F80 Stutter under load

[Mattf80]

Hello,

I am new to the forum. I have a 2017 M3 that I recently purchased. It had tune on it when purchased. I have since re tuned it to bootmod stage 2 ACN. Car has downpipes and exhaust. PPI showed no issues except for a crack in rear diff bushing which will be addressed soon.

It feels like it is cutting power when full throttle especially thru 3rd gear. I changed tune hoping that is what it was. I have also replaced spark plugs.

If anyone could chime in and help me figure this out I would greatly appreciate it! I have data logged the car. Hopefully these links below work to view logs.

https://bootmod3.net/log?id=6952d83e532aa95eb3c2e9a0

https://bootmod3.net/log?id=6952d751d04f8b5cfb464ede

https://bootmod3.net/log?id=6952d680532aa95eb3c2e98c

[afadeev]

Originally Posted by Mattf80

I have a 2017 M3 that I recently purchased. It had tune on it when purchased. I have since re tuned it to bootmod stage 2 ACN. Car has downpipes and exhaust. PPI showed no issues except for a crack in rear diff bushing which will be addressed soon.

It feels like it is cutting power when full throttle especially thru 3rd gear. I changed tune hoping that is what it was. I have also replaced spark plugs.

If anyone could chime in and help me figure this out I would greatly appreciate it! I have data logged the car. Hopefully these links below work to view logs.

You bought a hacked-up-car with weird mods that are (not surprisingly) giving you problems.

The simplest thing to do is to revert car to stock, then debug the problems (if still present) from there. If it works stock, re-introduce mods one at a time to find identify the problem (or skip the mods and learn to drive stock ///M3 properly). Otherwise, you will be conflating sub-optimal aftermarket tuning problems with (possibly) underlying issues with the used car.

This assumes you purchased the car with all the OEM parts included. If some are missing, then this is on you, sorry.

HTH,
a

[Mattf80]

Originally Posted by afadeev

You bought a hacked-up-car with weird mods that are (not surprisingly) giving you problems.

The simplest thing to do is to revert car to stock, then debug the problems (if still present) from there. If it works stock, re-introduce mods one at a time to find identify the problem (or skip the mods and learn to drive stock ///M3 properly). Otherwise, you will be conflating sub-optimal aftermarket tuning problems with (possibly) underlying issues with the used car.

This assumes you purchased the car with all the OEM parts included. If some are missing, then this is on you, sorry.

HTH,
a

Thanks for the reply. I do have all stock parts. All work was performed by reputable shop with receipts and maintenance. Down pipe and exhaust is a weird mod? I do appreciate the response and am inclined to agree reverting to stock is a good approach. I am hoping someone would be able to see data logs and and have an idea. Again thanks for the reply!

[NSX2M4]

From what I can read on these graphs, and I do not do tuned motors anymore is that you're targeting 24 PSI from tock turbos in the mid range and running pig rich fueling 11-12 AFR to prevent knock.

[Jaizero]

Originally Posted by Mattf80

Hello,

I am new to the forum. I have a 2017 M3 that I recently purchased. It had tune on it when purchased. I have since re tuned it to bootmod stage 2 ACN. Car has downpipes and exhaust. PPI showed no issues except for a crack in rear diff bushing which will be addressed soon.

It feels like it is cutting power when full throttle especially thru 3rd gear. I changed tune hoping that is what it was. I have also replaced spark plugs.

If anyone could chime in and help me figure this out I would greatly appreciate it! I have data logged the car. Hopefully these links below work to view logs.

https://bootmod3.net/log?id=6952d83e532aa95eb3c2e9a0

https://bootmod3.net/log?id=6952d751d04f8b5cfb464ede

https://bootmod3.net/log?id=6952d680532aa95eb3c2e98c

You have a pretty good sized boost leak from what I can see. You are not reaching the boost target, and your wastegate duty cycle is reflecting this.

There's no knock and very little to no timing corrections so that's good.

I'd be looking for a boost leak anywhere between the turbo outlets and the throttle body inlet.

Clean up your logs, here's a lot of crap in there that isn't needed. I have a couple posts out there that tell what PIDs you should be logging.

[Jaizero]

Originally Posted by NSX2M4

From what I can read on these graphs, and I do not do tuned motors anymore is that you're targeting 24 PSI from tock turbos in the mid range and running pig rich fueling 11-12 AFR to prevent knock.

Based on the ambient pressure in their logs I would bet they are at a higher altitude which would explain why the boost target is higher.

Either that or they are in the eye of a hurricane lol.

[Mattf80]

Originally Posted by Jaizero

You have a pretty good sized boost leak from what I can see. You are not reaching the boost target, and your wastegate duty cycle is reflecting this.

There's no knock and very little to no timing corrections so that's good.

I'd be looking for a boost leak anywhere between the turbo outlets and the throttle body inlet.

Clean up your logs, here's a lot of crap in there that isn't needed. I have a couple posts out there that tell what PIDs you should be logging.

Originally Posted by Jaizero

Based on the ambient pressure in their logs I would bet they are at a higher altitude which would explain why the boost target is higher.

Either that or they are in the eye of a hurricane lol.

I noticed that it wasn’t hitting boost target as well. I was thinking possible boost leak too. I am at higher elevation 4,800’. I will go through your posts and clean up logs. Thank you for the help!!

[Jaizero]

Originally Posted by Mattf80

I noticed that it wasn’t hitting boost target as well. I was thinking possible boost leak too. I am at higher elevation 4,800’. I will go through your posts and clean up logs. Thank you for the help!!

If you're still running the stock charge pipes I would look for any cracks in the pipes along with making sure the rubber O-rings inside the pipes at the turbo outlets are good.

Check the clamps on all of the couplers, you don't want them gorilla tight, this can deform the coupler and cause leaks, I usually torque the clamps to about 33-34 in/lb if you have the stock Norma Breeze clamps. Make sure they are pressed all the way against the intercooler inlets.

Also check the J-pipe coupler to the intercooler and the vent hose going from the J-Pipe to the driver side intake. The O-Rings can dry out on the vent hose and cause leaks. Apply a little bit of silicone lube to the O-rings to make sure they seal well. The same torque can be applied to the clamps on the J-pipe that is used for the charge pipe couplers. You want them tight but not cranked down so tight you can't turn it anymore.

If you haven't replaced the spark plugs, now would be a good time. NGK 97506 torqued to 18 ft/lbs (25nm) and gapped to 0.022-0.023 per Pro Tuning Freaks recommendations for BM3 OTS tunes.

It's possible you are running the stock spark plug gap if the car has never been tuned before. The stock gap is too loose for a tuned S55 and can cause misfires like you are experiencing.

Here is a DIY for the spark plugs. It's a bit of a pain the first time lol. https://f80.bimmerpost.com/forums/sh....php?t=1401532

[f80ma212]

Following, May be having a similar issue. Did you get this figured out?

[Mattf80]

Originally Posted by f80ma212

Following, May be having a similar issue. Did you get this figured out?

No, I have not.

[Mattf80]

Originally Posted by Jaizero

If you're still running the stock charge pipes I would look for any cracks in the pipes along with making sure the rubber O-rings inside the pipes at the turbo outlets are good.

Check the clamps on all of the couplers, you don't want them gorilla tight, this can deform the coupler and cause leaks, I usually torque the clamps to about 33-34 in/lb if you have the stock Norma Breeze clamps. Make sure they are pressed all the way against the intercooler inlets.

Also check the J-pipe coupler to the intercooler and the vent hose going from the J-Pipe to the driver side intake. The O-Rings can dry out on the vent hose and cause leaks. Apply a little bit of silicone lube to the O-rings to make sure they seal well. The same torque can be applied to the clamps on the J-pipe that is used for the charge pipe couplers. You want them tight but not cranked down so tight you can't turn it anymore.

If you haven't replaced the spark plugs, now would be a good time. NGK 97506 torqued to 18 ft/lbs (25nm) and gapped to 0.022-0.023 per Pro Tuning Freaks recommendations for BM3 OTS tunes.

It's possible you are running the stock spark plug gap if the car has never been tuned before. The stock gap is too loose for a tuned S55 and can cause misfires like you are experiencing.

Here is a DIY for the spark plugs. It's a bit of a pain the first time lol. https://f80.bimmerpost.com/forums/showthread.php?t=1401532

I will check all clamps and couplers. I have changed spark plugs for ngk97506 and gapped to .023.

I tried looking thru your posts and haven’t seen where you recommended why pids to log. Would you be able to let me know what I should be logging?

Thank you!