Hey Guys, when i start my sc400 it goes to 1.5k as normal but then immediately falls down below below 1k and bogs until it dies. Sometimes i try to rev it high when i start it, but it still shakes and bogs until it dies. Anyone experience this same problem? thanks in advance

 

Anyone have any guidance? I know this is a common problem. Any direction would help

 

some must know

 

Maybe the AFM on the intake?

 

I replaced the AFM already and there are no cells indicating it is the problem...seems like the car is stalling, but tries to stay alive...maybe fuel delivery??

 

My car does the samething but its a 5spd sc300,refer to the "car keeps bucking" thread to see what people have changed.I'm pretty sure they talk about the start up thing too.
Richard

 

At the basics,

How many miles on your 1992 SC400?
When was your last tune-up, replacing plugs, wires, cap, rotor, air filters?
Has the fuel pressure and volume per minute been checked for a degraded fuel filter or pump?
Have the exhaust back pressure checked?
Check and clean the throttle body?

 

122k miles, 10k miles ago i did spark plugs and wires, air filter. And no I have not checked th fuel pump. How do I do that?

 

replying to the very first post. My car did the exact same thing. I figured out it was the fuel pump electronic control unit (ecu). Had to take out the backseat and driverside panel that was next to the backseat.

Oh yea here's a way to make sure it's the fuel pump ecu causing the problem. using a paperclip jump the fp port and the b+ port on the diagnostic port on the engine. if it starts up fine then you know it's the fuel pump ecu because this bypasses the fuel pump ecu of course.

on my fuel pump ecu the big blue capacitor went bad and I replaced it myself. Had to do alot of research to get the capacitor part number.
let me know what you guys find out. I'll give you the details.

 

I have an idle problem sometimes as well;however, when I remove the vacuum hose it goes away. I think my problem is the IAC valve. The stepper motor needs to be cleaned to eliminate this issue. Maybe you can cjeck that out.

 

thanks everyone...ill try these things, but too bad my problem is intermitent and not always happening. I guess i will have to wait to try these things when it doesnt start.