Flat spot/Hesitation - Update

[Mac77]

Just replaced the coils and still have the problem. At a bit of a loss now  :not:

[David.]

Found this thread from BMWLT, http://www.bmwlt.com/forums/rt-series/5 ... -help.html

Exhaust gas analysis on a rolling road (dyno) might help to diagnose what is happening to the fueling (air/fuel ratio) under varying loads/rev. ranges.

A similar thread from BMWSportTouring, http://bmwsporttouring.com/ubbthreads/u ... ber=881615

[Mac77]

Thanks David. I use BP Ultimate, so not a fuel issue and TBs were only synced a couple of thousand miles ago.

[David.]

Has the Throttle Position Sensor (TPS) been reset.

"Another thing you might try is a battery disconnect for about 2 minutes, then re-connect the battery, then do a new TPS re-learn (key-on, do not start engine, then FULLY twist the twist grip to fully open twice (that will clear the fueling computer & re-teach the TPS)."

[Mac77]

Hi David. Yes, when I replaced the battery. If I get chance this weekend, I'll pop off the Tupperware and see if I can get a multimeter on the TPS. Can you get the back of the plug with ease?

[David.]

The TPS is on the LHS throttle body, the electrical connector/plug can be disconnected from here.

Found this thread from R1200R, http://www.r1200rforum.com/forum/bmw-r1 ... ndex3.html,
it describes a basic test of the TPS with a multimeter.

There is also a link to, "How to Test a Throttle Position Sensor", http://www.enduringautomotive.com/tps/

[Mac77]

You're a legend, thanks David. I'm bows under with uni work, but if I get the chance tomorrow, I'll get on to it

[Mac77]

hi all, ordered a TPS from Blade BMW in Longbridge as I'm visiting family. Luckily, they ordered me the wrong part (gear position sensor), so asked to speak to a tech. He was bloody awesome! Only charged me for 30 mins work to take her in the garage, run a full check of all sensors and software. All spot on. Diagnosis is a blocked fuel filler drain and slightly perished fuel cap seal allowing water in the tank and sitting in the fuel pump. On gentle acceleration, no issues, but on hard acceleration, the fuel demand is pulling the water through. Will order a new set from motorworks and I've just thrown some redex in the tank to see if that will pull the water through. Blocked drain has been jabbed at with a small cable tie (it was blocked). Riding from redditch to crewe tomorrow, the crewe to the south coast Monday afternoon, so hopefully will be a much more confident ride, knowing I gave power when I need it 🏍

[Mac77]

Disconnected both of the O2 sensors after the problem was getting progressively worse, inc MOG. now pulls like a train with no hesitation. Ordered a set from opie oils (£130!!!!) so, will fit them this weekend (if in any fit state after Army v Navy in Saturday...).


Spent a small fortune getting to the bottom of this. Just wish I'd done it sooner  :alas:

[Sullivj]

Shame the BMW specialist wasn't able to diagnose the problem for you!

[Sprintgull]

Well done Mac77 - persistence pays.  Now enjoy the rugby!!!! 

[Mac77]

My thoughts sullivj. They've not arrived yet, so looks like it'll be a late night in the garage this week