[t.webber@telus.net]

I have a 92 Tip coupe with 21k miles (Japanese import to Canada), so vacuum lines and rubbers are likely very dried out. Searched Renntech forum for same symptoms (924/944968) and found 6 common threads, with various cures proposed, hmmm.



My situation;

1) vibration effect is worst at cold start, then improves slightly when engine warm.

2) Replaced motor mounts (just done) makes vibration more noticeable.

3) Very Slight hunting (up/down) in the idle speed, cold or hot.

4) Vibr increases slightly when AC clutch is energised.

5) Vibr more intense when trans placed in drive, less intense in neutral.

6) No evidence of drivetrain slop or unusual bucking at 2500rpm in 2nd when float/coast/drive/float/coast/drive routine is done.

7) No abnormal vibration at ~ 3000 rpm. All ist gut >1300 rpm, except;

8) Will vibrate when lugging down in 4th < 1800 rpm at part throttle.

9) Soggy response when moderately blipping the throttle in neutral (at least, not as crisp as I would think a port-injected DME Porsche should be)



My plan of attack right now is as follows: 1) verify Tip motor mount version is installed. 2) verify balance shaft belt timing. 3) check fuel pressure reg (would love to know if Short-term Fuel Trim can be observed in DME 2.1 diagnostics - this would identify a vacuum leak, no?) and fuel pressure & manifold vacuum readings. 4) Re & Re intake, clean it and ISC and replace vacuum tube systems. 5) Inspect for driveshaft slop (free rotation through a few degrees) at trans end of torque-tube. 6) Re & Re torque tube and inspect rubber cush drive.



Comments, anyone, before I start this quest. Am I doing this in sensible economical order?

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[borz]

Tim, I have no suggestions to help remedy your problem but coincidently I just checked out a 968 tip in Florida that had the identical issues. I was all set to buy this car, price was right, lots of maintenance done, belts, motor mounts, brakes, seemed like a good deal to import into Canada. Went for a test drive , started the car and was surprized at the vibration, worse when engaged into drive, the car seemed to run smooth above idle but seemed a little lacking in response and acceleration. Bottom line, the vibration scared me away from making a deal , but I'm looking forward to hearing any reponses you get from the experts on this forum.

Ed

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[oppositelock]

Tim,

Your diagnostics are in good order. With number 2 definatly check that the engine timing is spot on. Mileage would indicate belts not being done, but may have been. If belts not done or inspection is indeterminate, then do belts NOW because of age. With numbers 3 and 4, it would be a very good idea to have injectors cleaned and checked. Again because of low mileage and sitting, injectors probably have varnish build up. Vibration very unlikely to be in driveline.

Good luck, Mitch

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[968crazy]

balane shaft is easy to mess up and if it is that you need to watch out because the vibration can start breaking parts like belt adjusters or even a/c compressors. usually it the belts are messed up someone has it 180degrees out its easy to screw up

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[968workaholic]

Take the big plug out of the tranis and try to move the torque converter. If you can do that to a point that seems excessive, your dampner plate is torn=$$$ <img src="/forum/images/smilies/968/mad.gif" class="smilie" alt="" /> That would be one the bottom of your list of things to check, but could be checked none the less. Your order is logical, try taking all of the accessory belts off of the front and see if that affects the vibration. It may give you a direction to go in.

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[sp4149]

[quote name='nein0neone' post='43458' date='Nov 11 2007, 02:42 PM']Tim, I have no suggestions to help remedy your problem but coincidently I just checked out a 968 tip in Florida that had the identical issues. I was all set to buy this car, price was right, lots of maintenance done, belts, motor mounts, brakes, seemed like a good deal to import into Canada. Went for a test drive , started the car and was surprized at the vibration, worse when engaged into drive, the car seemed to run smooth above idle but seemed a little lacking in response and acceleration. Bottom line, the vibration scared me away from making a deal , but I'm looking forward to hearing any reponses you get from the experts on this forum.

Ed[/quote]

This has been discussed a couple of times. When in gear the Tip has vibration issues when standing. The vibration disappears when the transmission is shifted into neutral or park. In our Cab the vibration is intensified and heard mainly in the side windows if rolled up. The noise disappears and the vibration seems reduced if the windows are down. Routine driving (fuel efficient) will program the Tip into pretty passive response, but aggressive driving changes the shift patterns and driving in #3 will lower the starting gear to #1, and of course there is manual shifting for a more lively car off the line.



-sp4149

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