Direct injection Diesels starting

[RalphM]

I have had a good few Diesel of different breeds and one thing I have noticed is common rail
engines after waiting for the glow light to go out, hot or cold take just a second or two to fire,
just a little longer that I expect, is this due maybe till the rail pressure rises or maybe till the
ecu as read a pulse from both the tdc and cam sensor? or maybe to give the oil pressure time
to rise? this is not just a Fiat thing and I don't see it as a fault just interested.

 

[bugsymike]

I tend to agree with you, and certainly notice the Doblo1.6 and 1.3 Multijet and some of the other Common rail engined vehicles crank a little longer, certainly longer than my older Iveco Daily's and Ducato 2.8 Sofim pre ECU Direct Injection engines which even in Winter time needed no heater plug and a bare flick of the starter to fire up. They were all turbo intercooled, the difference being non Common Rail and ECU.
I did wonder if they had higher compression ratio, but generally around 18:1.

 

[RalphM]

Yep must be something I have had mechanical cav pump engines that have started instantly it’s less than 2 secs but not instantly just feels a log time

 

[bugsymike]

Yep must be something I have had mechanical cav pump engines that have started instantly it’s less than 2 secs but not instantly just feels a log time

Mine were generally Bosch which I preferred.
Some of my earlier diesels BMC 1800 Sherpa etc. were indirect injection and CAV non turbo versions that cranked a little longer.
Later I had two LDV 200s with the Prima direct injection engine again non turbo in my case, the first an ex Wadham Kenning parts delivery van was excellent on performance and economy by standards of their time, the second one was an ex Electricity board van and no matter what I tried it was gutless and less economical, though clean burning.
I had three Peugeot 504 2.3 litre diesels non turbo, two pick ups and a Family estate, good performance and economy all did around 200k miles, I note they were 22:1 compression and good starters.

 

[AndyRKett]

My Golf and Wifes Mini both 2.0L Diesels, and both start like a petrol car. Turn the key or in the case of the Mini press the start button and they immediately burst into life as you would expect any car to do. Only in the coldest parts of winter is there ever any hesitation for a second or so for the glowplugs but on these cars its electronically controlled so no need for you to so anything just press the button as usually or turn the key and let go and it will start once ready.

The Punto 1.6 I had you had to hold the key till it was started and it would almost always take a second or two to catch when you started it.

Given fiat more or less phased out diesels around 2015 - 18 it may just be many of the fiat diesels still about are largely still based on old technology?

 

[RalphM]

I suspect it's waiting for the fuel pressure to rise as the rev counter moves more or less right away
so it must be getting a timing signal, will have to put a scanner on it and watch the pressure rise.