New Owner - Problems already

W

webrits

Member
Hi all,

I'm the proud new owner of a Z4 Coupe ! Only been 2 weeks but I'm drawing on the expertise of the forum...

I'm getting intermittent hesitation / misfire problems. It's only started this week and only since I've filled up with Tesco petrol (could that be the cause?)

When cold I get bad hesitation through the whole rev range when accelerating.
After 10 mins of driving if I turn off the ignition and start the car again it's fine.
Idle seems fine.
No warning lights etc.

I've read of problems with coils etc but haven't found a post describing how restarting the car cures it.
Anyone have these symptoms?
MAF ? Coils? Fuel?

I've ordered an OBD cable but will this show anything when I'm getting no warning lights?

Thanks all,

Paul
 
What octane fuel did you use? i always use Shell Vpower, not sure but dont think it likes bog standard unleaded .
 
We have the same engine and mine lives on the cheap stuff and performs excellently. It might be that it has been doing short journeys and just needs a nice long hoon, if that fails get it checked out.

Did you get an warranty with the purchase?
 
I didn't but is low miles - 38,000 and has full BMW SH and was serviced only 1000 ago by Cotswold so wasn't concerned.

I've given it plenty of 'hooning' so we'll see how it goes....
 
I think the slightly hesitant acceleration when its cold is normal. Hesitant once warmed up isn't. Could be bad fuel but just to pre-warn you mine started getting very hesitant a few weeks back during acceleration - I thought it was bad fuel but the car then broke down on me and it turned out to be a fuel injector which needed replacing.

First step would be try high octane fuel - however Tesco 99 is pretty strong stuff and has been found to be better than VPower in tests, or you could try running some fuel system cleaner through the car such as Slick50 fuel system cleaner, that would clean the injectors etc and hopefully remove any crud.
 
Tbh there is very little if any difference between the price of 'branded' petrol i.e shell and the variable shite that the supermarkets buy in.
I've had problems in the past with supermarket stuff in my cars and now I won't go near it as their attitude is ' prove it' which of course you can't.
Supermarket 'weedkiller' tends to miss out on all the wonderful additives that keep your engine/cat clean in an effort to keep the price down.
I used to know a guy in the refinng business years ago and he told me a few horror stories.... :evil:
 
Thanks for all the replies guys, here's an update.

Took it to my local independent and he plugged it in and the only code coming up was "2E69 Knock Sensor Error" it's not throwing up a warning light on the dash though. He also suspected crap fuel as the 1st port of call. So he put in some Forte fuel treatment and I topped it up for a second time with 1/2 tank of 99 Octane.
Still getting some problems on Friday so filled up with Shell V-power. Drove 225 miles (Cardiff - Manchester) on Friday and it was faultless, all day Saturday covered another 50 miles though some fantastic roads, again no issues at all.
Filled up today for the trip back with BP (I think) premium grade and has been hesitant and 'missing' all the way home.

So there we have it ! I'm no closer to knowing the cause of it. I can't imagine that the car loves V-power and nothing else. Injectors must be OK as it's intermittent.
Maybe Coil packs or MAF sensor? Surely if these were the problem there would be some other error codes showing up?

:x

Cheers
 
my recently departed 645 ran like a epileptic goat when my battery was goosed :? that turned out to be knackd alternator not doing its job ?
new battery & alternator / £500 & all was well in the world .
 
i have had my car 3 years now and 99% of the time i use tesco's bog standard petrol, never had an issue with it
 
No issues with any petrol I've used...

V power
Tesco momentum
BP ultimate

All good here :)


Sent from my iPhone using Tapatalk
 
I guess we can't blame it on fuel, too bad. Intermittent problems can be very hard to diagnose. As you have seen, the car records errors without turning on the SES lamp. The lamp goes on when when the system gets consistent errors. The anti-knock sensor could cause the problems you experience. When it thinks there's knocking, the DME first retards timing. If that doesn't work, it'll shut down specific cylinders to protect the engine.

Or it can be a symptom and not the cause. So it could be fuel or spark, or anything related that cause those things to happen. You may have to resort to swapping parts for lack of more definitive info. Difficult way to go with intermittent problems. Before you resort to that, do ensure your battery is strong and healthy. Search for more symptoms, such as air leaks, clogged filters, etc. Then try things that might be good to do in any case, like new plugs, cleaning the injectors, etc. Good luck!

(btw, I wouldn't rule out injectors because it's intermittent, there could be an occasional short in the solenoid, or the needle valve could occasionally stick, as examples)
 
lower intake boot could be cracked, doesnt that go to the idler valve? cheap to fix if it is. I used to have an issue where the car would run like it was missing every once in a while, when it was at operating temp. Found the lower intake boot had deteriorated in the folds. spent the 30 dollars and replaced it in 15 min and it has never happened since. Worth a look.
 
Thought I'd post an update to my problem.

Took the car to my local indi bmw specialist yesterday, the car was still showing the same error code and after testing the sensors (not sure how) they decided 1 of the pair was faulty.
They're both on the same loom so they replaced both (£54 for parts) and cleared the code.
Got the car back today and so far so good. Given her a good blast and the hesitation has gone for now but.... It does seem slightly sluggish, almost a bit less power than it had prior.
Is this due to the Ecu learning the new sensors.??

Thanks
 
Seems a bit under-powered either way. Obviously feels better in Sport mode but still not quite as 'peppy' as before during it's good periods.
 
I understand you replaced both knock sensors? Don't think there's any specific learning for those. Could be there's residual bad learning in general persisting from the misfire condition. Not sure how to initiate a fresh learning, disconnect the battery or ECU fuse for a while? There's also a throttle learning reset that might help a bit.

Another thought is the misfires caused by a build up of carbon on the plugs and/or valves. Maybe an Italian tune-up is in order. :wink: Try using premium brand fuel for a while, which has better cleaning additives. If all else fails, maybe arbitrarily change the plugs for good measure?
 
Tried the throttle reset and it seems much better.. Still not completely convinced its as it should be.
Time will tell..

Thanks all..
 
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