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      07-14-2017, 01:12 PM   #1
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Last edited by NO_USER_; 12-24-2018 at 02:57 PM..
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      07-16-2017, 07:24 AM   #2
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Quote:
Originally Posted by inline6ax View Post
Hi, people with catless downpipes on their M2, two questions for you:

1: What does your idle sound like after warmed up? Mine pulsates (about 70-80 rpm up/down via P3 gauge). It's consistent and you can hear it, but you barely see the needle move, if at all. Is that normal? I removed my intake as well to see, as the MAF is sensitive.. Tried both on a flash tune and stock tune.

2: If you have the chance to try (after a drive/warmed up), could you put the car in neutral (I have the manual 6 speed), tap the throttle quickly to raise the revs 300-450 rpm and let it drop. Does it drop back down under the idle rpm and almost seems like the car will die/stall (makes that sound and vibration feeling as if you're about to stall). Is that normal?

My car does both of these things when it's fully warmed/after a drive. Can't figure out if it's normal or not, doesn't seem right, but I've never been catless before. Happens with or without a tune, and with or without an intake. Initially thought it could be tune related/could be fixed. Could it be a boost/vacuum leak?

Any help is much appreciated!! Thanks!
I don't have an M2 but I have an n55 335i f30. My 2012 f30 was stock an never did it. However my stock 2013 does and til this day it'll pulsate one in a while. It's more pronounced with my downpipe now. Never had any issues though.
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      07-16-2017, 03:18 PM   #3
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Yup my M2 has had an off idle since I slapped my vrsf catless dp on. My 335xi with the same DP did the same aw well.
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      07-16-2017, 09:22 PM   #4
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Quote:
Originally Posted by Jadar View Post
I don't have an M2 but I have an n55 335i f30. My 2012 f30 was stock an never did it. However my stock 2013 does and til this day it'll pulsate one in a while. It's more pronounced with my downpipe now. Never had any issues though.
So it isn't always pulsating only sometimes? Mines always like that.
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      07-16-2017, 09:23 PM   #5
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Yup my M2 has had an off idle since I slapped my vrsf catless dp on. My 335xi with the same DP did the same aw well.
Thanks for letting me know!
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      07-16-2017, 10:08 PM   #6
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All normal. Without a tune
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      07-16-2017, 10:12 PM   #7
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Originally Posted by Twix View Post
All normal. Without a tune
My tune didn't fix that though...
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      07-17-2017, 05:30 AM   #8
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Yup tune or no tune it does it. Even on my dinan stage 4 big turbo upgrade
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      07-18-2017, 12:21 AM   #9
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What causes it to do that tho? Not enough backpressure due to being catless?
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      07-18-2017, 01:47 AM   #10
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I'm gonna go out on a limb here and say it's from a specific company's DP.
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      07-20-2017, 01:19 AM   #11
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none here but i did have it on the 135i with dp's
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      07-21-2017, 02:34 AM   #12
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Does anyone have the issue with the rpm dropping and almost dying with a quick tap of the throttle?
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      07-21-2017, 10:41 AM   #13
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Quote:
Originally Posted by Bimmer28312 View Post
I'm gonna go out on a limb here and say it's from a specific company's DP.
Mine has done it stock and with 2 different brand down pipes I think it could be related to injectors or maybe even the way the car cold starts. Once it warms up about 30-60 sec it stops.
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      07-21-2017, 11:29 AM   #14
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Quote:
Originally Posted by inline6ax View Post
Does anyone have the issue with the rpm dropping and almost dying with a quick tap of the throttle?
Damn that's bad no not that extreme for me. It's just lumpy for me. I've learned to live w it now almost 3 years.
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      07-23-2017, 04:52 AM   #15
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Quote:
Originally Posted by inline6ax View Post
Does anyone have the issue with the rpm dropping and almost dying with a quick tap of the throttle?
It used to happen on my 1M before I had the HPFP replaced, not sure if it was ever related but after I had the new "version" of the pump installed it never did it again. *I didn't replace the HPFP because of that, had to be done cause I had the other classic issues*

It was a very mild drop though that you cold see from the needle and feel, but not that severe to say the engine was almost stalling

Maybe fuel related issue? Have you tried refueling somewhere else or trying different gas?

Forgot to mention: stock car, no downpipes

Last edited by Alby_416; 07-23-2017 at 05:01 AM.. Reason: more info
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      07-23-2017, 08:26 AM   #16
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1: I have same movement of RPM via P3 gauge (50-70rpm). MPE only, stock downpipe, MT. Can hear it when outside the car and more pronounced at cold start up.

2: I get a similar occurrence at cold start up only. Sounds like it bogs down and may stall. Only happens for about 3 - 5 seconds.

Took to dealer for both situations and was told N55 do idle somewhat rough and with the MPE allows for it to be heard more clearly. I left the car at the dealer over night so they could get a cold start. They did ask if I had performed a tune in the car, but I hadn't and also suggested running 89 Octane over 91. I haven't as this seems like an odd solution.
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      07-23-2017, 11:54 AM   #17
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It's a searching idle due to the mixture of your MAF reading and 02 readings. A proper flash tune WILL sort it out, one designed for a catless setup. If someone takes the time to mess with those tables. Are you on the stock Intake? I noticed more idle issues due to the Intake vs the DP.

Honestly I'm not sure if it does anything harmful. I'm catless and I'm thinking the benefits of better flow and less restriction outweigh any idle issues. Any issues I would foresee would come at the end of the engines life. Slightly more wear on injectors/fuel system due to pulsing and possibly premature plug wear from rich conditions under vacuum.

The stumble is no fun when coming off throttle but that's the result of a AFR ratio that's constantly trying to self correct in a slightly rich/lean sway. Bootmod3 should do the trick.
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      07-23-2017, 01:13 PM   #18
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I've tried with stock and an Eventuri Intake, same results. So it seems the pulsating idle is normal? I use 91 gas from my normal spot and I've never had issues with fuel, so I don't think it's that. My issues aren't at cold start however it's after being warmed up. And the needle drop is very mild, and you slightly hear the engine is about to die it makes that weird "stalling" sound pretty quickly then comes back up to normal.

Thanks for all of your inputs guys!!
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      07-23-2017, 10:26 PM   #19
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Quote:
Originally Posted by inline6ax View Post
I've tried with stock and an Eventuri Intake, same results. So it seems the pulsating idle is normal? I use 91 gas from my normal spot and I've never had issues with fuel, so I don't think it's that. My issues aren't at cold start however it's after being warmed up. And the needle drop is very mild, and you slightly hear the engine is about to die it makes that weird "stalling" sound pretty quickly then comes back up to normal.

Thanks for all of your inputs guys!!
Okay cool. If it makes you feel better I think it's 100% normal. It seems this car running catless DP's without a tune to compensate will do it regardless. That low throttle dips bug me as well. I don't worry about it much though.

Maybe somebody has more insight into "leaning on sensors" to keep the car from stalling. Something is obviously working harder and not "happy". I'm just not sure if what's "stressed" is a quick wear item/parts or not.
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      07-24-2017, 09:10 PM   #20
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Quote:
Originally Posted by inline6ax View Post
Quote:
Originally Posted by ashburyn54 View Post
Okay cool. If it makes you feel better I think it's 100% normal. It seems this car running catless DP's without a tune to compensate will do it regardless. That low throttle dips bug me as well. I don't worry about it much though.

Maybe somebody has more insight into "leaning on sensors" to keep the car from stalling. Something is obviously working harder and not "happy". I'm just not sure if what's "stressed" is a quick wear item/parts or not.
VF tune doesn't fix it however...

Stock vs HEX it's the same thing for me regarding idle
That's strange. Maybe ask for revision? I'm sure PTF would let you know if there's doesn't, so you have something to work off of with VF.
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      07-25-2017, 10:45 AM   #21
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Quote:
Originally Posted by inline6ax View Post
Quote:
Originally Posted by ashburyn54 View Post
That's strange. Maybe ask for revision? I'm sure PTF would let you know if there's doesn't, so you have something to work off of with VF.
Yeah, they don't do revisions...

Just asking for a map without burble, been a month still nothing...whether it's trying to figure out why mine doesn't stop burbling or providing a map without burble so I can atleast enjoy the car.

PTF said tune + plugs could help...but also mentioned the N55 idle is sometimes rough from being catless. Atleast they provide some type of an answer, and a possible solution...
That's a bummer man. That's why I love the open source feel mixed with great custom options and service from PTF. I'll jump on the bandwagon soon enough. I'm waiting to see if someone cracks the ECU without pulling it out.
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      07-25-2017, 11:32 AM   #22
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That's a bummer man. That's why I love the open source feel mixed with great custom options and service from PTF. I'll jump on the bandwagon soon enough. I'm waiting to see if someone cracks the ECU without pulling it out.
Yeah man...

I say go for it! I don't think they'll figure out how to unlock the DME without removing it anytime soon (I'm sure they already know if it's even possible or not), that would be cool tho!!
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