MX83-1J cruise issues

**Mr DOHC** · 10-02-2007, 10:28 AM

i have a 1J in my cressida and i'm having an issue with the cruise

if i am doing 100k, hit the cruise and let off my foot straight away, it drops to 95k, cruise kicks in and takes me to 105, backs off to 95 back to 105 etc

if it does stay at 100k, and i come to a slight incline it can drop to as low at 90k, then it pulls the throttle on heaps, kicks down, hits full boost and rockets off to 110k, then it'll keep doing this, unless i level it out with the throttle myself, if there is even a slight bit of wetness on the road it'd spin us off into a pole at 100kph

has anyone had this type of problem

1 thing i can think of is if the MX83 cruise control is programmed to a responsive motor {no lag} pulls on a bit of throttle, enough for a 7M, but the 1J doesnt respond in time, and gets confused thinking that the hill is quite huge and pulls on more and then the 1J all of a sudden shoots of and its just a cycle

**sideshow** · 10-02-2007, 09:32 PM

it might be due to the engine having boost

not sure but u might have to run a valve or something

just remember seeing something like it

ive done 30 1js in cressidas and never had cruise probs i think

but could be boost related

**brett_celicacoupe** · 10-02-2007, 09:41 PM

its probably the cruise actuator pot. it has a diaphram much like your brake booster.

what happens is that the speed drops a few k and the cruise kicks in (as per normal operation) if it kicks in late then it needs quite a bit of throttle to get back up to the speed.

throttle + load (wind resistance) = boost.

the actuator operates off vacuum so it suddenly makes the situation worse. the actuator also has a pump for these occasions to create its own vacuum. this would cut in (but too late) and drop in HEAPS of throttle. once the car exceeds the desired speed limit, it backs off but it way overshoots.

try putting a one way valve in the actuator vacuum line

**Mr DOHC** · 10-02-2007, 11:00 PM

this is actually one of your wiring jobs sideshow

so which way do i put the 1 way valve, so pressure doesnt go TO the actuator, or away

**brett_celicacoupe** · 10-02-2007, 11:05 PM

position it so air can only leave the actuator, not enter it

**sideshow** · 10-02-2007, 11:08 PM

away i think so the actuator doesnt get boost

**PlacentaJuan** · 11-02-2007, 07:22 AM

some guy on cressida forums made a vacuum tank with pvc for his cruise contrrol, i dont think anyone else uses one but its an option; all cars seem to work differently hey

**ProjectSleeper** · 11-02-2007, 01:19 PM

I just run a one way valve on mine - allows NO boost to get to the actuator..

The vacuum tank was tried on mine, but in the end, wasn't needed, even after climibing a very long hill on cruise control, boosting at about 4-5psi, I have no problems. Even if I use the cruise control to accellerate up the hill and create MORE boost, the cruise still works fine..

BUT, if you want to get a vacuum tank to try, - VR/VS commodores have one that is suitable mounted in the front inner guard area on the passenger side from memory. (the one I used)

as to the laggy nature, as i poisted on toyotacressida.net - make sure all the throttle/cruise control linkages and cables are tight and allow minimal free play.