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406 hdi slow
Posted: Thu Jan 22, 2015 11:40 am
by topbuzz
hi all ive found this forum whilst browsing for issues on my 406 since ive owned the car it seems very sluggish on take off .from what ive read a lot seems to point to the maf sensor so today i unplugged it and it seems to have given me better power does this mean the maf sensor is goosed or what im gonna plug it back in and see the difference ..
Re: 406 hdi slow
Posted: Thu Jan 22, 2015 1:12 pm
by Uberderv
Could be. By unplugging it you make the ECU use a set of default values. As a low cost test remove the maf and look inside, you will see a section with a very thin flat wire at the end. Give that a blast with brake and clutch cleaner and see if it makes a difference when re fitted.
Re: 406 hdi slow
Posted: Thu Jan 22, 2015 1:15 pm
by Doggy
Hi and welcome aboard.
If you add your location, someone nearby may have diagnostic kit to prove if it's the MAF, or perhaps let you substitute theirs to prove a point.

Re: 406 hdi slow
Posted: Thu Jan 22, 2015 2:43 pm
by topbuzz
i live in fleetwood near blackpool if anyone has diag or more knowledge then feel free to pop round as my leg in plaster so don't really want to drive far at the mo
Re: 406 hdi slow
Posted: Thu Jan 22, 2015 3:40 pm
by Welly
Yours is a HDi 90 so as far as I recall the MAF is only there to check the EGR function.
The 90 is lazy but you could check the Turbo hosing's for signs of leakage etc.
Re: 406 hdi slow
Posted: Thu Jan 22, 2015 4:19 pm
by topbuzz
ok i have a haynes manual that came with the car so will study that and take a look..
ive had it on the motorway doin nearly a ton so the powers sort of there its just at junctions it doesn't seem to have much get up and go ..
Re: 406 hdi slow
Posted: Thu Jan 22, 2015 7:17 pm
by GingerMagic
Have you checked the slack in the throttle cable? Its basic stuff I know, but easily overlooked.
There should be a clip on the cable, by the throttle body, this needs to be pulled off ( ooer ) take up the slack in the cable and push the clip back on.
Next I would be using the super diesel for a tank or two to see if it improves the cars performance.
Re: 406 hdi slow
Posted: Thu Jan 22, 2015 7:25 pm
by rwb
The MAF reasoning sounds good to me.
Another possibility is a sticky EGR
Re: 406 hdi slow
Posted: Thu Jan 22, 2015 9:37 pm
by topbuzz
ok guys i will take alook over the areas hopefully tmoz and report my findings
Re: 406 hdi slow
Posted: Fri Jan 23, 2015 1:15 pm
by gumby6371
Not very familiar with the 90 do they have bulkhead EV's for the EGR and turbo? vac leak stopping the turbo actuator from opening? They're default postion is closed with no vac IIRC??
At least the lack of intercooler limits the possibilities, every cloud and all that.....
Re: 406 hdi slow
Posted: Fri Jan 23, 2015 5:14 pm
by Doggy
90's don't have a turbo electrovalve - just a mechanical wastegate
Re: 406 hdi slow
Posted: Thu Feb 19, 2015 9:52 am
by stuartkeith
the 90 is turbo? my 90 struggles to top 80mph. is this normal? Ive not worried about it, as im getting 6-700miles a tank from it

Re: 406 hdi slow
Posted: Thu Feb 19, 2015 12:53 pm
by Doggy
HDi 90's have a turbo, but lack the intercooler and electronic boost control the 110 has.
Power unsurprisingly, is 90 BHP. Should be good for about 105/107 real* mph.
Re: 406 hdi slow
Posted: Thu Feb 19, 2015 1:27 pm
by fattail95
My 110 pre-remap could see 120 given a long private* piece of road. So I'm sure a 90 could at least top 100, even though power is quite low they have decent enough torque.
Re: 406 hdi slow
Posted: Fri Feb 20, 2015 8:09 am
by stuartkeith
So normal then. Downhill can do about a ton.
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