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The real cause of injector rattle?
#1
Yeah another injector rattle thread Tongue haha.

I am wondering if there are any external factors that can be causing the rattle rather than just the injectors them selves. For example, too high fuel pressure (Dodgy FPR) unclean fuel (blocked or damaged fuel filter) Etc etc.

I got in my car today and usually I have a fair bit of rattle. Nothing stupidly bad but easily noticeable specially with the windows open. However today it was lovely. No rattle at all, really smooth and quiet. I did nothing different. Its been on the same fuel now for half a tank which is just shell regular diesel. Cant think why it would be so quiet.

It was like this the next 2 times I started the car today and drove it. But then after about the 3rd start and drive it went back to rattling again haha. It is so unpredictable. It's definitly the injectors as it goes when I let off the throttle and I think it goes after 3200rpm as well.

Could there be something really obscure causing it like worn cable sheath or bad connections when damp etc? Which earth point does the injector system use and where does the power supply for them come from?

What do you all think?

Jack
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#2
I solved my injector rattle.. It did necessitate fitting a monster turbo..
Given the choice between Niall and the sheep. I would choose the sheep!
/Toseland
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#3
(14-06-2015, 06:43 PM)JTaylor2005 Wrote: Yeah another injector rattle thread Tongue haha.

I am wondering if there are any external factors that can be causing the rattle rather than just the injectors them selves. For example, too high fuel pressure (Dodgy FPR) unclean fuel (blocked or damaged fuel filter) Etc etc.

I got in my car today and usually I have a fair bit of rattle. Nothing stupidly bad but easily noticeable specially with the windows open. However today it was lovely. No rattle at all, really smooth and quiet. I did nothing different. Its been on the same fuel now for half a tank which is just shell regular diesel. Cant think why it would be so quiet.

It was like this the next 2 times I started the car today and drove it. But then after about the 3rd start and drive it went back to rattling again haha. It is so unpredictable. It's definitly the injectors as it goes when I let off the throttle and I think it goes after 3200rpm as well.

Could there be something really obscure causing it like worn cable sheath or bad connections when damp etc? Which earth point does the injector system use and where does the power supply for them come from?

What do you all think?

Jack

Mine does exactly this, but coupled with a bit more smoke when planting the throttle and a little sluggishness. My LP pump is humming away intermittently too. Hoping to change that this afternoon.

Checking on PP2000, the only thing I noticed was the fuel pressure fluctuating a lot. My next port of call is the FPR, so will clean it up when I change the injectors to a set of refurbished 076 ones.

I'd like to sort this before I fit the FMIC.
2001 BMW 330Ci
2012 VW High Up
1988 205 GTi 1.6
1990 205 Mi16
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#4
Heard that the FPR can be a pain. Not sure why that would make the injectors rattle however. My car also has a habbit of the revs fluctuating at idle. There are a few things that can cause this by the looks of it :/
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#5
I seem to remember having a conversation where over-high rail pressure could accentuate injector rattle, it can certainly cause a fluctuating idle, so i'd be taking a look at that.
306 HDi Deathtrap - 130bhp / 220lbft
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#6
How would someone go about cleaning the fpr? Could lots of black smoke also be caused by that issue? I started and revved it today after cleaning up all the sensor cable joints and a cloud appeared behind the car haha. I'm pretty such I don't have a boost leak anywhere no either
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#7
I have a can of maf sensor cleaner which evaporates really quickly. Do you reckon that would do the job? Also would the seals need replacing or are they usually okay?
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#8
WD40 would clean it well enough.,.
Given the choice between Niall and the sheep. I would choose the sheep!
/Toseland
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#9
Wd40 won't do anything as its not a solvent, maf cleaner would be better but thinners/petrol etc would work much better once the o rings are removed
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#10
Think I just have mine a spray of wd40 and she was ite
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#11
Click the link in my sig, more info in there. I use carb cleaner these days.

What colour is the smoke amd how high did you rev it? Fairly normal for it to smoke a bit if you rev it hard in neutral, especially if it's mapped
306 HDi Deathtrap - 130bhp / 220lbft
...UPGRADING...



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#12
Hi all.This is my first post on this great forum.
I've had the same nasty intermittent injector rattle and after I striped and cleaned properly the main earthing points the problem disappeared completely.Now under acceleration the car sounds like a petrol car...really happy. It pulls much better as well.
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#13
Well now that's interesting. I wonder if perhaps a poor earth could inhibit the injector pulses, i'd be surprised as sparks plugs work on a much higher current and to my knowledge don't suffer as badly.
306 HDi Deathtrap - 130bhp / 220lbft
...UPGRADING...



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#14
See that's what I was thinking. If they are completely controlled by tiny electronic pulses having a bad earth could destroy the smaller pulses as the current wouldn't have enough umph to overcome the resistance. I have cleaned the ones I could find but they were only on the front under the air box and probably mostly for lights etc.

What other earth's are there? Also thanks for the info on the fpr as well Smile
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#15
Well they're not tiny pulses, it's an 80v firing pulse, hemce why i'd be surprised if earths are the issue. There are some on the inner chassis legs and wings and one on the front of the gearbox, clean up the battery negative terminal too.
306 HDi Deathtrap - 130bhp / 220lbft
...UPGRADING...



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#16
Will have a look. Need the ecu ground mostly as the injectors powered and earthed through the ecu.

Cheers Smile
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#17
Good point, had forgotten that. I *think* it loops back into the main loom earths, the wiring diagrams Cully supplied in the guide section should tell you what you need to know.
306 HDi Deathtrap - 130bhp / 220lbft
...UPGRADING...



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#18
The rattle is cause by pre injection.
I have been playing for some time with my 2.0 hdi 16v with costume injectors and they at start rattle bad.
So after playing with pre injection timing and pre injection quantity the rattle is quite better.
So the injector in fact don't produce the noise, the rattle is cause by the lack of precision from the injector to inject the correct amount of diesel at the precise timing, thus causing the nasty noise.
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#19
Has anyone ever got any genuine fix? Has anyone ever installed new injectors and it has actually totally fixed the really bad rattle?
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#20
I fixed my rattle with refurbished injectors, others claim some injectors from a 307 sorted theirs. When it comes down to it, from what i've seen reported online and in my own experience there doesn't seem to be a guaranteed solution or even consistent benefits from finding a solution.
306 HDi Deathtrap - 130bhp / 220lbft
...UPGRADING...



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#21
Nope doesn't seem to be. The consistent benefit though is that I completely dislike the injector rattle. Does my nut in haha. Would happily change to a different car just because of that annoying constant rattle haha. Tempted to get a dturbo tbf and have the more thump noise they have due to having pre injection chambers.
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#22
Does sound like yours has a particular problem, are you sure it's injectors and not a dying turbo? Oil from the inlet will cause early ignition knock.
306 HDi Deathtrap - 130bhp / 220lbft
...UPGRADING...



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#23
(16-07-2015, 04:49 PM)JTaylor2005 Wrote: Nope doesn't seem to be. The consistent benefit though is that I completely dislike the injector rattle. Does my nut in haha. Would happily change to a different car just because of that annoying constant rattle haha. Tempted to get a dturbo tbf and have the more thump noise they have due to having pre injection chambers.

307 injectors fixed mine, but they soon started to go again. Although you probably have something similarly bad to my brother, his is stupidly loud. Still runs fine and gets 45-50 MPG hooning round the lake district with canoes and shit on/in it.
Welding and fabrication projects undertaken, contact me for more information.

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#24
I was wondering about the turbo tbf but then I would suspect it would loose oil? It hasn't lost a lot at all over 6000 miles tbf and doesn't blow blur smoke at all. However the turbo could be showing it's self as a weakness which would explain the amount of black smoke (low boost or flow) and the small whine which a couple have people have said isn't an issue so I have ignored haha
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#25
Rattling injectors are just worn out injectors. Listen to a low mileage HDI engine and they don't make much noise at all.
HDI Tuning Ltd
www.hdi-tuning.co.uk
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#26
Mine is pretty low millage. It only has 70k on it. The injectors rattled anyway. I changed them to a much more modern set off a 307 hoping it would make it better but it has made it worse if anything. Surely in 6 years of development if it was the injectors causing this issue then Bosch would have managed to find a way of making them not sound like **** haha
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#27
Having done a lot of research I am wondering if anyone has ever looked into the effects of the engine temperature on diesel knock. Diesels work best when the cylinders are hot. This means that the diesel vaporises really easily and starts combustion easily. Having a colder cylinder means that the diesel doesn't vaporise as easily and forms lots of little blobs of diesel.

These blobs ignite in a much more fierce and uncontrolled way compared to how diesel should burn which is a smooth burn which spreads outwards evenly.

Looking at mine it rarely gets about 70ish *c. This would mean that the cylinder walls are a lot cooler than they should be so would cause these small blobs to exist. Also when engine temps are colder the injector moves earlier in the cycle. This basically is to compensate for how much longer it takes the diesel to ignite from these blobs rather than a fine mist and vapour.

It may not get rid of the physical injector rattle noise but may help with diesel knock if I am to make the engine run at the correct operating temperature of around 86c-90c which is what the gauge shows and also most thermostats are supposed to begin to open at 86c.

Another possibility is that the temperature sensors on these cars are rubbish. This would be the worse issue to have as if the temperatures are reading low the injection timing would move further forwards in the cycle even though the cylinders are reaching a good temperature. If this is the case then the explosion will occur quickly like it should but too far forwards in the cycle of the engine.

I am not really sure how much of a difference it would make in the real world but I am damn tempted to give it a go and see if I can make my HDI run at its correct temperature which I am convinced should still be higher than what it currently sits at now.
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#28
Well I know yours didn't have many miles on the clock but it didn't really look like a low mileage car to me... you never know when you buy a used car. Also when changing injectors, even if they came from a low mileage engine they may have been changed at some point, so it's hard to know.

If you want to test the running temperature theory, why not put a big piece of card in front of the radiator so that the engine gets nice and hot, then see if the rattling goes away? Would be an easy test.

My bets are that a good set of low mileage injectors would make it a lot quieter.

Pre injection is there to 'pre-warm' the chamber before the main combustion event, and it certainly does make it run a lot quieter than if you didn't have it.
HDI Tuning Ltd
www.hdi-tuning.co.uk
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#29
Going to have a look at the government website and see what the millage history of it is. If its crap its gone. I will get something else haha.
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#30
On my old 8v engine I put 076 injectors from a 307 but they were new and this solved the rattle
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