Slightly Rough Idle & Hesitation on Acceleration

[ryz4]

Hi all,

I recently bought a Z4 N46 e85 and have some slight issues with the car's idle and pick-up.

There's a brief pause from the engine when I accelerate in any gear, but is most present in 2nd & 3rd.
The car also idles quite poorly as it hunts for the desired speed.

Reading through the masses of posts on here I'd expect it to be the VVT system and the ESS. However, I've confirmed the VVT motor works fine and the Sensor also seems to be somewhat operative - doing runs in the car with the sensor unplugged makes a difference to the idle being more lumpy and even worse pick-up.

Further to that, I also set the VVT end limit positions and can hear the motor moving, so I'm happy that works and also set the minimum lift to 0.3mm.

I pulled the sensor and there is oil inside around the contacts, so I plan to get some contact cleaner and at least clean that for the time being.
But I know I will eventually/already need a new sensor.

Reading other posts I could start pointing fingers at most systems in the engine bay... where should I start with the testing/repair?
I've read others with similar issues replaced the throttle body and it fixed their issue, similarly replacing/cleaning the MAF sensor fixed the issue.

There are no codes for the sensor failing or EML coming on so I'm somewhat hopeful the sensor is okay at the moment.

Does anyone have suggestions on where I should start? I'd like to try anything free before I commit to spending some money on parts.

Thanks!

 

[tug]

Sounds like it just needs a good thrashing mate, kind of tired sounding if you will. Get the revs up to at least 4 after warmed up for a few weeks, in my experience the N46 likes to be lively. Also only use E10 95 mainly shell or BP. Could be the previous owner just used nasty supermarket sh!te. I found out the N46 does not run well on super plus/ momentum. Once cycled a few times in high revs the VVT will adapt to that and settle down to give a smoother ride.

Cheers, tug

 

[ryz4]

Thanks for the reply!

I don't believe the last owner ran it too much so this might be the case, im just scared of it firing back a EML and suddenly get worse!
I actually put about half a tank of V power in it to help flush it through, I'll stick with 95 and wont complain about it being a bit cheaper as well

Any ideas on the throttle response? I think I'll clean the solenoids and swap them over as well as cleaning the MAF + inspect the throttle body to see if that's opening freely...

Then probably save up for a new ESS. Have you had any luck with non-BMW ones?

Thanks, ryz

 

[tug]

Throttle body's are pretty cheap for these cars, i had to change mine some time ago and my new to me one came off an E92. Cant quite remember why i had to change it though.

When you mention ESS do you mean supercharger?

 

[ryz4]

Ah sorry no, I'm abbreviating Eccentric Shaft Sensor.

I wish it was a supercharger.

 

[tug]

Aaah! :lol: Was gonna say dont think a supercharger would work on a 2.0. Diff/Brakes etc. The throttle body would be a good shout though, after posting i remember now why i changed it. Poor performance, hesitation EML codes. The flap had, had it completely. After fitting (really easy) it went back to running perfectly again.

By the way i have owned mine for over 10 years and has always been my daily so if i can help from experience i will gladly.

 

[tug]

Oh, just another thing you could try before anything else, a throttle reset. Turn The key to 1 no engine, count to 15 ie 1 1000 2 1000 up to 15 turn ignition off then count to 15 again then immediately start the engine.

 

[ryz4]

That's brilliant to hear, thank you very much.

I'll try the "free" stuff first and see if there's any joy, as well as running the motor a bit more (might be worth noting its a 2005 and rolled over 103k now). But ill keep a look out for a cheap throttle body.

Cheers dude!

 

[enuff_zed]

I have a MAF and a throttle body. Both removed from an 06 model.
You can have them for the cost of postage.
If they fix it then maybe make a donation to the cost of running the forum.

 

[ryz4]

Hi enuff_zed!

I'd be more than happy to try them in the car for improvement that would be ace!
Should I DM you?

Also, i was looking for some MAF cleaner to try that first, but i can't find any. Would basic contact cleaner from Halfords work?
It claims to get rid of oil so i doubt it has any oil in the solution.

Thanks again.

 

[enuff_zed]

Hi enuff_zed!

I'd be more than happy to try them in the car for improvement that would be ace!
Should I DM you?

Also, i was looking for some MAF cleaner to try that first, but i can't find any. Would basic contact cleaner from Halfords work?
It claims to get rid of oil so i doubt it has any oil in the solution.

Thanks again.

I think I'd find proper MAF cleaner tbh.

https://www.ebay.co.uk/itm/373503406258

Send me your contact details on a PM and i'll let you know postage costs.

 

[ryz4]

Do either of you know what size o-ring i can put on the the eccentric shaft sensor's socket?
The yellow one on there normally has perished.

It's the one found on Pn: 12527515464

I'll try and replace that as well.

 

[enuff_zed]

Do either of you know what size o-ring i can put on the the eccentric shaft sensor's socket?
The yellow one on there normally has perished.

It's the one found on Pn: 12527515464

I'll try and replace that as well.

Do you mean this?
https://www.ebay.co.uk/itm/195925793927

 

[ryz4]

Ah no i mean the yellow o-ring on this part:
https://www.mlperformance.co.uk/pro...27515464-e64-e61-socket-housing-blue-inc-750i

 

[enuff_zed]

Not sure which part that is?
I’ve always changed the cam sensor which had the plug moulded in and sticks through the gasket I linked to

 

[ryz4]

Ah right okay.
That socket I linked is the plug for the Eccentric shaft sensor. I assume the O-Ring sides inside the body of the sensor and seals to the wall of it to ideally stop oil running down between the two of them.

I think it works like the very roughly sketched drawing below..?

 

[enuff_zed]

OK, I see the bit you mean. Yes ideally you need to replace that, but oil comes up past the gasket, then down into the plug. So if you clean it all up and fit a new gasket then no oil should be present in that area anymore.

 

[ryz4]

Hi All, just thought id update as i went along.

I took the vanos solenoids out last night and tested them, one of them was completely seized so i got that moving with some contact cleaner, as until it would feely move as i shook it. I got them both moving well before giving them a fresh coat of oil and refitting to the block (with critical help from enuff_zed, thanks again!). The engines definitely been tinkered with before as the solenoid 'spring plates' were on the wrong way around. Potentially not having the solenoids seated fully...

I also rigorously cleaned the e.s.s. connector from oil and reconnected them together. Which i hope will prolong the life of the sensor.

Went out for a drive after letting it warm up and i could hear the idle was lightly improved, although this doesn't seem to have fully fixed the issue I'm having, and pick up is still lacking

I'm also wondering now if there's something to do with the pedal as there's a deadzone in the first 20mm of pedal travel. Though I'm not currently sure how to tackle that!

 

[enuff_zed]

More likely to be the throttle body than the pedal I would have thought?

 

[tug]

Me too Martin, when mine had to be changed there was drag / hesitance on acceleration also.