Hey guys, my SC400 has been having some problems. It studders and shakes badly at all RPM's. The shaking gets worse with the AC on. At night, with the AC off is when the car runs the best, but still not very good. I recently changed my spark plugs and cleaned my TB, but that didnt really help. I also have used the fuel system cleaner a couple times and that didnt help either. Any thoughts on what the problem could be?
Thanks

 

I would check the Engine mount.

 

i would also check the tranny mount, steering rack bushings, wheel alignment, tire wear and see if any wheels are bent.

 

mite sound stupid but chek engine fan.

 

engine fan doesn't sound stupid.
make sure all the fluids are topped off... including power steering. If your power steering pump oil is low check if it's leaking as well. Also check the balance shaft, drive shaft and the rear axles and make sure you have enough oil in your diff.

 

Your plug wires may be bad. They become brittle with age and crack. The crack can allow it to arc out to nearby metal. For a quick check: make sure all the wires are visible - i.e. remove the plastic cosmetic covers to expose the wires and start the car. Make sure you do this at night or in a dark location such as a garage. If they are arcing you will easily be able to see it. Cover up the crack with some good electric tape and get some new wires ASAP. Let us know what you find.

 

yes im no mechanic but i figured fan blade because i got into a lil fender bender that broke a little piece of my fan blade. i had no clue and i thought it was my engine mount that got thrown off from the impact, but i never could have imagined such a small thing can make such a big difference. gotta new blade and everythin was brand new again!

 

So what did you find out on this one? Let us know.

 

I still havent found the cause yet. The problem has to be with something on the engine. When the car is idling, the exhaust sputters out the tailpipes. Its hard to describe but when i put my hand next to the tailpipe the exhaust will come out for a split second then stop for a split second , etc. Im going to change my spark plugs to see if that helps. Im changing the pcv valve tomorrow also.

 

Ok,

How many miles do you have?
Did you notice any oil residue on your old plugs?
Did you check your wires as mentioned above?
Are you certain that your MAF sensor is connected and working properly?
How long has this been happening?

To me, it sounds like an sensor failure....which leads me to this question - did the Check Engine light ever come on?

 

I'm telling you, if it's arcing to the surrounding metal, it will have the same exact symptoms you describe. Did you check it out at night yet?

 

I have 125k miles.
didnt notice any residue on the old plugs
I havent checked my wires, but that is the next thing I am going to replace.
I just replace my MAF sensor, iim sure its connected but not sure if its working properly.
Its been happening for 10-15k miles.

my check engine light only came on when i broke my old maf sensor, after i replaced it, the light went off but the problems didnt go away.


What are good plug wires to buy ?

 

I think most will agree that the factory wires are the way to go. A set from Carson Toyota will run around $90 shipped IIRC. Hope you solve your problem.

 

I'm having the exact same problem. I brought my car to the shop and they told me that my wires were bad and it was arcing by one of the spark plugs. I got my wires replaced 3 years ago so I don't see how they could go bad so quickly. Any ideas??

 

start with the wires...