2003 1.8T - intermittent misfire on starting

Hawkesman · 5th March 2019, 19:58

It doesn't do it every time I start it, but when it does it can go on for anything from 15 seconds to a minute before it clears and then runs fine for any amount of time until I switch off.

Sounds and feels like one cylinder in particular is missing as it has a regular 'beat'. I put new plugs in, but that made no difference. I'm guessing it must be either a dodgy plug lead or one of the coil packs, but I don't want to just randomly change things out in the hope of curing it.

Any ideas people? Thanks.

PS - when I changed the plugs the plastic tops of the plug lead covers just cracked and fell apart when I pulled on them - had to pull the remaining rubber part out with a pair of pliers! Other than that an easy job.

suzublu · 5th March 2019, 19:59

Symptoms of a failing inlet manifold gasket

stevestrat · 5th March 2019, 20:02

Check your coolant level in the header tank. 1.8 and 1.8T are prone to a weeping inlet manifold gasket, when the engine is cooling down/cold it allows a dribble of coolant into the inlet manifold which manifests itself with a rough idle on starting. Idle settles down once the coolant has burnt off.

cb750chris · 5th March 2019, 20:54

I did get asked to look at a car with a similar symptom, and after checking through all the obvious things, I ended up finding that the valve timing was 1 tooth out on the inlet cam. Not entirely sure how the rough running ever cleared itself.

But, check for leaking gaskets first.

Hawkesman · 5th March 2019, 22:58

Thanks guys. But surely that would cause general rough running, and not one particular cylinder to misfire, as I'm sure is the case in this instance as I can hear and feel that only one plug is misfiring?

stevestrat · 5th March 2019, 23:31

Coolant weeping into the inlet manifold primarily affects cylinder number 4 more than any other. Had it myself, most 1.8 and 1.8T owners will get it at some point if they haven't already.

roverbarmy · 6th March 2019, 09:39

When it's misfiring switch off and pull the spark plugs. Check for which plug isn't firing and see what is on the plug. As said, often a sign of a failing inlet manifold gasket, easy to change and not that expensive.

slovcan · 8th March 2019, 01:54

Perhaps putting a "skim" coat of RTV on the side of the gasket that fits into the groove on the intake manifold and another "skim" coat of RTV on the surface around the #1 & #4 ports? I think that would help prevent the gasket getting displaced when maneuvering it over the studs and also seal around #1 & #4 if there was any warping of the manifold.

Hawkesman · 8th March 2019, 12:44

Any recommendation for a brand for the gasket? Thanks.

Hawkesman · 8th March 2019, 16:35

Does anyone happen to know the torque settings for the manifold nuts?

Agree with the TLC. Mine's done 125k, so I check the basic stuff under the bonnet every couple of days, with a more thorough check if I'm driving any distance.

5th March 2019, 20:02	#3
stevestrat This is my second home ZT260 #243 (resting) Join Date: May 2010 Location: Prestonpans Posts: 22,479 Thanks: 650 Thanked 4,624 Times in 3,358 Posts	Check your coolant level in the header tank. 1.8 and 1.8T are prone to a weeping inlet manifold gasket, when the engine is cooling down/cold it allows a dribble of coolant into the inlet manifold which manifests itself with a rough idle on starting. Idle settles down once the coolant has burnt off. __________________ Steve T4 Location Map

5th March 2019, 23:31	#6
stevestrat This is my second home ZT260 #243 (resting) Join Date: May 2010 Location: Prestonpans Posts: 22,479 Thanks: 650 Thanked 4,624 Times in 3,358 Posts	Coolant weeping into the inlet manifold primarily affects cylinder number 4 more than any other. Had it myself, most 1.8 and 1.8T owners will get it at some point if they haven't already. __________________ Steve T4 Location Map

6th March 2019, 09:39	#7
roverbarmy This is my second home Roverless + 1.7D Sportage Join Date: Aug 2014 Location: East Norfolk Posts: 7,050 Thanks: 729 Thanked 2,021 Times in 1,449 Posts	When it's misfiring switch off and pull the spark plugs. Check for which plug isn't firing and see what is on the plug. As said, often a sign of a failing inlet manifold gasket, easy to change and not that expensive. __________________ Oil in my veins!

8th March 2019, 01:54	#8
slovcan Gets stuck in 75 Tourer CDT MK2 manual in Glorious Grey Join Date: Jan 2018 Location: Slovakia Posts: 987 Thanks: 926 Thanked 346 Times in 252 Posts	Perhaps putting a "skim" coat of RTV on the side of the gasket that fits into the groove on the intake manifold and another "skim" coat of RTV on the surface around the #1 & #4 ports? I think that would help prevent the gasket getting displaced when maneuvering it over the studs and also seal around #1 & #4 if there was any warping of the manifold. __________________ Southern Slovakia Anything can happen in Formula 1 and usually does - Murray Walker 1999 Triumph Trophy 900, Saddlesore 1600, Iron Butt Riders Association #63720 2005 Rover 75 CDT Tourer MK2

5th March 2019, 19:58	#1
Hawkesman Regular poster Rover 75 Saloon Join Date: Dec 2018 Location: Reading Posts: 43 Thanks: 22 Thanked 2 Times in 2 Posts	2003 1.8T - intermittent misfire on starting It doesn't do it every time I start it, but when it does it can go on for anything from 15 seconds to a minute before it clears and then runs fine for any amount of time until I switch off. Sounds and feels like one cylinder in particular is missing as it has a regular 'beat'. I put new plugs in, but that made no difference. I'm guessing it must be either a dodgy plug lead or one of the coil packs, but I don't want to just randomly change things out in the hope of curing it. Any ideas people? Thanks. PS - when I changed the plugs the plastic tops of the plug lead covers just cracked and fell apart when I pulled on them - had to pull the remaining rubber part out with a pair of pliers! Other than that an easy job.

5th March 2019, 19:59	#2
suzublu This is my second home rover 75 1.8 vvc club se wedgwood blue Join Date: Aug 2009 Location: Seaton Carew Posts: 26,920 Thanks: 65 Thanked 7,142 Times in 4,642 Posts	Symptoms of a failing inlet manifold gasket

5th March 2019, 20:54	#4
cb750chris Trader Rover 75 Tourer Join Date: Apr 2011 Location: Portsmouth Posts: 849 Thanks: 201 Thanked 292 Times in 200 Posts	I did get asked to look at a car with a similar symptom, and after checking through all the obvious things, I ended up finding that the valve timing was 1 tooth out on the inlet cam. Not entirely sure how the rough running ever cleared itself. But, check for leaking gaskets first. __________________ Now offering T4 services in the Fareham area Replacement keys programmed / supplied / cut Diesel 135 upgrade available IPK virginisation and T4 matching available Sorry, due to a big change in home circumstances, I am unable to do any large jobs at present, but can still offer evening time diagnostics.

5th March 2019, 22:58	#5
Hawkesman Regular poster Rover 75 Saloon Join Date: Dec 2018 Location: Reading Posts: 43 Thanks: 22 Thanked 2 Times in 2 Posts	Thanks guys. But surely that would cause general rough running, and not one particular cylinder to misfire, as I'm sure is the case in this instance as I can hear and feel that only one plug is misfiring?

8th March 2019, 12:44	#9
Hawkesman Regular poster Rover 75 Saloon Join Date: Dec 2018 Location: Reading Posts: 43 Thanks: 22 Thanked 2 Times in 2 Posts	Any recommendation for a brand for the gasket? Thanks.

8th March 2019, 16:35	#10
Hawkesman Regular poster Rover 75 Saloon Join Date: Dec 2018 Location: Reading Posts: 43 Thanks: 22 Thanked 2 Times in 2 Posts	Does anyone happen to know the torque settings for the manifold nuts? Agree with the TLC. Mine's done 125k, so I check the basic stuff under the bonnet every couple of days, with a more thorough check if I'm driving any distance.