Lazy cranking

by **ecuedit** » Thu Aug 23, 2012 8:39 pm

Was engine warm or cold when you did this measurement?
You can attach 5 files now.

by **Alex.T** » Fri Aug 24, 2012 8:18 am

ecuedit wrote:Was engine warm or cold when you did this measurement?

Warm engine.
But I forgot that I have Injectors cleaner in the fuel.
Maybe I redo the logging after cleaning

by **ross2482** » Fri Aug 24, 2012 9:10 am

Alex.T wrote:
ross2482 wrote:the ECU has to obtain crank \ cam synchronisation before it can start

Why is that?
Isn't everything syncronized by a belt ?!

Think about it logically ;)

You have sequential injection - The ECU needs to know which cylinder is on the exhaust stroke and which cylinder is on the injection \ firing stroke, so it can inject into the correct cylinder. It does this by using the camshaft sensor to determine the position of the camshaft - I.e which cylinder is going to need injection next.

This process can take up to 2 crank revolutions.

by **Alex.T** » Fri Aug 24, 2012 9:16 am

This sound logical, but then why other engines start in half revolution?
Don't they need to know which piston is on injection stroke?

by **ross2482** » Fri Aug 24, 2012 11:48 am

Which engines do you mean? I dont think I have ever seen a CR diesel engine start with half a revolution.

by **Alex.T** » Fri Aug 24, 2012 2:05 pm

I don't know what a CR engine is and what cars have it.
I mean why a XUD engine starts faster?
Why my old VW Polo 1.4 TDI from 2002 that also was common rail with EDC15, started much faster? - not in half revolution but usually in 1 rev, sometimes in 1 and a half but not more..

by **rlees85** » Fri Aug 24, 2012 2:14 pm

A XUD is purely mechanical and the injection pump is timed. So no need to sync.

My 2.2 HDI seems to start exactly after 2 revolutions, each and every time. I guess if your often seeing 3 4 or more revs then something might be not quite right.

I looked at your injector corrections also. My injector 1 frequently goes up to 3, and sometimes down to 2. It doesnt fluctuate quickly so I assume the injector is fine. I don't think I have ever seen it go down to 0.xx like yours does though... I would say your injectors are not perfect but not bad either.

by **Alex.T** » Fri Aug 24, 2012 2:38 pm

2 revolutions is not that bad if it's always the same..
The thing that drives me crazy is that my 2.0 doesn't start always at the same time.. sometimes it's 2 revs (rare) sometimes it's 3 and sometimes it's 4... It's annoying