p.hase

hello SC-lovers,

i am fairly new here, located right in the center of mercedes and porsche in stuttgart, southwest-germany and i have a 1992 SC400 bought now and i drive a LS430 since 2003. both very nice car. before i had an RX300 and LS400.

yes, i have used the search function! but i have not found following theme: "when trying to hold an average speed with the gas pedal or when the cruise control is set to a speed of lets say 50mph the engine does not run smooth at all. it is stumbling, struggling and feels like it has drop outs". mileage 93000.

the car is in very bad technical condition at this moment: brake fluid is black, air filter was black, spark plugs seem to be never changed, brakes are horrible, oil needs to be changed, alternator and steering pump are gone, ....

does the 1992 engine have an electronic gas pedal and can the pedal (potentiometer?) be worn out?

thanks in advance,

george/juergen

SORRY: forgot to mention - I LOVE THIS FORUM!!!!!!! HIGHLY PROFESSIONAL!!!!!!!

One HoT

iTrader: (5)

Welcome.!

First things first, you need to keep you car mechanically updated. It's time for your tune up especially with 100k fast approaching. I had this similar problem with my car at 40mph, it simply went away by itself over time. I'm sure if you get your car tuned up, this problem should go away.

audi2nr

iTrader: (1)

pretty sure its a mechanical throttle pedal. my 96 sc has a mechanical pedal.

SCV8

That's cool to live around car companies,huh?
I used to live in Dearborn, and see all the engineering prototypes running around.
My car was a turd when I got it w/70K on the clock.
I'd go and check the tranny, motor mounts as well, power steering pump can leak onto alternator too, use only Toyota ATF in the trans, try and use Toyota plug wires(alot of aftermarket don't fit), and get the Irridium sparkplugs.
Then when you get everything tuned/cleaned up, you'll be ready for any tuning modifications, if you're into that stuff anyways.

Nomis

[QUOTE=p.hase]spark plugs seem to be never changedQUOTE]

Your plug wires may be bad. They become brittle with age and crack. The crack can allow spark 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. Good Luck, SC's are Wunderbar!

techsc400

iTrader: (6)

It sounds like Throttle body needs to be cleaned. You should be able to find the thread about these steps in here.
Sure, spark plugs & wires, rotor, dist caps, etc (Major tune ups) should be done also.

Just my two cents.

Richie

Welcome to the club from a fellow European.

mikeloc24

George, you HAVE to get all this stuff taken care of. Until you have the car up to snuff maintenance-wise we can't accurately pinpoint what an issue may be. With a car is this shape many different things can be causing it to drive roughly. Be happy it's actually driving at all with sludge running through it's veins!! Seriously though, get all that stuff handled and report back. My guess is that the car simply needs basic maintenance (oil change, tune-up, brake job, coolant flush, tranny flush, new alt and p/s pump, etc.) It'll take a lot to get it running right, but we're speaking of basic maintenance here.

-Mike

p.hase

the toyota-dealer who "checked" the care before (what did he really do - drinking coffee?) sold the preowner 3 new batteries in 3 years but didnt care about the steering pump and alternator. it seems the alternator is running on 10%. the battery recovers through the night and on the next day i can drive for 10 miles and power is gone. alternator and steering pump are a black clump of oil. very ugly to work on.... the lady who owned the car before was stuck twice!!! and needed to be towed. i think this toyota-dealer did a great job in image loss for LEXUS!

i hope i can manage to drive to my nearest lexus dealer in stuttgart by myself. probably i charge the battery before with my LS430 and then "go".

thats what he said on the phone: the car just needs a regular "full check". in germany we call it "fitness" every 9000 miles which is only an 0-W30 oil exchange and some inspections and every 18600 miles is a "full check" where most of the fluids are exchanged. cost is about 350-400 US$.

also he will write me an offer for 1) spark plug exchange 2) alternator and steering pump replacement 3) timing belt replacement 4) gazis big brake replacement.

he said the stumbling engine may come from the old spark plugs. he wont inspect them and put them back - its the same work - he will replace them in any case. i agreed. he will install whatever i deliver to him - on my risk.

timing belt: its a 09/1992, i heard this engine is "non interference". this means the engine wont go dead but i can get stuck in the middle of nowhere and then i would be forced to replace the belt by "anybody". right?

i have noticed that the gas pedal is stuck a bit for the first time in the morning i press it and then it works fine. maybe some fat or oil here and there....

DetMich1

Non-interference means that even if the belt comes off or the engine is out of time, the valves never open far enough into the combustion chamber to be struck by the dome of the piston. In later engines with VVT (Variable Valve Timing) this sort of interference CAN occur. If it does you have the potential for BIG time internal damage. The SC and that 4.0 L V8 engine are terrific. I have a 1992 SC400 I bought new in 1992. It now has 336,000 Miles (560,000 km) on the odometer. Never had any internal problem with any part of the drivetrain. And, I was never as diligent as I should have been with routine maintainance. With even minimal care, the car should run for hundreds of 1,000s of miles.

p.hase

as i already said i had the steering pump and alternator replaced by a SC400 experienced lexus dealer what is totally unique in germany.

then this monday i did the "big service" for my SC400. 0W30 oil, air filter, A/T fluid, rear axe fluid, ....

it turned out the pre-owner didnt change the transmission oil, not the rear axe oil, and not the spark plugs for 95.000 miles. a shame. the air filter was black, so all oils. thats why i usually dont like buying cars from rich people - they never do anything on their cars and if something goes wrong the first word is "warranty".

i wanted him to install DENSO Iiridium SK20R11 plugs but the dealer insisted to install DENSO Platin PK20R11 plugs. was he correct?

i can tell you - all dropouts of the SC400 engine are gone, acceleration is totally different, engine runs supersmooth, cruise control is much smoother, really really nice ride.

the throttle pedal is still sticking when i press it "for the first time" in the morning. dealer said there is nothing to do on it - throttle valve is worn out. also i hear all 4 shocks making a loud grinding noise when i run over bumps - any idea what this is?

last thing is to install gazis LS400MK2 calipers and the 315mm Brembo rotors.

i am so happy with my SC400 i didnt drive with my LS430 for 3 weeks now.

aliga

iTrader: (147)

George,

Shame on you, I thought this car was for Tonya.

p.hase

gazi, good to hear you are alive!!!

you wont believe it, my father is here for a month for visit and he drives the SC400 daily. i guess he likes it. no compare to his nearly new Subaru Forester.

first he wanted tanjas toyota starlet because its so small but now he wants the SC400. hehe.

so we car-share. the SC400 is on the road day and night making miles and miles.

gazi, i must have MORE SC400's for Europe, 1996 and newer.

Richie

Good to hear it all got sorted.

/Aerostar\

iTrader: (2)

Gas pedal is mechanical, and your problem lies in your dirty air filter