406oc.co.uk

Hi there guys,

My peugeot 406 hdi 2.0 I've just bought from my dad has very poor acceleration below 3000rpm. I've replaced the MAF sensor with a £31 jobbie from ebay, and whilst it increased performance a little, its still not spot on. Its very odd, it seems to pull better if you use just 50% throttle and then gradually increase it to 100%? Any ideas?

Many thanks
Benjamin

EDIT: Fixed! Turns out the eBay MAF sensor was dead out of the box. New siemens one fitted, and its back to his usual self Thanks everyone for your help

is it a 110 or a 90 but i would still say its the maf i got one from the local factors that was faulty out of the box and i got 3 like it best to spend the moneys on a vdo or semans branded one as the will be better quoltey than an ebay special

I checked the MAF readouts on a diagnostic reader, and its performing as expected. However, when I checked absolute throttle position on the reader, it read 0.0% throughout the pedal range? Potentially TPS?

EDIT: TPS is fine, the diag machine was dodgy.

My friend has a delphi diagnostics machine so he'll take a look at it tomorrow... Anything specific to look out for? I love the car, but its really put a downer on ownership having problems straight away

Many thanks

Slack in the throttle cable?
A duff TPS should throw up 'engine anti-polution system defective'.

Otherwise, EGR? Boost regulator (if it's a 110)? (Both vac controlled.)

No slack in throttle cable, it is defo under full load when this is happening. It is a 110, how would I find out if it was the EGR or boost regulator?

It's most odd - if you gradually apply the throttle, like hold it at half for a few seconds, then full throttle, it picks up well and has FULL torque and power. But if you get straight on the throttle, it has no torque at all, hardly even pulls itself along. Getting slightly worried about it

Any more ideas?

Sounds like you need to eliminate the TPS.

Have a read of this.... viewtopic.php?f=5&t=20449&p=203858&hilit=+tps#p203777

Have you got cruise control?

You can use this to ' accelerate ' thus eliminating the TPS...

I also don't really rate the LMF MAF sensor, try to find a know working genuine one to test on your car, either from a mate or from a member here or PeugeotForum.

Does the 110 have a MAP sensor too?

GingerMagic wrote: Does the 110 have a MAP sensor too?

110's have the same intercooler and MAP sensor as 2.2's.

No cruise control unfortunately.

I do appreciate everyone's help

Right! Myself and a friend have been over the car, and done as much as we know how:

- Checked vacuum pipes - all ok, no leaks.
- All sensors are reading correctly, no duff ones to be found.
- Pressure on the common rail is normal.
- When it does boost, it holds it fine at ~14psi (0.9bar) as limited by the ECU.
- EGR is functioning normally, and as expected.

What else is there to do?

Many thanks!

where are you as if you are local to me i can give it a going over and see if i can fined any thing if you like

i am in sheffield south Yorkshire

Sounds like a communication error with the TPS to me, there was a modification years ago where the earth from the TPS was separated and ran on its own (I think it shares an earth with the MAF but used to give dodgy readings in some cases) also thoroughly check the condition of the wiring to these sensors as there may be an intermittent fault which only shows itself when you drive along (with the engine rocking around and yanking on the various wires etc).

If you get someone to rev the engine from idle, give it a good blip to 4000 rpm, hold your hand under the eggsauce tailpipe and you should get a massive blast of sooty-ish air, if it's irregular or sounds weird then maybe the eggsauce system is at fault; broken Catalyst, or detached sound-deadening material from inside the baffles. I once saw a car fart out a *massive* ball of mineral fibre from the tail pipe but when it first gets stuck in can block the flow of gases intermittently and cause poor performance.