[FotiosF90M5]

Lately my procede has been giving me some oscillation (I think thats the term) under heavy boost after around 4000 rpm's. Im on stage 1 with dci and 93 octane with ut ranging from 64 to 74. I have the latest canbus maps and lately its been doing it more. Its on and off and happens when I first start driving the car with ambient temp ranging from 45-65. As soon as it seems to go away after the car warms up more it comes back again under full throttle in higher gears. Ive tried all sorts of different settings and it seems nothing changes other than getting more powerful to less powerful with changes in user torque settings. Any one with knowledge (vendor or non vendor) can chime in and tell me what might be causing it or explain what the engine is doing while its happening I'd appreciate it. Its getting annoying lately and it seems since canbus came out my car hasnt been driving so good all the time. Its the first time I can say my procede is inconsistent. This was the reason I sold my jb3 and now Im having these problems again.Makes me want to not run a tune at all. Any input would be greatly appreciated.

[FotiosF90M5]

btw...no issues with the car at all when stock. I want this to go away

[Mr. 5]

Are you getting fluctuation of boost at full throttle?

[FotiosF90M5]

Originally Posted by Mr. 5

Are you getting fluctuation of boost at full throttle?

yup

[Mr. 5]

Mine is doing the same thing but it does it every time I floor it.
I'm curious if either the wastegates aren't closing all the way or if they are closing too much.
Are you hearing any ticking sound at all?
I just purchased a rear actuator and will be installing it this Friday because I think that it's the cause of my fluctuation.

[FotiosF90M5]

Originally Posted by Mr. 5

Mine is doing the same thing but it does it every time I floor it.
I'm curious if either the wastegates aren't closing all the way or if they are closing too much.
Are you hearing any ticking sound at all?
I just purchased a rear actuator and will be installing it this Friday because I think that it's the cause of my fluctuation.

Its funny you say that because lately for the first time I can really hear the ticking quite a bit. I just dont feel like taking everything off and bringing it to the dealer. Theyre just going to give me crappy software and erase my beloved pre 29.2 software. It has driven very well even with the ticking a few days ago so Im not sure how much it has to do with it.

[E92Fan]

I've had a similar problem recently, which spiralled into over-boosting on constant part throttle. Flashed the car back to standard, still went into overboost. Thought initially it was the downpipes because they were the last mod on the car, but discounted it because removing the precats shouldn't have any increase in boost pressure - should be the other way round. Checked the wastegates and actuator arms for tolerance, flat spots, restricted movements etc - no problems there as they are both new.

So I narrowed it down to the boost control valves. I replaced both of them, reinstalled the car, and hey presto completely even boost, no over-boost whatsoever, and that's regardless of whether the car ECU is stock or flashed.

[FotiosF90M5]

Originally Posted by E92Fan

I've had a similar problem recently, which spiralled into over-boosting on constant part throttle. Flashed the car back to standard, still went into overboost. Thought initially it was the downpipes because they were the last mod on the car, but discounted it because removing the precats shouldn't have any increase in boost pressure - should be the other way round. Checked the wastegates and actuator arms for tolerance, flat spots, restricted movements etc - no problems there as they are both new.

So I narrowed it down to the boost control valves. I replaced both of them, reinstalled the car, and hey presto completely even boost, no over-boost whatsoever, and that's regardless of whether the car ECU is stock or flashed.

my car has 39k on it and I wonder if thats the issue. was it a big job?

[f30er]

i've also noticed the fluctuating power but i'm on JB3. Thought I heard a slight ticking sound a few weeks ago but haven't heard it since. 52k miles and it just started happening a couple weeks ago....

[FotiosF90M5]

Originally Posted by e92er

i've also noticed the fluctuating power but i'm on JB3. Thought I heard a slight ticking sound a few weeks ago but haven't heard it since. 52k miles and it just started happening a couple weeks ago....

Is your warranty up? Just curious, Im debating extending the warranty because it is sooo expensive. Im going off topic in my own thread...lol

[f30er]

Originally Posted by fotios335i

Is your warranty up? Just curious, Im debating extending the warranty because it is sooo expensive. Im going off topic in my own thread...lol

I got the BMW Extended Warranty. Just don't feel like uninstalling the JB3 and taking it in until I get a better idea of what it is thats going wrong with it....

[FotiosF90M5]

Originally Posted by e92er

I got the BMW Extended Warranty. Just don't feel like uninstalling the JB3 and taking it in until I get a better idea of what it is thats going wrong with it....

Im the same way. I wont bring it in until something serious or obvious is messed up with it.

[Ilma]

Originally Posted by E92Fan

I've had a similar problem recently, which spiralled into over-boosting on constant part throttle. Flashed the car back to standard, still went into overboost. Thought initially it was the downpipes because they were the last mod on the car, but discounted it because removing the precats shouldn't have any increase in boost pressure - should be the other way round. Checked the wastegates and actuator arms for tolerance, flat spots, restricted movements etc - no problems there as they are both new.

So I narrowed it down to the boost control valves. I replaced both of them, reinstalled the car, and hey presto completely even boost, no over-boost whatsoever, and that's regardless of whether the car ECU is stock or flashed.

By boost control valves do you mean the wastegate actuators?

Didn't realize they were accesible enough for a DIY

FWIW, I don't get throttle oscillation where the car lunges back and forth, but I do see a bit of boost wobble on the boost gauge which I think might be normal as Shiv stated in another thread that he doesn't tune just boost, but rather he tunes for the volumetric efficiency of the motor.

However, I am experiencing an occasional loss of ooomph, usually in 3rd or 4th gear. This was reported on another thread by Edo as power just fading away on a gear change into 4th.

I find it happens to me too....but then symptoms disappear on the next pull.....so it's kind of random.

I'm speculating that perhaps it's throttle closure due to overshoot on the boost target sometimes.

While in 2nd gear, the pull is very strong and constant. On a gear change, the boost becomes unstable momentarily (the spike at shift point) and maybe it's overshooting target and causes the throttle plate to close up in order to get back onto target??

But I have no idea what I'm talking about....I'm just a bit paranoid.

[ianthegreat]

Originally Posted by fotios335i

yup

Mine has also been doing the same thing. I'm running JB3 1.22. I think it was mentioned before on the JB boards. Can anyone chime in if they have experienced this on 1.3??

I'm wondering if I'm leaking boost somewhere.

[Mr. 5]

Originally Posted by E92Fan

I've had a similar problem recently, which spiralled into over-boosting on constant part throttle. Flashed the car back to standard, still went into overboost. Thought initially it was the downpipes because they were the last mod on the car, but discounted it because removing the precats shouldn't have any increase in boost pressure - should be the other way round. Checked the wastegates and actuator arms for tolerance, flat spots, restricted movements etc - no problems there as they are both new.

So I narrowed it down to the boost control valves. I replaced both of them, reinstalled the car, and hey presto completely even boost, no over-boost whatsoever, and that's regardless of whether the car ECU is stock or flashed.

It sounds like we have different issues. Mine behaves perfect at stock.

Originally Posted by Ilma

By boost control valves do you mean the wastegate actuators?

Didn't realize they were accesible enough for a DIY

FWIW, I don't get throttle oscillation where the car lunges back and forth, but I do see a bit of boost wobble on the boost gauge which I think might be normal as Shiv stated in another thread that he doesn't tune just boost, but rather he tunes for the volumetric efficiency of the motor.

However, I am experiencing an occasional loss of ooomph, usually in 3rd or 4th gear. This was reported on another thread by Edo as power just fading away on a gear change into 4th.

I find it happens to me too....but then symptoms disappear on the next pull.....so it's kind of random.

I'm speculating that perhaps it's throttle closure due to overshoot on the boost target sometimes.

While in 2nd gear, the pull is very strong and constant. On a gear change, the boost becomes unstable momentarily (the spike at shift point) and maybe it's overshooting target and causes the throttle plate to close up in order to get back onto target??

But I have no idea what I'm talking about....I'm just a bit paranoid.

I think he's talking about diverter valves.

[ianthegreat]

I was about to suggest diverter valves. I don't know which to go with though - forge or RR. I'm wondering if using the stock rubber piping is sufficient (Forge), or if I should try the RR route.

[Ilma]

Right...that makes more sense now.

Thanks!

[kentgbr]

The tuners are using a PID algorithm for closed loop boost control. There are gains for the proportional, integral, and differential terms that are likely set based on data gathered from various vehicles. These affect the loop response and stability but may not be ideal for all vehicles because of mods, factory variations, etc. Would it be possible to allow end users a limited gain adjustment range for one or more terms to dial in the loops for individual cars?

[TMR]

This seems to be a very common problem i would think. I have had this issue since the dealer installed my new turbos and did not set my wastegates up correctly. I then tightened the wastegate and it did get better but i too saw it with the RevII and with the JB3. I explained to shiv what i was seeing and he emailed me a test map that did somewhat address the issue so i dont see why this cant be fixed or at least somewhat adjusted with software.

If you are running a RevII and have a rattle please PM me.

[E92Fan]

Originally Posted by fotios335i

my car has 39k on it and I wonder if thats the issue. was it a big job?

The two boost control valves are small - getting to them is a pain though. Have to get to the actuators and turbos from below, which means removing the downpipes. Car has now done 1000 miles with the new valves and it's brilliant

[NM_BMW]

Originally Posted by E92Fan

The two boost control valves are small - getting to them is a pain though. Have to get to the actuators and turbos from below, which means removing the downpipes. Car has now done 1000 miles with the new valves and it's brilliant

pics? or better yet point it out on realoem.

[FotiosF90M5]

the problem is so off an on. Some pulls are perfect. After a bit of driving without using much boost and then going WOT in 3rd or 4th at around 3-4k rpm's then it happens again. smooths out again after a few more pulls. Im tired of this and might remove the procede. My procede was perfect for so long and now it sux