S54 Engine Hesitation from Idle & Constant Throttle Input

Tcochrane92 · Post by **Tcochrane92** » Mon Dec 31, 2018 5:36 pm

I've read a couple threads on this, but apologies as I didn't want to read through dozens of pages to find the answer

My Z4m (69k miles) has engine hesitation when you blip the throttle. Happens from idle & also at higher revs. Especially noticeable when using cruise control at cirva 50mph - the car feels like it lurches when the throttle opens slightly to maintain speed.

Also when holding constant throttle input (small input, maybe 5% throttle), the engine lurches and hesitates unevenly.

I'm thinking it could be injectors, am I thinking along the right lines?
No fault codes

Cheers

Babw · Post by **Babw** » Mon Dec 31, 2018 6:13 pm

I had similar issues and cleaning the throttle bodies, ICV and replacing the TPS's cured the problem. (Did all this while installing my Karbonius intake and installing the Evolve Alpha-N map so potentially it's one or a combination of all of these that cured it.)

crustyclown777 · Post by **crustyclown777** » Tue Jan 01, 2019 12:12 am

TPS solved it for me. (Engine side)

Kern47 · Post by **Kern47** » Tue Jan 01, 2019 4:01 am

Had similar problems on other cars...
A bottle of Forte injector cleared it up for me, not had it with my S54 but that could be a good first port of call to see if it solves your problem...
Worst case scenario you've still got the problem but with (presumably) cleaned out fuel system for ~£10

ph001 · Post by **ph001** » Tue Jan 01, 2019 11:26 am

Yep, throttle position sensor would be my guess. The S54 has two, one is easy to get to, the other isn’t.

Tcochrane92 · Post by **Tcochrane92** » Tue Jan 01, 2019 1:04 pm

Thanks for the help guys. I'll pick up some injector cleaner and see if that works

Otherwise, which TPS do you recommend changing?

mpm · Post by **mpm** » Tue Jan 01, 2019 2:23 pm

The TPS further back tends to go more often due to the heat, it breaks down the internals.

Tcochrane92 · Post by **Tcochrane92** » Thu Jan 03, 2019 6:19 pm

Can someone advise if this is the right part please?

https://www.eurocarparts.com/ecp/c/BMW_ ... d6d&000576

Matt.13 · Post by **Matt.13** » Thu Jan 03, 2019 7:04 pm

Looks the right one to me

Spaniarduk · Post by **Spaniarduk** » Fri Jan 04, 2019 11:59 pm

Tcochrane92, are you going to replace it? The one by the throttle actuator? Let us know how you got on and what the result was

Post by **srhutch** » Sat Jan 05, 2019 12:06 am

Tcochrane92 wrote: ↑Thu Jan 03, 2019 6:19 pm Can someone advise if this is the right part please?

https://www.eurocarparts.com/ecp/c/BMW_ ... d6d&000576

Try carparts4less.co.uk same company but cheaper prices as long as you can wait a day or two for delivery

Spaniarduk · Post by **Spaniarduk** » Sat Jan 05, 2019 5:19 am

srhutch wrote: ↑Sat Jan 05, 2019 12:06 am
Tcochrane92 wrote: ↑Thu Jan 03, 2019 6:19 pm Can someone advise if this is the right part please?

https://www.eurocarparts.com/ecp/c/BMW_ ... d6d&000576
Try carparts4less.co.uk same company but cheaper prices as long as you can wait a day or two for delivery

Jeez... under 50 quid for exactly the same item!! And clearly, the website *is the same*! Thanks srhutch,

Tcochrane92 · Post by **Tcochrane92** » Sat Jan 05, 2019 10:15 am

Spaniarduk wrote: ↑Fri Jan 04, 2019 11:59 pm Tcochrane92, are you going to replace it? The one by the throttle actuator? Let us know how you got on and what the result was

I'm going to try some injector cleaner tomorrow - can't hurt.

Plus, I've just ordered the TPS from srhutch's recommended website - thanks!

I'll replace the TPS next weekend / weekend and update the thread on my findings.

Just to be sure - is it this part?

https://cdn4.pelicanparts.com/techartic ... /pic04.jpg

Are these clips re-useable?

https://cdn4.pelicanparts.com/techartic ... /pic01.jpg

Thanks all

Tcochrane92 · Post by **Tcochrane92** » Tue Jan 08, 2019 6:54 pm

So I replaced the throttle position sensor on the front of the engine (the one most accessible) and the car instantly feels better. The hesitation appears to have gone, the throttle feels very responsive and it revs very cleanly now.

: 20190105_132227.jpg (177.47 KiB) Viewed 2389 times

I've also put some injector cleaner into the fuel for a bit of extra help.

If I get any more hesitation, I'll replace the other TPS under the intake chamber too

Thanks all for your advice!

Spaniarduk · Post by **Spaniarduk** » Tue Jan 08, 2019 10:08 pm

Tcochrane92, excellent news! I feel tempted to spend the 50quid and replace it in mine. I have some hesitation between 2300 and 2800rpm and half throttle. Precisely the rev range where you cruise along.
I'm also planning on doing the valve clearance check in the spring, which I feel it's due at 30k miles.

Keep us posted!

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