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Shaking when accelerating above 60mph - 2001 BMW X5 3.0i Auto

Hello,

We have begun to experience an unsettling shaking when accelerating above 60 mph. Here are some details:

The shaking feels mostly from the front end, passengers in the rear can barely feel it if at all. The driver and front passenger can feel it easy. My interpretation of the shake appears to come from the front right, but I can’t be certain.
The shaking occurs when using the accelerator pedal, above 60mph. Meaning, the pedal needs to be pressed roughly 10% down in order for the shaking to start, anything less and there is no shaking. For instance, just cruising with my foot lightly on the pedal and maintaining the same speed results in no shaking. Likewise, slowing down using the brakes produces no shaking.
The shaking is not felt as much in the steering wheel as compared to the floor and seats where it is quite prominent.
When we first started experiencing the shaking, it was always typically on road trips at higher elevations. Road trips at lower elevations and we never experienced it. Until recently, it began to show itself at all elevations.
We can get the shaking to occur at speeds below 60mph, say 40mph but only if going uphill or if having been driving for an extended period of time. Cold start 40mph up hill results in no shaking. But highway driving 60mph + will for sure result in shaking, again only while accelerating not coasting or braking.

I have hooked up the BMW reader as well as a run of the mill OBD2 and found no codes.

Here are the repairs we have had conducted so far, since the onset of the shaking:
All wheels balanced and checked at tire shop
Front Flex Disc
Rear Flex Disc
Engine Mounts
Transmission (transfer case) Mount
Replace Front Differential Fluid
Replace Transmission Fluid

Other items that have been completed since the onset of shaking, but not due to the shaking (in case this helps narrow things down):
Oil and oil filter change
MAF sensor cleaned
Intake air filter changed
AC tensioner and belt, accessory tensioner and belt, idler pulley
Power steering fluid drain and refill
ICV cleaned
DISA cleaned and upgraded

Casual inspection of the front end shows nothing obvious. CV boots are intact with no rips or traces of grease leaking.

The last works completed on the car before the shaking begun were about a year prior to the onset of the shaking, we did fuel filter and spark plugs. But then we drove the car around 10 months with no issues until the shaking began.

In typical car talk fashion, I want to further confound things by throwing out there that we also have a very noticeable vibration at idle, in gear. Park and neutral have no vibration, but drive and reverse produce a pretty jaw rattling vibration at idle. When put into gear, the RPMs drop from around 700 to around 650 if that helps. AC seems not to affect it, but turning on high beams does (while low beams are already on, turning on the high beams while in gear makes the vibration increase). Although annoying, I can forgive this for an 20 year old car.

It’s the shaking at highway speeds that has me worried it will leave us stranded in the desert or in the snowy mountains somewhere.

Thank you!

I would say you might have two issues: the idle may be a idle air valve as the a/c being should raise idle by 75 to 125 rpm on your engine ( might be worth checking the compressor is cutting in if you haven’t already ) I’ve cleaned the idle valves sometimes with improvements and sometimes not.have you checked the front crank pulley is ok , try to pry it away with a bar, these were two piece joined by rubber and are a vibration damper.
The drive could be the front prop shaft uj at the transfer case end. Yours is also an early X5 so may have a basic transfer case or an atc unit, you can tell if the traction light on the cluster has just 4x4 or the rotating arrow.
Hope that helps

I’m going to leave the suggestions to the more experienced, but I must say this is the most thorough description of symptoms I have ever read. Excellent.

3 Likes

Great write-up but how many miles are on this car?

The vibration seems to be an engine condition considering how much stuff you’ve changed.

Has the engine had a compression test? Has a mechanic ridden in the car with his scanner trying to capture and engine problem in real time?

But I’ll throw out a Hail Mary here, too… have the brakes been serviced anytime in that one year interval? Have any of the brake calipers been replaced? Have the brake hoses ever been changed?

Thank you for the quick replies! Here are some follow-up answers.

I have indeed cleaned the idle air valve. When we changed out the belts and AC tensioner, accessory tensioner, and idler puller, I did check to see that the compressor was engaging with AC was on, and I think I have checked it again once since (we have a separate AC issue that I was going to ask about later on). I will go under soon and check the crank pulley. I’d hate for this to be the issue, but it might in fact explain both of my problems possibly… I don’t think the front shaft has a u-joint, but the back one does and I will have a look this weekend.

The car has around 120k miles. I have not had a compression test, nor done a scan while driving, but I will add those suggestions to my list. The vacuum lines were also replaced about 3 years ago. No brake service has been done recently, the fluid was flushed about 2.5 years ago (around time for another flush soon I suppose).

Thank you for the excellent suggestions and for giving me more insight into what I need to keep troubleshooting!

is there the possibility of an ignition miss / spark plug miss / coil misfire? High speed / under load could be some kind of an ignition issue. That would cause the engine to shake but only under those conditions. Are you / have you been getting ANY check engine trouble codes at all? (is the check engine light functioning? does it light up at self-test when ignition is switched to ‘on’ before starting the car?). Compression should be checked but I would think if compression is bad then this symptom would be present in the entire range of driving & acceleration. Last thing - make sure all the spark plugs are tight and all the way in. I’m not an expert but I mention these things as no one else has so far. good luck.

Another thought - you mention that this is an automatic transmission vehicle - is there the possibility of locking torque converter clutch malfunction or slippage? Acceleration under load should cause the locking T.C. clutch to disengage. If it doesn’t disengage that could force an ugly vibration under load. Again, I’m not an expert and am not sure how your transmssion is set up.