Its a re-map Jim, but not as you know it (One man's E89 N20 Dyno Tuning)

[Anonymous]

The background to this was that I bought a VSRF de-cat downpipe for my E89 N20 20i powered 'Yellow Peril'

I was not convinced that without re-visiting the re-map done by a Celtic dealer in 2017 that I would get all the benefits (predicted to be 10-15BHP, plus faster spool up time) and possibly may inadvertantly damge the engine in some way.

Living in the Scottish Borders we are a bit short on engine dynos so after monitoring The Peformance Centre ( https://www.performance-centre.co.uk/ )FB posts on various re-maps /tweaks decided to head across to sunny Sunderland for them to fit the new pipe and then hopefully a quick tweak and off I go..

So arrived yesterday (8th July 2020) at 11:00 am, assumed I would be done and dusted by 13:00.

So sat outside on a disused mini-bar fridge (due to no entry due to COVID), living the dream monitoring life in a Sunderland industrial estate.

They waited for the car to cool down and then fitted the new down pipe around 13:00 ish and then around 13:30 did the first run.

The chap (whose name I never got) was a taciturn individual who said little, but, by the body action I could see all was not going to plan.

A polite interrogation was then done as we looked at the Celtic tuned run with de-cat fitted..

As you can see the shape of the BHP/Torque curve was a stange hump-backed affair, but looking at it, the way the car drove accorded with the shape, ie big initial surge, then relatively flat, followed by a screaming rate of acceleration right at the top end.

I just assumed, never having had the car on the dyno that that was just the way all Celtic / other tunes were..

Also the techy couldn't persuade the re-mapped DME to accept his subsequent tweaks..

After lots of head scratching and comms with 'the supreme being' the mysterious owner, who was working remotely, the plan was hatched..

Re-load an original BMW s/w and map from BMW, re-run it to see if the 'faults' disappeared and then if OK re-map from there.

So over the next 2 hours that was done..you can see the OEM figures and then the new re-mapped figures.

A few observations

The car only made a little more BHP than the Celtic tune..266.5 BHP vs 261.9 BHP..however the area of increased BHP was massive over both OE and the Celtic tune.

Despite running 99 octane fuel once the initial re-map had been done there was negligble improvement from subsequent tweaks..

As Mr Taciturn said..some N20 engines want to keep on giving and some don't..looks like mine is one of them.

No satisfactory logic to it apart from follow up analysis where I notice both tuners and cars that seem to do better are often the later engines with the electronically controlled boost control rather than the earlier pneumatic version, as fitted to my car.

On the way home, it was night n day in terms of on the road performance, previously to get really good overtaking performance I would put in sports mode and change down a few gears ready to blitz and overtake, otherwise it would seem to take along time and just as the oncoming car was getting close, finally, the car would launch itself into the ever closing gap.

Previously when for example playing tail end charlie on Z4 forum runs I found it easier to run low revs and then overtake which correlates with the shape of the torque curve.

Now a wave of effortless mid range punch would propel me to the horizon on my private testing track known as the A696/A68.

The de-cat does make quite a bit more growl, but thanks to the exhaust valve, if you want to poodle discretely along then its still possible without sounding like the Corsa/Clio 'yoof'..

As I disabled the ASD (BMW Active Sound) system the only noise I hear is the real exhaust note..plus quite a nice whistle from the turbo..

At higher speeds the noise is lost in the wind and turbo noises anyway..

Given the massive change in mid range punch its difficult to ascribe any faster pick up to the VSRF pipe..

I took a few videos for those interested in how a dyno run looks plus the before/during/after BHP/torque curves..enjoy!

https://youtu.be/2NsSMXXRMms

 

[brillomaster]

wow... thats a HUUUUGE torque hole in the midrange! definitely something weird going on there. And yes, i'd imagine after having it rectified it was like a completely different car!

strange as you've made no more power at the very top end now, but where you actually need to shove for overtaking (ie midrange) there is bucket loads more power now. :driving:

 

[enuff_zed]

Well that is a weird result with the Celtic tune isn't it?
Do you think they are all like that or simply that, as you said, your car doesn't want to play.
I have still not committed to the remap yet, and tbh if it gave a curve like that I'm not sure whether I'd want it??
Hopefully the smartest bear on the forum will be along shortly to add his input. I'm sure his remap was rolling-roaded and didn't look like that?
And of course, the many others who have had either Evolve, Celtic or other remaps?

Regardless of the effect of the decat, the session was worth it for you it seems.

 

[enuff_zed]

Thinking on a bit, I wonder how much the Celtic map was affected by removing the cat?
I'm no expert in this area? Do remaps account for things like that at all?

EDIT: No, I just realised you said it was always like that. :roll:

 

[R.E92]

That dip in the midrange looks like either a torque limiter is retarding the ignition timing or the throttle is closing to restrict boost. Either way the Celtic tune wasn't getting the job done only managing to outperform the stock tune past 5100RPM. I'm guessing the dyno sheet that Celtic supplied first time around looked good? The probably use the same graph for every customer

It's not uncommon for that kind of thing to happen. Adding boost and timing is the easy part, dealing with the myriad of limiters and nannies is hard on new engines. A friend of mine went to Litchfield Motors to get his M140i tuned and ended up with exactly the same problem. After a few more failed attempts by Litchfield I ended up twisting his arm to get MHD instead.

 

[Mikopop]

Nice write up PB, I imagine you have fallen for your car all over again with that marked change in driving dynamics.

 

[buzyg]

Surely it should have been like that after the first tune up. :? Great that it's right now either way.

 

[Nictrix]

I have never understood generic maps that people use. I dont pretend to know the whole ins and outs of tuning.
From what I have always thought is that each engine is slightly different than the next and to get the best from a remap it has to be done on a rolling road with YOUR car being mapped, ie a custom map.
Now from what you are seeing the generic map was a waste of money and time and could possibly have damaged the engine.

 

[Anonymous]

I don’t want this to see this as a dissing of Celtic , not that I have any commercial or other interests in that company..

I can only come up with two options..

The guy doing the initial load which at that time required the DME to be opened up got it wrong in some way, wrong map, incorrect load etc

Or...the engine had already had been re-mapped and the Celtic was a second pass..though at that time, the Celtic guy. would have noticed any previous re-map attempts as it required physical access to the internals at that time..

The guys did load the very latest / last version of the N20 DME o/s and map..

Mr Taciturn did make the observation that like R.E92 observed it was like the throttle was being deliberate held back..

Anyway as Nitrix says it would be better to do a before n after on the same rolling road..that’s not a readily available option in some parts of the world..

 

[R.E92]

I have never understood generic maps that people use. I dont pretend to know the whole ins and outs of tuning.
From what I have always thought is that each engine is slightly different than the next and to get the best from a remap it has to be done on a rolling road with YOUR car being mapped, ie a custom map.
Now from what you are seeing the generic map was a waste of money and time and could possibly have damaged the engine.

There's surprisingly little difference between engines when it comes to output after tuning. They are all mass produced with very tight tolerances so the only difference in output comes from the fuel the customer puts in. Once an engine gets old things change as not everyone maintains a car at the same standard.

Both companies here have used a generic map maybe with slight tweaks to the ignition and boost control. The difference is that the generic map used by Celtic was duff. In fairness the Celtic map may have produced a good readout first time around, one of the difficulties with tuning cars is that some issues only occur at certain conditions and the conditions present on a dyno don't reflect the conditions of a road, that's why data logging during real world drive cycles is crucial for a good quality tune.

The Engineering Explained youtube channel had a great video recently documenting his issues with a supercharger kit. There's certainly an overlap with this topic in the tune issue regard, worth watching. https://www.youtube.com/watch?v=OKZSSHjLiy4

 

[enuff_zed]

Well, to be fair, though I may have missed it, I've never seen you comment on the way the car performed before. Which now seems to exactly mirror what the Celtic map shows.
So my question would be to others with this map, plus those with Evolve ones, as these two seem to be about the most common/biggest players............. Does anyone else experience the kind of performance that [ref]Pbondar[/ref] did with the initial Celtic map? Or is this perhaps a one-off for some obscure reason?

 

[enuff_zed]

I have never understood generic maps that people use. I dont pretend to know the whole ins and outs of tuning.
From what I have always thought is that each engine is slightly different than the next and to get the best from a remap it has to be done on a rolling road with YOUR car being mapped, ie a custom map.
Now from what you are seeing the generic map was a waste of money and time and could possibly have damaged the engine.

There's surprisingly little difference between engines when it comes to output after tuning. They are all mass produced with very tight tolerances so the only difference in output comes from the fuel the customer puts in. Once an engine gets old things change as not everyone maintains a car at the same standard.

Both companies here have used a generic map maybe with slight tweaks to the ignition and boost control. The difference is that the generic map used by Celtic was duff. In fairness the Celtic map may have produced a good readout first time around, one of the difficulties with tuning cars is that some issues only occur at certain conditions and the conditions present on a dyno don't reflect the conditions of a road, that's why data logging during real world drive cycles is crucial for a good quality tune.

The Engineering Explained youtube channel had a great video recently documenting his issues with a supercharger kit. There's certainly an overlap with this topic in the tune issue regard, worth watching. https://www.youtube.com/watch?v=OKZSSHjLiy4

I suppose the thing now would be to send the rolling road graphs to Celtic and ask for their thoughts?

 

[Nictrix]

I have never understood generic maps that people use. I dont pretend to know the whole ins and outs of tuning.
From what I have always thought is that each engine is slightly different than the next and to get the best from a remap it has to be done on a rolling road with YOUR car being mapped, ie a custom map.
Now from what you are seeing the generic map was a waste of money and time and could possibly have damaged the engine.

There's surprisingly little difference between engines when it comes to output after tuning. They are all mass produced with very tight tolerances so the only difference in output comes from the fuel the customer puts in. Once an engine gets old things change as not everyone maintains a car at the same standard.

Both companies here have used a generic map maybe with slight tweaks to the ignition and boost control. The difference is that the generic map used by Celtic was duff. In fairness the Celtic map may have produced a good readout first time around, one of the difficulties with tuning cars is that some issues only occur at certain conditions and the conditions present on a dyno don't reflect the conditions of a road, that's why data logging during real world drive cycles is crucial for a good quality tune.

The Engineering Explained youtube channel had a great video recently documenting his issues with a supercharger kit. There's certainly an overlap with this topic in the tune issue regard, worth watching. https://www.youtube.com/watch?v=OKZSSHjLiy4

If you can put 2 brand new engines on a dyno and get different power outputs for both then in my mind putting the same map on each engine would not get the best from both. A custom map surely is the only way to do this.
Going on from this, 2 cars at 5 years old could be completely different again after they have been used or abused differently and a generic map that might suit one might not suit the other. Again surely a custom map is the only way to get the best out of them.

 

[R.E92]

If you can put 2 brand new engines on a dyno and get different power outputs for both then in my mind putting the same map on each engine would not get the best from both. A custom map surely is the only way to do this.
Going on from this, 2 cars at 5 years old could be completely different again after they have been used or abused differently and a generic map that might suit one might not suit the other. Again surely a custom map is the only way to get the best out of them.

Where did you get the idea that two brand new identical cars would have different outputs? I see lots of claims of varying stock outputs on new cars on the dyno but that variability is with the dyno rather than the engine. I'd be shocked if outputs vary by more than 1 or 2 horsepower if done under more scientific conditions.

Modern engine control units aren't rigid, they target a certain load value so if the car is in a hot country at high altitude it will produce more boost to compensate for the lower air density and will lower boost targets at areas with higher air density. There's a lot more flexibility than you appreciate in the engine operation.

 

[Nictrix]

If you can put 2 brand new engines on a dyno and get different power outputs for both then in my mind putting the same map on each engine would not get the best from both. A custom map surely is the only way to do this.
Going on from this, 2 cars at 5 years old could be completely different again after they have been used or abused differently and a generic map that might suit one might not suit the other. Again surely a custom map is the only way to get the best out of them.

Where did you get the idea that two brand new identical cars would have different outputs? I see lots of claims of varying stock outputs on new cars on the dyno but that variability is with the dyno rather than the engine. I'd be shocked if outputs vary by more than 1 or 2 horsepower if done under more scientific conditions.

Modern engine control units aren't rigid, they target a certain load value so if the car is in a hot country at high altitude it will produce more boost to compensate for the lower air density and will lower boost targets at areas with higher air density. There's a lot more flexibility than you appreciate in the engine operation.

This is only my opinion but even if there is only a 1 or 2 hp difference this makes each engine slightly different and a different tune for each may be required.
Used to see it a lot with bikes when the local dyno had BHP days and everybody would put their bikes on to see who had the highest bhp. Same manufacturer bikes would produce different bhp results which would mean even with tight tolerances in manufacturing there are still differences.

 

[Smartbear]

Well that is a weird result with the Celtic tune isn't it?
Do you think they are all like that or simply that, as you said, your car doesn't want to play.
I have still not committed to the remap yet, and tbh if it gave a curve like that I'm not sure whether I'd want it??
Hopefully the smartest bear on the forum will be along shortly to add his input. I'm sure his remap was rolling-roaded and didn't look like that?
And of course, the many others who have had either Evolve, Celtic or other remaps?

Regardless of the effect of the decat, the session was worth it for you it seems.

My evolve map didn’t have the dip in the midrange like that, I’m sure that can’t be typical as plenty of people use Celtic and are happy with the results, it’s also a very good reason to get your car Dyno tested before/after tweaking as it would have been obvious to the operator that something was amiss & the car wouldn’t have been sent out like that! :?

Rob

 

[mcbutler]

Did you do any runs on the dyno before fitting the decat. If not then I dont think we can criticise any map done for a none decat car. My 35i has a celtic stage 1 map. I had both downpipes replaced by VRSF decats and returned to celtic for my £80 retune and sensor delete. The car made a very flat and unpleasant noise before the remap and I was not getting any sensor errors either!!
After the decat tweak I gained 25BHP!!!!!
Celtic maps are very aggressive I find (and like)...

 

[Smartbear]

Did you do any runs on the dyno before fitting the decat. If not then I dont think we can criticise any map done for a none decat car. My 35i has a celtic stage 1 map. I had both downpipes replaced by VRSF decats and returned to celtic for my £80 retune and sensor delete. The car made a very flat and unpleasant noise before the remap and I was not getting any sensor errors either!!
After the decat tweak I gained 25BHP!!!!!
Celtic maps are very aggressive I find (and like)...

Pete says the cars driven like that since it was remapped (with cats)....
Rob

 

[mcbutler]

Did you do any runs on the dyno before fitting the decat. If not then I dont think we can criticise any map done for a none decat car. My 35i has a celtic stage 1 map. I had both downpipes replaced by VRSF decats and returned to celtic for my £80 retune and sensor delete. The car made a very flat and unpleasant noise before the remap and I was not getting any sensor errors either!!
After the decat tweak I gained 25BHP!!!!!
Celtic maps are very aggressive I find (and like)...

Pete says the cars driven like that since it was remapped (with cats)....
Rob

Might be a good idea to send a copy of the dyno to celtic for comment, may even get a refund!

 

[Colin_E]

Well my recent Celtic tune (self administered via their eMotion device) seems completely at odds with your comment about dropping gears / building revs to overtake.
The torque & low rev performance made far more of an impression on me than the raw power (not that there was any lack of that either). One of the first things I noticed was a much reduced tendency for my auto box to change down under acceleration. Even switching to sport doesn't always correlate with dropping a couple of gears as it used to.
Nor is that a brief surge which tails off as your graph might suggest.
Of course doing it the the way I did means I don't have any Dyno graphs to prove anything either way!