Shuddering/slipping at speed

[V8BOSS]

I have a VZN130 surf that we have recently installed a 1uz into. We retained the A343h surf trans and swapped the bellhousing and torque converter onto the A343 from the lexus box. I've now had this problem twice while driving on the motorway where the whole truck starts to shudder through the driveline/engine very violently and feels like it is losing all drive as well. I can hear the engine revving when I push down on the gas, but with no effect. If I turn the overdrive off and on a couple of times, it seems to sort itself out, but it never lasts long enough (about 7-8 seconds) to really get my head around it. Has anyone got any thoughts on what it could be?

 

[earthman]

I had similar(ish) symptoms and eventually lost all power in the driveline. This was pre-conversion when I still had the old 3vze V6 puss bucket with the A343H tranny in it though. It Ended up being the speed sensor on the back of the A343H transfer case.

Because the puter uses the speed sensor to know when to change gears, when the speed sensor went it just revved all over the place with zero power to the wheels.

don't know if this is what your problem may be but it is a place to start. You could probably pick one up from the wreckers for $10. If problem goes away then its all sorted, if it persists then it is something else and you have a spare speed sensor!

 

[V8BOSS]

Did it also affect the speedo? I think it might have two different sensors for the speedo and speed sensor, but could be wrong!

 

[earthman]

Yep, it did. Is your speedo being affected?

The speedo would cut out and go crazy a couple of times in the 2 week lead up to the eventual total failure. When it did fail the only gears that would work were first and reverse, because you could select these specifically with the shifter and it needed the speed sensor to select any other gear.

I read somewhere that the 3vze-A343H Auto ECU used the dash speedo as a backup (is this correct?). Don't know how it would all affect a 1uzfe-A343H Auto setup like your one though, as mine is now 1uzfe-A341E.

It was the speed sensor right at the back of the A343H auto transfer case near the output shaft that failed, due to the companion flange nut coming a tiny bit loose and creating a drive-line vibration at about 80kmh which eventually chewed the plastic cog on the end of the speed sensor. The speed sensor may look something like the pictures below.

Please let us know how you go!

 

[V8BOSS]

No, I dont think it did affect the speedo, but to be honest I was concentrating more on getting out of the fast lane and getting out of peoples way than what the gauges were doing! It is an annoying thing, and the worst thing about it is that I don't trust it now, at least until I narrow down where the fault is.

 

[earthman]

Hey V8BOSS, Any updates?

 

[V8BOSS]

Not really no. It hasnt occured again, but I must admit I am still wary of it so have been reluctant to take it out of auckland JIC it craps itself. But I have been giving it a hard time when driving it around! Fuel consumption is pretty bad too. 340kms for a tank (about 60 litres) so might have another issue there.

 

[bilby]

Hey V8Boss, I have a 92 ls400 and twice at approx 80 KMH the whole car started to shudder until I pulled over and it stopped!! Any idea?Idle was fine and reved clean when in nuetral.Accelleration after this was fine also.
Felt like a wheel loose

 

[earthman]

V8BOSS, Any more issues? did you get to the bottom of this ghost in the machine?

 

[samsdad]

Hey V8Boss, I have a 92 ls400 and twice at approx 80 KMH the whole car started to shudder until I pulled over and it stopped!! Any idea?Idle was fine and reved clean when in nuetral.Accelleration after this was fine also.
Felt like a wheel loose

Check your engine and gearbox mounts. They are prone to breaking on LS/SC400s

Also to the point of the thread while sometimes you can use the V6 autos behind the V8 they really don't last long so you end having to change to the V8 auto with some bits from a diesel surf (adapter and transfer case) given that the V6 uses the integrated transfer case

 

[bilby]

Hey Samsdad,
Did that but its still there, only occasionally though. I pull up then take off again and its gone.Feels like it comes from the rear end, checked it out and nothing loose there. Pretty weird

 

[samsdad]

Go back to basics...Check plugs and leads to eliminate a misfire and check trans fluid condition to eliminate slippage