DSC and reduced power

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Hairycheeks
Joined: Fri 20 Mar, 2015 17:06
Posts: 35

  Z3 roadster 3.0i

DSC and reduced power

Post by Hairycheeks » Thu 21 Jul, 2016 23:19

Hi guys, I can't get my car into my local garage until Monday so I'm looking for some advice here. I've just completed the NC500 in my z3 3.0, fantastic by the way, get in done! Anyway, I was taking a long corner downhill in the wet around 80mph when I hit a little pot hole, it wasn't a teeth grinding moment it was just a little one. My DSC light flickered then stayed on and my rev counter bounced to 0 then back up. I pulled over and the car sounded a little rougher. Left it half an hour because I thought maybe I had been pushing it too hard. Started it up and it took 5 or so seconds to start. At first I thought it was a fuel problem as I was driving away it felt like I was towing a caravan or the fuel was being restricted. After nursing it home it felt more like the DSC had kicked in permanently, I could still get up to speed but it took a while. Please don't tell me it's my DSC unit. Any advice or knowledge welcome

NZ00Z3
Joined: Thu 23 Jun, 2016 02:26
Posts: 68

  Z3 roadster 3.0i

Re: DSC and reduced power

Post by NZ00Z3 » Fri 22 Jul, 2016 04:53

You'll need to pull the codes to get any idea of what's wrong. We'll be guessing otherwise.

The M54B30 engine uses the main throttle as the throttle control for the DSC, so the DSC overrides your right foot.

The Idle control valve is used as the main throttle up until about 30 MPH (50 kmph) then the main throttle comes in.

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2128

  Z3 roadster 1.9

Re: DSC and reduced power

Post by Del » Fri 22 Jul, 2016 06:56

My guess view is that it is too much of a coincidence that this happened immediately after a spirited drive in the wet and hitting a pot hole. I suspect the traction control was triggered and the ECU “forced” the throttle to “rein in” its operation and thus cut the car’s power. If it’s not clearing itself after a few stop/start driving cycles I would suspect damage to a wheel or tyre (or tracking) that is still fooling the ECU into believing that one or more wheels are not rotating together at the same speed.

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Brian H
Joined: Tue 16 Dec, 2008 19:55
Posts: 2503

  Z3 roadster 3.0i

Re: DSC and reduced power

Post by Brian H » Fri 22 Jul, 2016 07:36

What is the status of your DSC lights now? Are they on or off? Did you notice one or both of your rear wheels getting warm/hot?

Hairycheeks
Joined: Fri 20 Mar, 2015 17:06
Posts: 35

  Z3 roadster 3.0i

Re: DSC and reduced power

Post by Hairycheeks » Fri 22 Jul, 2016 09:03

I checked all wheels after it and there was no heat. The DSC light has been on since and hasn't turned off. Car is very sluggish to start also. I know I won't know until I get it on the computer but I was hoping someone had faced similar problems. I have driven the car since hoping it would clear but to no avail

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Brian H
Joined: Tue 16 Dec, 2008 19:55
Posts: 2503

  Z3 roadster 3.0i

Re: DSC and reduced power

Post by Brian H » Fri 22 Jul, 2016 09:16

With the DSC light on it could be something as simple as a sensor, the car thinks it is permanently in a state of flux and that is why it is sluggish, give me a shout if you want me to hook up my PC to see if we can see anything.

Hairycheeks
Joined: Fri 20 Mar, 2015 17:06
Posts: 35

  Z3 roadster 3.0i

Re: DSC and reduced power

Post by Hairycheeks » Fri 22 Jul, 2016 09:26

That is what I am hoping Brian, that I have maybe just upset a sensor rather than something a lot more expensive. That would be grand if you had any free days anytime soon

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Brian H
Joined: Tue 16 Dec, 2008 19:55
Posts: 2503

  Z3 roadster 3.0i

Re: DSC and reduced power

Post by Brian H » Sat 23 Jul, 2016 08:30

I am around this weekend, drop me a PM and we can see if we can sort something out.

Hairycheeks
Joined: Fri 20 Mar, 2015 17:06
Posts: 35

  Z3 roadster 3.0i

Re: DSC and reduced power

Post by Hairycheeks » Sat 23 Jul, 2016 20:07

Thanks for the offer Brian, managed to get it into an auto electrician today around the corner from me. His computer said it was the crank shaft sensor but surely the engine management light should have been on? He said he was surprised the car was still going. He managed to clear the code and the car went back to normal. I want to know why it happened and why it was so easy to sort without replacing the sensor. He told me to keep and eye on it and if it happens again he'll replace it.

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Robert T
Site Admin
Joined: Mon 12 Jun, 2006 11:35
Posts: 10049

  Z3 roadster 1.9
Location: Cheshire

Re: DSC and reduced power

Post by Robert T » Sun 24 Jul, 2016 12:00

Clearing the code will not have fixed the problem. If the car went into limp mode, then it may allow it to return to normal for a while. These sensors tend to go intermittent rather than failing outright, so I suspect the problem will return. I had a camshaft sensor go on mine and it wouldn't run for more than about 10 seconds. AA man came out, fiddled with the HT leads and it went back to normal. Got diagnosed next day and it reported camshaft sensor, so it was replaced and has been fine since, as I had no desire to repeat breaking down on a busy dual-carriageway.

Cheers R.

Sent from my SM-T810 using Tapatalk
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
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Hairycheeks
Joined: Fri 20 Mar, 2015 17:06
Posts: 35

  Z3 roadster 3.0i

Re: DSC and reduced power

Post by Hairycheeks » Sun 24 Jul, 2016 14:41

Thank you for the feedback Robert I appreciate it. I love quite rural so no dual carriageways thankfully but I fully expect it to come back on. I'll give it a month to come back on, if not I'll replace it anyway. Cheers

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