Tuesday, March 06, 2012 - 11:30 am, by: Ros Johnson(Ros)
Hi, My Lexus SC400 is over revving when cold. However once it is warmed up it goes back to normal. As I do a lot of small trips in it, it is doing it most of the time. It also picks up speed without acceleration and I have to control it with the brakes.
I have taken it to 4 mechanics in the Brisbane north area and no one knows how to fix it.
Does anyone here know anything about this, please?
Thanks Ros
PS The radio works some times and not other times so it sounds like a lose wire or something similar. Could the electrics have anything to do with the engine problem?
Tuesday, March 06, 2012 - 04:21 pm, by: Ros Johnson(Ros)
Hi Drew, Thanks for your reply.
No I didn't know that cars normally rev higher when they are cold. I am a woman in my sixties and I don't know a lot about car engines. But I have had this car for many years now and it has never done this before.
It normally runs around 500 but now it keeps constantly going from around 1500 to 2000 every second and it makes a very loud noise. When I took it to one mechanic I said "My car is making a surging noise" and he said "Yes I know I could hear it." and he was inside the shop and it was a fair way away outside.
The thing is, that when I have been driving it for about and hour, it suddenly goes back to how it used to be, very calm and quiet, and stops making that noise.
Also when it's revving and I am going along at around the speed limit, if I take my foot away from the pedals it keeps crawling up on its own. As it's digital it's very easy to see.
Now it's starting to kind of hesitate and then go, hesitate and go, but not as fast as the revving up and down.
Thanks again Ros
Peter Nitschke Junk Filterer South Australia UZZ30 UZZ31
Wednesday, March 07, 2012 - 01:30 am, by: Jamie Richards(Nwb40gt)
my car had a issue like that once it was my spark plug leads that were faulty, replace them & spark plugs and it's all good now, hope this info help's.
Friday, March 09, 2012 - 05:19 pm, by: Mark Donovan(Mark_donovan)
Hi Ros - I had this same issue. All the above suggestions are valid, but mine turned out to be the main engine computer (engine ECU) after I ruled out each of the above. It had begun to fail owing to some of the circuitry getting too old.
It can be repaired, or you can source a replacement from a newer Toyota V8 engined car. I recommend replacing instead of repairing.
The ECU sits under a plastic shroud under the carpet in the front passengers footwell.
Wednesday, March 14, 2012 - 06:19 pm, by: Ros Johnson(Ros)
Thanks everyone for your help. I am pleased to report that it was fixed yesterday. Yes Mark it was the ECU and I had another one put in. When you are are not mechanically minded yourself, it's really good to find someone who knows what they are doing with these cars.
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