2muchpsi

Well the car is a 93 Sc300 5 speed. 153,XXX miles.

Problem:
The car drives fine 99% of the time. I've put 200 miles on it since I picked it up, some city and some highway, and it drives like a dream almost always.
However, a hardcore studdering occurs, where the car jerks so badly and wants to die at anything under full throttle. If you give it full throttle while this studdering is going on it pulls through it. This studdering only occurs when the car is warmed up, and you drive it kinda hard for a while.
After driving the car hard I noticed that the catalytic converter in the exhaust manifold was crackling loudly and glowing orange. However, upon inspection the cat is not melted or deformed, and still looks fine. This leads me to believe it is a fuel delivery problem.

Last time I took the car out for testing I drove it hard for about 15 minutes and it was fine. WHen i got within a block of my house it started the studdering/shuttering again and I limped it home. It died pulling into my drive and woudln't start again, so i pushed it to its parking spot. I came out an hour later and it started right away but idled at about 500rpm, and was just misfiring/studdering like mad. I reset the ecu and the car fired right up and idle perfectly. I have since put over 100 miles on it with no problems.

The clues point to something relating to fuel controlled by the ecu, but these cars are too expensive to start throwing parts at without being certain.

I need your help here! I know there's more knowledge on this board than in the Lexus dealer, so help a brotha out!

Thanks!

TheMole

iTrader: (13)

If you think it is fuel related you can try this thread:
https://www.clublexus.com/forums/sho...d.php?t=291189

Do you get any Check Engine Lights(CEL)?
Is the maintenance up to date? ex. spark plugs, cap/rotor, clutch...
Also look into the oxygen sensor.

Answer300

iTrader: (3)

when my SC did this, you would never guess what it was.



the continuity in the charging system. does it lope like a cammed v8 @ idle?

2muchpsi

No CEL's Charging system is new. I havent checked the ignition system but due to the randomness and correction by resetting the ECU, I don't believe it is ignition. I have a fuel pump ecu in the mail and I'm going to try that.

Thanks for the input and keep the ideas coming!

k4rr

The dealer has to have some type of data logger that plugs up to the lexus.

That way they can drive it and monitor what happens when the problem occurs.

play123boi

iTrader: (1)

I had a leak in my system due to cracking vacuum lines on my SC4 15 dollars had me up and running again.
PS the dealer sucks and is overpriced you might want to find a good reliable mechanic.

got_trd

if your cats are crackling and rattling around that means they're bad..... you probably have too much backpressure which is making the car run like crap except at wot when its forcing the exhaust flow out of your exhaust..

Dx3

iTrader: (13)

He may be on to something...

Jonny

shlounek

iTrader: (1)

no its prolly your fuel pump ecu. I had the exact same problem.

When it gets hot. it starts messing up, until the car stalls on you somewhere, it will just start to get worse. Just do the 12V mod. Guaranteed that is your problem, give it a try and see what happens.

bio3m

iTrader: (1)

Check these issues
1. Cat is clogged, my buddy had this problem once
2. Fuel Filters
3. Maybe plugs

My money is on the cat being clogged though

shlounek

iTrader: (1)

fuel pump ecu my friend !! as a test.

open your diagnostic port and jump the B+ and FP pins with a paper clip. And go out and drive it like crazy. And see if the problem, if it fixes it my paypal addy is ..... loool

2muchpsi

thanks for the tips, I'll jump those connections tonight and go beat on her for a while and report back!

I jumped the connections and took it out for a hard drive, drove perfect for 30 minutes then started acting up again. I limped it home and it didnt wanna stay idleing. Now it starts but Idles down super low. Also smells like raw fuel coming out the exhaust! Ugh!

$C300

iTrader: (1)

is there black smoke coming from ur tail pipes?

TheMole

iTrader: (13)

If it smells like raw fuel coming out of the exhaust, that tells you it is running rich. Look into factors that would cause it to run rich.

shlounek

iTrader: (1)

it could be ur fuel pump? you are having fuel delivery issues.

When electronic compenets get hot they ussually mess up. make sure you eliminate ur fuel pump ecu, and get another pump and see what happens.

Or if you have a fuel pressure regulater you can measure the psi of fuel should be in the 40 -45 range.

I still think its ur fuel pump ecu, maybee you have a faulty ground etc.