Hi guys,

My sc400 has recently started stalling when placed into drive or reverse. Runs fine in park or neutral, but as soon as a gear is selected, it starts to run rough and stall.

If the car has been left and is cold, i am able to drive for a minute or so without it stalling.

After this, every time it will instantly idle rough and stall when put into gear.

Have bypassed the fuel pump ecu, have also checked the IAC valve and that is working fine.

Any ideas of what the problem could be ?

Any help much appreciated.

Cheers

Joel

 

Strangely enough, it might be something to do with your reverse light/brake light. When you put the car in reverse, you put your foot on the brake pedal, then not only do the brake lights illuminate, but so do your reverse lights. I have a similar issue and I found that it might be something to do with the lights. Of course, it could be a dozen other things; ie; IACV is always a suspect, along with the main ECU, Vacuum leaks, etc.

 

Might be the torque converter clutch. Designed to improve
MPG by locking up the converter, if it fails to release it stalls
the motor. Do the symptoms resemble a manual trans car
stalling when the clutch is let out too quickly?

 

This was my first thought also.

 

Tabaka - That is interesting you mention that. I have been receiving a rear tail lights warning on the dash recently, maybe it could be linked somehow?

Mcomer - I will def look into this. And yes as you mentioned it does feel like you are stalling a manual transmission, after the car has stalled for the first time.
Yesterday I started the car cold, put it in drive with the handbrake on and let it sit. After about two mins it starts to get lumpy and after another couple of mins it died. But of course if I put it back into park or neutral as its about to stall, the revs pick back up and its fine.

 

Lexus master tech here, It may be as simple as a torn intake tube (the rubber tube going to the throttle body). When the engine is placed into reverse, or drive, the engine shifts, and opens the tear in the tubing allowing unmetered air to enter the engine causing the engine to stall. If that is the case, a roll of duct tape can get you by until a new one can be purchased.

 

Hi there, thanks for this. I inspected the tube last night but could not see or feel a visable tear. Maybe it is worth wrapping the tube with a roll of duct tape and see if this makes a difference?

 

a better way would to spray the intake area with a flammable aerosol like brake cleaner, and see if the engine idles up at idle. For Example, if you spray the intake boot with the vehicle idling, and the idle noticeably increases like you are revving it, you have a vacuum leak, and need to fix it.

 

Hey guys,

A quick update in regards to this issue.

Car was stalling as of normal.

The next day I unplugged the connector to the IAC valve, started the car, trying to find idle, put the car in drive an reverse and guess what the car did not stall!

Turned the car off, plugged back the connector to the IAC and re-started the car. Car ran fine and did not stall. Drove the car for 30mins and was absolutely fine.

As to how this fixed the problem I have no idea. Maybe with the IAC valve unplugged, it was forced to reset? or maybe stopped something it was doing?

I really am clue less why this would occur.

Hopefully this helps some other people with the same Issue, will continue to drive it and see if the issue comes back.

Thanks for the help again guys !