Warm Start RPM Stumble

[dml5055]

I'm having this weird issue when I start the engine when it is warm and the rpms will stumble. I need to give it a little gas to get the revs up and then it will idle normally.

Cold starts however are normal.... Can anybody think of a cause for this?

Thanks!

[Simmsled]

I would bet you a cold beer that you have an injector that leaks down when the fuel rail is pressurized and car is off.
My car has this EXACT failure mode and I have a new injector arriving today.

here is a thread to cross reference... Leaky Fuel Injector (http://www.zhpmafia.com/forums/showthread.php?6857-Leaky-Fuel-Injector)

18601

[ryankokesh]

A+ diagnostics work!

[LivesNearCostco]

Seeing those injectors makes me want to pull my fuel injection rail and inspect them! I have to do that anyway to remove the intake manifold so I can replace a coolant pipe (been on my to-do list for many months).

I have had a warm-start stumble for a while though it seems to happen less frequently recently. The engine shakes but does not seem to be misfiring. Revving it or pushing in the clutch pedal eliminates the shaking, and it also goes away on its own after 10-20 seconds. Assumed it was a flywheel problem, but now wondering if it could be dirty or leaky injectors.

[Simmsled]

A+ diagnostics work!

Thanks!!!


Seeing those injectors makes me want to pull my fuel injection rail and inspect them! I have to do that anyway to remove the intake manifold so I can replace a coolant pipe (been on my to-do list for many months).

I have had a warm-start stumble for a while though it seems to happen less frequently recently. The engine shakes but does not seem to be misfiring. Revving it or pushing in the clutch pedal eliminates the shaking, and it also goes away on its own after 10-20 seconds. Assumed it was a flywheel problem, but now wondering if it could be dirty or leaky injectors.

What you are describing are the other characteristics of the issue!
Its really not hard at all to check them.

[dml5055]

Thanks! What's the difficulty of a DIY? I replaced the water pump myself a couple months ago, easier or tougher than that job?

[danewilson77]

The one circled in red does not look like the one with the clean tip?

"No flamesuit required"

[Simmsled]

Thanks! What's the difficulty of a DIY? I replaced the water pump myself a couple months ago, easier or tougher than that job?

It is easier than water pump, I'd say. Definitely less time. No special tools needed. The closest thing to special would be the torx I used to remove the cabin filter tray screws. Only other tools are really a 10mm socket with extension and a flat head screwdriver.
I swapped my injector for a new VDO/Siemens unit today and it is PERFECT. SOO happy.



The one circled in red does not look like the one with the clean tip?

"No flamesuit required"

The main pic was taken just after fuel pump priming.
Takes a little while (maybe 2 to 3 minutes) to really notice the seepage.

The red circle is an 'after' fuel pump priming (>3 minutes).

[danewilson77]

Understood

"No flamesuit required"

[Simmsled]

Just a follow-up a few days in...

By replacing the leaky injector:
+ I haven't had a single warm start issue! Starts every single time, the exact same way.
+ My gas mileage has improved around 1.5 mpg (could I have really been losing that much fuel?!?)
+ Power delivery is smoother (this makes sense, but really did not expect it)

100% happy guy.

[danewilson77]

Great news.

"No flamesuit required"