406oc.co.uk

Hi All,

So I was having trouble with my car limping several times a week, I have since massively improved this by remapping the car, blanking the EGR, removing the EGR and doser solenoids and running new vac pipes.

Now the car still limps but it's only done it twice and four weeks apart, so much better. I think the reason it may still limp now is because I get a boost solenoid fault, but I don't think I've blocked the air Doser properly. I've blanked the vac ends near the solenoids.

Does anyone have any info of how to delete or properly blank the doser? Read a few threads but not 100% sure exactly what I need.

Thanks in advance!

Wading through old posts found this one, sorry for the late reaction.

I disabled my air doser simply by unplugging the vacuum tube and driving a small screw in it (to prevent it from leaking and losing vacuum by sucking air).

That works and has never resulted in limp mode for me.

Can you confirm what engine you have?

The 2.2hdi ideally needs a doser bypass kit, and a lower boost pipe from a 2.0hdi, as the factory doser will leak even if the vacuum supply is removed.

If you have a 2.0hdi then the doser can be bypassed by using an intake pipe from a later 406 that never had one from the factory.

Boost solenoid fault is hard to pinpoint as faulty as the diagnosis would detect an over-boost issue - unless of course the sensor is unplugged..?

GingerMagic wrote: ↑Sat Dec 12, 2020 10:32 pm Can you confirm what engine you have?

Not sure who you are asking, but I have a 2.0 HDI, same as the Grand Vitara (see "Power train" in the right panel of this wikipedia page).

I've never experienced any boost loss with my air doser unplugged. But indeed, replacing it by a straight intake pipe would be a more elegant solution.

It is very important that the vacuum system does not leak, it is indeed used to control the turbo boost.

"boost solenoid fault" sounds like an electrical issue. The engine ECU will be able to see if the boost solenoid is actually (electrically) connected. If the boost pressure is too high or too low (due to e.g. leaking vacuum), this will give an fault code indicating a problem with the boost pressure.

Here is an example of a boost pressure fault:



See third entry from top: "Intermittent fault. Turbo pressure regulation Turbo pressure measured too low"

I agree the description suggests an overboost issue, especially If it only happens during acceleration.

Boost solenoid fault codes are most commonly due to a disconnected or faulty solenoid/wiring, but can occur when one of the supplies to the ecu is missing. In this case the ecu will misinterpret the lack of a +12V supply as an open-circuit solenoid when checking the external circuitry as the ignition is turned on. ( I had this on a Citroen Xsara HDi 90 that cut out & refused to start. It had a blown fuse for 1 of 3 ecu feeds but generated a solenoid open circuit error code when checked with a professional standard generic diagnostic system).

- Use Lexia/PP2K if you can
- Are all the electrical connections unchanged? (solenoids still connected in the correct order)
- Vacuum leaks are what catches most people out. As others have said it's vital to have the boost control working correctly and every unused connection properly sealed

frog wrote: ↑Sun Dec 13, 2020 9:03 am

GingerMagic wrote: ↑Sat Dec 12, 2020 10:32 pm Can you confirm what engine you have?

Not sure who you are asking, but I have a 2.0 HDI, same as the Grand Vitara (see "Power train" in the right panel of this wikipedia page).

Sorry Frog, my question was for the OP....