cause of misfire on 1.8t

Yorkshire GOC · 21st January 2021, 12:08

Well having had a misfire on my car garage has tested cylinder compression - cylinders 2,3, and 4 show 120 psi and Cylinder 1 60 psi - dont think it is HGF as i have no other symptoms - garage suggests it maybe a damaged or dropped valve . However he also said 120 psi on the other 3 cylinders seems low as well.

Thoughts anyone

Odd Job · 21st January 2021, 12:17

The engine is turbo charged, so 120 psi MAY be ok for the other 3 cylinders. Turbo engines have lower compression to begin with, but end up with being very high compression as the turbo comes on full boost.
Obviously 60 psi for the other cylinder is far too low.

The only true way to tell what's going on is to remover the head and examine.
Sometimes even with an endoscope you cant see the full state of things.

T-Cut · 21st January 2021, 12:27

Ignore - I read Cylinder 1 60psi as 160psi.

TC

Yorkshire GOC · 21st January 2021, 12:58

Quote:

Originally Posted by Odd Job

The engine is turbo charged, so 120 psi MAY be ok for the other 3 cylinders. Turbo engines have lower compression to begin with, but end up with being very high compression as the turbo comes on full boost.
Obviously 60 psi for the other cylinder is far too low.

The only true way to tell what's going on is to remover the head and examine.
Sometimes even with an endoscope you cant see the full state of things.

The engine repair guy i have just booked in with confirmed your thoughts that a turbo charged car has low values so he thought the other 3 were ok.We will see.

Lovel · 21st January 2021, 14:16

Just for a relative comparison on mine. 47k 1.8T Turbo engine readings were 190,180,180,190 across the board, hot with full throttle and fully charged battery. My engine has sometimes had a wee misfire when giving it stick, then the next time it is perfectly ok.

I changed the head for a brand new one at some point and guess what the occasional misfire was still there, compression values were near identical to the original readings.

I found NASP engines can be in the range of 220psi. However different gauges will give different results at the end of the day, and they say a a percentage difference between the cylinders is what you are looking for .

Yorkshire GOC · 21st January 2021, 14:22

will let everyone know what they find.

21st January 2021, 12:08	#1
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,066 Thanks: 1,842 Thanked 623 Times in 469 Posts	cause of misfire on 1.8t Well having had a misfire on my car garage has tested cylinder compression - cylinders 2,3, and 4 show 120 psi and Cylinder 1 60 psi - dont think it is HGF as i have no other symptoms - garage suggests it maybe a damaged or dropped valve . However he also said 120 psi on the other 3 cylinders seems low as well. Thoughts anyone __________________ 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 January 2021, 12:17	#2
Odd Job Gets stuck in MG ZT 2.0 cdti Join Date: Aug 2019 Location: Derby Posts: 909 Thanks: 298 Thanked 191 Times in 149 Posts	The engine is turbo charged, so 120 psi MAY be ok for the other 3 cylinders. Turbo engines have lower compression to begin with, but end up with being very high compression as the turbo comes on full boost. Obviously 60 psi for the other cylinder is far too low. The only true way to tell what's going on is to remover the head and examine. Sometimes even with an endoscope you cant see the full state of things. __________________ ….And the latest thing to break is..... ### MG STANDS FOR "MY GREMLIN" !!!

21st January 2021, 14:16	#5
Lovel I really should get out more....... P6B, L550, Imp, F56, Commando Join Date: Nov 2006 Location: Aberdeenshire Posts: 2,886 Thanks: 352 Thanked 677 Times in 440 Posts	Y Just for a relative comparison on mine. 47k 1.8T Turbo engine readings were 190,180,180,190 across the board, hot with full throttle and fully charged battery. My engine has sometimes had a wee misfire when giving it stick, then the next time it is perfectly ok. I changed the head for a brand new one at some point and guess what the occasional misfire was still there, compression values were near identical to the original readings. I found NASP engines can be in the range of 220psi. However different gauges will give different results at the end of the day, and they say a a percentage difference between the cylinders is what you are looking for .

21st January 2021, 14:22	#6
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,066 Thanks: 1,842 Thanked 623 Times in 469 Posts	will let everyone know what they find. __________________ 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 January 2021, 12:27	#3
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	Ignore - I read Cylinder 1 60psi as 160psi. TC