HELP - 3L Diesel Lumpy engine caused by Air Compressor Load

[rb0135]

Hi All,

I really need help/suggestions.

Please bare with me while I explain.

Ive been having an issue ever since my harmonic balancer died in February (maybe just a coincidence). The issue is a rough, lumpy engine, loss of power, vibration at any speed (not large but something like a misfire).

So, just reccently, after going through 2 different independant mechanics that have tested the injecters (they are perfectly in spec), compression (perfectly in spec on all cylinders), cleaned the EGR, checked for codes (nothing except Aux Fan failure), plus one mechinic (who installed the new harmonic balancer), having it for 2 days, drove it some 180KM to say there is nothing wrong with it and he cant feel any vibration (turns out he didnt have the air con on... see below), etc, etc, we find that the Air Conditioning compressor is getting rather noisier than previous and looks like it is about to die as if you turn the Air Con off, the car has its smooth 3L diesel power back with lots of torque, no vibration, etc.

So, this vibration, lumpy engine issues seem to be when the "old" air conditioning compressor is on... right... wrong..

After going to another mechanic, I have had the Air Conditioning compressor changed with a brand new one and I put in the new Aux fan (for the 2nd time in 6 years). This same mechanic is Car Airconditioning certified to do all the gasing as well.

Well, the new air conditioning compressor with new gas creates the exact same problem as the old compressor as well as being noiser than the one that was meant to be failing. I just cant believe it. If you switch the Air Con off and on, you can hear the engine go from a nice smooth idle to a rough, lumpy idle. If your travellling you will feel like a misfire vibration, turn the Air Con off, instantly, perfectly smooth. Turn it back on, lumpy, missing feel again.

In other words, it seems the compressor when the Air Con is turned on creates a huge load that the engine "cant" compensate for. It gets worse the more you travel (ie the more the car warms up).

I have also noticed the Aux Fan is always on (I know for a fact it would only come on when needed, even when the Air Con was on previously) and that the Air Con compressor is always on. Never cycles. It seeems that I am always getting cold air in the cabin, where previously it seemed to blow cold to cool, then only when needed to control the temperature.

I havent taken it back to the mechanic yet. I will be ringing them today as I have been doing some experiments to get more data.

3 Mechanics and not one of them seems to want to sort out the issue.

I am turning to you guys to ask for help. Maybe you have come across the exact issue. If you have a thought in your head, please respond as any thoughts are good thoughts. I have all the BMW software, so maybe you guys know in INPA or DIS whether there is a test procedure for the Air Con.

Could it be a sensor that is not showing up as a fault that is not telling the ECU to compensate for the load? Could it be over/under gased (I read somewhere I think if it is over gased, the compressor will never turn off). Could it be I need to reset the ECU paraemters for the Air Con now it has a new compressor?

Glad to supply any answers to questions you might have to help diagnose this.

Thanks for any replies,
Rob

[lezmtaylor]

A long shot, could it be the ''hedgehog'' ?
Plenty of posts re HH.

Lez

[rb0135]

[quote="lezmtaylor"]
A long shot, could it be the ''hedgehog'' ?
Plenty of posts re HH.

Lez
[/quote]

Hi Lez,

You know what.... that thought has crossed my mind. I thought I knew all about the "hedgehog" until just recently, when I read hidden in some forum that it does more than just the fan control. I found out it is part that controls most of the climate system.

The climate control fan is fine (meaning it doesn't stay on as reported when turned off) but you never know, it might be failing. I have 175000km's on the car, and it has lasted this long.

Thanks,
Rob

[X5-D-Sport]

The FSR - HedgeHog can fail... and still turn the fan ok, it can also fail by causing a parasitic drain & flatten the battery - and till turn the fan OK.

[rb0135]

Well, to report back, the Hedgehog is not causing the lumpy running when the air is on (tested with a new one).

When the air is on, I think it is putting enough load to show another problem.

Although I said it was perfectly smooth, after a lot more experimentation, I am now noticing it isnt (with the air off). There is a small amount of roughness, which gets worse over distance/time, and worse in peak hour traffic when not moving much (never experienced previous to Feb when the Harmonic Balancer went).

I cant believe no one has ever had a lumpy E53 diesel, more evident with more load. Surely someone has had this issue with their X5 E53 diesel.

[X5Sport]

Have you had the compressor checked? If it is causing excess engine load that would upset the idle.

[henrym3]

Have you looked in at the pulley area while a/c is off and then get someone to switch it on and watched for any sign of imbalance taking place.

[rb0135]

Thanks for the replies:

@X5Sport - Compressor is brand new. It has been checked and pressures are all good

@henrym3 - Yes, no change of balancing. I put a white mark on the Harmonic Balancer as an indicator

Now, what I noticed, RealOEM showed I should have had a pulley that the air compressor belt rode on. I did not have this in mine, but had a direct drive belt from the Harmonic Balancer to the Compressor. Now, the mechanic even thought the belt wasn't a stretch belt, so as it got warmer during use the belt would have got tighter (which as stated the warmer it gets the more vibration I get) I have found out a few on the forums have the same setup. Well, I went and added the pulley and the different belt that is recommended in Realoem. THis fixed the vibration by 30%, but still there.

I have taken the belt off and ran the engine for a bit without any load from the compressor.

This showed there is still a vibration issue from the engine, just that the extra load of the compressor accentuates the issue.

I'm leaning towards a faulty injector although they have supposedly been "checked".

I'll be running all the INPA injector tests over the weekend and hopefully that will pinpoint my issue.

Thanks,
Rob

[Smeeagain]

I had a similar issue with the aux fan permanently on. Turned out it was not the compressor but aircon sensor switch (separate to the compressor and relatively cheap part and quick installation as afar as I recall). Interestingly the sensor did not come up on the software when he scanned it to read for error codes but the guy said he was convicted through a process of elimination that it was the sensor. And it was.

Not saying that is your issue, but if the sensor is faulty and then results in the load changing,as X%Sport said, and that results in the misfire then one links to the other to the other.