406 2.1 td engine hesitation

GSB · Post by **GSB** » 14 Nov 2005, 15:16

Hi all, a 98 on 150,000m.
Most of the time the car runs fine. However occassionaly and becoming more frequent it's as though the engine misses a beat. It can be just once or continuous, when this is the case if I ease of the throttle and then accelerate again it clears it. It does not seem to make any diff if hot or cold or under load or not. Car is reguarly serviced and all filters changed.
When problem occurs management light flickers on but does not stay on.
Before I take it to be 'plugged in' at Peugeot (of whom going on past experience I don't have much faith) I hope someone may have an idea where to look.
Thanks.

rich201283 · Post by **rich201283** » 02 Mar 2006, 18:25

My car is missing beats too, If you start it up and flick the ignition off then on quickly does the management light go of, If you find out off peugeot what it is can you let me know

pugxpert · Post by **pugxpert** » 02 Mar 2006, 21:28

does engine light come on when it misses? really need a fault code out of ecu to give you a clue,could be rotor postion fault in pump or coolant temp,injection needle lift signal,throttle postion sensor the list goes on??

rich201283 · Post by **rich201283** » 02 Mar 2006, 22:20

Can you help

My car is a 406 dt 1998
The car is constantly missing, I had the fault code read (Start of injection fault) But nobody seems to know what this is? it run hotter and if i flick the ignition on/off quickley the management light will go off and rev up normally but as soon as it goes back to idle it comes back on.

I have disconnected both the tdc and the injector sensor and the tacho still works when either are disconnected,

When i disconnect the brown pump wire the engine doesnt change?

Somebody said it will need a replacement pump, what do you think?

pugxpert · Post by **pugxpert** » 03 Mar 2006, 08:04

start of injection i would say that is needle lift sensor,ecu calculates advance required by adjusting inside pump then it measures actual injection time on needle lift sensor on injector,check your pump timing is correct ,bolt holes line up on pulleys on cambelt if that is ok may be an injector fault?

rich201283 · Post by **rich201283** » 03 Mar 2006, 16:45

How can you test the needle lift sensor? as i have unplugged the tdc and the lift sensor and the tach works on both, If i unplug the needle lift sensor it runs even rougher

I have noticed if i start it the k light is off and then it comes on a few seconds later, When this comes on if you listen u can hear the turbo whine a little bit more that then the k ligh is off, The car was over filled with oil about 2 years a go and was running on its own engine oil, Dont know if this has blocked something and caused this problem, I can by another pump off another car tommorow but not sure if this will fix it

pugxpert · Post by **pugxpert** » 03 Mar 2006, 18:31

when it ran on its own oil how was the engine stopped? key off on ignition does not normally stop this,if igntion off and engine was still doing stupid rpm no diesel would have been entering fuel pump so no lubrication,possible damage then to fuel pump internals?? and possibly turbo they dont like running on there own oil,have seen pistons break up as well.not too sure if pump is at fault but ,with a laptop you can look at parameters inside pump rotor refrence and position go to your local lucas dealer they may be able to pludg in there equipment which is more geared up for pump diagnosis.

Dave Burns · Post by **Dave Burns** » 03 Mar 2006, 19:36

As suggested, check the timing holes all line up correctly first.

The brown plug on the pump goes to the solenoid valve, this valve adjusts fuel pressure in the pump body, this internal fuel pressure acts on a piston that rotates the roller ring to alter injection timing, just as in the old style all mechanical pump.

If the brown plug is pulled and there is no change in engine note, it must allready be at full advance, causing a heavy metallic knock sound.

If though as you say when the injector lift sensor is pulled, the note changes or engine stalls, then the solenoid valve is at least doing something, wether it is working correctly and the fault lies elsewhere is the question.

My next step would be to try another known good ECU if possible.

With the tacho still reading stable using either the lift or TDC sensor, it must be assumed that they are functioning normally, if the ECU can generate the tacho signal from those inputs, it should be able to use the same quality of input to adjust the timing, plus I would think a point of injection fault could only be registered by a properly working lift sensor.

You can't look inside this pump electronicaly as its not of the EDC (electronic diesel control) type.

Overspeed may well damage this (or any other) pump but it will still be lubricated, even with the ignition off the lift pump is still going if the engine is turning.

Dave

pugxpert · Post by **pugxpert** » 04 Mar 2006, 15:01

all 406 2.1 dt had the lucas epic type injection system,has a fly by wire throttle control and fuel dilevery is controlled in pump by 2 taper type wedges which is seen as rotor position in parameters read with a lap top,the 1.9td had the bosch vp20 system which can also read some ecu parameters but limted as this system only controls advance.when running on its own oil solenoid would shut off fuel supply into pump when ign turned off and internal pump pressure would be lost and poss lack of lubrication.

Dave Burns · Post by **Dave Burns** » 04 Mar 2006, 15:48

Sorry should have made clear, I am refering to the post by rich201283 and his 1.9td. not to the original poster who hasn't been back in nearly four months.

The only internal electrical device on the 1.9td Bosch pump is the solenoid valve, and all you can test it for is the integrity of it's winding.

The old mechanical lucas pumps will stop fuel entering the pump when the solenoid is switched off, the Bosch solenoid on the other hand does not cut the fuel supply entering the pump, it only cuts the fuel supply from that in the pump body to the high pressure cylinder at the center of the distributor head.

This is why air leaks are so problematic for Bosch equiped engines, because the stop solenoid doesn't act on the supply line, there is nothing to impede the progress of fuel running back to the tank when there is an air leak present, usualy in the leakoff pipes.

So as long as the engine turns fuel will be pumped into and out of the pump body, solenoid on or off, in any case lubrication does not rely on any internal pressure, merely that the revolving parts are totaly immersed in fuel.

Dave

pugxpert · Post by **pugxpert** » 04 Mar 2006, 21:49

no prob dave

GSB · Post by **GSB** » 01 Aug 2006, 15:23

I think this has been cured by luck and might help someone in the future. The problem was liveable with, however about a month ago my brake lights were staying on or flickering after braking. After checking various connections etc I buried my head in the footwell to try and find the brakelight switch (a pig of a job). It appeared that the small bracket/plate on the brake pedal was not lifting high enough to close the sensor on the switch to allow the lights to go off. I managed to stick a small spacer on the bracket and the lights now work fine. A bodge I know but apparently you have to remove the steering column to get at or replace the switch. A few days later (and up until now) I realised that the engine hesitation had not happened since. I then recalled that when I previously had the fault codes read one of the possible causes was ‘brake/accelerator inconsistent’ this of course meant nothing to the guy who read the codes. I am wondering that if the switch has a fault and was telling the ECU that the brakes were on while I was driving could this have caused the original problem.
Anyway I have my fingers crossed.

pugxpert · Post by **pugxpert** » 01 Aug 2006, 17:59

yeah i think that is it,if ecu see's brakes on but still throttle opening it thinks fault with throttle potentiometer so shuts engine down for safety,try driving down the road left foot braking will go down to 1100 rpm and engine light on