Unsteady rev mainly in idle

Hi Everyone,

i've an TD5 MY2002 (15P) with ~180.000km.

Sometimes i've an unsteady rev. I was notice this behavior first in idle. I've a "test track" where i can reproduce it by 100%. The track has 8km and is upwards a small hill only some meters. When i arrive the idle is unsteady. When i'm driving back at home idle os ok.

It looks like that this issue is only when engine is warm. When idle is unsteady, it fluctuate between 720 - 760 rev. I think i've reproduced it also when i'm standing at 2200 revs but this is difficult... some diagrams:






I've disconnect the air flow meter and also the ambient pressure sensor without success, you can see this in the first diagram. In the last diagram you will notice a small noise on Accel track 2 but i think this cannot be the issue, or?

I've made a lot of things in the car because I got it in a really bad condition. Things that are new:
- Fuel filter, fuel pump, non return valve (it was missing at all), diaphragm valve (no air in fuel system)
- Oil pump
- A new cylinder head because engine had fuel in oil including all the seals, hydraulic lashers
- Overhauled injectors
- Air flow meter
- No oil at the ECU because of a oil barrier

Has anybody an idea what i can check next?
Thank you in advance.
Best Mario

Hi I had this on my old disco td5 and it was number 3 injector

Regards

Besides of the fluctuate rev, the engine is running like charm and i didn't have the issue everytime....i assume if an injector is the root cause the issue should be stable?

Look at the clutch switch also the hydraulic fluid In the clutch if it has any air in it. It can activate the switch when hot {the air expands when heated} but have no effect on clutch operation.

Only clutching at straws but you could check the fuel pressure regulator, check for small leak and there is a gauze filter fitted in the cylinder head behind it, and check for good connection at fuel temperature sensor.

Are you’re injectors green top or black?

I've cleaned the connections of the clutch switch and fuel temperature. I've also disconnected these two connection when i have the issue without success.

I've found out that my low/high switch was not working, the ECU thinks i'm always driving in low, not sure if this can cause the issue.

When i'm waiting ~2 minutes, the idle becomes steady i think this is because the engine is "cooling down"....

My injectors are green on top.

Mario110 said:

I've cleaned the connections of the clutch switch and fuel temperature. I've also disconnected these two connection when i have the issue without success.

I've found out that my low/high switch was not working, the ECU thinks i'm always driving in low, not sure if this can cause the issue.

When i'm waiting ~2 minutes, the idle becomes steady i think this is because the engine is "cooling down"....

My injectors are green on top.

Click to expand...

If you can try another set of injectors please do so

I've fixed today the high/low switch which makes no difference with my issue but now the Defender is much better on gas.

Another set of injectors will be really luxurios Unfortunately i didn't have one and the prices are really high...

Hi, i've got a set of reconditioned injectors and the idle is now steady and the engine is running smoother. The first recondition was going really wrong!

The last thing i have is now a knocking sound when the engine is warm. Please have a look here https://instaud.io/3Y3a

I'm not sure how to describe it but hopefully you will hear these tack tack tack tack....sounds.

Any ideas? I've also replaced the fuel regulator and the injector loom....so...most things are new....

Hi that knocking sounds isn’t bad, heard a lot worse, may I please ask what engine oil you are using?

Yes sure - it's Eni i-Sint SAE 5W-30 filled in. Do you know what is causing this sound...is it an injector, is it the ignition itself...?

Knocking noise possibly injectors not set properly, check they bottom out then wind back 360 degrees with cam at highest on each lobe.

As johnlad rightly mentions make sure the injectors are correctly set... if you are certain this is correct then please try Total quartz 7000 10w40, quite expensive but it is fabulous oil with regards to antiwear ( check on YouTube ) 5w30 is too thin for the td5 imo,

I'm certain about the injector adjustment, because the other injectors had the same sound and these were mounted by another mechanical. The interesting part is, that i only hear this sound when the engine warm, maybe this because of the oil or because of the rev speed is higher when it's cold. When rev speed is > 740, the sound is gone. Another guy, which was doing almost the same on his engine (new AMC head, injectors etc.) has the same symptoms (louder than on my engine):

Maybe....this sound is normal but i really want to get sure....Thanks a lot.

As the oil gets hot it gets thinner as you know, certain oils mostly the modern stuff isn’t brilliant for the td5 as it wasn’t designed for low ash oils and is a fairly old school engine really... Try Total quartz 10w40 and report back and thank me later

Thanks, next time i will try the other oil - maybe
Today i've had some fun on the unpaved road and observed that this knocking sound is going away when I'm in idle rev going downhill, so it has something to do with the injection/ignition of the diesel. I cannot find any issue so far, it's driving really good. I've made a new video for comparision (details in video)



Maybe like Discodevon said, this sound isn't really bad - unfortuantily i didn't have any TD5 driver in near....

Hi.....I've made another video when my engine is cold and was started for first time on the day.



The difference is audible. It would be really nice if the engine would always sound like it does in cold condition. My fear is that in the long run the engine will be damaged....

Dude, with all due respect stop worrying about it! If it starts well doesn’t smoke too much and pulls ok then don’t panic about it... Put a decent engine oil in it to start with!!