Strange Starting Issue

[tonedef 9]

It might seem I’m doing it the wrong way round but because of the recent wet weather I’ve been commuting on the motorbike rather than the Corrado as I’d rather the car stays clean and dry! This means that I start the car, drive it out of the garage get the bike out or in and put the car away, maybe five minutes tops running time twice a day.
A few times it’s been really weird starting, it seems to spin over really quickly almost like the engine’s got no plugs in, then it splutters into life until it finally settles to running on all six after maybe 30 seconds or a minute. Other times it starts completely normally.

I’d suspect a plug or injector if it wasn’t for the fast spinning, can the oil non-return valve between the block and the head allow head pressure to fall overnight which then needs to rebuild in the followers once it starts? Would that decompress the engine, it’s not clattering like they do after a long lay up?

Going for a run today which might resolve it but just puzzled!

[1xshaunx1 27]

Have a check on the coil pack and it’s wiring 

[tony_ack 0]

I have something similar on mine, turns out the starter wasn't engaging the flywheel every time. It gets worse when being used rarely, and goes away completely after a few weeks regular use. Not sure if it's a faulty solenoid or ignition switch (which I know is on its way out)

If it is the starter, the rough running could be because the engine's being flooded when you turn the key and the starter doesn't engage?

Another possibility is the valves could be sticking open when you crank?

[Dox 23]

Fast cranking can be tappet jacking due to excessive oil pressure, the tappets prevent the valves from completely closing giving the starter an easy time.

if you search others have had similar diagnosed at stealth As faulty oil pumps

Edited August 20, 2020 by Dox

[tonedef 9]

Thanks for the replies, and suggestions.

It's definitely turning the engine over every time so the starter's engaging fine, it does sometimes seem to disengage as if the engine's spinning faster than the starter can keep up with, a second attempt will almost always start it when this happens.

I'm sure it's OK electrically as it runs fine the rest of the time. It's always runs smooth and never seems to hesitate, probably aided by the OBD2 management, I forget what it was like before that.

Tappet jacking definitely seems like it could be a consideration and of course there might be a sticking follower, I replaced them when I rebuilt the top end, that was fourteen years but only around 20,000 miles ago. I'm also running 268 cams so the followers have a bit more work to do than standard. I'll probably put an oil pump on this winter's list, can't hurt after 25 years can it although it's a shame to do the oil as that's only a few hundred miles old, good job I bought 25 litres of Synta!