UPDATED::: Z4M S54 Engine Hesitation - POLL

RedUn · Post by **RedUn** » Fri Jul 20, 2012 12:47 pm

Thats interesting as even though my hesitation is fixed now it still takes between 3-10 cranks to start?

bertman · Post by **bertman** » Fri Jul 20, 2012 1:59 pm

Ditto

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bertman · Post by **bertman** » Tue Jul 24, 2012 7:20 am

Looks like the ratio of affected to unaffected cars is starting to even up

I can report that after a week of driving with the ECU up the hesitation is back which I'm really disappointed about

How are you getting on RedUn ???

RobertRO · Post by **RobertRO** » Wed Jul 25, 2012 6:41 am

Following Karsten's (53Fatman) feedback I have just purchased a TPS (p/n: 13637840383). I plan to replace it during next weekend (July 28/29), as it takes some work to reach the throttle body actuator, and I'll report back.

bertman · Post by **bertman** » Wed Jul 25, 2012 6:47 am

Looking forward to the results RobertRO. Mines back with BMW

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Adam D · Post by **Adam D** » Fri Jul 27, 2012 11:11 am

Also very interested in his findings, how do you get the the offending part

Steve220 · Post by **Steve220** » Fri Jul 27, 2012 5:08 pm

Does anyone know where the standard engine earth lead is on these cars? I had similar issues with previous cars, i always end up putting more earth lines from the engine to the chassis - mainly because most sensors work on a common ground, if its poor then the signal from them won't be clear. I also found the engine turned over and idled better

Those of you that have the problem - what spark plugs are you using and to what gap?

Cool Z4 · Post by **Cool Z4** » Fri Jul 27, 2012 5:17 pm

This hesitation from my understanding is also in the 3.0i engine as well. Well, at least it happens in mine and a friend of mine, which he told me that it is a common occurance in the 3.0i's. I would really like to get it resolved.

sammyz · Post by **sammyz** » Fri Jul 27, 2012 8:01 pm

Redun seems to have disappeared

Perhaps his car's running so well he's been out every day in the sunshine!

RedUn · Post by **RedUn** » Fri Jul 27, 2012 11:35 pm

Sorry for the delay guys!

500 miles done now and it's still fixed? The other day I thought it had come back but I tried it just tonight just to make sure and it's definately fixed!

Starting is still the same though.

BTW i've spoke to my man at the dealers and the TSB for the starting issue is not for M's.

I'm doing another 500 this weekend though so I will report back when I get to 1k miles.

bertman · Post by **bertman** » Sat Jul 28, 2012 3:21 pm

Glad to hear you're still in the clear Redun!
Looking forward to hearing about your install RobertRO

RobertRO · Post by **RobertRO** » Mon Jul 30, 2012 7:10 am

As promised, I have replaced the throttle actuator TPS during the weekend.
Although it immediately solved the hesitation problem, I would not yet declare it as "the fix".

I am cautious because by replacing the TPS I have also performed a throttle reset. During the work, the car has been sitting for 5 hours without power (negative battery lead disconnected). Other users' experience shared here in this forum has shown that what was initially thought to be a solution was proved bogus by a revived hesitation within 500 Km.
After replacing the TPS I drove only 225 Km (~140 miles). Considering that I use the Z4M only during the weekends, you may want to wait another week for my next report. I planned a 400 Km (~250 miles) trips for the next weekend (Aug. 4/5).
On the other hand I am quite optimistic, considering that I have performed numerous throttle resets in the past, and none of them had such an immediate positive impact on the hesitation issue, as it happened after replacing the TPS last weekend.
But only mileage will tell

Here's some info about replacing the throttle actuator TPS. The itself job it's simple, but if you've never removed before the intake manifold then it's great to have the BMW TIS software at hand. Time needed: cca. 3 hours.
1. You need to buy a throttle position switch (TPS) p/n 13637840383.
2. Remove the top section of the air filter housing. Picture: http://82.78.8.129/mye28/z4/TPS/TPS_pic1.jpg.
3. Remove the intake manifold (also known as airbox or air collector). Picture: http://82.78.8.129/mye28/z4/TPS/TPS_pic2.jpg. Note that you can remove and then refit the airbox to throttle bodies clips without the special tool. For reference, check this thread: http://www.z4-forum.com/forum/viewtopic.php?f=9&t=40502.
4. In order to take out the TPS, you must remove the two Philips screws. Picture: http://82.78.8.129/mye28/z4/TPS/TPS_pic4.jpg.
5. Here's a view of the throttle body with the TPS removed. Mind that you must take out the green O-ring of the old TPS, as the new TPS comes with its own. Picture: http://82.78.8.129/mye28/z4/TPS/TPS_pic5.jpg.
6. Refit everything back.

Suggestion: while you're there it's a good moment to clean the idle control valve (ICV) and the throttle bodies. You must remove the ICV, clean it and then fit it back. It's very easy. For the throttle bodies, push the actuator level by one hand to open the throttle butterflies, and carefully clean each throttle body and butterfly with the other hand. You need a carburetor cleaner spray and some clean rags. Make sure you don't drop anything down the intake!

inkey$ · Post by **inkey$** » Mon Jul 30, 2012 8:52 am

Happened once about 6 months ago. My fix was to reset the throttle via key method (on for 10-15 secs then off again). Seemed to do the trick.

2006/52k miles

In case anybody wants to try it...

http://www.z4-forum.com/forum/viewtopic ... t+throttle

bertman · Post by **bertman** » Mon Jul 30, 2012 9:10 am

Great write up RobertRO and sounds very, very promising. Did you notice any other changes to the cars performance? More lineal acceleration etc??

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RobertRO · Post by **RobertRO** » Mon Jul 30, 2012 9:39 am

Other than fixing the hesitation issue, I haven't noticed other changes.
But, as I mentioned above, I must add more miles and hope that the hesitation does not reappear, before considering that replacing TPS is the real fix.

This morning I've started the car, after it sat overnight after yesterday's trip. I let it warm up (without driving off) for a few minutes, and pressed the throttle from idle now and then. No hesitation at all. So yes, it looks promising.

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