FAQ - 406 D8 petrol (Excl. V6) running & starting problems*

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FAQ - 406 D8 petrol (Excl. V6) running & starting problems*

Post by jameslxdt » Wed Sep 26, 2007 9:36 pm

I HAVE MANAGED TO RECOVER THIS GUIDE FOR ALL OF US TO USE

Now Edited for turbo models

Mods could you please sticky this guide i have made, but do not lock it so members can post there comments 8)

thanks


406 D8 petrol (Excluding V6) running and starting problems

as this subject comes up quite a lot i thought i would make a guide on the fixes for D8 petrol running and starting problems, this doesnt cover the V6 as i have never had the honor of working on the V6 and i am demonstrating on my car, which is 2.0 16v XU10J4R RFV, all petrol 406's execpt the V6 have XU engines hence why it applies to all the models!
Right first on the list:

Stalling, rough/harsh gearchanging (manual only) and high idle

the most common cause of these problems is a faulty or lazy stepper motor, usually cleaning and re-synchronsing it can cure all of these problems
the stepper motor can be found on the throttle housing
see the pics below
NOTE: turbo models are slightly different !

turbo 8v

Image
non-turbo 16v

Image

going by the second photo -
for the moment ignore the blue circle
the pink circle indicates the throttle housing on the first pic and the red circle on the first one
start by removing the airbox as shown below

Image

Image

please ignore the green circle, the red circle is the stepper motor, it should have AMC printed on it, some have phillips also
undo the connector with 4 wires on it
the undo the two torx 20 screws and pull it out

Image

this is what you should have
the red area indicates where the carbon buildup occurs, clean this with brake cleaner or carburretor cleaner, dont worry about getting it inside it, this helps to a certain degree
now refit everything, taking note to put back all the various vacuum hoses and electrical connectors
now once all is together, get in the car and turn the ignition on for 30 seconds, then switch it off for another 30 seconds, repeat this 3 times, on the 4th time you turn the ignition on DONT touch the throttle, start the car and alow it to idle for another 30 seconds, now go for a drive for about 20 minutes and all should be well!

Running Problems

remember i told you above to ignore the blue circle, now this is what we are concerned about, if you have a rather annoying hesitation between 2000 and 3000 rpm at part throttle when the engine is warm, then you will most likely have a faulty oxygen sensor, they are also often refferd to as a lambda probe
the picture below is a close up of the blue circle in the first picture above

Image

the red circle indicates the plug for the oxygen sensor, lift the red part up with a screwdriver, and pull the front part out leaving the red part where it was, now go for a drive, the car should now drive faultlessley and it WILL NOT trigger the K light as the engine management is too stupid to know somethings not right
you can drive arround like this without a problem, untill your MOT then you will need to have the sensor replaced

Starting Problems

if your car is refusing to start and the keypad/immobiliser is functioning accordingly then most likely the TDC sensor, or Top Dead Centre sensor is faulty, its often called a crank angle sensor, crank position sensor or engine speed sensor, it basically informs the engine management of the position of the crankshaft so it can time the injection and spark correctly, what usually happens is the thermostat housing, positioned directly above the sensor developes a leak and shorts the sensor internally rendering it usesless, i will now demonstrate how to test the sensor

Image

airbox removed for clarity
ignore the red circle
in the green circle is where you will find the connector for the TDC sensor
its a brown color
now i have removed the sensor for clarity here, but to test it, you need to un-plug it
BUT LEAVE IT FITTED!!

Image

the pins i have circled above are the ones we are concerned with
now grab yourself a multimeter like so

Image

you dont need a very expensive one like mine, i use it for work everyday, anyone will do
now set it too A/C voltage, or Alternating Current, this is ESSENTIAL otherwise this test is pointless

now attatch the leads to the sensor plug, NOT the harness plug as shown below

Image

taking note again, i have the sensor removed for clarity, you still need yours fitted to the car

now with the multimeter attached and set to A/C voltage, get a friend to try and start the car, a good sensor can read anything between 1.5v to 3.5v, BUT as a general rule 1.0v should be ample enough to start, if this not the case, then leave the pins attached, and turn the multimeter to measure resistance in Ohms, now generally anything above zero is good, if you have very low voltage and open circuit or low resistance, then the sensor is almost certianlly faulty, now the good news is they only cost about £22+VAT from pug
and if you follow the cable its bolted into the top of the gearbox with one 10mm bolt, undo this and it simply pulls out, BEFORE fitting the new sensor take not of what i mentioned above, these sensors only usually fail if the thermostat housing leaks directly above the sensor, which is quite a common problem, so make sure you remendy the leak before fitting the new sensor otherwise you will be looking at needing another new one pretty soon!

IF ANYONE SPOTS A MISTAKE PLEASE LET ME KNOW SO I CAN CORRECT ACCORDINGLY
Last edited by steve_earwig on Mon Sep 11, 2017 7:14 pm, edited 3 times in total.
Reason: Pics more to 406oc photobucket account
Peugeot wrote:what are you worried about? we made car that lasted 10 years"..."Zat is very goode non? :|
FAQ - 406 D8 petrol (excl. V6) running and starting problems

carpcatcher
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Re: FAQ - 406 D8 petrol (Excl. V6) running and starting problem

Post by carpcatcher » Mon Oct 29, 2007 7:29 pm

Hi, have done all of the above, think this was very clearly explained, and went without hitch.
Only problem is has not cured the problem.
This being a fluctuating tick-over of between 400 to 900 rpm.
This often involves the engine stalling.
Apart from embarrasing, its also dangerous.
Any further advise please ????
Thanks, Dave

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Re: FAQ - 406 D8 petrol (Excl. V6) running and starting problem

Post by jameslxdt » Mon Oct 29, 2007 8:36 pm

probably need a new stepper motor then, was yours the AMC type?
Peugeot wrote:what are you worried about? we made car that lasted 10 years"..."Zat is very goode non? :|
FAQ - 406 D8 petrol (excl. V6) running and starting problems

carpcatcher
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Re: FAQ - 406 D8 petrol (Excl. V6) running and starting problem

Post by carpcatcher » Tue Oct 30, 2007 7:51 am

Yep, was that type. Heavily carboned, but cleaned up ok. Any idea on £? Can do myself so no labour. Thanks

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jameslxdt
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Re: FAQ - 406 D8 petrol (Excl. V6) running and starting problem

Post by jameslxdt » Tue Oct 30, 2007 9:39 pm

ive seen them on ebay for about £30, pug stealer wants nearly £70!!
Peugeot wrote:what are you worried about? we made car that lasted 10 years"..."Zat is very goode non? :|
FAQ - 406 D8 petrol (excl. V6) running and starting problems

carpcatcher
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Re: FAQ - 406 D8 petrol (Excl. V6) running and starting problem

Post by carpcatcher » Fri Nov 02, 2007 12:00 pm

Thanks for all your help, waiting for delivery of new stepper (ebay £2.99 !!!!).
Hopefully will cure.

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Re: FAQ - 406 D8 petrol (Excl. V6) running and starting problem

Post by mjb » Sun Jan 20, 2008 4:37 pm

For 2.0 turbo and 3.0 V6 users:

It a different method for us guys. The 2.0T doesn't have a stepper working on the throttle, presumably because there's already enough things screwed onto the throttle body. Instead there's a second air feed into the throttle which comes from the main air pipe from the intercooler. In James' post in the first picture, in the purple circle you'll see an inch-wide pipe coming from the throttle and turning right then down. It's this. In the way of this air pipe is a large unit called the Idle Control Valve (ICV). This can get fouled with oil from the turbo and as a result will result in poor idling especially when cold. You can find the ICV under the upper radiator hose.

Unlike stepper motors, the ICV's replacement at £170 would cost more than a new tubby. Thankfully it's cleanable.

1) *VERY CAREFULLY* unclip the metal clip from the electrical connector and pull the connector off
2) Unclip the hose going from the ICV to the throttle body
3) Unclip the large black plastic clip going around the ICV
4) Unclip the ICV from the short hose coming from the main air pipe and manoeuvre the ICV out.
5) Unclip the hose from the ICV and clean it out with carb cleaner
6) Clean the ICV with carb cleaner
7) Reassembly is the reverse of disassembly :)

Pictures to come when it's not raining so heavily


3.0 V6

Similar to the above, but the ICV is located to the rear of the throttle body. I've been informed it'll need the metal clips replacing with jubilee clips on reattachment. Pics to follow when I get round to doing the job.
Last edited by mjb on Thu Sep 04, 2008 2:17 pm, edited 1 time in total.
<steve_earwig> I think this forum is more about keeping our cars going with minimal outlay than giving our cars more reason to go bang

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Re: FAQ - 406 D8 petrol (Excl. V6) running and starting problem

Post by steve_earwig » Sun Jan 20, 2008 6:16 pm

James, did you figure out the macro button on your digicam yet? :P :cheesy:
Unskilled meddling sin©e 2007

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1991 Yamaha TDM850 - fuel leaks galore!
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Re: FAQ - 406 D8 petrol (Excl. V6) running and starting problem

Post by GoldenBlunder » Wed Sep 03, 2008 8:08 pm

THANKS for this as I aint got a manual and it most likely not in it .Is the stepper motor really a seloniod as it looks like it should operate like one and does it cut off air/crankcase gasses to the idle system.Also if you know what is the black mushroom shaped object connected to the top crankcase breather ,mine lets air through both ways and is a bit gummed up.Lots of things to go wronge on this setup I'm used to simple old fords.

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Re: FAQ - 406 D8 petrol (Excl. V6) running and starting problem

Post by mjb » Thu Sep 04, 2008 2:14 pm

GoldenBlunder wrote:Is the stepper motor really a seloniod as it looks like it should operate like one and does it cut off air/crankcase gasses to the idle system.
It does the opposite - When you take your foot off the accelerator closing the throttle body (which is spring-loaded to shut) at a standstill, the solenoid pushes the same mechanism and opens the throttle to let air into the engine and prevent a stall. When you try to start moving without using the accelerator, it's the solenoid pushing a little bit harder which keeps the revs at idle. When you're driving normally, it backs off to let you have full control of the throttle. When you're moving it'll let the throttle close all the way to save fuel when you're using engine deceleration, then engage when revs drop to idle
<steve_earwig> I think this forum is more about keeping our cars going with minimal outlay than giving our cars more reason to go bang

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Re: FAQ - 406 D8 petrol (Excl. V6) running and starting problem

Post by mjb » Thu Sep 04, 2008 2:18 pm

Edited my above post as it suits the V6 too
<steve_earwig> I think this forum is more about keeping our cars going with minimal outlay than giving our cars more reason to go bang

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