Dyno trouble shooting session of Z4M ESS VT - 525

[drbvac]

Originally Posted by gmd2003

You embarrassed some of the Porsches especially the Cayman with the wing - good on ya ! The GREEN M-3 must be a write off - scary considering what he probably paid for it in race trim - looked like a lot of fun - hard to tell top speed on the straights = ??

[GuidoK]

Originally Posted by Str8 RippiN

On a side note i was going three digit speed when it came on one time, which is scary when you loose power steering and brakes randomly. I quickly turned the car off and turned it back on, but this is a very serious issue with the kit none the less.

How can you loose power steering and brakes in limp mode?
Those are mechanical systems on a z4m. As long as your multibelt doesn't snap you have power steering afaik, and as long as your engine is running (at any speed), you have vacuum to use the brake booster. The remaining vacuum (in case your engine stops alltogheter) is held up by a one way valve, so there's always vacuum for 1 stop.

Loosing brakes all together is only possible if you have a leak in the lines or the mastercilinder breaks or something like that.

Just my 2ct.

[Rated M Roadster]

Originally Posted by GuidoK

How can you loose power steering and brakes in limp mode?
Those are mechanical systems on a z4m. As long as your multibelt doesn't snap you have power steering afaik, and as long as your engine is running (at any speed), you have vacuum to use the brake booster. The remaining vacuum (in case your engine stops alltogheter) is held up by a one way valve, so there's always vacuum for 1 stop.

Loosing brakes all together is only possible if you have a leak in the lines or the mastercilinder breaks or something like that.

Just my 2ct.

Um, limp mode shuts the engine off... You can be doing 150mph and it will still shut your engine off.

[gmd2003]

Originally Posted by drbvac

You embarrassed some of the Porsches especially the Cayman with the wing - good on ya ! The GREEN M-3 must be a write off - scary considering what he probably paid for it in race trim - looked like a lot of fun - hard to tell top speed on the straights = ??

Thanks. , the top speed on the straight is 147mph by gps .

[gmd2003]

Originally Posted by GuidoK

How can you loose power steering and brakes in limp mode?
Those are mechanical systems on a z4m. As long as your multibelt doesn't snap you have power steering afaik, and as long as your engine is running (at any speed), you have vacuum to use the brake booster. The remaining vacuum (in case your engine stops alltogheter) is held up by a one way valve, so there's always vacuum for 1 stop.

Loosing brakes all together is only possible if you have a leak in the lines or the mastercilinder breaks or something like that.

Just my 2ct.

The brakes and steering still work but the engine completely shuts down . In a high speed corner with the rear loaded losing power suddenly causes a shift in weight off the loaded rear wheels and ....... Spin time . Very dangerous .
George

[GuidoK]

Originally Posted by Rated M Roadster

Um, limp mode shuts the engine off... You can be doing 150mph and it will still shut your engine off.

I thought limp mode was a stationary rpm mode (1300rpm or so) or a max speed mode?
Otherwise there is no 'limp'

But still with shutdown: as long as you do not press the clutch you engine keeps spinning



That you loose traction is of course confusing (so in theory dangerous if you're not experieced or unable prepared), and it upsets the balance, but as long as you dont start to brake excessively, or regain drive(which you wont) you should be fine. Just a matter of keeping your head cool. I've dealt with this situation too (the m54 ts2 kit also can have the exact same quirks in certain situations as i found out.....)


But my point was that the describes flow of events was not possible imho (if i'm wrong: please explain), not that it would be potentionally dangerous or annoying. Describing the exact event is important to investigate possible solutions to the problem (that's the whole point isnt it?).
Also limp mode should generate a specific bmw eobd code which you can read with inpa.
It might be sensible to do that if possible.

[Gt4]

Originally Posted by GuidoK

I thought limp mode was a stationary rpm mode (1300rpm or so) or a max speed mode?
Otherwise there is no 'limp'

But still with shutdown: as long as you do not press the clutch you engine keeps spinning



That you loose traction is of course confusing (so in theory dangerous if you're not experieced or unable prepared), and it upsets the balance, but as long as you dont start to brake excessively, or regain drive(which you wont) you should be fine. Just a matter of keeping your head cool. I've dealt with this situation too (the m54 ts2 kit also can have the exact same quirks in certain situations as i found out.....)


But my point was that the describes flow of events was not possible imho (if i'm wrong: please explain), not that it would be potentionally dangerous or annoying. Describing the exact event is important to investigate possible solutions to the problem (that's the whole point isnt it?).
Also limp mode should generate a specific bmw eobd code which you can read with inpa.
It might be sensible to do that if possible.

Even if you press the clutch pedal it won't change anything, engine stay at 1300rpm.

And trust me, if that limp mode happen during a hot lap on the track with a driver that is able to push the car to the limit of the grip, it is dangerous!

[gmd2003]

Originally Posted by Gtfour

Even if you press the clutch pedal it won't change anything, engine stay at 1300rpm.

And trust me, if that limp mode happen during a hot lap on the track with a driver that is able to push the car to the limit of the grip, it is dangerous!

+1000 thank you !8
It happened to me at 100 mph in an off camber sweeper , in which I was using the throttle to balance the car . The rpm drops to 800 with massive engine braking and 0 throttle response . It's game over no matter how good a driver you are in that situation ,guidok don't tell me it's not possible . I have the 10 k repair bill to prove it .
George

[GuidoK]

Originally Posted by gmd2003

+1000 thank you !8
guidok don't tell me it's not possible . I have the 10 k repair bill to prove it .
George

Then tell me how it IS possible to loose both power steering AND brake booster in limp mode???

Because THATS what were talking about here.

A bill doesnt 'give' a technical explanation, so i'm not sure what your trying to say with that statement other than crashing a car.

[seank]

I do not see any where that GMD2003 (george), said that he lost power steering and braking. Just looses power completely.

[Beedub]

[ZStig]

don't see the point of arguing with each other here

[GuidoK]

Originally Posted by seank

I do not see any where that GMD2003 (george), said that he lost power steering and braking. Just looses power completely.

He said

guidok don't tell me it's not possible

I assume that he meant that 'it' referred to loss of braking and/or power steering, cause that was what I was saying. I don't know what 'it' could mean other than that, but please enlighten me.

That he can loose power in limp mode..... well... yeah..... that's what limp mode is all about isn't it? (I haven't said otherwise I think?) And that you can crash your car at the track......that happens too (all the time....). Be happy that you can live to tell I guess...

But it boggles my mind that no one else catched that limp mode couldn't result in loss of power steering or brake failure, and that something else must happen to be the cause of that (Not that that isn't possible: 2 unrelated problems at the same time!).
And it's strange that no one (apart from this minimal post) have read their car with INPA and posted some printscreens after such a major failure as more VT-XXX owners apparently have had the same problem (at least: you won't know that until you analize your DME if you catch my drift ). I mean: that's where problem soving starts.....(first thing I do is hook up the laptop....)
That the car goes into limp mode is not the problem, but the result of the problem. The problem lies in the DME deciding to go into limp mode, because he sees some parameters. Those parameters can mean the problem (that's probably hardware), or the interpretation of the DME can mean the problem (tuning).

[gmd2003]

Originally Posted by GuidoK

He said

I assume that he meant that 'it' referred to loss of braking and/or power steering, cause that was what I was saying. I don't know what 'it' could mean other than that, but please enlighten me.

That he can loose power in limp mode..... well... yeah..... that's what limp mode is all about isn't it? (I haven't said otherwise I think?) And that you can crash your car at the track......that happens too (all the time....). Be happy that you can live to tell I guess...

But it boggles my mind that no one else catched that limp mode couldn't result in loss of power steering or brake failure, and that something else must happen to be the cause of that (Not that that isn't possible: 2 unrelated problems at the same time!).
And it's strange that no one (apart from this minimal post) have read their car with INPA and posted some printscreens after such a major failure as more VT-XXX owners apparently have had the same problem (at least: you won't know that until you analize your DME if you catch my drift ). I mean: that's where problem soving starts.....(first thing I do is hook up the laptop....)
That the car goes into limp mode is not the problem, but the result of the problem. The problem lies in the DME deciding to go into limp mode, because he sees some parameters. Those parameters can mean the problem (that's probably hardware), or the interpretation of the DME can mean the problem (tuning).

I never said I lost power steering or braking at any point . Don't know why you thought that . You made it seem with your overall comments and post that this was a minor issue that could never cause one to lose control . That is what I was responding to. Of course I've had my car ECU scanned and have commented on this extensively in other posts . The only ECU fault that is present is in regards to the brake booster system .
Not sure who pissed in your cornflakes . I'm just trying to help out the Z4M community with my trouble shooting and extensive track experience .

[ZStig]

Can't an Iphone program called Rev, along with a OBD2 blutooth transmitter do datalogging? Or something similar. Would be nice to run this on the track

[gmd2003]

Originally Posted by ZStig

Can't an Iphone program called Rev, along with a OBD2 blutooth transmitter do datalogging? Or something similar. Would be nice to run this on the track

I do have a kiwi Bluetooth with the dashcommander app . It's great for logging temps , timing , IAT's etc . Nothing is abnormal when the safe mode occurs . It's tough to use on track bc it is constantly losing connection bc of the ancient slow OBD 2 speed of our ECU

[gmd2003]

Just had a great weekend back at Roebling with the Darkside PCA. I hit a new personal best lap of 1:20.5 , consistently beat a modded 997 GT3 RS on Hoosier R6's and hit 150mph by Aim solo GPS on the front straight also my personal best by 2mph. I just installed my DKF catless S pipe and it def made a difference up top. Per usual i had two episodes of the limp mode over the 8 sessions but I'm a pro at a quick restart while rolling now Hopefully ESS will have a fix for use soon other wise the car is running perfect now. I'll post some videos in the track section later. FYI the Hankook Ventus TD C30 (hard compound) is a great performance option for those who drive to the track like me , they are doing fantastic wear wise as well. Its looking like the fronts will last 6 days and the rears about the same. This will make it the fastest and most durable tire I have used thus far including extreme performance street tires as well as DOT R's. NT0-1 , Michelin sport cups, Re-11's,Michelin PSS, BFG rivals.
George

[ZStig]

Originally Posted by gmd2003

Just had a great weekend back at Roebling with the Darkside PCA. I hit a new personal best lap of 1:20.5 , consistently beat a modded 997 GT3 RS on Hoosier R6's and hit 150mph by Aim solo GPS on the front straight also my personal best by 2mph. I just installed my DKF catless S pipe and it def made a difference up top. Per usual i had two episodes of the limp mode over the 8 sessions but I'm a pro at a quick restart while rolling now Hopefully ESS will have a fix for use soon other wise the car is running perfect now. I'll post some videos in the track section later. FYI the Hankook Ventus TD C30 (hard compound) is a great performance option for those who drive to the track like me , they are doing fantastic wear wise as well. Its looking like the fronts will last 6 days and the rears about the same. This will make it the fastest and most durable tire I have used thus far including extreme performance street tires as well as DOT R's. NT0-1 , Michelin sport cups, Re-11's,Michelin PSS, BFG rivals.
George

Thats amazing. Beating a track setup gt3. Doesnt get any better than that! Makes me feel much better about the hassles of takong this car past 8psi

[gmd2003]

Oh it's def worth it ! Our cars are great platforms , I was even beating his apex speeds . Given his modded GT3RS mark 2 has at least 475 hp , better gearing ,weighs 200 pounds less than me, and can get in the gas much earlier coming out of turns( aero , rear engine and 335 R6's ) it's a testament to the performance of the kit that I was hitting 2mph faster speeds than him at the end of the straight despite starting in 5th gear to avoid limp mode . The GT3 RS driver is a friend and I was able to look at his Aim solo data so no conjecture . As expected he would pull early , then I would close rapidly at the end of the straight .

[gmd2003]

Here is the session with the 997.2 GT3 RS in the Black group .

[Beedub]

incredible that a tuned z4m can run with the big boi's like this.... even with the limp mode its kicking ass, cant wait to see what you can do without the limp problem!!

[gmd2003]

Here is my fastest session of the day with a 1:20.5 lap. Me and a 2400 pound E30 were tearing through the field . I slowed down to let him by at the end so i could get him on film. He was a great driver , and a little crazy lol.