[Run262]

Hi all,

I have a 1994 968 with Tiptronic. Just recently, whenever I engage to Drive or R position, the engine shakes and stumbles like misfiring. I tried to drive, using tiptronic setting at 2 and push the gas down hard, the engine smooths out and power seemed to be back. By the way it idles smoothly!

Is it a vacuum leak or ignition components, cap & roror and wires, going bad? Please help



MinhD

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[flash]

with it at "2", when you step on it hard, what happens is that it downshifts to first gear. see if it runs right by manually putting it in first and shifting manually.

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[Run262]

Hi Flash, I did shifted manually. At 1,2 or 3 if I keep the rpm up, the engine smooths out!

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[flash]

what do you mean :if i keep the rpm up"? how high do you have to go? it should be smooth right off idle.



what i am trying to determine is if the problem is engine or transmission related, and to do that, we need to see if it acts differently in the same gear, at the same rpm, whether in tip mode or manual mode.

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[Run262]

Let me say it again,

-at idle engine runs smoothly in park

-start put it in gear, either D, R or manually 1,2,.. engine shakes like misfiring

-if I hold the brake and rev'ed the engine high to 3000 rpm or higher, the "misfiring" stopped, no more shaking!

Does it make more sense. Thank you.



MinhD

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[flash]

not sure how you hold the brake, in gear, and rev it to 3k. that should be snapping stuff all over the place



does it "misfire" in neutral?



if you are driving, and gradually accelerate, from low rpm to high, does the misfire go away abruptly or gradually?

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[Run262]

No it does not "misfire" in neutral.

When I am driving and accelerate it seems the car abruptly stop the misfiring! If I keep on increasing the rpm, it runs like a champ.



MinhD

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[flash]

i'm thinking you should look at your motor mounts. when they fail on a tip, the car will shake violently and rattle like in its death throws. a smooth acceleration, or revving when not under load, will minimize this

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[Porsche968CS]

I put my money on the damper plate... We had exactly the same symptoms two months ago.

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[Run262]

Thanks, Flash!

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[flash]

could be the damper. typically though there should be a "clank" sound that accompanies the problem

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[Run262]

[quote name='Porsche968CS' timestamp='1377719229' post='148223']

I put my money on the damper plate... We had exactly the same symptoms two months ago.

[/quote]



What is the damper plate? How did you fix it?

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[flash]

to fix the damper, you have to remove the transmission and torque tube. the part is about a grand. labor is 12-16 hours

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[Porsche968CS]

That is the rubber piece between flywheel and torque tube. Unfortunately (this is not what you want to hear) it's a pig to replace. You can try to check its condition by looking thru the inspection hole in the front bellhousing.



Here is another example:



http://m.youtube.com/watch?v=v5i88fdA5rI...5i88fdA5rI

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[Run262]

Thank you!

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[Inkedupfatboy]

I hope that damper thing is a tip problem and not a manual thing - I have spent enough money on this car already

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[Run262]

Yeah, it's expensive parts for either motor mounts and damper plate!!!



Anyone has removed a 968 transmission before? I did removed a Honda Accord manual transmission and it was not that bad.

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[flash]

the tip is a bugger. because it's a transaxle, it's big, heavy and awkward. it also must be completely disconnected from the torque tube, which must also be removed. with the manual box, it's a lot easier

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[gbarrier]

Keep holding the brakes and revving it to 3,000. The new flex plate AND motor mounts you'll need should solve the problem.

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[Run262]

[quote name='gbarrier' timestamp='1377729318' post='148254']

Keep holding the brakes and revving it to 3,000. The new flex plate AND motor mounts you'll need should solve the problem.

[/quote]



Well, sorry for my English! I was telling that to Flesh just for illustrating my points. The more I rev the engine when I drive, the smoother the engine is running.

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