Help...

Brian in MN

Brian in MN

Daily Driver
Hi all, so my X is stalling out. It's an 85' and will kill, usually while costing to a stop (i.e. approaching a stop light). It doesn't happen all the time but at least once during my 15 minute joy rides I take every week or so. When it dies, it's very sudden and with no warning. While running, it runs beautifully - very smooth, no misfiring or hic-ups... It'll just quit and always starts right back up. Though I've only casually tried this, it seems like if while costing to a stop, I keep the revs up it'll be less likely to stall (idle seems fine). Thai, our local X guru just helped me replace the cap, rotor, plugs and wires. I've experienced the same stalling pre and post this work. BTW, I'm pretty helpless with mechanical stuff so don't hesitate to talk to me like the kindergarten mechanic that I am. Looking forward to your insight... Thanks!:eek:mg:
 
Sounds like it could be a vacuum leak - for example one of the hoses to the aux air valve, inlet hose cracks around the PCV hoses, etc..
On decel it will be much leaner, and excess air drawn in will stall the motor. The fact that keeping the revs up a tad helps suggests the same, since as long as the throttle is open, the injectors are still supplying fuel.. that's where I'd start looking, anyway.
 
Well, one possibility...

that you probably don't want to hear is burned exhaust valves. I had a car with the same symptom (stalling on coasting). But it also had a rough idle, which you did not mention. A leak-down compression test can disprove this problem.

Pete
 
Thanks guys...

When Thai was over he thought that he heard a vacuum leak! :sun:I bet that's it. Where and what do I look for/listen for to figure out if this is the case?
 
Pretty easy actually... Use an UNLIT propane torch...

... or a can of WD40 and squirt around the suspected areas like vacuum hoses and intake gaskets... moving SLOWLY, while the engine is idling.

If and when the engine speeds up... there is your leak!
 
I'm not too familiar at all with the FI system the X1/9s have... the 83 I bought came with the engine in several boxes! (I'm really hoping I have all the parts!)

I'm curious, do these cars have a throttle 'dampner'? My miata has one... and it has a system that uses a AFM... I know that the dampner slows the throttle down when you lift of the gas... so it sort of eases down to idle speed rather than slamming shut the throttle body shut (which must freak the ECU out a bit) I know that on the miata if your car is dying in situations like this, one of the items that is suspect is the dampner... letting the butterfly slam shut too fast and making the car stumble or die.

No idea if the X1/9 even has one though...
 
The guys are right

Look for a vacuum leak. On deceleration the fuel system is already going lean and with the vacuum leak on cracked or broken rubber. Look very close and bend the rubber with your hands in bend areas to expose possible cracks. It will usually result in a stall while coming to a stop.
 
Would starter fluid suffice? I use it when I am testing vaccum leaks with my webbers but never thought of it with my FI car.
 
Another choice might be related to the fuel pump switch in the AFM, it may be closing completely when you let off and stalling the engine due to no fuel delivery.
 
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