Inconsistent Horsepower

[LRGM3]

Hi all, I have a 2015 M3 with the BM3, Intake/charge pipes, midpipe but otherwise the car is stock.

I have tried both the Stage 1 91 octane, as well as the Stage 1 93 octane tune but am having the same issue.

The problem is, the car feels inconsistent on how much power it is making. I tried to match it to air temp, or other conditions, but there is a noticeable difference. This isn't like a butt dyno thing where sometimes it feels a bit faster, it is noticeable faster as confirmed by myself and many other people, feeling like a 400hp car vs a mid 500 hp car like I think it should.

It actually feels like it starts to make more power when I am part throttle, vs when I go to full throttle - perhaps due to timing.


I sent the datalog that I have posted here to Protuning, and they said they thought the octane that I had was no good.

I have tried adding octane booster ( this was on Chevron 94 in canada, which I have heard has had its negative reviews), but I didnt notice much of a difference.


This log was taken before the octane booster on Chevron 94 only. The pulls are not great since I didnt have a place to do some really fast/long ones, but if you look at the first part of the graph when Im in 3rd gear, or the last part of the graph 3rd/4th, it looks as though the timing is quite inconsistent/low compared to other graphs ive seen. Also, I think the laptop lost connection on one part of the log as it moved around but ignore that.

The car also has stock spark plugs ( only 20,000 KMS / 12,500 Miles on it) but I wondered if that could be an issue.

Any advice would be great!

Thanks!

https://www.bootmod3.net/log?id=5efa...90c615652d4c52

[LRGM3]

For reference, this is another stage 1 datalog I saw - at the same RPM etc there is a lot more (and consistent) timing (although the IAT is lower)

https://www.bootmod3.net/log?id=5df5...729b7bf244d256

[Twistm4]

Originally Posted by LRGM3

For reference, this is another stage 1 datalog I saw - at the same RPM etc there is a lot more (and consistent) timing (although the IAT is lower)

https://www.bootmod3.net/log?id=5df5...729b7bf244d256

Your timing is getting all sorts of correction. Try better gas. Also check plugs. Try putting 3 gallons of e85 in to help up the octane without resorting to nasty octane boosters. However, the way it looks it seems like it could be plugs or a mix of both.

[LRGM3]

Originally Posted by Twistm4

Your timing is getting all sorts of correction. Try better gas. Also check plugs. Try putting 3 gallons of e85 in to help up the octane without resorting to nasty octane boosters. However, the way it looks it seems like it could be plugs or a mix of both.

Thanks for the reply! I will try some E85 and also changes the plugs and report back!

[TKT2SPEED]

Your first log posted has almost 6 degrees less timing than your cold IAT post. I think mostly your feeling the timing being backed down probably from poor fuel. Be happy its is otherwise you may be looking at a bigger problem.

Significant difference in Iat's between both logs your ambient temps must have been hugely different? That going to make the car power level feel different too but no where near as much as 6 or 6 degrees of timing.

[Twistm4]

Just to add here. Octane boosters do work. The problem is they leave behind some pretty nasty residues that stay on nearly everything it touches. On my mk7s I would run octane boosters and notice the plugs life would be significantly decreased. I ran it once or twice on this platform but also had to change plugs. Considering its about a 3-4 hour job for someone that's even done a dozen of them already it really isn't worth it with e85 and fuels like ignite so available.

[LRGM3]

Originally Posted by TKT2SPEED

Your first log posted has almost 6 degrees less timing than your cold IAT post. I think mostly your feeling the timing being backed down probably from poor fuel. Be happy its is otherwise you may be looking at a bigger problem.

Significant difference in Iat's between both logs your ambient temps must have been hugely different? That going to make the car power level feel different too but no where near as much as 6 or 6 degrees of timing.

Hey there, thanks for the added reply.

I definitely did not make it clear what the two logs were from - the second log with the colder IAT (and higher timing) was another vehicle - just a BM3 log I found online from someone with the same tune - I was simply using it as a reference point but maybe not a good one since the conditions were so different!

I will be trying to get to the E85 station today ( there's only one a ways from me ) and am looking forward to reporting back!

[Bmwlmr99]

which tune?