Auto to manual 6 speed

[Nash]

Do I have to do anything to the ECU when going to manual from auto ?

[keron]

No it will work exactly the same….

[Mike2JZ]

You need to use a manual ECU in an ideal world. It will work on an auto ecu, but can get weird behavior on auto ecu with manual box.

[Homer]

On 8/30/2024 at 4:03 PM, Mike2JZ said:

You need to use a manual ECU in an ideal world. It will work on an auto ecu, but can get weird behavior on auto ecu with manual box.

Ah crap. I’ve heard of this for years but never any technical detail as to why. There was previously suggestion about pulling timing at shift points but they vary, so I’m not sure…

[Mike2JZ]

Theres a few things going on with this type of setup, I've never gone as far as scoping each pin or trying to get the JOBD output working to see ignition timing or other values to try and diagnose it fully but I've been able to confirm the following on a few cars. 

a) Normally with auto shifter it gets signals sent to auto ECU for P/N/D/R/L/2/3/Overdrive/Manual etc . With a manual none of these signals other than NSW (Neutral) is still recieved by the ECU, so it seems auto ECU always considers the car to be in Neutral, as NSW pin is always grounded on a manual box.  The idle air control valve & ignition timing values around idle change based on weather you are in neutral or drive with an auto, as being in drive will load up the engine more. This is what I think causes the main issue with stalling with auto ECU's. A dirty hack that can get around this is to bump up the throttle set screw a bit to allow more air to enter the engine through the throttle. Don't forget to recalibrate the TPS sensor afterwards to keep ECU happy.

b) Back to back on the dyno i've tested auto and manual ECU's on a manual converted TT car and the manual ECU made more power everywhere and the turbo transition happened sooner. Presumably auto ecu being in Neutral has less timing compared to if it was in drive and more than likely has different turbo VSV activation maps based on RPM/Speed/TPS/Gear Mode etc.

c) Not all but some manual converted cars on auto have shit top end power, graph on dyno is horrible. Seems likely its pulling timing for gear shift compared to a manual ECU that will just keep going to the limiter. RPM limits can also vary by ~500rpm at times as well sometimes changing for no reason. 

 

You can of course still drive the car with auto ECU and manual box and it will feel ok, but theres more left on the table usually by going to a manual ECU.  All of the above is mainly tested with Jspec pre facelift cars. Can't remember if i've seen this behavior with UK cars before or not, but as UK ECU's are way more sensitive compared to Jspec it wouldnt suprise me if it had loads of warning lights and codes. Facelift auto ECU's really dont work well manual swaps as they are lacking certain speed signals so the car hits a rev limiter really early on. 

 

So yeah with all the above mentioned, my recomenation is always manual ecu when doing gearbox swap or go to a standalone ECU and save yourself the aggro. 

Edited September 2 by Mike2JZ (see edit history)

[Nash]

Hi Mike, thanks for the info, what is a standalone ECU ?

[AC93]

55 minutes ago, Nash said:

Hi Mike, thanks for the info, what is a standalone ECU ?

Aftermarket ECU, such as Link or Syvecs. Allows full control and adjustment of engine modules, engine safety features etc. 

[Nash]

Thanks AC, what sort of price ?

[Homer]

2 hours ago, Nash said:

Thanks AC, what sort of price ?

Anywhere form £1.5k to over £4k for the ECU, plus mapping. The only downside is I'm not sure sequential turbo function is available with standalone.

[Homer]

15 hours ago, Mike2JZ said:

Theres a few things going on with this type of setup, I've never gone as far as scoping each pin or trying to get the JOBD output working to see ignition timing or other values to try and diagnose it fully but I've been able to confirm the following on a few cars. 

a) Normally with auto shifter it gets signals sent to auto ECU for P/N/D/R/L/2/3/Overdrive/Manual etc . With a manual none of these signals other than NSW (Neutral) is still recieved by the ECU, so it seems auto ECU always considers the car to be in Neutral, as NSW pin is always grounded on a manual box.  The idle air control valve & ignition timing values around idle change based on weather you are in neutral or drive with an auto, as being in drive will load up the engine more. This is what I think causes the main issue with stalling with auto ECU's. A dirty hack that can get around this is to bump up the throttle set screw a bit to allow more air to enter the engine through the throttle. Don't forget to recalibrate the TPS sensor afterwards to keep ECU happy.

b) Back to back on the dyno i've tested auto and manual ECU's on a manual converted TT car and the manual ECU made more power everywhere and the turbo transition happened sooner. Presumably auto ecu being in Neutral has less timing compared to if it was in drive and more than likely has different turbo VSV activation maps based on RPM/Speed/TPS/Gear Mode etc.

c) Not all but some manual converted cars on auto have shit top end power, graph on dyno is horrible. Seems likely its pulling timing for gear shift compared to a manual ECU that will just keep going to the limiter. RPM limits can also vary by ~500rpm at times as well sometimes changing for no reason. 

 

You can of course still drive the car with auto ECU and manual box and it will feel ok, but theres more left on the table usually by going to a manual ECU.  All of the above is mainly tested with Jspec pre facelift cars. Can't remember if i've seen this behavior with UK cars before or not, but as UK ECU's are way more sensitive compared to Jspec it wouldnt suprise me if it had loads of warning lights and codes. Facelift auto ECU's really dont work well manual swaps as they are lacking certain speed signals so the car hits a rev limiter really early on. 

 

So yeah with all the above mentioned, my recomenation is always manual ecu when doing gearbox swap or go to a standalone ECU and save yourself the aggro. 

Thanks Mike, that's really good to know and makes sense. It might explain 2 of the issues I'm seeing with my car as well, so I'm a bit stuffed. I doubt my chances of finding a UK spec manual ECU.

I really need to get my car to you for a dyno run...

[Swampy442]

Nice reply Mike.

OP I have a GTE manual ECU sat in my unit

[Nash]

Did you try the auto ECU first Swampy ?

[Swampy442]

Yes it came from a running car

[Homer]

@Mike2JZ I managed to source a UK spec Ecu and swapped it today. You were absolutely correct on the two and half issues. I really appreciate your post as without it I would have spent a lot of money and time trying to solve these issues.

The car now has more boost on the first turbo and transitions to the 2nd one smoother and sooner. The 2nd turbo now comes online more reliably and for the first time works in first gear.

Its also got a little more power at the top end and doesn’t seem to drop off like before.

The only thing that’s not changed is the low idle however that’s probably caused by me not having the 2nd o2 sensor in installed yet.

[Mike2JZ]

cool glad to hear its made a difference, seems similar to the experience ive had swapping from auto to manual ecu. 

with the low idle, it may be worth cleaning out the throttle body and idle control valve with carb cleaner, then reseting the TPS based on TSRM procedure.