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06-17-2013, 05:37 PM | #1 |
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Lunging on cold start in first
I know this is a common "problem" but I am wondering how bad it is for people. Taking off normal to quickly in first on a cold start I will sometimes get intense lunging where it seems impossible to modulate the throttle (especially while my body is being jerked back and forth). Definitely has passengers to go WTF. I usually throw the clutch in and shift to second to stop it and smooth sailing from there.
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06-17-2013, 05:40 PM | #2 |
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Normal unfortunately. Cold, high revving race motor has to have some trade offs
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06-17-2013, 05:42 PM | #3 |
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It's pretty normal for a manual transmssion car. At cold start, the RPM is higher than the regular idle RPM. When you engage the clutch it is at a higher RPM so if you drive it as you normally would, it will shoot forward like you describe. Also, the engine is in open loop operation so the gas pedal will seem to be more sensitive than normal - that causes the jerkiness.
Best thing is to wait about 20 seconds for the idle RPM to go back down to normal (under 1000 rpm) then drive... or modulate your clutch and gas foot better so it doesn't do it. This is perfectly normal behavior on a manual transmission car... I've had this on all my previous manual cars.
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06-17-2013, 05:55 PM | #4 |
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Also happens with DCT as well, but less prone. DCT seems to slip a bit or engage more slowly on cold start.
Having the cold start disabled significantly increased the cold drivability.
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06-17-2013, 06:04 PM | #5 |
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Yeah let it warm up a bit, even for a little bit. Don't just get in, start up and expect to jam.
Don't worry you'll get used to this (like we all did) and you'll develop a sense of touch on the gas and clutch. Smooth and gentle on the gas so you won't look like a kook in front of your friends. Save the show time for when the engine warms up. I bet when you try some hard acceleration later on you will experience some "speed wobbles" as your foot goes back and forth during acceleration. Your friends will be saying "wtf" at that time too lol!
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06-18-2013, 05:38 AM | #6 |
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doesnt disabling the cold start have negative effects? i assume that process is doing SOMETHING to the engine.
plus, i love the way it sounds all clanky and grumpy
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06-18-2013, 06:01 AM | #7 |
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On my car, putting throttle response on normal rather than sport when the engine is cold reduces the trailer hitching feel considerably.
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06-18-2013, 06:07 AM | #8 |
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Clutch in, give it a little blip and try again. This behavior is completely normal, although its severity seems pretty random. Sometimes I only get a little chugging, sometimes a lot.
By the way, this is not an M3-only thing. My 6MT 335i did it as well...owned that car for 4 years and I never understood why it did this. Kinda felt better about it when the M did it too
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06-18-2013, 09:07 AM | #10 |
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06-18-2013, 10:56 AM | #11 |
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Cold start is for warming up the cats. My understanding is that it serves no other purpose. Many people remove this feature when they switch to no cats or high flow cats. Cold start became obnoxiously boomy/loud after switching to the evo exhaust.
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06-18-2013, 12:04 PM | #12 |
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The day I installed my catless setup both of my neighbors came out of their houses after I started it up to see what all the noise was about. My wife also said she could feel the house shaking. Needless to say I got cold start tuned out. Initial driveability is much improved but I do miss the sound. Unfortunately, nobody else shared my enthusiasm for it.
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06-19-2013, 03:45 AM | #13 | |
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06-19-2013, 09:45 AM | #15 | |
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Like you said, a quick kick at the clutch usually alleviates it and I can modulate the throttle and clutch engagement to eliminate it as much as possible. |
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06-19-2013, 11:29 AM | #16 | |
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06-19-2013, 12:15 PM | #17 |
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06-19-2013, 12:45 PM | #18 | |
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Exactly.. Or buy her something at the same time always works too.. "Honey, I need engine software to make my car go Vrooom, here's a diamond ring for you" "I love you"
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06-19-2013, 12:53 PM | #19 |
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When it happens I just lift off throttle for a second and then is fine
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06-19-2013, 08:58 PM | #20 |
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