner wheelarch liner and the bottom of the bumper to help keep any water out, I will replace the snorkel in due course as well as putting the car up on ramps and checking the inlet piping from turbo to intercooler very closely...

Last (I promise!) question...

The leak at the bottom of the intercooler - is this something which I need to do something about ASAP? Lots of the second hand intercoolers have oil/gunk in the same place as mine and a new one is over £120. I assume waiting till apres the MOT (in May) which needs 2 rear tyres at least would be fine - seems to have plenty of boost now but I have been used to very little recently!

Many thanks again to all who posted.

[myglaren]

I had a new intercooler last year as mine was punctured. I had no symptoms and fitting a new one has made no discernible differenc.

I suppose it depends on how bad it is and you can be certain it will never get any better.

I was given the option of a second hand one but there is no way of knowing how long one will last so opted for a new one at £118, at least there is a warranty with it and it looks nice and shiny for now.