1.8 Turbo hesitation/stutter under full throttle - Page 5

COLVERT · 17th July 2020, 12:30

One last thing.

Years ago garages used to test spark plugs in a small machine with a window at the top. The plug was screwed in from below so that the points were visible through this small window.
When the machine was switched on the plug began to spark.

Then the chamber in which the pug was fitted began to pressurise. This simulated what happens in the combustion chamber of a car AS THE REVS RISE.

If the plug was in poor condition the spark would suddenly disappear as it began to track down the central electrode and to earth.

Whether anything like this could happen in an engine whilst it was running I'm not sure.----

The rise in combustion chamber pressure makes the spark voltage rise as it fights the pressure to jump the gap.

This increased voltage could make old spark plug leads begin to track to earth as the insulation can no longer stand the higher voltage pressure.

Just a few thoughts on your problem.--

Mean & Green · 19th July 2020, 20:01

New coils FIXED!

I should have just went with my instinct and replaced them from the start. I didn’t change them initially as I was told it wasn’t the coils at fault by Brian when he plugged in his T4.

Also my garage after being asked the direct question could it be the coils, when I had them check the waste gate actuator said they doubted it.

So I could have fixed it for £40 all along. Oh well, it’s only money eh? At least I’ve got the peace of mind of a new turbo and perfectly good one as a spare. Look on the bright side and all that

gnu · 19th July 2020, 20:59

Glad it’s fixed

COLVERT · 19th July 2020, 21:17

Great news. It just had to be those sparks.---

My post, 41, was a very near miss.--Lol. Coils not leads but sparks just the same.

Happy motoring.---

Mean & Green · 20th July 2020, 12:21

Yes I’m relieved it’s fixed. Just a shame I was led onto chasing an over boost issue it didn’t have.

I can now stop the endless test runs at full throttle and just enjoy the car in a more sedate manner, knowing all is well.

Yorkshire GOC · 20th July 2020, 12:43

Always start with the obvious.

Mean & Green · 20th July 2020, 17:01

Quote:

Originally Posted by Yorkshire GOC

Always start with the obvious.

Yes I wish I had now, instead I listened to Brian.

It was nice of him to offer his help which I appreciated, but his advice led me onto a merry go ‘round. Never mind, no one to blame but myself - lesson learned.

Yorkshire GOC · 21st July 2020, 17:52

In 7 years of ownership - i have had hesitation and stutter on 2 occasions one really bad one not so - with the diagnostic showing multiple cylinder misfire - both times coils/leads.

Mean & Green · 21st July 2020, 21:54

Quote:

Originally Posted by Yorkshire GOC

In 7 years of ownership - i have had hesitation and stutter on 2 occasions one really bad one not so - with the diagnostic showing multiple cylinder misfire - both times coils/leads.

Can I ask, do you have a Z&F or Kmaps as they are now called remap on yours?

Yorkshire GOC · 22nd July 2020, 12:41

Yes i do - last 18 months or so - no problems to date - runs sweet and true and with some punch.

19th July 2020, 20:59	#43
gnu Gets stuck in MG ZT Join Date: Apr 2018 Location: Bristol Posts: 696 Thanks: 332 Thanked 164 Times in 133 Posts	Glad it’s fixed __________________ gnu

19th July 2020, 21:17	#44
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	Great news. It just had to be those sparks.--- My post, 41, was a very near miss.--Lol. Coils not leads but sparks just the same. Happy motoring.--- Last edited by COLVERT; 20th July 2020 at 17:21..

20th July 2020, 12:43	#46
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,067 Thanks: 1,842 Thanked 623 Times in 469 Posts	Always start with the obvious. __________________ She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide.

21st July 2020, 17:52	#48
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,067 Thanks: 1,842 Thanked 623 Times in 469 Posts	In 7 years of ownership - i have had hesitation and stutter on 2 occasions one really bad one not so - with the diagnostic showing multiple cylinder misfire - both times coils/leads. __________________ She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide.

22nd July 2020, 12:41	#50
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,067 Thanks: 1,842 Thanked 623 Times in 469 Posts	Yes i do - last 18 months or so - no problems to date - runs sweet and true and with some punch. __________________ She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide.

17th July 2020, 12:30	#41
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	One last thing. Years ago garages used to test spark plugs in a small machine with a window at the top. The plug was screwed in from below so that the points were visible through this small window. When the machine was switched on the plug began to spark. Then the chamber in which the pug was fitted began to pressurise. This simulated what happens in the combustion chamber of a car AS THE REVS RISE. If the plug was in poor condition the spark would suddenly disappear as it began to track down the central electrode and to earth. Whether anything like this could happen in an engine whilst it was running I'm not sure.---- The rise in combustion chamber pressure makes the spark voltage rise as it fights the pressure to jump the gap. This increased voltage could make old spark plug leads begin to track to earth as the insulation can no longer stand the higher voltage pressure. Just a few thoughts on your problem.--

19th July 2020, 20:01	#42
Mean & Green Regular poster MG ZR Join Date: Jun 2020 Location: Newcastle Upon Tyne Posts: 93 Thanks: 53 Thanked 30 Times in 19 Posts	New coils FIXED! I should have just went with my instinct and replaced them from the start. I didn’t change them initially as I was told it wasn’t the coils at fault by Brian when he plugged in his T4. Also my garage after being asked the direct question could it be the coils, when I had them check the waste gate actuator said they doubted it. So I could have fixed it for £40 all along. Oh well, it’s only money eh? At least I’ve got the peace of mind of a new turbo and perfectly good one as a spare. Look on the bright side and all that

20th July 2020, 12:21	#45
Mean & Green Regular poster MG ZR Join Date: Jun 2020 Location: Newcastle Upon Tyne Posts: 93 Thanks: 53 Thanked 30 Times in 19 Posts	Yes I’m relieved it’s fixed. Just a shame I was led onto chasing an over boost issue it didn’t have. I can now stop the endless test runs at full throttle and just enjoy the car in a more sedate manner, knowing all is well.