Pd9264

sjc246

That's great to hear. I seriously doubt the conductor plate had anything to do with it (although definitely good that you replaced it while you were in there). That is not the kind of problem that a bad conductor plate causes.

Assuming that the fix is more than temporary, my money is on the Sonnax parts. The more I think about it, the more it makes sense. The commanded shift pressure/volume at low load is far less than at WOT, so a valve body problem could definitely cause excessive slipping only at low loads (which I'm assuming results in an automatic power cut until the gear is fully engaged). That could also explain why the problem seems to be exacerbated by the larger throttle body in most cases: the shift pressure most likely increases based on throttle position and a larger throttle body gives you more power at lower throttle position so the shift pressure will be unintentionally reduced, meaning more slipping (this is just a theory, I'm not 100% sure this is how it works).

I'll be installing the Sonnax parts in my valve body as soon as possible and I'll report back if that fixes my issue as well.

In the meantime, please keep us updated on how your car is doing! I have tried a few things with adaptations and tunes which seemed to help for a short period, but the problem always came back right away. I think we may have finally solved the mystery (hopefully...).

Pd9264

right been drivIng the car a little more. And although the gearchanges are much smoother and firmer. I do still get a very slight power delay once the new gear has been selected. Although it is very minimal compared to before. but all in all I’m very happy with the results.

also my next modification is an 82mm throttle body so I will see how she feels after that.

Pd9264

sjc246

That sucks. I really had my hopes up. Thanks for updating, though!

This definitely seems to be some sort of problem with the transmission adaptations. Not the gearshift adaptations as in clutch fill time and stuff like that, but rather the way the car is supposed to "learn" how you drive and adapt the engine and transmission behavior to suit your driving style (I believe it adjusts shift points, throttle response, and shift firmness). If I drive the car hard for a while it pretty much disappears, but once I drive it normally, the problem returns. Same thing with disconnecting the battery.

I'm out of town on business all week, but next week I'm going to connect an oscilloscope to the position sensors of both the throttle body and bypass valve to get a better idea of what's going on here. (Live data is so slow on these cars that I don't think I'll get anything meaningful with OBD logging, even with DAS).

GinDistiller

Yeah that's a bummer. I keep hearing about TCU tunes not making a big difference, but I wonder if they would for people with these issues? RaceIQ states "torque limiters raised" and faster shifting. Might be worth pulling the trigger to try, I agree this sounds like a software issue. I have asked Tony at RaceIQ about it twice over the last few months but no response...

sjc246

Unfortunately, I don't think a TCU tune will help (unless the problem is TCU related and someone can figure out exactly what is causing this and make a new tune to fix it). I have a Eurocharged TCU tune and I have also test fit an un-tuned TCU. There was minimal if any difference. The issue nearly disappeared after swapping TCUs (swapping to either the tuned one or the un-tuned one), however, it soon came back each time (I swapped back and forth a few times). I am not 100% sure, but I believe that people are also having the same issue with Tony/RaceIQ's tune and I know that at one point Tony had worked on fixing this specific problem with no success

GinDistiller

Maybe we should just be driving in dyno mode the whole time then?

I had the same results swapping TCUs. My other thought is trying a modified valve body, there's a local guy that makes a '150%' VB that essentially increases pressure across the board, maybe that would power through the issue...

Pd9264

Think Iv sorted my problems.

iv had a new tune from race iq loaded onto my car and now the car is a complete different drive. No more jerky ness.

I recon that the last person who owned my car. Originally had a 77mm clutched pulley fitted. And a eurocharged map. Then his magnet went bad so fitted a 74mm fixed pulley instead. And I recon he never changed the tune from a clutched pulley to a fixed pulley.

The car drives spot on now. Gear changes are better and less jerky. No more dead spots at low rpm. No more feeling like Iv let of the gas when gear changes.

I actually enjoy driving it now. Also Iv upgraded to 550cc injectors, 82mm throttle body and a 70mm fixed pulley . And race iq tuned for this.

Darin Schnoor

Bumping this thread, glad I stumbled on it. I've been having exactly the same issue of power dropping off on upshifts that all of you have had. It feels a bit like a student driver learning a manual trans and is just not that fun to drive, as every shift induces an annoyingly slow yet firm head jerking. I have the VRP 76mm clutched pulley and RaceIQ ECU and TCU tunes. The problem started after installing those mods. I've also tried multiple adaptation resets (both in the trans and engine), trans fluid/filter changes, battery disconnects, etc. I always get the same result I'm reading about here: better for a few days, then back to the same problem.

It sounds like cleaning the throttle body and bypass valve may help, along with their electrical connectors. Did you ever find out anything with your oscilloscope testing?

Anyone ever figure this out? I'd love to get this solved!

GinDistiller

There is a new TCU tune available from another member that gets rid of the power loss between shifts, it all has to do with torque management settings. You should be able to find it searching as it came out in the last few months. Totally transforms power between shifts, it became more noticeable after your power mods because of the extra torque and the trans trying to 'protect' itself.

oneslow55

Actually has to also do with a dip in timing in between shifts ,i adjusted my file and after felt like a power shift in between gears as no timing is being pulled.

Darin Schnoor

Great to hear! I found the user and ordered his TCU, looking forward to installing it soon.

Unfortunately, I have no ability to modify the RaceIQ maps myself, but if the issue continues after the new TCU, I'll reach out to them regarding the timing being pulled.

Ugur e55

Did you find what the problem was for the jerking at light throttle? I have the same problem after i did my pulley 77mm fixed and tune. Feels ike a misfire indeed but i dont think it is actually a misfire.

vzqk50

Any chance you can share the specifics of the fixes in a single post. If I am understanding, it sounds like the new TCU tune is the number 1 fix, but also an ECU tune helps. I run a bone-stock 2003 E55 with the issue, so anything I can do to fix it would be appreciated.

Thanks!

cdk4219

Jerking between 1st and second when cold? Or all gears?

vzqk50

In my case, the jerkiness occurs in upper gears 3/4/5 at around 1800-2000 RPM. I have been convinced it was misfiring, but no DTCs set for misfire. I did receive a DTC over the weekend for a "slight" EVAC leak. I opened and closed the gas cap and it has not reoccurred. However, that did not change the jerkiness. I have tried Using manual mode shifting, sneaky reset, and other purported fixes with no luck. Of course, been through the whole coil pack, spark plug, etc... fixes. I do need to check the injectors, but I only use Shell Nitro. At first that seemed to help, but that may have been a combination of things I switched at the time. Crazy thing is it still does zero to 60 in ~4.5sec with lower fuel and just me.

zerocat101

I have the fix for transmission issues

vzqk50

so I was looking at an aftermarket TCU. Is there a unit you would recommend? I have a good scan tool and definitely not misfire related. It almost feels like the old locking torque converter issues from the 1980s GM cars. My scan tool won’t load a tune, so I would have to find a shop to load it.

any other thoughts or recommendations?

GinDistiller

Zerocat's TCUs are awesome, really makes these feel more like the 7sp newer transmissions, halfway between those and the MCTs, very nice feedback without any jerkiness.

Get ahold of a STAR tool, get into the TCU and shut off the torque converter lockup and drive to see if your issue goes away. If it doesn't you've got engine related issues, if it does...well look at TCU, lockup solenoid, torque converter, conductor plate etc. You can also look at adaptations to guage health of your transmission clutch plates etc.