No boost 2.2dci

[tronside]

Greetings

What started out as intermittent loss of turbo boost has become permanent loss of boost

Diagnostics brings up only two faults ,  thermoplunger circuit open or short to earth

And glow plug relay circuit open or short to earth.

I have triple checked the vacuum lines and induction pipe work for leaks all ok

Tested voltage at boost sensor and turbo actuator solenoid both ok

Checked that there is vacuum to  turbo nozzle actuator from vac pump (three times !)

Visually checked that actuator and nozzle in turbo move freely , both ok.

The problem started on a four hour trip every twenty minutes boost would disappear then twenty minutes later it would be back to normal again, each time boost disappeared the MIL light came on.

This continued for a couple of weeks , now boost is gone completely I have a suspicion ECU is putting car in limp mode for some reason but haven't a clue what it could be. I have spent many hours under the car and would appreciate any ideas as to what the cause might be.

Cheers.

[Waldo]

Hi,

Note that the following is based on my experience with Peugoet HDI engines, but I believe the DCI is also using the Bosch EDC15 ECU?
I would start by checking the MAF (mass air flow) sensor.
I have seen similar problems with no fault codes showing in the ECU, I spend a lot of time chasing the fault until I ran out of ideas and changed the MAF sensor with a spare I got.

You can either remove and carefully clean the MAF sensor or simply buy a new one.

Do you have a diagnotics tool that will log data?
If so you could check the readings of one or more sensors and check that the values are correct?

If the ECU get a wrong reading from the MAF it will cut off the turbo boost (it could be other sensors as well, but my money is on the MAF).
Depending on the readings it might not create an fault that will show up in the log.

Kind regards,
Valdemar

[BrianM]

Yes the dci has the bosch ecu. Check live data to see if you have maf values. What is the fault code. Get a copy of ren visuals wiring diag & fault diagnostics. With the code you can look up a repair guide. Mine had several faults that turned out to be trapped injector & sensor wires inder the cover. The dci is known for connection corrosion so you will need to check from sensor to ecu. With more than one fault I suspect wiring short somewhere. Get hold of the loom between the engine & rad, under the battery & give it a wiggle. Mine would cut the engine out!

[tronside]

Ok thanks guys !

Yes Waldo its the Bosch ecu you mentioned , I have cleaned the MAF twice and unplugged it to see if the engine ran better or worse it made no change but the ecu logged it as MAF circuit open. I will try to locate a new one.

Good point Brian about the loom it touches the engine in multiple places so I will give it a yank and inspect where I can get at it.

I have a maxi diag FR704 diagnostic scanner, it has live data function but won't work on the g9t does anyone know if it can be upgraded to use that function ?

[Waldo]

Hi,

The Maxidiag will show the fault codes, but live data logging is only possible if the ecu is OBD compliant.
Depends on the year and ecu version. From year 2004 all should be OBD compliant, if the car is older some are others aren't.

The two faults you have logged (glow plug relay and thermoplunger) should not affect the engine performance.

If you can't log any data you will really need to go through the electrical connections and sensors.
As mentioned I would start with the MAF.
From my memory others that could influence the turbo boost are:
Boost pressure sensor (mounted near the intercooler)
Fuel rail pressure sensor

Ideally you need a tool that can log the values during a test drive, but as mentioned if your car isn't OBD compliant you will need the dedicated diagnostics software for renault.
I don't know what software is needed as I have only worked on PSA engines.

Regards,
Valdemar

[BrianM]

The 704 is a good device but limited. Is live data only on the obd option? Don't think Matras are complient of this age. I bought a chinese clip interface which works a treat.
Let me know the fault code & I will look up the renault fault repair document for you. It is very concise step by step repair guide for stupid renault mechanics! Listed per fault code.
Brian

[tronside]

Thanks Brian I would really appreciate that info

DF094 is the thermoplunger code

DF091 is the heater plug code

The FR704 I have is EOBD and OBD11 compatible and the manual claims it can read live data in both modes , but trying the live data just gives me function not supported on this vehicle but the manual also states it will only work with post 2004 diesel euro cars so I'm lucky to even get fault codes with it !.

[tronside]

Sorry made an error

DF061 for the glowplug relay fault

[Waldo]

Hi,

As I mentioned the two fault codes you have listed are not related to the lack of turbo boost.
You should of course investigate at some point, but if you don't experience temperatures <5C they aren't that important.

You will find a lot of usefull information in the following document:
http://www.matrasport.dk/Cars/Espace/vault/JE/3444A.pdf

[BrianM]

Hi, it i all in this document: http://www.matrasport.dk/Cars/Espace/vault/JE/NT3919A.pdf

[Sparky]

Have you tried cleaning the EGR valve as this will stop the turbo working if it becomes jammed up with debris ?

Just a thought.   

Regards Sparky

[tronside]

Ok seems I have fixed the problem ?

On the UK Renault forum I found a post about people complaining of the buzzing coming from the turbo actuator solenoid mine was making no noise...one person mentioned they took the cap off the solenoid and tightened the small bolt in the centre slightly and that stopped the noise .

I removed my solenoid from the car it rattled sometimes when shook but then the small disc inside would get jammed so I slowly undid the bolt in the centre till it would rattle without jamming , plus I have sprayed electrical cleaner into the inlet and outlet plus down the small bolt which is also a breather and I have got boost back !

Only problem is it sounds like there is a giant bumblebee under the bonnet .

Sparky I have removed the EGR from my engine , the housing was not the type with the damper valve in it so I took the whole assembly off and replaced it with a straight piece of pipe , I do get an EGR shortcircuit fault warning from time to time because it isn't connected but it doesn't affect the engine.

Thank you Waldo and Brian for those two PDFs I hadn't seen them before they are very useful.

Cheers.