Go Back   The 75 and ZT Owners Club Forums > The 75 and ZT Owners Club Forums > Technical Help Forum
Register FAQ Image Gallery Members List Calendar Mark Forums Read
Notices

Reply
 
Thread Tools Display Modes
Old 14th October 2021, 22:06   #1
Norway
Newbie
 
MG ZT-T

Join Date: Jul 2020
Location: Skotselv
Posts: 22
Thanks: 6
Thanked 4 Times in 3 Posts
Default Cold start misfire ZTT 1.8T

A little while ago my ZTT started misfire upon cold starts! It will run on 3 for about 15-20 seconds before the last one wakes up! Having read some forum thread about similar issues I immediately ordered a black Viton inlet manifold gasket and full ignition set with spark plugs and leads and coils from DMGRS and swapped everything as soon as it arrived but it made no difference! Funny thing is it drives and pulls absolutely flawlessly 🤔It seems worse if it’s partially humid outside! There’s no sign of head gasket failure ore compression loss and there’s no fault codes stored so now I’m right confused 🤷NAUGHTY WORD-♂️


Sent from my iPhone using Tapatalk
Norway is offline   Reply With Quote
Old 15th October 2021, 08:56   #2
stevestrat
This is my second home
 
ZT260 #243 (resting)

Join Date: May 2010
Location: Prestonpans
Posts: 22,424
Thanks: 650
Thanked 4,624 Times in 3,358 Posts
Default

Is it a plastic inlet manifold? They can warp very slightly out of shape and replacing the gasket doesn't stop it weeping.

What gap did you set on the new plugs? 1mm is the manufacturers recommendation but taking them down to 0.7mm will improve the idle and response.
__________________
Steve


T4 Location Map
stevestrat is offline   Reply With Quote
Old 15th October 2021, 09:42   #3
Norway
Newbie
 
MG ZT-T

Join Date: Jul 2020
Location: Skotselv
Posts: 22
Thanks: 6
Thanked 4 Times in 3 Posts
Default

Yes it is plastic manifold! I didn’t check the gap on the spark plugs as I thought buying them from a specialist they should be okay 🙈They are Denso plugs by the way! I’ll check the gap when I get home!!


Sent from my iPhone using Tapatalk
Norway is offline   Reply With Quote
Old 15th October 2021, 10:24   #4
stevestrat
This is my second home
 
ZT260 #243 (resting)

Join Date: May 2010
Location: Prestonpans
Posts: 22,424
Thanks: 650
Thanked 4,624 Times in 3,358 Posts
Default

1.8s turbo and N/A run much better with a smaller gap than the recommendation.
__________________
Steve


T4 Location Map
stevestrat is offline   Reply With Quote
Old 15th October 2021, 10:55   #5
TourerSteve
Loves to post
 
TourerSteve's Avatar
 
Rover 75 Tourer

Join Date: Jul 2016
Location: Withernsea
Posts: 436
Thanks: 43
Thanked 290 Times in 167 Posts
Default

Quote:
Originally Posted by stevestrat View Post
Is it a plastic inlet manifold? They can warp very slightly out of shape and replacing the gasket doesn't stop it weeping.

What gap did you set on the new plugs? 1mm is the manufacturers recommendation but taking them down to 0.7mm will improve the idle and response.
I agree with stevestrat
Both points valid, but as the the misfire appears to be consistent for first 15-20 on engine start up I would revisit and check your inlet manifold for warping as is consistent with coolant passing into the inlet port , Have you had to top up the coolant level ?
Plug gaps set at 0.7 mm does improve running and appears more critical for turbo than the nasp

Last edited by TourerSteve; 15th October 2021 at 12:06..
TourerSteve is offline   Reply With Quote
Old 15th October 2021, 18:30   #6
Norway
Newbie
 
MG ZT-T

Join Date: Jul 2020
Location: Skotselv
Posts: 22
Thanks: 6
Thanked 4 Times in 3 Posts
Default

Yes but I don’t know if that’s the reason as I’ve had various types of coolant leaks to fix over the last months! I’ve not seen any excessive smoke from the exhaust either! This doesn’t happen everyday either! Today when I was going home from work there where no misfire on start up. Only seemed a bit hesitant for a couple of seconds. But I’ll check the plug gap and sort the last little coolant dripping and monitor the situation!


Sent from my iPhone using Tapatalk
Norway is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 12:53.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright © 2006-2023, The Rover 75 & MG ZT Owners Club Ltd