Question about the math for EOC vs Coast?

[California98Civic]

Originally Posted by bentring

Speaking to those of you who have bump started for thousands of miles, does it seems not to affect the durability of the transmission? My owners manual specifically states not to push start it, and it's been years since I've kept up with auto tech so I didn't know if anything in manuals has changed to make it a bad idea, or if they were just covering liabilities.

It might just be about liability. You should research it further. I have been bump starting for about 60,000 miles now. Both the transmission and the CAT are fine, though I did swap the trans for taller gearing. Each trans has about 30,000 in bump starts on it. Neither has been compromised by it, to my knowledge. Both are old transmissions with mild shifting issues and some needed replacements like seals, or bearings, or maybe a syncho could use replacing because shifting has gotten clunky in a place or two... totally normal kinds of wear for transmissions with 100,000 or 200,000 miles on them. As importantly, there are lots of other people here who have been doing this a long long time without incidents.

But you should research your car and the reasons for that warning before you attempt it, would be my recommendation.

james

[PaleMelanesian]

My Civic's transmission and clutch were just fine when I retired it at 200,000 miles, 50,000 of that being super-bump-start eoc hypermiling. I only have 20k on the Fit now so I can't say one way or the other.

The Civic would go into Closed Loop mode almost immediately on a bump start. The Fit isn't so generous, taking ~5 seconds of Open Loop before it switches. I try to do longer cycles because of that - more closed loop time during a longer pulse, and then I coast longer.

A good bump start is very gentle. It shouldn't be much stress on any components. It's a 2-step process for best smoothness. Use top gear, or 4th if you're below 10 mph. Lift the clutch just until it brushes contact, then push it back down while the engine spins up. Then choose your gear and shift like you normally would.

[bikeprof]

Now we are starting a new parameter, worrying about the life of the CAT.
Hmmm, most of us drive at low RPM's/low engine demand, just that is trouble for a CAT! CAT's need high temps to work more proper, no?