Engine vibration

Hi,

I have an early P38 DT which suffers from engine vibration/shake not too serious but annoying. This happens anywhere between 1200 and 1500rpm when the engine isn't working very hard, it feels like the engine is only running on half the cylinders. It idles fine and runs fine above 1500rpm and the vibration is less of noticable at 1200-1500rpm if hte engine is working hard. It doesn't matter which gear I'm in. I have heard of some diesel engine suffering from 'engine wobble' I wondered if this is what I'm experiencing or could it be insufficient fuel? Should I try putting some injector cleaner through it? I'm pretty sure its always done this (I've had the car about 3 years) but I'm sure it is worse now.

Any suggestions as to what to look for?

TIA,
mikeateves

Sounds like a dodgy sensor to me, could be MAF/intake air temp sensor/ camshaft position sensor etc etc best to get a diagnostic done have you got a multimeter??

I have some info on how to test the sensors but you would need an electrical tester.

Hi,

Thanks for the reply. Yes, I do have a multimeter.

Hackett said:

Sounds like a dodgy sensor to me, could be MAF/intake air temp sensor/ camshaft position sensor etc etc best to get a diagnostic done have you got a multimeter??

I have some info on how to test the sensors but you would need an electrical tester.

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Diesel engine??

Hi,

Yes.

mikeateves said:

Hi,

Yes.

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Sure a diesel has these sensors, 4 cylinder 200 or 300tdi? I am not aware of these on this engine.

Is it chucking out black smoke during missfire, if so good chance its the injectors, but no harm in adding fuel cleaner to see what happens.

Most engines have a damper on the engine usually built into the crankshaft pulley, sometimes this can cause engine vibration, but I get the feeling that it's a missfire, but you should know by a loss of power when it happens.

Hi,

What relevant sensors are there on the BMW 2.5 diesel engine? Can't say I've noticed any black smoke or noticable loss of power I just get a (low frequency) vibration. If I take my foot off the gas it goes away or if I accelerate it goes away (at least it becomes unnoticable). At the affected RPM range if the engine is working hard then it doesn't happen. Its only when the accelerated is pressed a small amount. Am I right in thinking these vehicles are fitted with a potentiometer on the accelerator? I wonder if this is worn and sending incorrect values to the engine management resulting in not enough fuel being sent to the engine.

mikeateves said:

Hi,

What relevant sensors are there on the BMW 2.5 diesel engine? Can't say I've noticed any black smoke or noticable loss of power I just get a (low frequency) vibration. If I take my foot off the gas it goes away or if I accelerate it goes away (at least it becomes unnoticable). At the affected RPM range if the engine is working hard then it doesn't happen. Its only when the accelerated is pressed a small amount. Am I right in thinking these vehicles are fitted with a potentiometer on the accelerator? I wonder if this is worn and sending incorrect values to the engine management resulting in not enough fuel being sent to the engine.

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Is it not a 95 model my disco is a 97 and has a throttle cable I thought that all the electronic ****e came in with the td5.

The only sensor that I am aware of is for the egr, and with mine connected or blanked I found no difference in power, so I would be tempted to say it has little say in what happens in your engine, part from sludgeing it up.

Sure your vibration is not an engine/gearbox mounting, does it do it when stationary, if so stick in fuel cleaner and see how you get on.

ive got an identical problem. Mainly noticeable in higher gears to me, when you press the accelerator a small amount get a shaking through the stick, bit like when you put a normal car in too high a gear going too slow. cant decide what it is. Thought i might get the timing checked.

I'm going to try some injector cleaner and see if it helps although I don't hold out much hope.

mikeateves

Providing there isn't anything truly wrong with your RR and your still not satisfied with the amount of vibration, one solution is a harmonic damper which is supposed to help reduce vibration through the drive train.

Looks a bit like this...well actually exactly like that!

mikeateves said:

I'm going to try some injector cleaner and see if it helps although I don't hold out much hope.

mikeateves

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Don't be negative, it does no harm and in actual fact is good for it.