406oc.co.uk

Hi I have a ropey beige estate that does its job beautifully however recently its stopped boosting, I have no error codes currently and car hear a small amout of hiss from the crap clip on the concertina pipe to the hdi but nothing massive.

Its idles fine and will rev cleanly but just has no boost, Has anyone got any common propblem pointers please?

Swap the vacuum pipes over on the bulk head on the solenoids. Could be one of them failing...

The HDi 90 doesn't have a turbo boost control valve, it's a mechanical wastegate.

Most likely a boost leak, or just possibly a seriously blocked air filter.

Its got a newish filter (3-4000 miles) and its quite clean, I will have a look at the waste gate vac pipes

Hi, Right I had a look yesterday and I the turbo spools up fine but its dumping its boost so 2 quick questions:

1) the 90bhp turbo just has a mechanical wastegate does it have any vacuum operated attachment which opens it up so it just vents?

2) If the egr is open all the time will that cause the the turbo not to boost as much and just feed it into the air intake?

Fairly sure thats your problem, Blank it off with a thin metal plate and block the vacuum lines, Done mine with a ball bearing up the rubber vacuum pipes.

Steve

Egr is fine, found a split on the rubber boot on the air intake to turbo coupling.

Fixed that the only codes are airflow meter. So even though I think it's fine I'm gonna pinch my mates . My hunch is a blocked exhaust at the moment causing the turbo to suffer from excess back pressure

The 90 has either 1 or 2 vac solenoids. The one that's always there is for the egr. The one that may be there is for the air doser which simply blocks the air intake when you turn the engine off to prevent clatter and run-on; I think only 01--02 cars jave it.

What exactly is the MAF error? The system can tell, for example, that too little air is coming in for the given engine speed etc. This happens when you blank the egr (too much air is coming in because no exhaust is being recirculated), but doesnt cause a fault in this case.
Or could it be a duff MAF? (Unplug it and see whether there is a difference. This will cause a fault code.)

if you unplug the airflow it will only pull 2700rpm. its a single soliniod egr.

it was the airflow in the end. unusual the way it manifested the fault as normaly they are flat off boost yet this was fine.

cheers for the help. It just needs a gear rod set now.

Hi sorry to return to this old thread but this is exactly the symptoms I have with my 110HDi. It started off by the boost only coming in at 3k, now it doesn't appear to be boosting at all.

I've blanked off the EGR, and like you when I disconnect he MAF it won't run above about 2.7k and generates an error light. I don't have a code reader.

When you say it was the "airflow" do you mean the airflow sensor in the Air filter box? Did you just replace it with another one? Is the sensor cleanable/repairable?

Should the engine run OK with the MAF disconnected? I read somewhere about people running round with the wires off until they got around to repairing it properly, but as I said mine won't run without it.

Thanks for any help anyone can give!

Max

Midgetmax wrote:When you say it was the "airflow" do you mean the airflow sensor in the Air filter box? Did you just replace it with another one? Is the sensor cleanable/repairable?

They mean the mass air flow sensor, (MAF), located at the air box outlet. Easiest / cheapest test is to borrow a known good one for 5 minutes - add your location, someone nearby may be able to help.

I'm in Wiltshire, near Devizes.

The car just feels "constipated". The last time I had a 406 feel like this was on a petrol one, and the cat was blocked. But at over 200 notes for one of those I hope it's not!

Midgetmax wrote:Hi sorry to return to this old thread but this is exactly the symptoms I have with my 110HDi. It started off by the boost only coming in at 3k, now it doesn't appear to be boosting at all.

First thing that springs to mind is the vac supply and turbo vac solenoid.

Midgetmax wrote:I've blanked off the EGR, and like you when I disconnect he MAF it won't run above about 2.7k and generates an error light. I don't have a code reader.

As exected.

Midgetmax wrote: When you say it was the "airflow" do you mean the airflow sensor in the Air filter box? Did you just replace it with another one? Is the sensor cleanable/repairable?

Yep. Not repairable. The Peugeot docs say, in red letters, not to use compressed air on them!

Midgetmax wrote:Should the engine run OK with the MAF disconnected? I read somewhere about people running round with the wires off until they got around to repairing it properly, but as I said mine won't run without it.

No.
The idea is: if you unplug it and there isn't a difference then that's probably the problem because if you unplug it then there should be a difference.

Thanks, that's a help.

If you look on you tube there a lots of vids detailing the cleaning of MAF sensors with electrical contact cleaner, the general concensus is to remove it from the car and blast plenty of spray cleaner on the sensor wires and filter grid. Do not attempt to clean/wipe it just lots of spray, leave to dry then refit.

I will stress I've never done it and don't know of anyone that has so it's an at your own risk job, but if you have access to a known good MAF sensor and can confirm yours is knackered it can't hurt for the price of a can of spray tho. I picked some up in the local 99p shop a couple of weeks back so it won't break the bank.