M52 6cylinder Throttle Response

[IanA]

Hi- I now own two of these and have found that when releasing the throttle pedal, the engine speed does not decrease as quickly as I'd expect.
Is this:
1. a characteristic of these engines
2. a sticking throttle cable
3. something else
Many thanks
Ian

 

[motco]

Is it fly-by-wire? My M54 is and it does exactly as you describe. It makes manoeuvring a real pain. Somewhere there is a procedure for resetting the throttle response on FBW cars, that might help. I seem to remember key in position II for ten seconds, key OFF ten seconds, start the engine and that should be it. Other procedures may be available!

 

[Steve Medlock]

I've always found the same thing and it sort of slows down your gear changes. Advice was to change out the throttle cable which is a fairly easy job but my old cable was in good condition so i didn't notice any difference.

 

[Rudyrov]

No Doubt it's the "smog containment system" doing its thing to reduce acid reflux!
Seriously, I have noticed the run on between shifts and I did find a solution or at least something that helped.
There is a wire on the clutch pedal switch that triggers the starter to work and triggers the speed control to disconnect, when that wire is not connected at the clutch switch the run on is noticeably less. The car starts without the need to depress the clutch and the cruise control stops working altogether.
So, I reconnected it because I want to use the cruise control, if somebody can figure out what to do so it doesn't affect the cruise control I will disconnect it again.
Any wiring gurus out there?

 

[Steve Medlock]

Ok, although mine never had the smog stuff and no switch on the clutch pedal either.

 

[Rudyrov]

Well, so much for my circumstances !!

 

[BillyB]

Agree @Steve Medlock. Mine's the same and I changed the throttle cable thinking that it was a problem but no difference and the throttle linkage is all spotless and lubricated also my local BMW indy guys don't find it a problem it seems to be the design.

 

[Rudyrov]

Agree @Steve Medlock. Mine's the same and I changed the throttle cable thinking that it was a problem but no difference and the throttle linkage is all spotless and lubricated also my local BMW indy guys don't find it a problem it seems to be the design.

I'm quite sure its part of the smog equipment, probably slows the decrease in exhaust gas heat to the catalytic converter si it can fully burn what's going to it as the throttle drops. (that's all a guess but makes sense to me)

 

[IanA]

Thanks for the comments- has anyone on here fitted a lighter flywheel?

 

[Dino D]

Are you guys talking about fly by wire models?
Ie M52B28TU and M54?

I’ve experienced this on the 3.0 engines and varied from car to car (e46), also on 2.2 Z3. When I did an lpg conversion we mapped the lpg ECU to minimise it.

My early 2.8 is cable throttle and has none of that lag, just gets a stiff throttle every few years and wants a new cable.

It did start doing it after I did a remap and open induction kit- a little restriction in the elbow going between the main intake pipe (after MAF) and down to what I think is the ICV sorted it.
The remap place said they see it on cars with open filters and a remap but some Googling brought up this solution , I think I first saw it on bimmer forums.
It’s a 10mm socket slight drilled out - trial and error until you find the size opening that gets rid of it (too small and it won’t idle).

 

[Dino D]

Thanks for the comments- has anyone on here fitted a lighter flywheel?

I don’t believe that will solve the issue, it seems to throttle map related.

@Lee has a lighter flywheel and can tell you if it made a difference on his.

I’ve been looking at lighter flywheel options and the consensus is not to go too light on these cars.

kits vary from £600- over 1k for DKM, Competition Clutch etc.

spoke to these guys today

BMW Single Mass Clutch Kit & Flywheel - RTS

Engine Code: M54B25, M52B28, M54B30, M54B22, M52B20, M52B25 BMW 530i E39 BMW 528i , IL E38 BMW Z3 2.8 E36 BMW Z3 3.0 E36 BMW 320i E46 BMW 323i E46 BMW 323ti E36 BMW 325ti E36 BMW 520i E39 BMW 523i E39 BMW 525i E39 BMW Z3 2.0 E36 BMW Z3 2.2 E36 RTS … Continue reading "BMW Single Mass Clutch...

www.rtsperformance.co.uk

And they do a SMF but balance it up the same weight as the standard DMF so 14kg. They have 4 larger springs on the clutch to help protect the gearbox and diff.
They feel that the BMW 6 and some VW engines don’t do well with very light flywheels (unlike some Honda engines which cope very well).
As it’s only £340 and made in UK Ive ordered one and @Lee will let me know if it’s rubbish or not once he plays with it!

Have you done the remap, M50 inlet, throttle body enlargement and induction kit yet? I kicked myself for waiting so long. Should have done it agars ago.
Just the generic remap on its own made a huge difference before that lot - nice and responsive.

 

[IanA]

Have you done the remap, M50 inlet, throttle body enlargement and induction kit yet?

Can that inlet be fitted to the double VANOS motor?

 

[IanA]

I've just removed the inlet hoses and got direct access to the throttle body and its butterfly. The return spring feels really strong and able to "snap off" when the throttle is released. So it's not a sticky cable...

 

[Steve Medlock]

I've just removed the inlet hoses and got direct access to the throttle body and its butterfly. The return spring feels really strong and able to "snap off" when the throttle is released. So it's not a sticky cable...

Ian, Do you have standard air filter boxes or cone filters? Just picking up on what Dino said.

 

[IanA]

All standard fitment, air filter box etc. I'd got used to it with my 2.8 but the 2.0 I've got recently does it as well.

 

[Lee]

Can that inlet be fitted to the double VANOS motor?

To answer your question yes you use the M54B30 manifold.

To answer your original post these engines do have a slight characteristic of being a bit sluggish with the throttle response, although it shouldn’t too noticeable. To sharpen the engine up best place to start is make sure you’ve got no vacuum leaks, working Maf, and clean ICV etc.

There’s one thing me and Dino have done which he’s not shared. If you after more of a motorbike rev’ing feel to this engine you’ll need to fit a restrictor in the idle control valve line, this will allow the revs to drop quickly when blipping the throttle.

 

[Steve Medlock]

Ok, I was shortly going to go back to the standard air box to see if that made a difference but sounds unlikely. I favour Dino's suggestion that its probably the Idle Control Valve being slow to return.

 

[Steve Medlock]

To answer your question yes you use the M54B30 manifold.

To answer your original post these engines do have a slight characteristic of being a bit sluggish with the throttle response, although it shouldn’t too noticeable. To sharpen the engine up best place to start is make sure you’ve got no vacuum leaks, working Maf, and clean ICV etc.

There’s one thing me and Dino have done which he’s not shared. If you after more of a motorbike rev’ing feel to this engine you’ll need to fit a restrictor in the idle control valve line, this will allow the revs to drop quickly when blipping the throttle.

That sounds promising Lee - what sort of size restriction did you end up with?

 

[Dino D]

To answer your question yes you use the M54B30 manifold.

To answer your original post these engines do have a slight characteristic of being a bit sluggish with the throttle response, although it shouldn’t too noticeable. To sharpen the engine up best place to start is make sure you’ve got no vacuum leaks, working Maf, and clean ICV etc.

There’s one thing me and Dino have done which he’s not shared. If you after more of a motorbike rev’ing feel to this engine you’ll need to fit a restrictor in the idle control valve line, this will allow the revs to drop quickly when blipping the throttle.

Ah yes that!

I only had to do that after the remap though - the remap chap said it’s more common with open filters but I never had the issue until the remap (and have had the open filter before that).

the ‘restrictor’ is 11mm socket slightly drilled out dropped into the pipe just at the elbow.

it was trial and error for me with regards to drilling out the socket- it wouldn’t idle with the socket as is so slowly drilled it out until it did. Too big and it won’t restrict enough so you just take out a little at a time until you find the sweet spot.

 

[Dino D]

Just dig out the pics.
It was actually an 11mm.
Goes into the hard plastic elbow piece which sits in the area circled in the pic (the white tape around the pipe was to cure a small split!)