Engine neutral/coasting car dies

neutral/coasting car dies

I was coasting downhill in neutral and all of a sudden my car looses power. no brakes, no power steering. the engine just stops. i'm still rolling. so i start the car again. it turns on.

i'm freaked out. i reach a stop light, and i notice the rpms dipping real low like 300rpm. so i punch the gas, and the car still stays on.

when shifting slowly between gears, the rpm dips really low again 300rpm. so i'm tapping the gas to keep the car running. and what's interesting is that the car doesn't shiver or shake like i had a bad gas and cluch mixture while taking off. it just dies.

i reach another intersection red light, and the car idles perfectly fine at 800 or 900rpm. i try coasting again after take off in neutral and the car almost dies again. i put it back in gear to keep the rpms up

i just installed my header and cold air intake. i hope it's not affecting anything.

oh yeah this phenomenon is on and off. the car only died on me once. other than that, when i reached an intersection and stopped, i kept eye on my tachometer and if the rpms dipped real low, i step on the gas or rev the engine. there were no check engine lights on.

It sounds like a vacuum line is cut.

hehe wikituner is right. LOL Maybe I should change my name to Dr. Wikituner? hahaha

i'll post a vid of my gauge cluster on youtube. it's really weird.

I found this on an AUDI forum. Rollatuner110, you might be right!!
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Stalling? Sticky Deceleration Valve? (Manual Transmission)


If your car stalls when coming to a stop and you have a manual transmission, one possibility is the deceleration valve is sticking open which would create a huge vacuum leak. Normally the idle stabilizer control unit turns this valve (solenoid) on and intake vacuum opens it, when you let off the gas and the RPM's are above 1200 RPM .


When the Decel valve opens it basically creates a big vacuum leak between the rubber boot above the CIS air flow plate and below the plate in the lower air filter housing. This big leak allows the CIS air flow plate to drop down and effectively shut off the fuel during deceleration so as to keep emissions low.


These valves have been known to stick open and then not shut when the RPM drops below 1200 which causes the big vacuum leak and the stalling. The valve is buried behind the r/side fender behind the CIS assembly. You may need to pull the plastic fender liner out to get to it.


The small vacuum hose from the decel valve should be connected to the back of the intake manifold via the small metal pipe fitting. There may be a plastic tee fitting nearby which also connects this manifold hose to the lower fitting on the waste gate solenoid. Basically this hose has intake manifold vacuum/pressure applied to it.


There is a larger rubber hose ~3/4 inch diameter that you can see from above that is routed from the big CIS intake boot down behind the fender to the decel valve (just in front of the fuel filter), if you are able to pinch off this hose, you can see if the car no longer stalls during deceleration.


You could also have a problem with the idle stabilizer control unit, or the temp sensor for this unit, the idle stabilizer control unit could be defective and keeping the decel valve on even after the RPM drops below 1200 RPM. Go to the CIS Fuel System page, Idle Mixture sectionfor more details on this idle stabilizer system.


Here is a picture of the valve and the location on the CIS air filter box.

The air to fuel ratio wouldn't be able to make the car stall. The fuel ration is regulated my computer. I doubt it would all of a sudden go haywire and cause the car to stall. It's due to a leak(s) in a vacuum hose(s). jcrwzr already knows about this. I forgot which line it is. He can delve into this in more detail.

yeah this happened to me once or twice but hasnt happened in a while i think it has to do with the air to fuel ratio and cumbustion wrong ratio and the car starts shaking. Because the only other way it shakes is when i rev the car real high the engine shake makes the car vibrate more.