[ManiacGT]

Thanks, so am I right in thinking that if we're getting overboost (boost mean over boost target) which is perhaps too transient to generate a code or the DME thinks it can control it, this is likely due to the wastegates being held closed when they should be open?

If that's so, then my research suggests that vacuum holds the WG closed and not open so surely faulty solenoids would likely leak and cause underboost rather than prevent WG's being held closed and cause overboost?

[CarAbuser]

Originally Posted by ManiacGT

Thanks, so am I right in thinking that if we're getting overboost (boost mean over boost target) which is perhaps too transient to generate a code or the DME thinks it can control it, this is likely due to the wastegates being held closed when they should be open?

If that's so, then my research suggests that vacuum holds the WG closed and not open so surely faulty solenoids would likely leak and cause underboost rather than prevent WG's being held closed and cause overboost?

The job of the solenoids is to regulate the vacuum at the wastegates. If they are not functioning correctly then you can see both underboost and overboost.

[ManiacGT]

MHD have responded that the logs look ok though he did ask for one more log just containing the shift event itself, so I'll try and sort that asap.

In the meantime, to avoid doubt, I've found a place online that can supply two brand new OEM solenoids for £120 so I've ordered them anyhow as they're a relatively inexpensive investment.

[ManiacGT]

So after a few weeks of the issue being much less noticeable and my thinking this is a result of the adaptive tables provided by MHD, the car has gone back to its much poorer upshifting, power delivery state. No codes still and same fuel.

The only thing I have noted and I've noted this before but not consistently, is that the car has low fuel (50 mile warning came up in last couple of days).

LPFP? (HPFP again?)

[marcvtec]

Just wondering do you have downpipes with cats and mid pipes with cats ?
Do you warn up the car and idle for 5 min prior to drive.

What I am hint at is are you cats clogged ??
This happened to one of my cars and wow made a huge difference after I changed them.

Did you change the boost solenoids yet ?

[ManiacGT]

It’s a stock car, faults only ocurred after new injectors and new water pump (overheated).

Solenoids are on order and I hope to change those out soon. Low fuel causing poorer running tho, why would that be related to overheat/water pump/injectors?

[ManiacGT]

Originally Posted by CarAbuser

Since you had injectors replaced I would also verify that BMW installed the decoupling rings along with the injectors. This can be done visually with the engine cover removed.

That's the most common error made when installing injectors and it seems to coincide with the times that the faults started.

So I bought the required tools and removed injector six today to check the decoupler question. The decoupler was installed.

While I didn’t take out every single injector to check, this would give me some indication that at least they didn’t forget to install them.

So the new turbo pressure converters arrive next week and I’ll report back once they’re installed.

After that it’s going to have to be a process of elimination. Checking and or replacing coil packs, plugs, other sensors that might contribute that don’t cost half the value of the car etc

Shame the logs never showed anything. I expected they would give me somewhere to start. You/and these forums have been more helpful.

[langsbr]

Did you replace the Teflon seal on the injector before you reinstalled it? If not, as a precaution I would recommend not driving the car until you do. That may be a bit over zealous, but if the deal is not correct, and they are one time use, it can damage the cylinder head.

[ManiacGT]

I purchased everything I needed, did some reading and followed a by the book approach. A faff considering all I wanted was to check.

I suspect in time as more faults start to occur I’ll just end up changing the car but for now I’m going to spend just a little on it to see if I can hold on to it.

While dropping the roof recently I got all sorts of messages from boot open to roof system faults etc.

I’ve a feeling this car won’t age well.

[CarAbuser]

Originally Posted by ManiacGT

So I bought the required tools and removed injector six today to check the decoupler question. The decoupler was installed.

While I didn’t take out every single injector to check, this would give me some indication that at least they didn’t forget to install them.

So the new turbo pressure converters arrive next week and I’ll report back once they’re installed.

After that it’s going to have to be a process of elimination. Checking and or replacing coil packs, plugs, other sensors that might contribute that don’t cost half the value of the car etc

Shame the logs never showed anything. I expected they would give me somewhere to start. You/and these forums have been more helpful.

Logs normally show up problems and in your case there does seem to be a problem with the boost going over target during the shift hence the suggestion to replace the boost solenoids. Not as cut and dry as some issues though.

If you are on the original coil packs then it's always good preventative maintenance to replace them but I doubt they have anything to do with the problem.

Replacing vacuum lines is always time and money well spent. It cost me £20 for the parts and 30min of my time to replace them. The Z4 engine bay has plenty of room so it's a much easier task for us.

The 35i is the most high maintenance car I've ever owned though. The N54 engine combined with the E89 chassis would be ruinous to keep on the road without a warranty. I love mine since all the common faults have occurred and been rectified with new parts but wouldn't buy another! Probably the same story as you in that regard.

[ManiacGT]

New solenoids/pressure converters installed.

No improvement. So I’m going to replace plugs next as I’ve discovered they weren’t replaced after the overheat. After that as much as I don’t like spending on a goose chase I’ll spend what I can to replace sensors etc and past that it’s going to have to go.

[ManiacGT]

Here's a new graph. Sport mode, normal driving (not wot). You can see around 204.38 (time) that although accel pedal slowly increases, throttle closes for a short period, fuelling modes change, load request etc all drops without any corresponding reason I can see. boot mean rises but this is presumably a direct reflection of the throttle closing (it certainly mirrors in the graph).

Why when the pedal is increasing, does load, torque, throttle all drop away for a short period before coming back? Shortly after, the car upshifts.

To me, this is exactly the sensation I'm feeling, a drop off of torque before an upshift.

https://datazap.me/u/maniacgt/post-t...-28&zoom=31-53

[RSL]

Those don't look like stock spool mode cutoff RPMs or maybe I don't have the resolution to see properly on my phone. Have you modified this bin? Part-throttle isn't as easy to diagnose as WOT, but boost mean goes way over target there, which would result in a throttle closures just like WOT. VANOS can change drastically between spool and cold/warm running tables, especially cold, and has a big impact on boost and calculated boost and, thus, load, torque, etc.

In spool before shift, out of spool for shift, back into spool after shift would be expected to cause larger spreads (less smooth) on parameters (MAF, AFR, VANOS, timing, etc), but I don't really see WGDC responding to spool mode, maybe because of the boost overage already in place.

[ManiacGT]

Originally Posted by RSL

Those don't look like stock spool mode cutoff RPMs or maybe I don't have the resolution to see properly on my phone. Have you modified this bin? Part-throttle isn't as easy to diagnose as WOT, but boost mean goes way over target there, which would result in a throttle closures just like WOT. VANOS can change drastically between spool and cold/warm running tables, especially cold, and has a big impact on boost and calculated boost and, thus, load, torque, etc.

In spool before shift, out of spool for shift, back into spool after shift would be expected to cause larger spreads (less smooth) on parameters (MAF, AFR, VANOS, timing, etc), but I don't really see WGDC responding to spool mode, maybe because of the boost overage already in place.

This is a stock car. Factory software.

It’s been suggested before that boost mean goes way over target but wouldn’t that be a result of the throttle closure causing back pressure in the chargepipe?

Would this narrow the suspect to the vanos/solenoid? Stuck WGs? I seem to see the result of what’s wrong but not the cause.

[RSL]

Originally Posted by ManiacGT

This is a stock car. Factory software.

It’s been suggested before that boost mean goes way over target but wouldn’t that be a result of the throttle closure causing back pressure in the chargepipe?

It's chicken and egg with that and why you won't see it on custom tunes usually. DME's response to overshoot is to drop WGDC and close throttle to maintain calculated pressure in the intake manifold, but at the same time then causes an even larger build up of pressure in the chargepipe.

If you think the throttle is closing itself causing the boost mean increase, you can remap the pedal or kill the closures. It shouldn't rise as much without the closure, but pretty positive it will still rise the way things are there.

Edit: it may not a physical/electrical problem at all, maybe just a matter of environment, how you operate the pedal and the stock bin. I'll flash mine back to stock and see what it looks like.

[ManiacGT]

Thing is before new injectors and a new water pump by the dealer this car was as smooth as.

I don’t know whether the dealer did something that’s caused this or whether when the car overheated due to the water pump failure it took something else with it.

No codes means dealer is clueless.

The drop in power before upshifts at WOT feels severe and quite alarming as it results in the weight of the car being thrown back and forth violently in normal mode meaning there’s also some loss of control as the car struggles for grip and balance.

[ManiacGT]

Btw thanks for the help, it’s beyond frustrating that I can’t fathom this.

[RSL]

No problem. Yeah, gremlins can be a pain. You are logging these with DTC fully off, right? Traction control will cut things, but it doesn't look severe enough for it to be that and wouldn't expect much traction problem at part-throttle unless you're on loose sand or something.

Doubt it had anything to with the overheating. Car has almost no torque if it goes over 250F and is essentially not drivable. Only way head or something might've been messed up is if you kept it idling while it was that hot. More likely, they updated or reset something. Is INA0S your native rom or did MHD update it from an older rom?

Flashed mine back to stock, but haven't gone anywhere yet to log.

[ManiacGT]

Only used MHD for logging to date so it’s on factory, not yet flashed anything. Considering it tho to see if it resolves any crappy data/settings.

DTC on or off makes no difference and this is as you mention just normal driving on city roads.

[GODDSPD]

Originally Posted by ManiacGT

Only used MHD for logging to date so it’s on factory, not yet flashed anything. Considering it tho to see if it resolves any crappy data/settings.

DTC on or off makes no difference and this is as you mention just normal driving on city roads.

Flashing a tune is so easy that I’d do it just to mentally cross that off the list if nothing else. It’s possible that BMW updated the flash while it was in for service and for some reason the car doesn’t like it.

[RSL]

Originally Posted by GODDSPD

Flashing a tune is so easy that I’d do it just to mentally cross that off the list if nothing else. It’s possible that BMW updated the flash while it was in for service and for some reason the car doesn’t like it.

Definitely easy to try a flash, but I wouldn't do v8. They're just as jammed up on requests as stock, I'd try a v7.

https://datazap.me/u/rsl/testing-pt-0?log=0&data=2-3-4-5-21-24&solo=24&zoom=12-47

I have no similar issue on the stock bin, but I'm also on a 3.5 bar TMAP and don't have the constant mean over target that you do, mostly only on shifts and immediately drops after shift. Your spool mode is definitely odd though and not helping.

https://datazap.me/u/maniacgt/post-turbo-solenoid-replacement-log-2?log=0&data=3-4-5-24-27&solo=27

Your boost mean is going up well before throttle closes, it just goes up more when throttle closes. Your boost target does go up there as you press the pedal more, but not as quickly as real boost does.

Couple things you can try:
- Flash the stock map with linear throttle option
- Adjust the torque request in that area
- Modify the MAP conversion
- Reduce WGDC adder in that MAF range
- Retard intake VANOS a bit in that area
- Can dumb down the throttle closure response a bit, but no reason for it on a more dialed in setup

[ManiacGT]

I’ll charge up the battery this morning and then setup the battery charger in support/mem mode and give it a try.

Ive had so called pro do this before and they bricked the car (long ago way before any engine issues) which resulted in it being flat bedded to the dealer. So flashing makes me nervous!