Legnum Stalling

[Legnum in America]

Car starts perfectly fine if it sits for a few hours, but if I drive for more than 20 minutes and restart the car it stalls and the RPMs start low before climbing up to normal levels. Sometimes the TCL lights flash while RPMs are low. Giving the car a little gas prevents it from stalling but RPMs are not stable. Eventually the RPMs will start to level itself out, but otherwise I'm getting this constantly.

 

[mezje]

Dartboard says stepper motor.

 

[Legnum in America]

Dartboard says stepper motor.

This has been happening since I bought the car over 2 years ago. It just seems to happen more frequently.

I replaced the stepper motor 3 months ago thinking it was the cause.

 

[mezje]

Check for vac leaks

 

[Legnum in America]

We are still dealing with winter here and it got pretty cold over the weekend going to have to wait till next weekend. Do you know any weak points where a common vac leak could be? When I am at boost it stays at 15 psi and doesn't drop until gear shifts. Would have vac leak be pulling air into the system or leaking air?

 

[BCX]

Both potentially, if after turbo. Under boost, itll be a boost leak.

At idle, it will be a vac leak.

In both cases, the leak will cause the ecu to misfuel as air is bypassing the MAF/engine.

Under boost, it'll be rich (black smoke)

At idle, it usually manifests as idle problems and other small issues.

Check all hose clamps for intake, intercooler, throttle. Anything after the MAF.

Post turbo: Check no issues with intercooler. Wg solenoid vac hoses, powersteer vac hoses. Turbo outlet orings.

Pre turbo: PCV, air breather (connects just after the MAF)

Otherwise, upper or lower intake gaskets? TB butterfly shaft seals? TB gasket? injector seals? Charcoal canister (there is a check valve that needs to work)

If you've got TCL, theres all the extra stuff on the firewall.

 

[jdmftwyo]

If you find yourself in the Detroit area I have a smoke machine. Makes for finding these issues way easier.

 

[BCX]

Another way to confirm, if you want to confirm vac leaks, use a vac gauge.

I believe the manual has a standard value at idle from memory.

Otherwise what @6A13TT TYPE S said in the other thread.