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Peugeot 2.0 307 HDi 2002 - Low supply voltage to injectors #

Posted by Matthew Parr on April 2, 2011, 6:11 pm

Year of Manufacture *: 2002
Engine Size and Code *: 2.0l

Hi there, this is my first technical post so if i miss somthing please be nice :0)

I am currnenly having a look at a 2l 307 hdi non start. I have done the following.

Checked for fuel supply (low pressure side)

Check for switching at injectors, I done this with a noid light and got a faint flash then nothing, if i stopped cranking then started again the same would happen.

Check inductive crank sensor, for both ac voltage generation and the resistance of the sensor = all ok.

Check feeds/earth to hall camshaft sensor, got my 5v, 12v and a good earth (volt dropped these also)
I have also checked for switching with a led light. = all ok.

I then went back to the injectors and checked for a 12v ign feed......(admittedly should have done this already!) I am getting 1.5v supply to the injector!

This is where i need some help, I cannot work out with my wiring diagram where the feed for the injectors come from, I have checked all live feeds to the ecu and all are reading battery voltage.

I may have missed somthing obvious but need a little guidance.

I have a obd package but it will not read live data whilst cranking so i cannot tell you the fuel pressure or whether the ecu knows whether the engine is spinning (rpm signal)

Many thanks in advance, Matt

Re: pug 307 hdi low supply voltage to injectors

Posted by Michael Whitworth <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT5568' width='330' height='300' border=0 style='border:none;'> on April 2, 2011, 6:34 pm, in reply to "pug 307 hdi low supply voltage to injectors"
Mike Whitworth - Administrator

Hi Mathew,

First of all congratulations on your first post on UKAT, It wasn't too bad........

An engine code would be useful, But, your tests are OK, to a degree, as far as they go with the equipment you have to hand however a better understanding of the operation of modern common rail diesels is essential as well as the correct equipment to test it with. Unfortunately you appear to have neither.

You could use a voltmeter to test for High pressure at the HP sensor but you need diagnostic comms with the ECU to make any further progress with this job.

The ECU will not fire the injectors until it sees a pre determined High fuel pressure.

Also these injectors may be Piezo or Capacitive Discharge.. Either way you can not test for voltage at the injector with a voltmeter. Idealy you need a scope with a low amps current clamp.

For these reasons I suggest you cut your losses and move on to something you are equiped to deal with and if you want to diagnose faults on these you need to think about training or self study plus better equipment.

This is not meant to offend you, I am just playing Devils Advocate.

HTH

Mike

M.O.M. Miserable Old Manc

Re: pug 307 hdi low supply voltage to injectors

Posted by Matthew Parr on April 2, 2011, 7:30 pm, in reply to "Re: pug 307 hdi low supply voltage to injectors"
Message modified by board administrator April 4, 2011, 3:50 pm

Thats fair enough, thankyou for the response. I was under the impression I should be getting a 12v supply to the injector which is earthed through the ecu to make the circuit? I know that I would be getting a completely different signal if it was a pizo injector which im pretty confidant it isnt as I have a self study programme on this engine which indicates its safe to use a noid light. I am limited with equipment as im just looking at the car for a family member on the drive.

I have got 2010 autodata which gives a test for the hp fuel sensor but only if the engine is running or at 3000rpm. I get a voltage fluctuation with the engine cranking.

Many thanks again, Matt

Re: pug 307 hdi low supply voltage to injectors

Posted by Carl Ford <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1822' width='330' height='300' border=0 style='border:none;'> on April 2, 2011, 9:03 pm, in reply to "Re: pug 307 hdi low supply voltage to injectors"
Carl Ford

Hi matt
not being able to see live data on cranking may be a problem but first what voltage is the signal from the rps actually displaying on cranking? If it only rises slightly try disconnecting the return line and make sure you don't see any fuel coming out as you carnt build up pressure if the system is not sealed don't no if this will help you at all just what I would possibly do before taking a car back to the workshop.
Regards
Carl

Re: pug 307 hdi low supply voltage to injectors

Posted by Mark Carter <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on April 3, 2011, 2:51 pm, in reply to "Re: pug 307 hdi low supply voltage to injectors"
Mark Carter

Hi Matt,

>>> I was under the impression I should be getting a 12v supply to the injector which is earthed through the ecu to make the circuit?<<<

You are thinking petrol, and not diesel.

As others have said the ECU will not fire the Injectors before it sees a pre set rail pressure.

The operating voltage of the injectors will be anything from 60 volts up to 200 volts depending on system.
The amps ramp can exceed 20 Amps. HTH

Regards Mark

Modern cars, Its all wizardry and witchcraft

Re: pug 307 hdi low supply voltage to injectors

Posted by Ed Kaps on April 4, 2011, 1:18 pm, in reply to "Re: pug 307 hdi low supply voltage to injectors"
Message modified by board administrator April 4, 2011, 3:50 pm

Hi Matt
In addition to what others have mentioned, your noid light/led tester is of little use here(or in most other situations), milliamps will flash an led but do nothing for any injector, As Mike has mentioned you need the right kit and good technical info to ensure you don't waste more of your time.
Ed Kaps

Re: pug 307 hdi low supply voltage to injectors

Posted by Shaun Dale <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT2719' width='330' height='300' border=0 style='border:none;'> on April 9, 2011, 9:18 pm, in reply to "Re: pug 307 hdi low supply voltage to injectors"

Hi Matthew,
I agree with all the comments made about having the equipment and the know how, however we all have to learn somewhere... There was a time when the world's expert on these looked at one for the first time.
From memory these use approximately 90V on the injectors. The ECM will not fire the injectors until a minimum rail pressure is achieved, about 160 bar on this car if I remember correctly. Check for excessive injector leakage, remove the injector leak-offs, close off the return pipe with a pipe clamp or you will get diesel everywhere. Get an assistant to crank the engine and observe the amount of leakage from each injector, in most cases if one is faulty the difference is so marked you cannot mistake it. Obviously it is preferable to use a set of leak-off bottles but if you take precautions to catch the leakage with tissue and don't crank for too long and get diesel everywhere then you should be ok. If your assistant is on the ball you can do this test with no spilt diesel at all.
Not being able to read rail pressure on cranking is a big draw back for you, is the battery fully charged? I find many ECMs stop talking on cranking if the voltage drops just a little bit too far.
Shaun

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