Some more bump starting discussion

[JanGeo]

Hey I rolled down a parking lot a few weeks ago and bump started my xB - it started easier than using the starter motor . . . leads me to believe that I have some battery cable issues maybe . . . anyway working on a 450 mile tank and the gas light came on - another fillup tomorrow at S&S with my 10 cents a gallon discount coupon - got three of the suckers and can't burn the gas fast enough to use them before they expire next month on the 23rd.

Also just took about 50 lbs of "junk" out of the back - tools and stuff in boxes I was lugging around - need to check out the back seat removal next.

[Compaq888]

I bumpstarted it again today. I still need to learn how to make it smooth. I'll be working on that next.

[Sean88]

I've been successfully bumping with my '92 Civic and have added the technique of letting out to start and then quickly putting back in. Every once in a while the car fails to start which leaves me in a bad spot. I think it might get flooded somehow since if I pull over and crank it it still won't start but if I open the throttle then it catches. Anyone else experience this?

Sean

[SVOboy]

Sounds like your main relay is going! I need to do my write up!

[GasSavers_brick]

I've experienced no-starts if I jump the gun on disengaging the clutch after the first bump, but 99% of the time I'll get it on the second try. 1% of the time I'll just give up and key-start if I've lost too much speed, but I have yet to have the key fail me. (I better go knock on wood or something...)

[AlexK]

I tried a bump start in 5th gear at 40 mph and it wasn't that violent. I was expecting the tires to chirp and the car to lurch when I popped the clutch but it wasn't that bad. So what is the advantage to injector cutout over ignition kill? With ignition kill there would be a fresh fuel charge in the cylinders and an easier restart, right?

[CO ZX2]

Originally Posted by AlexK

I tried a bump start in 5th gear at 40 mph and it wasn't that violent. I was expecting the tires to chirp and the car to lurch when I popped the clutch but it wasn't that bad. So what is the advantage to injector cutout over ignition kill? With ignition kill there would be a fresh fuel charge in the cylinders and an easier restart, right?

I would not POP the clutch. Let it out gently, helps cushion the shock.

I had ignition kill switch first but seemed to take too long for the engine to die. Also think that the injectors may dribble gas, mine seemed flooded at times on restart.

I really like the injector shutoff, engine shuts down immediately and starts cleanly.

[diamondlarry]

Originally Posted by CO ZX2

I would not POP the clutch. Let it out gently, helps cushion the shock.

I had ignition kill switch first but seemed to take too long for the engine to die. Also think that the injectors may dribble gas, mine seemed flooded at times on restart.

I really like the injector shutoff, engine shuts down immediately and starts cleanly.

What I usually do is let the clutch out far enough to start the engine then quickly shove it back in to let the engine come up to speed before continuing down the road.

[AlexK]

From a conservation of energy standpoint, letting the clutch out slowly wastes energy (slows the car down while the transmitted torque builds up enough to overcome the compression and start the engine). It also wears the clutch pads. Popping the clutch wears the clutch less and saves energy but jolts the drivetrain more. My experiment showed me that the jolt isn't too bad in my car.

Maybe this should be in it's own topic. Do you guys double clutch when shifting from neutral to say 5th gear after a P&G cycle? I do to save wear to the synchros in my transmission. You can't double clutch when the engine is off, so there will be some synchro wear happening.

I am obsessed with FE but more obsessed with mechanical wear. From my experiences with many cars, the transmissions and drive trains break before the engines wear out (with proper oil changes). I need to decide if the increased wear and hassle is worth the FE benefit.

[MetroMPG]

If you start engine-off coasting, Alex, your MPG is going to go throught the roof