VS 05/96 V6 AUTO ACCLAIM

[buccac]

Hi out there.
Background my VS is a 75k km one pensioner owner really good mech. condn. but as my previous VS the 4L60E is not the smartest box on the market, this ones worth spending a little doe on.
So my question is what can be done without box out to improve the shift I'm not looking for miracles just two things:
1. A little firmer quicker shifts up and down.
2. My main bug bear is the box holding on to higher gears when going to accelerate out of an intersection it changes late and with a thump from back near the diff, centre bearing and diff all good, any suggestions ?
Options I have been told about
1. Transgo/Sonnax line pressure boost valves work if that's the case which one is better?
2. Corvette servo another option?
Cheers
CB

 

[losh1971]

Corvette servo big job for little gain if the trans is still attached to car. Boost valve won't firm up shift but it will make it shift smoother. Best thing is shift kit. The kit reams out the valve body and fits a bigger piston, should also contain boost valve as well. Shift kit is ok but normally done on rebuilt trans where internals have been strengthened to take the firmer shifts. Shift contains other parts that firm up shifts. Try fitting a new TPS firstly they control a lot of the way a trans shifts. If they start to fail all sorts of problems can occur, clunking IIRC can be one.

 

[buccac]

What l did with the TPS, after you reminded me about it was a method l employed on a R31 Skyline I used to own it had an adjustable TPS which allowed me to have some control over shifts, after a bit of trial and error l ended up with shorter closer spaced shifts allowing me to use power mode button more effectively when needed also helped fuel economy.
So what l did with the VS is round filed the TPS mounting holes so it would rotate clockwise by about 5mm this has had the same affect to some degree it has really stopped a lot of the flaring and changes are under more control to the point that l won't touch the box now it's never going to be Jayco box but it ain't half bad.
Cheers

 

[BlackVXGTS]

Hmmm. I think your result might be wishful thinking. From the Holden VS Service Manual.

THROTTLE POSITION (TP) SENSOR

The Throttle Position (TP) sensor is connected to the throttle shaft on the throttle body unit as shown in. It is a potentiometer with one end connected to 5 volts from the ECM/PCM and the other end to ECM/PCM earth. A third wire connects from a sliding contact in the TP sensor to the ECM/PCM allowing the ECM/PCM to measure the voltage from the TP sensor. As the throttle is moved (accelerator pedal moved), the output of the TP sensor changes. At a closed throttle position, the output of the TP sensor is below 1.25V. As the throttle valve opens, the output increases so that, at wide-open throttle, the output voltage should be about 4 volts.

By monitoring the output voltage from the TP sensor, the ECM/PCM can determine fuel delivery based on throttle valve angle (driver demand). A broken or loose TP sensor can cause intermittent bursts of fuel from the injectors, and an unstable idle, because the ECM/PCM interprets the throttle is moving.

The TP sensor is not adjustable and there is not a set value for voltage at closed throttle because the actual voltage at closed throttle can vary from vehicle to vehicle due to tolerances. The ECM/PCM has a special program built into it that can adjust for the tolerances in the TP sensor voltage reading at idle. The ECM/PCM uses the reading at idle for the zero reading (0% throttle) so no adjustment is necessary. Even if the TP sensor voltage reading were to change for some reason, the TP sensor will still be 0% because the ECM/PCM will learn the new value and it will become the new closed throttle value to be used and no driveability complaint will be present because the ECM/PCM learned a new setting. A TP sensor circuit problem will set DTC 21 or DTC 22.If the internal spring in the TP sensor fails, the TP sensor will be stuck high. A sticking TP sensor should set DTC 19.

 

[buccac]

Thanks for the reply I'm a bit late acknowledging your reply, so thank you I understand what your saying.
1 . So had the shift kit fitted (Transgo -stage 1) plus new accumulators, feels better still a little flaring but better. Issue of thumping still exists, accumulators were changed as I thought they were plastic but found them to be alloy as you know plastic ones break and wear which reduce their ability to smooth the gear changes. I was led to believe that updating them would smooth out the changes, also changed TP sensor. So somewhere in the drive line this slackness exists centre bearing checked and diff is fine any ideas?
2 . I'm loosing coolant probably head gasket I get pressure build up in the system and was spluttering a bit on first start until it clears itself I added sealer which stopped the spluttering but coolant still disappears so not sure how that works, nothing in oil! Can you advise if this isan issue with the ecotec.
Cheers

 

[vs-lover]

Are there any signs of coolant on the ground at any stage and when you say coolant loss, how much and how quickly are we talking here ?

 

[buccac]

Are there any signs of coolant on the ground at any stage and when you say coolant loss, how much and how quickly are we talking here ?
Coolant loss not visible around and under vehicle at any time even after driving when pressure is up no sign of a leak, probably looses about 300-500ml over a distance of 14-20km.
Letting engine cool down enough so I can remove cap, which is cool to the touch, I find system is still under pressure and coolant gushes out of the radiator. The next morning I can remove cap and level in radiator is down near the bottom of top hose. The overflow tank seems always at the same level seems like its not doing it's job, I checked for blockages in return hose, nothing!
So are there issues with the heads on the these engines? I just like to know because if I have to take the heads off I'd like to know what specifically I'm looking for.
Thanks for your time
Cheers

 

[Lex]

Ecotec (v6) engines usually have problems with the LIM (lower intake manifold) gaskets. The coolant leaks through there. Signs of the LIM leaking are sludge under the radiator cap & oil cap. If you are lucky, sometimes you only have to retension the lim down (tighten the bolts).

 

[vs-lover]

Yes it certainly sounds like you are suffering coolant loss at the valley gasket area and thus not seeing it appear on the ground. I have done many sets now on these engines and thoroughness is the answer to doing this job correctly and thus this will have your coolant surge tank clean again after you clean out the oily film that tends to find its way into the plastic tank.

 

[buccac]

Yes it certainly sounds like you are suffering coolant loss at the valley gasket area and thus not seeing it appear on the ground. I have done many sets now on these engines and thoroughness is the answer to doing this job correctly and thus this will have your coolant surge tank clean again after you clean out the oily film that tends to find its way into the plastic tank.

Thanks for the advice I checked as you advised but nothing, I don't have any oil contamination anywhere, valley is dry and clean, reservoir just coolant, oil cap clean. I ran it on idle with radiator cap off and just let heat up I noted frothing rather than just odd bubbles overflowing out of radiator. I also noted that every so often a bubble would build up and basically pop and then I would have to add extra coolant to bring back to level with top of the radiator, probably about 150 ml then frothing would begin again.
When driving temp varies per normal but can drop down to below first line on the gauge and that worries me as I think there is no coolant passing thru the thermo so it's not registering coolant temp.
I'm convinced it's the HG or maybe a cracked head? funnily enough engine runs smooth and clean and as I said above the spluttering on cold first start, indicative of coolant in the combustion chamber, has disappeared after adding the HG sealer, still doesn't explain coolant loss though. The other reason I think it's the HG is that there is no vacuum in the system that would normally suck lost coolant from the reservoir back into the system thus balancing pressure/vacuum state when everything is fine. Rather as advised above the system is under pressure even 4 hrs later which counteracts the vacuum normally present.
Does anyone know of a fair priced engine shop as I will have to have the heads inspected and machined near Parramatta.
Cheers