Poorly Z4M, Idle bounce and poor throttle response/misfire

[pilchardthecat]

I put shell super unleaded in my car the other day, not really noticed the difference or does it take a few fills to notice the added benefit of the 20-30 bhp that someone meantioned somewhere on this forum :roll:
tht would be like adding a tuning chip to the car?
off topic slightly

It takes a few fill-ups. My understanding is that the other way it happens quickly (when you put 95 in after 98/99 it senses the knock and changes the timing quickly to prevent damage) but it's more conservative when changing the timing to take advantage of higher octane fuel

 

[BMWZ4MC]

I put shell super unleaded in my car the other day, not really noticed the difference or does it take a few fills to notice the added benefit of the 20-30 bhp that someone meantioned somewhere on this forum :roll:
tht would be like adding a tuning chip to the car?
off topic slightly

It takes a few fill-ups. My understanding is that the other way it happens quickly (when you put 95 in after 98/99 it senses the knock and changes the timing quickly to prevent damage) but it's more conservative when changing the timing to take advantage of higher octane fuel

I would agree with this given the way the car performs with different fuel types. Mine prefers Shell, and runs less well with high octane fuels from other companies such as BP or Tescos.

 

[RedUn]

Taken from the first post...

"From idle if you apply the throttle anything other than a gentle squeeze the engine misses and coughs before the revs zoom up (they zoom up as well as a healthy Z4M I recently compared it to). The stumble is very obvious in the exhaust note."

Is this normal? mine does the same?

 

[Andy]

Mine can be a bit spluttery when cold until you've been up the rev range to "clear it's throat" ..

I personally think 90% of this thread is based on fuel.. if you're having noticeable problems, I'd do a throttle reset and put at least 4 tanks of super through it to see if it improves

 

[Beedub]

Mine can be a bit spluttery when cold until you've been up the rev range to "clear it's throat" ..

I personally think 90% of this thread is based on fuel.. if you're having noticeable problems, I'd do a throttle reset and put at least 4 tanks of super through it to see if it improves

may well be right about the fuel thing, im not getting any such issues but run a true 105-110 octane fuel mix, vpower with sunoco 110 unleaded race fuel.... car is buttery smooth in all instances.

 

[RedUn]

I run it on V Power every tank although I've no idea what the previous owner was using so may take a few tanks to sort it out?

I've put one of them redex complete fuel cleaners through it and changed the plugs thats helped a bit.

I'll do a search for throttle reset and see if that makes a difference!

 

[RedUn]

Update - throttle reset did nothing!

Currently running some BG44K through it with a tank of v power, will report back with some findings!

 

[breezer]

Damnit Exdos, I found this (extremely) old thread while looking into potential airbox mods and read through 14 pages hoping for the big 1% reveal that never came!

You tease!

 

[Anonymous]

{"]Ok, looks like I'm joining the ranks of this problem.

Its most noticeable on tickover. If I floor the accelerator the first second it hesitates. Blipping the throttle gets the same hesitation. I do notice it when driving off, same sort of hestitation sometimes.

I've carried out the throttle reset and no difference.

I first noticed this problem directly after having some 'options' switched on at an Indy a few months back (auto door locking etc) However at this point it was only very slight.

It seems to have got worse just lately, possibly after fitting the GruppeM?

Edit: Just been doing a search on M3Cutters to see whether those guys have had it and if they have resolved it. Noticed this:

.....
There is nothing wrong with cleaning out the MAF aslong as you let it dry, I used the Halfords stuff too and It took ages to fully dry inside.

The only thing the MAF doesnt like is dirty fingers/oil coatings from induction kits.

Mine definitely got worse after I fitted the GruppeM. I probably got the MAF dirty, I wasn;t particular careful with it :roll: So first stop give that a clean I think.

Interesting one - mine also started doing this (dropping idle when clutch depressed) just after fitting my GruppeM...

Think I'm going to take it apart and have a look around tonight...

 

[dannytheduck1985]

Mods: Not sure if this is the best place to post this but since the S54 is only fitted to the M is seems the best place for other M owners to see it/help out Happy for it to be moved if its a problem.

Heya all,

Been having a bit of a rubbish time of late with my Z4M.

Symptoms are:

When dropping to idle the revs fall too low and bounces back up again. If the air conditioning is not running its worse and can sometimes stall if the computer doesnt catch it quick enough. This can be a pain in stop start driving or shuffling up to a roundabout No EML faults are thrown.

From idle if you apply the throttle anything other than a gentle squeeze the engine misses and coughs before the revs zoom up (they zoom up as well as a healthy Z4M I recently compared it to). The stumble is very obvious in the exhaust note.

If you hold moderate revs and flutter the throttle the engine seems to get confused and starts popping through the exhaust, overfuelling/missing? It doesnt seem to follow the throttle input.

Engine slow to start, needing 3-4 turns of the motor from cold.

Solutions/ideas:

So far the dealer has change the AFM - this has made the engine much less raspy and the fuel economy has improved 10-20%, whilst thats nice (although I miss the rasp!) its not touched the idle bounce or issues above. They seem convinced it was fixed and were glowing how it has restored my lost performance... its as flat as a fart compared to the other Z4M I went in yesterday

Google suggests all manner of sensors could be at fault:

Idle control valve
Throttle position sensor
Throttle potentiometer
Exhaust oxygen sensors
Inlet/Exhaust Cam angle sensors
Crank speed sensor
A vanos problem.
Coil packs - although a bit lethargic it will rev out smoothly to redline once this initial stumble is over which makes me think its not a coil pack fault.

Before I go back and express my frustration has anybody had a similar problem or solutions?

Any help is desperately appreciated

I had the same problem mate. Threw up all fault codes under the sun. Cut a long story short, problem was the alternator not charging battery properly. The ecu gets confused because the low power. If you test the alternator it will probably test fine but there's a data module that sends feed back to the ecu. This was knackered on mine.
Car runs mint now.

If you get stuck I'll put you onto an ex ralliart and cosworth auto spark who will find the problem