Engine code P0174, vacuum leak, o2 sensor? uneven fuelling

carguy143 · 2nd July 2014, 18:42

Hi all.
Driving home from work a couple of nights ago I got the error code P0174 which indicates bank 2 is running lean. I checked all clips, sensors and easy access hoses were tight and cleared the code. Well, the code has come back tonight as I was driving home from work. I've used torque to check the o2 sensors which does suggest that the sensor on bank 2 (rear bank?) is more erratic than that of bank 1. I did have the upper inlet manifold off a couple of months ago.

If it helps, I have checked the fuelling on both petrol and LPG (using the LPG supplied software) and there is a difference between the banks, although the fuelling between cylinders are even.

Am I right in thinking there is a vacuum leak coming from somewhere? If so, where should I start? Or is it an o2 sensor? Incidentally, running a check for fault codes doesn't flag anything up for an o2 sensor.

Thanks in advance.

Rik.

carguy143 · 3rd July 2014, 17:50

Well I have ordered a replacement set of engine breather hoses, the hidden ones underneath the inlet manifold along with new upper inlet manifold gaskets. Let's see how it does.

rich17865 · 3rd July 2014, 17:53

Running lean, is it possible the upper inlet manifold is letting in air somewhere?

Maybe the vacuum connection for the LPG kit?

carguy143 · 3rd July 2014, 18:11

Quote:

Originally Posted by rich17865

Running lean, is it possible the upper inlet manifold is letting in air somewhere?

Maybe the vacuum connection for the LPG kit?

I thought of that, but when I sprayed a load of carb cleaner in the general area, nothing happened.

carguy143 · 9th July 2014, 22:52

Well I've replaced most of the vacuum pipes as a matter of course, including the upper inlet manifold gaskets and I am still having issues. The short term fuel trim appears to show the car is over fuelling on bank 1 and under fuelling on bank 2. I've no idea where to go with this now.

rich17865 · 10th July 2014, 06:17

When running on petrol, gas, or both?

carguy143 · 10th July 2014, 07:07

Quote:

Originally Posted by rich17865

When running on petrol, gas, or both?

Both.

I've read it could be anything from coil packs, to timing or even the o2 sensors being plugged in to the wrong place.

rich17865 · 10th July 2014, 07:32

Coil packs are considered by many as a service item. When were they last changed?

carguy143 · 10th July 2014, 08:51

Pass on that one rich. What's the best way to test them? I'm unsure if the fronts can be swapped with the rears on a v6. Six coil packs could be pricy.

rich17865 · 10th July 2014, 08:52

At the sort of mileage you have done, I suspect the originals should have been changed by now.

Although, it does still seem like an inlet leak to me.

2nd July 2014, 18:42	#1
carguy143 This is my second home MG ZT 190+ Join Date: Jul 2011 Location: Skelmersdale, Lancs Posts: 3,027 Thanks: 163 Thanked 161 Times in 122 Posts	Engine code P0174, vacuum leak, o2 sensor? uneven fuelling Hi all. Driving home from work a couple of nights ago I got the error code P0174 which indicates bank 2 is running lean. I checked all clips, sensors and easy access hoses were tight and cleared the code. Well, the code has come back tonight as I was driving home from work. I've used torque to check the o2 sensors which does suggest that the sensor on bank 2 (rear bank?) is more erratic than that of bank 1. I did have the upper inlet manifold off a couple of months ago. If it helps, I have checked the fuelling on both petrol and LPG (using the LPG supplied software) and there is a difference between the banks, although the fuelling between cylinders are even. Am I right in thinking there is a vacuum leak coming from somewhere? If so, where should I start? Or is it an o2 sensor? Incidentally, running a check for fault codes doesn't flag anything up for an o2 sensor. Thanks in advance. Rik. __________________ "You don't park a ZT, you simply allow it to rest until next time." It may not happen very often but if I say something helpful please hit the "thanks" button as it helps other users. Thank you. No. 16 of only 52 Nocturne Blue 75/ZT ever produced. ONLY TEN of these were ZT 190+ http://badges.fuelly.com/images/sig-uk/263467.png Last edited by carguy143; 2nd July 2014 at 18:46..

3rd July 2014, 17:50	#2
carguy143 This is my second home MG ZT 190+ Join Date: Jul 2011 Location: Skelmersdale, Lancs Posts: 3,027 Thanks: 163 Thanked 161 Times in 122 Posts	Well I have ordered a replacement set of engine breather hoses, the hidden ones underneath the inlet manifold along with new upper inlet manifold gaskets. Let's see how it does. __________________ "You don't park a ZT, you simply allow it to rest until next time." It may not happen very often but if I say something helpful please hit the "thanks" button as it helps other users. Thank you. No. 16 of only 52 Nocturne Blue 75/ZT ever produced. ONLY TEN of these were ZT 190+ http://badges.fuelly.com/images/sig-uk/263467.png

9th July 2014, 22:52	#5
carguy143 This is my second home MG ZT 190+ Join Date: Jul 2011 Location: Skelmersdale, Lancs Posts: 3,027 Thanks: 163 Thanked 161 Times in 122 Posts	Well I've replaced most of the vacuum pipes as a matter of course, including the upper inlet manifold gaskets and I am still having issues. The short term fuel trim appears to show the car is over fuelling on bank 1 and under fuelling on bank 2. I've no idea where to go with this now. __________________ "You don't park a ZT, you simply allow it to rest until next time." It may not happen very often but if I say something helpful please hit the "thanks" button as it helps other users. Thank you. No. 16 of only 52 Nocturne Blue 75/ZT ever produced. ONLY TEN of these were ZT 190+ http://badges.fuelly.com/images/sig-uk/263467.png

10th July 2014, 08:51	#9
carguy143 This is my second home MG ZT 190+ Join Date: Jul 2011 Location: Skelmersdale, Lancs Posts: 3,027 Thanks: 163 Thanked 161 Times in 122 Posts	Pass on that one rich. What's the best way to test them? I'm unsure if the fronts can be swapped with the rears on a v6. Six coil packs could be pricy. __________________ "You don't park a ZT, you simply allow it to rest until next time." It may not happen very often but if I say something helpful please hit the "thanks" button as it helps other users. Thank you. No. 16 of only 52 Nocturne Blue 75/ZT ever produced. ONLY TEN of these were ZT 190+ http://badges.fuelly.com/images/sig-uk/263467.png

3rd July 2014, 17:53	#3
rich17865 This is my second home Transit Connect Join Date: Feb 2011 Location: Crewe Posts: 9,532 Thanks: 868 Thanked 1,619 Times in 1,095 Posts	Running lean, is it possible the upper inlet manifold is letting in air somewhere? Maybe the vacuum connection for the LPG kit?

10th July 2014, 06:17	#6
rich17865 This is my second home Transit Connect Join Date: Feb 2011 Location: Crewe Posts: 9,532 Thanks: 868 Thanked 1,619 Times in 1,095 Posts	When running on petrol, gas, or both?

10th July 2014, 07:32	#8
rich17865 This is my second home Transit Connect Join Date: Feb 2011 Location: Crewe Posts: 9,532 Thanks: 868 Thanked 1,619 Times in 1,095 Posts	Coil packs are considered by many as a service item. When were they last changed?

10th July 2014, 08:52	#10
rich17865 This is my second home Transit Connect Join Date: Feb 2011 Location: Crewe Posts: 9,532 Thanks: 868 Thanked 1,619 Times in 1,095 Posts	At the sort of mileage you have done, I suspect the originals should have been changed by now. Although, it does still seem like an inlet leak to me.