Problem with MY99 911 Tiptronic.
01-17-2011, 07:42 PM
#1
Drifting
Thread Starter
Problem with MY99 911 Tiptronic.
Hi! My 99 911 tip is acting funny and I just wondered if anyone else had experienced this.
Under hard acceleration, everything is normal but, when you are just normal-driving in auto mode, you can feel what feels like the clutches slightly engaging, then releasing, as though it were searching for a gear. It is like you were driving a manual with your foot on the clutch and just slightly pressing then letting off. The RPM's will rev about 100 RPM's then drop back down to normal. This happens about every 2 seconds as you accelerate. Also, if you shift to manual mode, the steering wheel switches don't work, while this is happening. Once in a while, it will not do this and the switches will work in manual made but probably 90% of the time it acts up as explained above.
I hope that describes what is going on well enough. If you have experienced anything like this, please let me glean any information you may have about it. I would just like to have an idea of what I am talking about before I take it to a tech! Thank you in advance!!!
Under hard acceleration, everything is normal but, when you are just normal-driving in auto mode, you can feel what feels like the clutches slightly engaging, then releasing, as though it were searching for a gear. It is like you were driving a manual with your foot on the clutch and just slightly pressing then letting off. The RPM's will rev about 100 RPM's then drop back down to normal. This happens about every 2 seconds as you accelerate. Also, if you shift to manual mode, the steering wheel switches don't work, while this is happening. Once in a while, it will not do this and the switches will work in manual made but probably 90% of the time it acts up as explained above.
I hope that describes what is going on well enough. If you have experienced anything like this, please let me glean any information you may have about it. I would just like to have an idea of what I am talking about before I take it to a tech! Thank you in advance!!!
01-17-2011, 09:36 PM
#2
I don't have any solutions for you, but I have some thoughts. I've got a tip and every once in a while, it will "surge" as you described, though it is pretty subtle and it only happens between 2,000 and 2,500 RPM in second gear.
I've recently learned that the tip torque converter has a lock-up clutch that is programmed to lock-up at certain RPM ranges. This locks the tranny to the engine speed so you get full power transfer. So my guess is that you may be right at the transition of the lock range and the tip computer is locking and unlocking the stator, or you have a physical or electrical fault with the lock-up clutch in your torque converter.
Just found this info on common auto tranny trouble on google that may be of some help: http://www.aa1car.com/library/2003/ic60340.htm
I've recently learned that the tip torque converter has a lock-up clutch that is programmed to lock-up at certain RPM ranges. This locks the tranny to the engine speed so you get full power transfer. So my guess is that you may be right at the transition of the lock range and the tip computer is locking and unlocking the stator, or you have a physical or electrical fault with the lock-up clutch in your torque converter.
Just found this info on common auto tranny trouble on google that may be of some help: http://www.aa1car.com/library/2003/ic60340.htm
Most late-model automatics have some type of lockup torque converter to improve fuel economy. If the lockup fails to engage, there will be some slippage and fuel economy will drop. Causes here include a bad lockup solenoid, incorrect sensor input information to the transmission controller or PCM (typically a speed sensor) and hydraulic control problems. If the lockup fails to release, the engine may shudder and die when coming to a stop. Causes here include a faulty lockup solenoid, a sticking lockup valve, grounded lockup solenoid wiring or a missing lockup solenoid spacer plate screen.
Lockup shudder is another complaint that may be encountered. This refers to a vibration that is felt just before or after lockup occurs. This kind of problem can be hard to diagnose because the cause may be the torque converter, transmission or engine. Bad motor mounts, engine misfire, a bad CV joint or U-joint, etc. can all cause vibrations that may be felt as a shudder throughout the drivetrain.
Lock-up stall test:
A "stall test" can be used on many transmissions to check its ability to hold torque and the operation of the converter one-way clutch. Some manufacturers don't recommend using a stall test because it stresses the transmission, so if you use this procedure, do not do it for more than five seconds at a time. Before conducting a stall test, check the fluid level and condition. Chock the wheels and set the parking brake. Start the engine and place the transmission in drive while holding the brake pedal under firm pressure so the vehicle doesn't move. Then push the accelerator to the floor while holding the brakes on. Note the maximum rpm that the engine reaches. This is the stall speed. If it is lower than specifications, the torque converter one-way clutch is slipping. If the stall speed is higher than specifications, the transmission is slipping. Possible causes include a low fluid level, restricted fluid filter, a sticking pressure regulator valve, slipping clutches, bands, shaft splines or one-way clutch.
Lockup shudder is another complaint that may be encountered. This refers to a vibration that is felt just before or after lockup occurs. This kind of problem can be hard to diagnose because the cause may be the torque converter, transmission or engine. Bad motor mounts, engine misfire, a bad CV joint or U-joint, etc. can all cause vibrations that may be felt as a shudder throughout the drivetrain.
Lock-up stall test:
A "stall test" can be used on many transmissions to check its ability to hold torque and the operation of the converter one-way clutch. Some manufacturers don't recommend using a stall test because it stresses the transmission, so if you use this procedure, do not do it for more than five seconds at a time. Before conducting a stall test, check the fluid level and condition. Chock the wheels and set the parking brake. Start the engine and place the transmission in drive while holding the brake pedal under firm pressure so the vehicle doesn't move. Then push the accelerator to the floor while holding the brakes on. Note the maximum rpm that the engine reaches. This is the stall speed. If it is lower than specifications, the torque converter one-way clutch is slipping. If the stall speed is higher than specifications, the transmission is slipping. Possible causes include a low fluid level, restricted fluid filter, a sticking pressure regulator valve, slipping clutches, bands, shaft splines or one-way clutch.
01-19-2011, 03:45 AM
#3
Rennlist Member
While you first description sounds like the Lockup engagement - the point about the Tip Switches not working make me suspect you have a problem. First thing to check would be fluid level but if it where mine I would have it looked at pronto. These Tip Trannys are very reliable, but you do not say how old the car is - miles, and the history of maint i.e. service to the transmission? This could be simple - speed sensor - or the beginning of something serious. These things need a pro to evaluate.
08-20-2011, 02:14 AM
#4
2nd Gear
Join Date: Aug 2011
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Hi Slick,
i dont have any answers for you either, but am experiencing very similar symptoms in my '00 Boxster S. Have you had any luck getting yours to work properly? i'd be keen to hear what the fix was.
in mine, it seems as though the torque converter has stopped locking up, which results in the fluctuating revs under load since it's operating just like a normal slush box without a lockup mode.
regarding the shift buttons, i have found that mine work with the steering wheel adjusted to be in close to the dash, but when extended out they dont work 90% of the time. i put this down to a dodgy earth or loose plug behind the steering wheel, but havent had a chance to go digging for it yet.
has anyone else had problems with the torque converter lock up??
i dont have any answers for you either, but am experiencing very similar symptoms in my '00 Boxster S. Have you had any luck getting yours to work properly? i'd be keen to hear what the fix was.
in mine, it seems as though the torque converter has stopped locking up, which results in the fluctuating revs under load since it's operating just like a normal slush box without a lockup mode.
regarding the shift buttons, i have found that mine work with the steering wheel adjusted to be in close to the dash, but when extended out they dont work 90% of the time. i put this down to a dodgy earth or loose plug behind the steering wheel, but havent had a chance to go digging for it yet.
has anyone else had problems with the torque converter lock up??
08-20-2011, 12:09 PM
#5
Rennlist Member
Are we talking after warmup? Until temps get up to "normal"...Mine does that also but goes away once the temps are up...either way...i can switch to manual without a problem..cold or hot
I would start with why you can't switch to manual
I would start with why you can't switch to manual
