S50 vibrates power loss above 4.5K

[bmwstudent]

Rig up fuel pressure gauge and drive it. Note the gauge when you have the problem, and compare against spec. That will eliminate at least the fuel supply question.

[marek|steezkal]

So it sees positive changes when you replaced ignition stuff (plugs, wires). Maybe the new plugs aren't gapped quite right? Check to make sure they're all to spec.

[M3PO]

So it sees positive changes when you replaced ignition stuff (plugs, wires). Maybe the new plugs aren't gapped quite right? Check to make sure they're all to spec.

It ran the same on the old bosch coppers as it does on the NGK Paltinums other than the slight miss at idle is gone.

Putting in some used coils cured the EXTREME power loss I had above 4.5K but the issue I have now seems to be slowly getting worse. Possibly the used coils are crapping out.

[arams325]

Im having this same exact issue on my s50 and it just died on me today im hoping its fuel pump related ill let you know what fixes my issue

[M3PO]

Im having this same exact issue on my s50 and it just died on me today im hoping its fuel pump related ill let you know what fixes my issue

Yes, please do. I'm at the point where I just have to throw parts at it. Which I obviously don't want to do.

[E30FreaK89]

I'm haveing the same problem. I just put new coils with spark plugs and seemed to fix the misfire. Still have the power loss and my ecu seems to get really hot!

[Bmwdayz]

I'm having the same issue as well. When it's cold it has tons of power spins tires up to 3rd gear then when it's warm the power falls off after 4500. I've changed and checked the most important sensors. O2 and plugs look great, my mileage is around 27 on the freeway. Vanos is working as it should. I checked the coils and changed them for a spare set I had. It just has a slight miss once in a while and power falls off around 4500. I did notice I usually run 91 and I'm traveling for work an have been using 93 octane which helped the problem a lot! Only thing I can thing of is the Turner chip I have sucks haha. I also noticed I ordered the chip for a 413 and looked the numbers up and it happens to be for 506 ecu. So I swapped a 506 ecu and there was still no change.

What gives? haha

[Bmwdayz]

I did replace a dead low pressure pump in my tank. But I don't think my fuel pump has anything to do with it unless when it gets warm the pressure falls off.

[M3PO]

I was running on a 413 Red with OEM S50 software with just the immobilizer deleted. I swapped in an unmodified 413 Red and it was much better for a few days but now the problem has returned. I swapped back in the first DME and the problem is present.

So it seems DME related but I'm wondering if something is damaging the DME.

[M3PO]

Tried a 3rd DME (413 Red with M50 chip) without any positive results.

Drove a few blocks with the O2 unplugged. No change, no CEL.

Unplugged the MAF. It stumbled but recovered and ran the same. Bad MAF?

[GDA]

Tried a 3rd DME (413 Red with M50 chip) without any positive results.

Drove a few blocks with the O2 unplugged. No change, no CEL.

Unplugged the MAF. It stumbled but recovered and ran the same. Bad MAF?

I would have guessed coils, cam position sensor or MAF and in looking at your post you also noted...

-MAF plug was cut off my harness, soldered new one on

Have you checked to make sure this wiring is all good? MAF is pretty sensitive so I'd be looking closely at this situation if it were mine.

[M3PO]

I would have guessed coils, cam position sensor or MAF and in looking at your post you also noted...

-MAF plug was cut off my harness, soldered new one on

Have you checked to make sure this wiring is all good? MAF is pretty sensitive so I'd be looking closely at this situation if it were mine.

I fiddled with the solder connection today with it running and the idle didnt change.

Each wire is individually soldered and heat shrinked and then they are all heat shrinked together.

[M3PO]

Drove it with the TPS unplugged and it ran like shit with 1000 rpm idle.

I have convinced myself that it is the coils again. I did the Bentley test on them all and they passed. I did the same thing on my old set and they passed too. But it fell on it's face with the old coils. Visually, they have the same cracks.

I broke down and paid $300 for a new set of coils. Will update once they are installed.

[M3PO]

Brand new coils didn't do anything.

Banged on the crappy aftermarket cat I have and noticed rattling. Gonna cut that POS out and see if that's it.

[Bmwdayz]

So I noticed I was getting an intermittent vss. Sometimes it worked and other times it didn't. So I moved my speed sensor wire from the green plug in the back of the cluster to the yellow plug pin 26 before going into the cluster. I have since noticed I have a very free reving motor all the way to redline with way more power!