Automatic Transmission Faults - Advice Appreciated

[meetone]

G'day,

Wondering if anyone has had similar faults to me and asking for a bit of advice before I get quotes for a rebuilt box.

The car has 195K's on it, and as far as the history goes I'm not sure if it has ever had the tranny replaced - It's just the stock 4spd Auto.

Symptoms are:

When cold, shifting from R to N results in an audible cluck
When cold, if I shift fairly quickly from R to D, the car will stall (you have to engage N, wait a few seconds, then select D)
When cold, first gear appears not to engage properly, and will rev the motor to around 3K RPM at 20 KP\H until second gear engages
When hot, and the hammer is down, third gear completely disengages when the car tries to upshift into top gear at around 4.5K RPM(i have to back off, wait for 4th to engage, then continue on)

I completed a transmission service about 10K's ago using a coopers filter and DEX IV oils, I was going to do yet another tranny service this weekend to see if it will help. There wasnt any abnormal metal pieces or anything nasty in the pan, although the oil in it was disgusting.

As a side note, I've checked all the error codes on the dash and there was nothing to report (looking for wheel speed sensor faults or anything similar). About 15K's ago, I did recieve a TPS over-voltage error so I replaced it with a new unit from Auto Pro. When the dash warning light came on, the car did pick up in revs when cruising quite significantly.

If anyone has some advise on where to go next, that'd be great!

Cheers.

 

[vx_commodore]

It's not 100% that you will need a new box.

I'd take it to a professional transmission shop and see what the say, It could be just a sensor inside the box.

Does it slip during normal gear changes?
Did all this start after you did the service?

 

[SID888]

Sounds more like the TPS is shot.

 

[meetone]

It used to be a bit problematic before the service, it would be a bit sticky in 3rd and reluctant to kick down. The lag in first gear when cold was a new symptom after the service.

When the car warms up and has gone through the gears a couple of times, it shifts without problems and is very smooth. Often I can't even feel it shift.

I only recently replaced the TPS after going through the error codes when I replaced oil/plug/leads/filters (oil,fuel,air). I've also cleaned out the throttle body as the pedal was getting sticky.

 

[vx_commodore]

I'v see transmission's that wont kick into gear when cold or will act odd when cold.

It was due to hardend seal's wierdly. In the cases i'v seen.

Sometime's on old warnout gearboxes it's the old oil that seem's to keep em going, Changing the oil actually kill's them faster, I had a box die on me 1 day after service.

But it could just be something simple, It somewhat does sound electrical, Best bet would be ring a transmission store and see what they think... Better than getting stuck somehwere.

 

[mummbles]

my VT auto was behaving very much the same up until recently.
I also thought it was the TPS, but after some reading I found that this can also be caused by the MAF. I figured a can of MAF cleaner is cheaper than a TPS, so what the hell.
That was about 5 weeks ago now and I haven't had the code reappear at all, and the box is back to shifting normally again.
Give it a go, you've nothing to lose.

 

[meetone]

Gave the MAF sensor a hit with CRC MAF sensor cleaner, got a bit of dirty brown run-off come from the spray so it was probably a bit dirty but sadly still the same symptoms =(

I think this weekend I'll reset the ECU, complete another transmission service and take it for a long drive then reckech for any error codes. May as well do the lube service and the same time, what the hell.

Thanks for all your input, I'll update this page tomorrow after ive completed the above.

 

[som]

Firstly you live in Canberra,if I were a transmission I wouldn't want to do anything too quickly when I was cold so why not let it warm up a bit and with gentle pressure feel your way between park,reverse,drive etc. On a more serious note it's really likely that most of your problem is a simple tuning issue.Sounds unlikely I know but go and buy yourself a set of GENUINE plugs and leads,no matter how old yours may be,and wait to be surprised at the difference.(including shifts at speed and on hills when it feels like your torque converter is on its way out).. I've been around for almost 65 years and I've never owned a car with a gearbox that was so sensitive to engine tune.At the end of the day you have nothing to lose cos a set of plugs and leads are a regular service item.Engine and gearbox mounts may also be worth inspecting .195,000km is nothing .430,000km still all original drive train

 

[som]

If you could borrow a coil pack from a mate's car they're always worth a look too. Good luck mate

 

[meetone]

Thanks for the tips Som. As a side note, I smoke so I let the car warm up for a few mins before driving off, and i'm never in a rush to be at work anyway!

I have replaced the plugs and leads about 15K's ago usuing NGK plugs and Bosch leads. When I bought the car the guy who owned it before me didnt run them through the engine bay properly and one melted on the exhaust header (so I had no choice but to swap them out). From what I'm gathering, seems people are leaning towards an electrical problem. Is it possible that the TPS over-voltage code I recieved not long ago be causing this? Also I haven't checked anything to do with the IAC, would replacing the IAC be worth a shot too?