Transmission??? TPS?? Something Else???

[Maccar]

Hi all. It would be great to pick some of the very astute posters brains on here and try to nut a problem on my vt 5l Calais. The car is on duel fuel but I don't think that has any relevance to whats happening here. I don't have a great deal of history on this car as I only bought it in Sep last year. Anyway the problem, going on a family holiday, towing a aprox 600kg trailer and car full of kids/wife and stuff. Driving along great on freeway. After about 40mins of driving car starts to jerk (still on freeway about 90kph) engine light comes on. I pull over and car idles fine engine light still on. Turn off ignition wait restart and try again on petrol trying to make like a little easier on the car. Up to speed ok then happens again almost instantly. Ok loose the trailer at a servo (thanks 7/11) return to freeway homeward bound and car drives perfect minus trailer!!! Get home and I learn how to check codes. I get 19 and 35 Tps stuck open and idle control valve or something like that. Ok so since then (we borrowed my brothers hilux for the holiday!) I have on hot days run into similar problems minus the jerking and the trailer. Car will drive fine until engine light comes on and throws same codes. However now the transmission seems to be throwing its hat in the ring for its claim to the problem. Last Saturday after code, again on freeway, I noticed I no longer had a kickdown from 4th at lower speeds. When i did come to a complete stop at the end of the freeway and take off again transmission changes were very rough from 1st to second and remained like that until i got home. Also the kickdown from 4th failed to work under acceleration however changed perfectly manually. I guess my big question is. Do you guys think its likely TPS alone, Transmission alone, Both! Or something else. Im leaning towards Change tps, hook the boat up on a hot day and see how i go. (Ill make sure my brothers free with the hilux!) I know duel fuel 304's sometimes throw a code because of the tune but i don't think its a tps code.
Thanks for reading, any input would be great.

 

[accentstencil]

If the TPS is faulty I think that will impact on gear changes. Reset the codes and see if that code returns.

 

[Immortality]

Definitely, the transmission shift points are set in tables TPS (load) Vs road speed to determine the gear change points.

 

[Jxfwsf]

As above, TPS is faulty and needs replacing, you have the code and symptoms to confirm it (while you're there clean the throttle body and iac out with some carby cleaner).

With the trailer loaded you were slowing the car down enough to have to push the go pedal that little bit more to where the fault is in the sensor...
Did have about 2 paragraphs written trying to explain how the sensor works but it was more complicated than saying replace it.

 

[Maccar]

Thanks guys. I've ordered tps via auto barn so I'll find out soon enough. I reset the codes last night and gave it a good run today to see if I could make it happen. Drove to work in cool, had no problems and checked codes upon arrival. Code 35 alone and I'm guessing this is the code that's common to duel fuel. On the way home it was hot and sure enough on the freeway after I put cruise on it threw the engine light on and the transmission pattens changed after that. It wants to stay in 3rd at speed. It will drop to fourth with no accelerated at all. But then once in fourth it won't kick down automatically. And as previously mentioned the gear changes from take off were harsh. As soon as car is turned off and re started it drives like nothings happened. Its almost as if that code is causing the auto to go into a safe mode or something! Anyway thanks for the help I'll let u know how I go. Oh and. Auto barn cheaper by about 200 from repco and holden

 

[Jxfwsf]

200? what sort of price are they asking for it???? were they going to fit it for you?

 

[Maccar]

Repco and Holden were around the 250 mark autobarn 52 eBay 32 autobarn clear winner there I reckon

 

[9C1pack]

"Its almost as if that code is causing the auto to go into a safe mode or something!"

Yep that's what is happening, after a bad enough code is logged, it fail safes to "limp home mode" which only has access to 1st & 3rd (I think) it resets back to normal if you pull over and turn off and restart the car.
The trans may be overheating, going by your description it seems to happen while towing. I was told to use 3rd while towing unless it is flat terrain, as the trans constantly going from 3 to 4 th and back creates heat, heat is deadly to auto transmissions.

 

[BlackVXGTS]

Repco and Holden were around the 250 mark autobarn 52 eBay 32 autobarn clear winner there I reckon

Sounds like Repco and Holden thought your VT was a VT2 with the LS1 5.7l engine.

I have attached some instructions for replacing your TPS. Make sure you don't lose the drive adapter or the two washers on either side of the spring. Also make sure you lubricate the washers and the drive adapter with some high temp grease.

 

[drewVHSS]

While your throttlebody is off, not only should you look at replacing the TPS and IAC (they're cheap to replace even if they're not the culprit)
But have a good look at the wires for the TPS plug and the IAC plug, also while you're at it, check your plug for the 2 wire coolant sensor too. If the insulation has gone hard with heat/age/oil etc they've also probably got cracks in them too.
moisture gets' into the copper wire also they can short out too.
My VQ s2 caprice (dual fuel) was doing the same thing recently, engine cutting out and dying under load, I haven't replaced any sensors etc yet but I did spend last sunday cutting back my wiring and soldering on new plugs from a butchered loom, I did tps, iac, CTS and also recently vkberlina and I redid the two wires for my coil.
Problem has gone away.
For you having an electronic auto instead of cable kickdown, your problem will show more issues than my car but the cause is essentially the same, either dodgy tps and iac or the wiring has failed with age.