Diesel knock on cold start, Lift Sensor?

TeddyMcB · 2022-11-22 20:33:27

Hi all, I have a 2005 Dispatch 1.9 diesel face lift with a diesel knock on cold start which quiets down as the engine heats up but not completely. It started suddenly and sounds like rod knock but it is not. I believe it is diesel knock because it does not knock when coasting in gear, no fuel being used at this time. If I rev the engine, it knocks as I push the accelerator but stops briefly as I take my foot of the accelerator again no fuel being used during this brief time. Back knocking on tick over. So after reading a lot both here and online I see the Lift Sensor on the injector 4 is a possible cause. I note disconnecting it makes no difference to the Knocking and this also makes me believe it is the culprit. I measured the resistance of the sensor which is 100 ohms and that is what a good sensor should read. I traced the 2 wires back to the ECU and both have continuity to the connector (Pins 2J and 3K) of the ECU. However, I have not yet checked if connections make their way to the ECU circuit itself. (Through the multi plug connector) After checking the wiring diagram the pins (2J and 3K) are the correct ones. I have no warning lights on the dash when engine is running but they do come on with ignition as I would expect. So my questions are
1: Could the Lift Sensor be faulty and still read 100 ohms?
2: If the lift sensor is faulty would I expect to see a light on the dash?
3: Is driving it with the knock bad for it I wanted to take it for a spin and get the Injector cleaner I added to the tank to do its thing.
I don't have the van long and it had passed its annual test about 500 miles before I got it so should have been running well then and I drove it for about 3 weeks with no sign of Knock before this started.
Any thoughts please?

TeddyMcB · 2022-11-22 21:00:06

I believe the engine is a DW8B and it has 220K KM

AlvyLad · 2022-11-22 21:00:56

My old escort van had excessive knocking, lasted for about a month, before had to scrap it, as timing chain stretched and that was jamming output valve ('s) repair wasn't worth it.
ANW, hope it's not the case and it is just an electrical repairable as per your good research so far. More knowledgeable people should clarify bit better, I hope

TeddyMcB · 2022-11-22 22:45:11

Thanks AlvyLad lets see what happens. Also just to add to the detail above the Van has no issue starting so I am ruling out fuel pump and glow plugs.

JohnDragonMan · 2022-11-23 00:22:45

i know it sounds nuts, but try unplugging the ECU and then start it. the DW8 is a funny old engine as it will still start and run all be it rough with no ECU.
if it starts the "same way" as it did when it is plugged in it could be the alternator on the way out not giving out an engine "running" signal as the crank sensor may be a little tired and not detecting RPMs below say 600.
diagnostic live data would confirm this while its cranking.
its a shame they do not have a cam position sensor as then it would tell you if they were not aligned up correctly (one tooth out).
oh and i forgot to add, it could be the ECUs (not dash) temperature sensor become out of range. i think these have 2 temp sensors. they usually default to -40.c (or lower!) when they fail so that causes all kinds of hell.

hope this is of some help...

Last edited by JohnDragonMan (2022-11-23 00:25:32)

TeddyMcB · 2022-11-24 14:45:33

JohnDragonMan, I unplugged the ECU (2 connectors) and it starts and sounds the same however the alternator was changed recently and looks new. Could it be a blown ECU? Is anything codes to the ECU? I don't believe the injectors are in this van. Could I just drop one in or would it need an auto electrician.
This Van has one green Temp sensor and does not have the blue one beside it (directly below the rad expansion tank). It also has one on the RAD and there is a sensor on top of the Expansion Tank. Do you know which does what. I test the green one later. Thank you I am going to price an ECU in the scrappy now. Thank you for the help.
All comments welcome please.
Thank you.

JohnDragonMan · 2022-11-24 15:28:44

ahh well if it acts the same without the ECU plugged in try checking the resistance on the crank position sensor. or for what they cost just try changing it. its can be a little bit of a pain to get to but its located just above the bell housing under the water jacket.. thing.. undo the plug, and use a 10mm spanner to loosen the bolt. you dont have to take the bolt out all the way. once the bolt has been slackened back turn the sensor 90 degrees or so while pulling up and it should just come out. grab another from a scrap yard.. both HDI and DW8 engines use the same sensor which is nice. then install it into your van.
see if that fixes it

before you install it check the 2 ends of the sensor side by side to see if your one has had the tip snap off. i had it once where the tip of the sensor had smashed off and the little magnet in the end of the sensor had broken up and got stuck to the flywheel causing false readings when i replaced the sensor again.

hmm... see my post here:
https://dispatchexpertscudo.org.uk/foru … 7973#p7973

what i did was pack the sensor out with a few washers so it was not as close to the flywheel

ive fixed 3 of our type of vans with this knowledge so far! be nice if your the 4th!

these old hybrid systems are quite nice in that the injectors do not need to be coded to the ECU so any injectors can be used anywhere in the engine so long as they come from another DW8. the ECU only exists for refinement.. make it nice and smooth. (you know, something old mechanical diesels just "did")
its a different story for the HDi but to some extent it can still work however its more of a "luck" thing... (the replacement injector has parameters close to the old injector).

if all else fails, you can just install an injector pump from a non turbo XUD to your DW8. you can just leave the ECU unplugged then.

also an engine management light is NOT an MOT fail on vehicles older than 2008 smile

something you dont really need to know but it also means that in the event of say a large EMP or solar flare that would destroy electronics.. your old DW8 would still run... all be it rough! cant beat the old XUD engine though.. 100% mechanical. if all electricity on earth just stopped working, that would still run if you bypassed the stop solenoid (take it out, cut the end of the plunger off and refit)

what? ive done a lot of playing with these things.

Last edited by JohnDragonMan (2022-11-24 15:51:48)

TeddyMcB · 2022-11-24 16:31:47

Thank John I have taken the Crank Sensor out and I see 385 ohms across the 2 terminals of the sensor, does that sound right? I have ordered one any way. The tip is not broken it is all intact.

Casper · 2022-11-24 19:23:02

Has these vans goy hydraulic tappets? I had a Fiat Stilo that sounded crap when cold. Oil filter change cured that as apparently dirty old oil can clod the oilways.

TeddyMcB · 2022-11-26 12:45:43

Casper, I dont believe this is mechanical tappets or oil shortage, I am confident it is Deisel knock, I did squirt a little oil in to the valve cover when it was just started and it made no difference. Also the knocking stops when coasting in gear (i.e. when no fuel is being injected).

JohnDragonMan, I have fitted the new Crank Sensor and it made no difference. Also the resistance reading on the old was the same as the new. I also notice the engine runs the same with the Crank Sensor disconnected which is to be expected I guess as it is connected to the ECU and it runs the same with no ECU also. What parts are coded to the ECU i.e. what would I need to change if I wanted to try a different ECU? No warning lights when running and Dash Temp gets to 70 degreed which is normal. What about the advance solenoid?

TeddyMcB · 2022-11-26 18:55:47

I have finally got my Delphi to read the Codes on the Van this was after I cleaned up a very dodgy chassis Earth going to the ECU. Perhaps that brought the ECU back online. As I said before it ran the same with the ECU plugged out or in. The van also sounds a little better but is ticking over a little high at just over 1000 RPM. I can see in Live data that the Injection actual is 26 Degrees and the Injection request is 3.8 at idle. I also have a P0102 code which is Mass Air flow low input. I also have P0170 which is Fuel Trim Malfunction Bank 1. It is also running hotter than usual at about 90 degrees as opposed to the usual 70 fan is running and I can feel pressure in the pipe from the rad to the thermostat (it is not rock hard but you couldn't compress it easily). I will leave it cool down and do some internet searching. However perhaps some one will get a clue or suggestion from this. Thank All

JohnDragonMan · 2022-12-01 02:24:45

ahh well if you can read codes the ECU is working again. so that now sounds like that issue is sorted.

the mass air flow.. unplug it for now and see if anything changes. my van had a fault with the MAF when i bought it, i just ran around with it unplugged till i got the replacement come through. as when it was unplugged i got full power back.

now interesting on the p0170 code.. fuel trim. that may be the fact its detected knocking, it may be that the pump or cam is not in sync, it could also be the advance solenoid.
however
my money is on that mass airflow meter acting up. if the ecu cant detect what airflow is coming into the engine, it does not know how rich or lean to make each injection.

get that MAF unplugged and report back! i mean, it may be worth changing it for the £14 they cost now. it is getting on for 20 years old. the little heating elements on it are not really made for 20,000 cycles haha

TeddyMcB · 2023-02-17 20:46:06

OK sorry for the delay John, but I am back at this again, MAF plugged in or not makes no difference. Also I read in the manual that Pin 2 (MAF) should have 12 Volts and it does not. Am I correct to assume the 12 Volts should come from the ECU. I want to check the power to the ECU itself and its outputs and inputs as my code reader is no longer communicating with it. Does any one have a pin out for the 2 ECU connectors so I can check for bad connections please. Also if I get another ECU can it just plug in or is there coding required please? I dont know if I have Bosh or Lucas Pump but it is a Face Lift MK1 and I think they are Bosh, can I tell by looking at it? or can any one tell me which numbers in the VIN tell me the pump type? Lots of questions guys sorry but I have some time now and want to get this sorted. Van ran OK yesterday with no knocking but bck doing it again today. I am suspecting my ECU is not doing any thing any quick way to check that?

JohnDragonMan · 2023-02-18 02:16:03

hmm interesting, so it could be a intermittent power issue for the ECU.. it could be a bad earth strap or the ignition switch is worn out..

see, its hard to tell when the ECU is running on a DW8 as you have no lift pump (in tank fuel pump to hear) its handy for diagnosing if the ecu is getting power, and if the immobiliser has been lifted (if the transponder in the key has been read correctly).

i sadly do not have the ECU pinout for any of these vans (i do for the old Mk1 Punto 75..somewhere not much use here sadly) sorry.

yes, photos are always helpful. i will just be googling the and compairing how it would look to the bosh or lucas pumps however. not sure if the vin can tell you what pump it has.

TeddyMcB · 2023-03-06 19:06:43

Thanks John, I am nearly sorted I believe. I had a broken wire in the loom going to the ECU so soldered that. I changed the MAF for a new one and swopped the vacuum lines going to the egr throttle because they were connected incorrectly. This has it running with no knock once it warms up a for a few min and power seems OK. I asked a question on a seperiate thread about the yellow voltage tag on top of the injector pump as I suspect that is what the potentiometer out put should be at tick over is tha5 correct? I will set that tomorrow and see if it smooths things out a little more.

TeddyMcB · 2023-03-14 19:52:23

I have the sorted the engine running rough issues and am posting this in case some one else suffers the same problems with knocking. It was down to broken wires in the loom. Six broken wires which disabled many things including the Advance solinoide, the throttle position potencometer, the MAF and the lift sensor. All the breaks were in the section of loom which leaves the ECU and goes to the right. Just above the fuel pump is a bracket which holds the loom in place. Undo the 8mm nut so you can get the wires out of the trunking. Inspect these before replacing any electronic components. Next job is my pixelated odometer and spinning door locks. Thanks for the help I would not have gotten sorted with out all the great info on this site. I find garages are fine for replacing clutches or doing specific definitive tasks but no one wants to fault find issues with an old van like this, so you just have to get help and advice from sites like this.

Jumpy-Joe · 2023-09-10 21:25:21

Lifting this thread… My old girl har developed a diesel knock, with the engine management light turning on. Tried to disconnect the lift sensor, and the sound is unchanged. Also if I disconnect the yellow connector on the ECU, nothing happens. Haven’t tried anything else yet. The problem started as a intermittent issue, but has moved on to be more or less permanent. Any ideas as to where I should start looking_

The Dispatch | Expert | Scudo Hub

Get help & share your Citroen Dispatch (Jumpy) | Peugeot Expert | Fiat Scudo tips

#1 2022-11-22 20:33:27

Diesel knock on cold start, Lift Sensor?

#2 2022-11-22 21:00:06

Re: Diesel knock on cold start, Lift Sensor?

#3 2022-11-22 21:00:56

Re: Diesel knock on cold start, Lift Sensor?

#4 2022-11-22 22:45:11

Re: Diesel knock on cold start, Lift Sensor?

#5 2022-11-23 00:22:45

Re: Diesel knock on cold start, Lift Sensor?

#6 2022-11-24 14:45:33

Re: Diesel knock on cold start, Lift Sensor?

#7 2022-11-24 15:28:44

Re: Diesel knock on cold start, Lift Sensor?

#8 2022-11-24 16:31:47

Re: Diesel knock on cold start, Lift Sensor?

#9 2022-11-24 19:23:02

Re: Diesel knock on cold start, Lift Sensor?

#10 2022-11-26 12:45:43

Re: Diesel knock on cold start, Lift Sensor?

#11 2022-11-26 18:55:47

Re: Diesel knock on cold start, Lift Sensor?

#12 2022-12-01 02:24:45

Re: Diesel knock on cold start, Lift Sensor?

#13 2023-02-17 20:46:06

Re: Diesel knock on cold start, Lift Sensor?

#14 2023-02-18 02:16:03

Re: Diesel knock on cold start, Lift Sensor?

#15 2023-03-06 19:06:43

Re: Diesel knock on cold start, Lift Sensor?

#16 2023-03-14 19:52:23

Re: Diesel knock on cold start, Lift Sensor?

#17 2023-09-10 21:25:21

Re: Diesel knock on cold start, Lift Sensor?

Board footer