Calling all N20 powered E89s with a re-map..limits of the 8HP auto box reached?

[Anonymous]

Background

As so of you know I tweaked my N20 E89 with a series of tuning changes taking it from a baseline of 184 bhp 309 nm torque and ending up at over 300 BHP and 450 nm torque with a series of tunes and new hardware.



The issue I've been trying to bottom out is a misfire that I stumbled on (pun) when using full throttle.

I'm encountering a bad misfire but only on full throttle typically overtaking a line of cars when pressing on is a good idea.

It only and obviously appeared when chasing SammyZ and PaulGS1000 in their re-mapped 35is and Porkster Boxsters..

So around 4k-5k a bad misfire sets in..if provoked black clouds of smoke..no faults codes..

I took it to the tuners (since the last visit downgraded from de-cat to sports cat without a re-tune).. they noticed a small reduction in power with a small intermitent stumble..

Suggested it may be plugs,coils, injectors, HPFP..very helpful.

Did some research and yes in the US quite a few 28i N20 engines had misfire due to HPFP.

So had new improved HPFP and injectors fitted..no change.

Fitted new plugs and coils ..no change

Did some more reading..big turbos sometimes need small spark plug gap 0.22 vs 0.3 ..no change..

Reached out to R.E92 for help..with his help using Protool did some data logging..

Started doing more research..

So the ZF 8HP45 box fitted to N20 E89s has a torque limit of 450 nm..BUT..on 3rd gear and 6th only 360 nm..

It appears (subject to a revisit to the tuners next wednsday) that the ZF box's TCU is telling the N20 DME to back off when it gets to 360nm..in my case by backing the timing off and in conjuection with my tune ..causing a full rich misfire..

Of course if you have a manual car then this doesn't happen..

So has any E89 N20 with an auto box and a re-map tried to do a max power 3rd gear acceleration to the redline?

For those that are interested you can see on this chart that the timing (one line until in green until it splits out) goes into a wobbly mode once you hit 3rd gear..top line is torque with a nice climb through first and second..

 

[enuff_zed]

Firstly, that is an expensive fact finding mission!
At least you know the car now has mostly new bits on it.
Have you reset the plug gap now you know it's not that? Did you notice any difference?
Mine isn't running the massive torque figures your has so even if it weren't a manual I would be of no help to you.
Still interested in following your 'journey' as I think the saying now is.

 

[Mister T]

Interesting, do you think they'll be able to code it out?

It looks like variants of that gearbox are good for up to 1000nm, so should be easy to find upgrade parts if required.

 

[Anonymous]

Firstly, that is an expensive fact finding mission!
At least you know the car now has mostly new bits on it.
Have you reset the plug gap now you know it's not that? Did you notice any difference?
Mine isn't running the massive torque figures your has so even if it weren't a manual I would be of no help to you.
Still interested in following your 'journey' as I think the saying now is.

Yes a very very expensive waste of bits..still enough parts to keep me going past 1 million miles...

Is your an auto? Looking up your's seemed 'weaker' on torque so probably never would be an issue even with an auto?

 

[Anonymous]

Interesting, do you think they'll be able to code it out?

It looks like variants of that gearbox are good for up to 1000nm, so should be easy to find upgrade parts if required.

There is only currently one coder in town XHP..sadly they don't do an E89 version..

Even if you could swap hardware (which would be very very expensive) its the s/w that's missing..no s/w no can do..

 

[enuff_zed]

Firstly, that is an expensive fact finding mission!
At least you know the car now has mostly new bits on it.
Have you reset the plug gap now you know it's not that? Did you notice any difference?
Mine isn't running the massive torque figures your has so even if it weren't a manual I would be of no help to you.
Still interested in following your 'journey' as I think the saying now is.

Yes a very very expensive waste of bits..still enough parts to keep me going past 1 million miles...

Is your an auto? Looking up your's seemed 'weaker' on torque so probably never would be an issue even with an auto?

Nope manual. Yes mine didn't seem to reach the higher peak torque of some others, (for reasons unknown despite a long investigation), so it wouldn't trouble the box regardless. But the spread of that torque is wide and flat. Now I'm used to it I have occasions when any one of three gears will pull just the same.
I can imagine yours must be more akin to thrust!

 

[Anonymous]

Firstly, that is an expensive fact finding mission!
At least you know the car now has mostly new bits on it.
Have you reset the plug gap now you know it's not that? Did you notice any difference?
Mine isn't running the massive torque figures your has so even if it weren't a manual I would be of no help to you.
Still interested in following your 'journey' as I think the saying now is.

Yes a very very expensive waste of bits..still enough parts to keep me going past 1 million miles...

Is your an auto? Looking up your's seemed 'weaker' on torque so probably never would be an issue even with an auto?

Nope manual. Yes mine didn't seem to reach the higher peak torque of some others, (for reasons unknown despite a long investigation), so it wouldn't trouble the box regardless. But the spread of that torque is wide and flat. Now I'm used to it I have occasions when any one of three gears will pull just the same.
I can imagine yours must be more akin to thrust!

As you said, normally there is precious little need to explore the upper echelons so that's why I think its taken me so long to find this issue (COIVID didn't help)..

Its only in the company of others who wish to travel very quickly where this issue manifested itself or when trying to overtake 7 cars on a rainy road in Argyll n Bute..-

 

[warmasice]

Manual conversation?!

 

[Anonymous]

Manual conversation?!

I think it’s the only reason I’ve found for a manual box

I’ll live with my actions pro-temp

 

[Smartbear]

Manual conversation?!

That sounds like a talking point
Rob

 

[warmasice]

Oh blimey. You know what I meant! Haha!

 

[mcbutler]

I would think that coding out the gearbox linit siganl if even possible (?? for RE) the result would probably not be very positive long term.

 

[Anonymous]

I would think that coding out the gearbox linit siganl if even possible (?? for RE) the result would probably not be very positive long term.

Hello..au contraire the coding has taken place many times in 1000s of other BMWs with the same gearbox, xHP is the relevant coding tool.

There are complex answers to your relatively direct question which are covered in greater detail by there guys..

https://www.xhpflashtool.com/blog/

So the damage / wear related implications especially if you avoid the attraction of launch control and race speed shifts for relatively minimal periods of time of exra 'stress' are minimal.

The issue is that BMW encrypts the details on top of what ZF does..and..the work required to unravel /support this requires a 'tune' per car/engine/market combination so say a 3 series N20 20i is not one tune but 18 tunes..

So the number of sad bunnies with E89 auto with N20 that want a re-map is a very small number compared to 3 seies guys..

I have written to them but are not expecting a positive oucome..

 

[R.E92]

Unfortunately removing the signal is just as much work as increasing the limit.

Gearbox torque limiters are a huge headache for tuners as typically people who develop engine tunes are a different crowd to those who develop gearbox tunes (which there are very few of). At the engine side you can just lie to the transmission and only tell it you are producing 350nm (or whatever figure would be just below the current limit).

You might be able to log the calculated torque in pro tool and see how far above the threshold you are going. If only by a small margin then you can just lower it slightly.

There is the possibility that this is another torque limiter in the engine that the tuner missed. It's almost impossible to tell what limiters come from the gearbox and which come from the engine itself without having the software to analyse. I've been through that on the N54 and even with full access to the program software it's hard work.

 

[2k35is]

Not sure if this will help.
Looked at having my 2009 325d with previous autobox (Xf6hp?) at e-maps. I thought gearbox would be same in the 325D as the 330D(both 3 litres) but looks as if has a lower maximum torque - which I'm also sure was stated on e-maps web site. May be worth putting your reg no into the emap information on the site and see if it gives any info. Would expect any decent remaper to have this info before taking torque over maximum recommended my gearbox manufacturers .

 

[Anonymous]

Not sure if this will help.
Looked at having my 2009 325d with previous autobox (Xf6hp?) at e-maps. I thought gearbox would be same in the 325D as the 330D(both 3 litres) but looks as if has a lower maximum torque - which I'm also sure was stated on e-maps web site. May be worth putting your reg no into the emap information on the site and see if it gives any info. Would expect any decent remaper to have this info before taking torque over maximum recommended my gearbox manufacturers .

I think as R.E92 has stated its a split world between the engine guys and gearbox gurus..for info the web site you reference doesn't even list E89s...the xHP guiys seemed to have success with the 6HP on E89s but so far not so on the 8HP..sadly..

 

[Anonymous]

Unfortunately removing the signal is just as much work as increasing the limit.

Gearbox torque limiters are a huge headache for tuners as typically people who develop engine tunes are a different crowd to those who develop gearbox tunes (which there are very few of). At the engine side you can just lie to the transmission and only tell it you are producing 350nm (or whatever figure would be just below the current limit).

You might be able to log the calculated torque in pro tool and see how far above the threshold you are going. If only by a small margin then you can just lower it slightly.

There is the possibility that this is another torque limiter in the engine that the tuner missed. It's almost impossible to tell what limiters come from the gearbox and which come from the engine itself without having the software to analyse. I've been through that on the N54 and even with full access to the program software it's hard work.

Now that I've 'mastered' data logging in Protool I'll go out on my private test track and try and log all the torque values I can find..

 

[cwunch]

Now that I've 'mastered' data logging in Protool I'll go out on my private test track and try and log all the torque values I can find..

Hi, did you come up with any numbers?

Mine is also remapped to 260hp, 455nm. I did not have any chance for full pulls on each gear.
(I also did not wanted to do, because 455nm of torque feels a bit high for me. I am even thinking to lower it to 400 sth, if possible, to keep the parts happy.)
but I will try and share my experience asap.

Here is my dyno;

 

[B21]

Well to cut a long story a storm in the tea-cup..

Assuming you had a re-map rather than a plug in box, which you have, I discovered that the TCU in the 8HP talks to DME and if required quietly part throttles the DME back.

This normally only applies to 3rd and 6th

In practice it’s non eventful, especially as the load is transient.

Unfortunately due to the limited time / point in the life cycle the 8HP box in the N20 E89 cannot access the various s/w tools to ‘tweak’ the box..