HDI turbo not kicking in

[jameslxdt]

just a quick thought, do the brakes seem as effective as before?
on my old hdi, the brakes were awful, and it would only have turbo occasionally as the vacuum pump was pooped and didnt have a enough suck to keep the turbo going

[mjb]

on my old hdi, the brakes were awful, and it would only have turbo occasionally as the vacuum pump was pooped and didnt have a enough suck to keep the turbo going

Dare I ask how the brakes and vacuum to the turbo (wastegate?) are linked?

[jameslxdt]

the turbo wastegate control valve works backwards in a HDi, vacuum not positive pressure controls turbo pressure, i.e. you apply vacuum for more boost (longer PWM) or less vacuum for lower boost (shorter PWM), unlike a petrol turbo where boost pressure to the wastegate regulates boost, so in a HDi if you have sod all vacuum you will get no boost, as the wastgate is spring loaded wide-open at atmospheric pressure

[mjb]

i thought that's how they'd work anyhow, to avoid catastrophic failure if regulation failed?

So if i pull the wastegate solenoid out of my dad's turboless tubby, it should be permanently on boost (providing the turbo's not seized - dunno if it is or not)?

Or am I over-simplifying things here?

[jameslxdt]

i think the petrol tubby has 3 pipes on the valve, the way to tell if its the valve is to leave the connector on, but attatch the pipe from the inlet manifold to the wastegate, it will have slightly more lag and may hit limp mode in arround 2nd or 3rd gear

[mjb]

given limp-home on a tubby is basically just disabling the turbo (no evident rev limits or anything)... ;)

[Welly]

On a Diesel the intake system is just a big hole that the piston draws air into, it has no throttle butterfly and cannot create it's own vacuum so all Diesels have a vacuum pump. It's fitted to the end of the camshaft on the HDi but some lesser Diesel have the vac pump fitted to the alternator which makes a replacement alternator very expensive.

[jameslxdt]

mostly vauxhalls

[darrenwall]

fooking useless so called independant " experts " . first of all they told us it was the FAP and charged us over £420 to fix ( before we picked it up the mechanic said he drove it for about 5 or 6 miles and it was fine ) it was really no different to when we dropped it off so we took it back . then they told us that the EGR valve was showing up as a fault and then they said it wasnt ! now i just been told by my mother who phoned them today to find out when she was having it back that they have sent the intercooler of to an " engineer " for some reason !
i cant wait to phone them in the morning to give the fookers a piece of my mind !

[jameslxdt]

this is just not on, yes the HDi's can be a right bugger to diagnose, but thats no excuse for spending £420 of the customers money for the fun of it, i would get on to trading standards

[darrenwall]

she gonna phone trading standards tomoro and she gas got no intention of paying anymore cos her reciept says that the fault was cured and there was " no faults present " , i think they just seem to be taking the piss now

[neildavies]

I hate it when garages play guessing games with customer's money. I had the same problem wth a dealer once, ended up £200 out of pocket having the fuel additive topped up when it wasn't needed. My olny conslation is that it would've needed doing sooner of later anyway.

[darrenwall]

she picked the car up today after being charged another £150 ( but she is going to the trading standards ) but thats the elast of her problems now .
it run perfectly right up until the moment her boyfriend filled it up with PETROL . they drove it about half a mile before she heard 2 big knocking noises ( in her own words ) and smelt petrol , it was then they realised wot happened and shut it down
the RAC are on their way as i type this to tow her home and drain the tank but before i go tomorrow and flush the system and change the filter how do i totally drain the system ( common rail and everything ) cos i know how to do it on an old type diesel but not these and would it have caused any problems being run on petrol for a few mins ?
thanks guys

[mjb]

ouch!

[neildavies]

How gutting is that, bad luck there. I don't claim to be any expert at all, but I've heard that HDi's and the like ain't as forgiving as old style diesels when it comes to having petrol in them. If I remember, some people would put a bit of petrol in old style diesels to clean the system or something.

Hope it'll be ok now after a clear out and she can start to have some troule free motoring again.