Noises and a jumping car

[stefan86]

I have a automatic 96 VS Acclaim V6 3.8 with an odo at 194 300 and it have just started to do this strange thing.
If you drive it up to 80 or 100 km/h and keep it steady on that speed for a while and then push the pedal down just a little bit to accelerate the car makes a really fast strange clunky noise, start to shake and wont accelerate.
The problem is easy fixed by pushing the pedal down almost all the way and it jumps down a gear and accelerate perfect.

Is it my gearbox that is starting to fail or is it something else?

[soop]

Sounds like your gearbox is a bit sad.
Whats the fluid like?

[RX25SE]

You may have a shuddering clutch in the lock up converter.
Do an auto trans service and add a tube of 'Shudder Fix', avalable on eBay I believe.

It may also be an ignition missfire, such a leads.

To pick the difference between a shuddering clutch and a missfire is tricky as they feel almost the same.

[stefan86]

I checked the gearbox fluid and it was perfect red, not thick and good level.
I will try the Shudder Fix and see what happens.

[RX25SE]

Shudder Fix works best with new fluid.
Trans fluid can look OK but still may need to be replaced.
The problem may be oil related as a gum may have formed on the lockup linings causing the shudder.

I recommend changing the fluid.

I do mine every 20,000km and never had any trans issues. Has 170,000km on it.

[Davidcoolaye]

I agree with RX25SE keep good oils up to your gearbox and diff (same with engine) on a regular bases and I doubt you'll ever have an issue with it. I also change mine every 20,000. My VX has 221,000kms on it and doesn't even as much as flare during gear changes.

[hako]

I reckon your problem is ignition related. When you are cruising at above 80kph and the torque converter has locked up (to provide no slip = economy), the injectors lean right back and you need a good spark to fire a very lean mixture. From memory, others have found problems with the coils and/or the DFI module. Both are a lot cheaper to fix than a transmission problem....probably will cost 1/10th of the cost of a reco transmission.
So, if it was me, I'd do a codes check Checking error codes VR/VS (Revised)
this may give an indication of the problem.
I'm only guessing, but I figure if it is the torque converter clutch shuddering, it would also happen when first engaged and also when cruising, not just when increasing speed.

[stefan86]

I did the test and got a few codes:

Code 12 - System Pass (OK)
Code 44 - RH Oxygen Sensor Lean (O2)
Code 46 - No Reference Signals while cranking
Code 47 - Crank Angle Reference Signal
Code 49 - Crank or Cam angle Sensor Intermittent
Code 64 - LH Oxygen Sensor Lean (O2)
Code 92 - Low Speed Radiator fan response signal

I really dont know what to read from these codes, but maybe someone knows?

[hako]

The codes 47 and 49 are interesting - may indicate the CAS or DFI is on it's way out as I mentioned in my previous post - either may cause ignition problems which usually don't go away. However, it always pays to wipe the codes (remove battery for 30 secs) and retest after a day or two just to be sure. If both those codes come back, I'd replace the CAS with a new one (under $100) and if no improvement pickup a secondhand DFI module off Ebay or the wreckers and fit that (~$50). Neither is difficult to replace except the CAS needs a harmonic balancer puller which is not all that expensive.