SOLVED!: E53 X5 3.0 sounds like dying banshee on fire when I take my foot of the gas

[IkirisTheX5]

Originally Posted by andrewwynn

The problem is sensors soft fail long before they up and die so the real diagnoses is "does the car stall when you give 10-20% throttle and let off".

Most often you will only get random misfire codes nothing related to CPS before you will have a failure worth replacing CPS.

Helpful when you have multiples you can swap sides or another car you can swap the sensor from.

I hear you guys... I'm inclined to just swap it out since the cost and effort to do so appear to rank near a one or two out of ten on the this-X5-is-making-me-lose-my-mind scale...

Just to confirm, we are talking specifically about the intake cam sensor (see image attached from FCP Euro), or should both, including the exhaust side, be of concern? Just in terms of available parts online, it doesn't look like the exhaust cam sensor needs replacing all too often.

Regarding the test in the Auto Repair Guys video (that dude is great btw, I've learned so much from him about BMWs), are you saying that test may not necessarily be conclusive for me if the sensor is only soft failing vs total breakdown failure? He mentions that when connected to the signal wire (5V wire) and you wave a metal object in front of the sensor the voltage reading on your multimeter should drop to zero, "it's an on off switch". If the sensor was failing and not failed, would it shoot out a reading perhaps of less than 5V but greater than 0? Or do you mean for a soft failing sensor you couldn't replicate the precise conditions under which it fails in order for that test to be accurate?

In terms of codes being thrown, since the CCV, DISA, and other stuff got replaced the only codes registering on my silly $25 reader are P0171 and P0174 - "System Too Lean Bank 1" and "...Bank 2" - and they only pop up every other day or so after driving for an hour +, and most often at idle is when I notice the CEL flares up... Seems like you're saying those are not necessarily indicative of a failing CPS however, right? (If not, but you have any ideas on why banks 1 and 2 are running lean I'd greatly appreciate that intel as well!)

As always, thank you guys for your time!

[andrewwynn]

Tip on m54 and intake CPS; screw routing under the intake. This was my first BMW repair and it must have taken an hour to follow the factory path.

The second time I did this repair I went over the top of the intake and it took 30 seconds. Literally 120x as fast.

Lean codes usually a crack in the small part of the intake boot or at the o-ring on the DISA valve.

Venting some butane/map gas around the intake while monitoring rich/lean via O2 sensor or short term fuel trim (also sometimes from rpm) is second best to using smoke to find intake air leak.

Soft failing CPS will still send a square wave (on/off) just that the timing won't match the timing of the cam. It will sometimes be a little early or little late.

Notice in the video how the CPS flips as he moves the metal near the CPS. When worn out that distance won't be the same as new and throws off the timing.

The timing is critical to the millisecond level and when the cam is suddenly where it can't logically be you'll get timing errors that will give you misfire.

The intake CPS is the usual culprit and almost always the first to fail.

On my wife's '01 e53, and my '01 e53, the intake CPS soft failed about 128-130,000 miles.

On wife's the exhaust CPS failed about 170-180,000 I forgot exactly when and on mine it hasn't failed yet at 201,000 miles.

Idle is when vacuum is highest and so when most likely for intake leak to be this most problematic.

Start with checking for cracks in the small hose of the intake boot. That failed on both our M54 motors before 150,000 miles and was the cause of the same lean codes you are seeing.

I've additional gotten the same codes after repairing DISA. The seal wasn't tight. Repaired with Teflon tape. (special kind that changes color under pressure so I could tell when I had enough)

[bcredliner]

Whenever I have any symptoms that might be a vacuum leak that is not quickly visually obvious I do a smoke test. I think it is a must have tool for a DIYer. There are several Youtube videos on making a smoke tester. I used a variation of this one. https://www.youtube.com/watch?v=Np_duzsaZxI&t=10s Big box stores have new paint cans, the propane regulator, the air nozzle, the right wire and grommets. I used a drill bit to drill holes rather than risk drilling too big a hole. I tested for resistance before winding the wire around the wick. You can use the jump connections under the hood for power. After using it a couple of times I changed the clamps to clamps that are bigger and much stronger, about half the size of jumper cable clamps, as cheap clamps were failing. I changed to longer wire and tubing so I could set the can on the garage floor since it was always in the way or sliding around and I didn't like it in the engine bay. I use baby oil instead of mineral oil.


Note that it is important not to use much air pressure. It should inflate the rubber glove but it should be soft to the touch.

[andrewwynn]

My latest acquisition is a high end smoker. I work on enough cars "it's time".

My car has been running slightly lean for months not usually enough to set a code but sometimes.

Then bonus started setting a code for leak in the evap/ tank.

[IkirisTheX5]

Good stuff, guys

I ordered the CPS and it should be here mid-next week. Will keep you updated on whether it fixes the acceleration hesitation.

I was just looking at smoke testers online. I don’t know if I trust myself to build one from scratch lol, but I’m willing to give it a shot if the ones I’m seeing in the $70-$100 range are crap and the only reliable options are $200+ ones. You guys know anything about the $75 models on eBay/Amazon? Andrew, how do you like the model you got?

[andrewwynn]

I haven't fired it up yet but I was not loving the feedback on the $150 models so I went up to the next tier. I will report on its function as soon as I fire it up.

[Fifty150hs]

Originally Posted by IkirisTheX5

Good stuff, guys

I ordered the CPS and it should be here mid-next week. Will keep you updated on whether it fixes the acceleration hesitation.

I was just looking at smoke testers online. I don’t know if I trust myself to build one from scratch lol, but I’m willing to give it a shot if the ones I’m seeing in the $70-$100 range are crap and the only reliable options are $200+ ones. You guys know anything about the $75 models on eBay/Amazon? Andrew, how do you like the model you got?

I bought one off Amazon or Ebay, I don't remember which, but it was inexpensive and it works fine. There's really not much to them. If I'd had time I probably would have built one myself. Helped my find a crack that wasn't obvious in my intake boot.

[IkirisTheX5]

Originally Posted by andrewwynn

Tip on m54 and intake CPS; screw routing under the intake. This was my first BMW repair and it must have taken an hour to follow the factory path.

The second time I did this repair I went over the top of the intake and it took 30 seconds. Literally 120x as fast.

Lean codes usually a crack in the small part of the intake boot or at the o-ring on the DISA valve.

Venting some butane/map gas around the intake while monitoring rich/lean via O2 sensor or short term fuel trim (also sometimes from rpm) is second best to using smoke to find intake air leak.

Soft failing CPS will still send a square wave (on/off) just that the timing won't match the timing of the cam. It will sometimes be a little early or little late.

Notice in the video how the CPS flips as he moves the metal near the CPS. When worn out that distance won't be the same as new and throws off the timing.

The timing is critical to the millisecond level and when the cam is suddenly where it can't logically be you'll get timing errors that will give you misfire.

The intake CPS is the usual culprit and almost always the first to fail.

On my wife's '01 e53, and my '01 e53, the intake CPS soft failed about 128-130,000 miles.

On wife's the exhaust CPS failed about 170-180,000 I forgot exactly when and on mine it hasn't failed yet at 201,000 miles.

Idle is when vacuum is highest and so when most likely for intake leak to be this most problematic.

Start with checking for cracks in the small hose of the intake boot. That failed on both our M54 motors before 150,000 miles and was the cause of the same lean codes you are seeing.

I've additional gotten the same codes after repairing DISA. The seal wasn't tight. Repaired with Teflon tape. (special kind that changes color under pressure so I could tell when I had enough)

Done! Just took it for a quick test drive and absolutely zero hesitation at acceleration. Love it! Thank you guys so much for your insight. And, yes, absolutely the way to go is running the lead up over the intake as opposed to following the factory path. Makes it 100x easier. Thank you thank you thank you!

[Overboost]

Good call Andrew!

[andrewwynn]

Originally Posted by IkirisTheX5

Done! Just took it for a quick test drive and absolutely zero hesitation at acceleration. Love it! Thank you guys so much for your insight. And, yes, absolutely the way to go is running the lead up over the intake as opposed to following the factory path. Makes it 100x easier. Thank you thank you thank you!

Six minutes vs. 90 = 90/6=15x but definitely feels like 100! It was the first fix I did on my m54 and when I did my wife's I picked the up and over route! So glad my trick helped!


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