N54 135i surging ever so slightly.

[choppedliver]

Hi all,

Got an odd one. Car is 2009 135i, with Catless DPs, IC and Procede (yeah it's that old). Anyways the car has recently and it seems to be getting more pronounced surging ever so slightly at constant speed.

Its kind of hard to notice on Sydney roads but last night on the M2 I managed to really feel it. Basically on cruise or human it surges ever so slightly up and down every 5 seconds or so. It's very subtle and I thought I was going mad. The surge is like 20-50rpm at 100-110km/h so I can't imagine we are on boost at all.

I think this morning now that I'm keyed into it, was happening even more obviously in 2nd gear. That said the procede can be a bit spiky in low gears so it could be that.

I have tried in bypass, map1 and map2 on the procede with no change so it's not ruled out by any means.

The car seems to pull fine.

I did get a MAP error last week that was cleared and not re-occured. Car has plugs and coils about 30K ago. Fuel pump was replaced years ago by BMW.

Any pointers to save a lot of troubleshooting and time wasting? It would be better if it was less subtle.

Thanks

Byron

[vtl]

I had a procede and certain settings can make the car run weird. Even when I was sure all the settings were correct I had weird issues with vanos and the tune overall wasn't that smooth. Stuff like O2 simulation can really stuff things up in a subtle way.

The best advice I can give you is to remove the Procede all together and run a MHD flash tune. Reprogramming the factory ECU is worlds better than running a tuning box that intercepts the signals from the ECU and fools it into running more boost. MHD also has inbuilt logging features which make diagnosing your car so much easier.

I regret not taking out mine sooner, the flash tune runs so much smoother and has been trouble free. Map 0 doesnt mean the tune is fully bypassed. Physically removing it is the way to isolate it.

[135i2]

I had the same issue years ago.

Turned out to be HPFP on the way out.

[tawfeeqh]

Originally Posted by 135i2

I had the same issue years ago.

Turned out to be HPFP on the way out.

I recently had low rpm surging too and long crank times, although im on 100% e85 so kind of expected in Winter. Changed the HPFP and injectors and the surging is now gone. Perhaps it was the HPFP for me too

[drjekl]

My car on freeway would act weird at times (procede) going to cobb flash cured this as VTL pointed out.

[choppedliver]

Sounds like getting rid of proceed and going MHD is the go. Might even pick up some more power!

Will try this first.

Thanks

Byron

[totti84]

KM's on vehicle? Have you cleaned your intake valves?

[choppedliver]

Originally Posted by totti84

KM's on vehicle? Have you cleaned your intake valves?

Hi,

93,000 and no. It's on the list soon.

Byron

[totti84]

Wow i'd hate to see what your valves look like, I'd be putting this on the top of your list!

[choppedliver]

Originally Posted by totti84

Wow i'd hate to see what your valves look like, I'd be putting this on the top of your list!

As the car drives fine, is responsive and pulls well I've never really been worried.

Perhaps I'll do that and the MHD (more power I would think) anyway. What's the going rate for this?

We shall see how it goes.

Thanks for the help.

Byron

[choppedliver]

An update. All fixed.

Procede gone
Walnuts blasted
MHD custom tune.

Car is massively smoother and is way more responsive and has so much torque. The DPs and IC are now working.

Best thing I've ever done.

Thanks

Byron