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      04-13-2014, 04:17 AM   #1
Juggernaught5
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hesitancy at speed when turning

I've noticed a hesitancy when turning at speed, such on a wide radius turn on the freeway. It occurs when going about 60 to 80 mph. It feels like the car gets hit with a gust of wind, and cycles irregularly. I'm not noticing any steering vibration, change in rpm or engine noise, or the issue occurring on slower or tighter turns. It goes away when the turn is complete.

Has anyone else experienced this?
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      04-13-2014, 08:39 AM   #2
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What condition are your tires in, and when was your last alignment?
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      04-13-2014, 10:38 AM   #3
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Have you replaced your rear trailing arm bushing (RTAB). Under acceleration a worn out one can make turning feel really odd. Kinda like the back of your car doesn't want to turn.
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      04-13-2014, 08:18 PM   #4
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Tires are fairly new, and were just aligned a month ago when the brakes were redone. I'll check the trailing arms - thanks!
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      04-14-2014, 02:15 AM   #5
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RTABs for sure. When I was under the car to change them (before I realized I was sent the wrong ones...) I grabbed the trailing arm and moved it in all sorts of directions. Also, my rear tires are worn significantly more on the insides than out, and much much more than the fronts.

Hope this is the case for you. easy fix! and an excuse to get powerflex. haha
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      04-14-2014, 03:14 AM   #6
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Are you refering to engine hesitancy? if so I'm not so sure trailing arms are the culprit. My first inclination is towards fuel delivery. How full is your gas tank when this happens? does it happen on turns to both directions or just one?

I had an old mazda that when I threw it into a corner to the left when the tank was low the car would almost die right out. The first few times it happened it was actually a little scary until I figured out why it was doing it.

I'm not familiar with where in the tank the fuel pump draws from on these cars but it might just be a configuration issue. Try keeping the tank relatively full for a bit and see if it continues.

I tend to explore the simplest and easiest possibilites first

Good luck!
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      04-14-2014, 09:01 AM   #7
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Oil level
Traction Control
RTABs

check those in order? (re the Traction Control just shut it off and go take the same corner)

I have bigger tires in the rear than on the front so my TC went bonkers before I realized what was happening. Now I just hit the fun button before I go anywhere.
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      04-14-2014, 05:10 PM   #8
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I only notice it at high speed, on the freeway - wide radius curves. It literally feels like a huge gust of wind - a brief slowing, that will pulse two-three times during the curve. It happens regardless of fuel level.

I have the sport suspension with wider rear tires and 19 inch wheels, with run flats. I have to take the freeway tonight - will turn off the DTC and see if this changes anything.
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      04-14-2014, 09:49 PM   #9
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What are your tire sizes front and rear?
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      04-15-2014, 02:30 PM   #10
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Quote:
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What are your tire sizes front and rear?
dis man knows what i'm talkin about
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      04-16-2014, 11:16 AM   #11
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Turns out I have 18 inch wheels - BMW 108 two piece.

Front tires are: Yokahama Advan Sport Z.P.S 225/40 RF 18

Rear tires are: Bridgestone Potenza 255/35 R 18

Size-wise, these match the sizes on the tire sticker on the door jam. Both sets appear fairly new - quite a bit of tread left. I've only had the car for two months now, so I don't know when they were installed.

The issue still occurred with the DTC off. It feels less pronounced during right turns than left.
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      04-16-2014, 11:20 AM   #12
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It looks like you have Run Flat Tires (RFT) on the front and not the back. RFT's are notorious for tramlining. search it on here. Might explain what you're feeling especially if you are new to this car. I find it's more pronounced on the highway due to the grooves in the road.

Just a thought....
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      04-16-2014, 11:34 AM   #13
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Are you trying to approach these high speed sweeping turns at speeds significantly higher than the posted recommended speed, or are you just cruising through these "turns" like everyone else?
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      04-16-2014, 01:24 PM   #14
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I thought it was a sideways gust of wind when I mentioned the RTAB. Now I'm thinking fuel delivery. How many miles on your car? Have u ever changed the fuel filter?
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      04-16-2014, 02:53 PM   #15
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Quote:
Originally Posted by Jumbosock View Post
I thought it was a sideways gust of wind when I mentioned the RTAB. Now I'm thinking fuel delivery. How many miles on your car? Have u ever changed the fuel filter?
Aren't these internal? They are only "visually" inspected on the second service interval.
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      04-16-2014, 03:54 PM   #16
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The fuel filter looks like a PITA to get to since its internal but it IS changeable.
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      04-24-2014, 02:30 PM   #17
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So I've spent a week trying to repeat this with some sort of consistency on various freeway and street curves. I'm going to rule out the fuel pump, as I'm not seeing any drop in revs and the hesitancy isn't as abrupt as I would expect if there was a loss of fuel to the engine. There seems to be a correlation with a change in the roadway (expansion joint, tarmac wear) that suggests to me that the issue is tire related. Perhaps the run flats in the front have some sort of play in them that's not transmitting through the steering wheel? Or they are tramming...

The alignment appears on-track if I drive and let go of the steering wheel - wondering if this may be a bushing issue...
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      08-13-2014, 09:53 AM   #18
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I just came back from Los Angeles, where this issue made driving on the poorly maintained freeways there terrifying. I put the car in the shop, and it's been diagnosed with 1) the left rear tire has odd camber, causing the car to swing out during turns, 2) both front tires have excessive toe-in, and 3) the run flats on the front (Yokohama Advan Sport Z.P.S) are tramming along any irregularity in the road. My mechanic stated he thinks they are the worse tires he's experienced this issue with.

Correcting the alignment issues has done wonders, and I'm going to get non-run flats this weekend to match the rear non-RF tires (Bridgestone Potenzas).
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