Over fueling on 1 bank -V6?

[Simon.h]

Over fueling on 1 bank -V6?
Hi I have a V6 MG ZT 2.5 with lpg, its been on the car for 1-2 years, with no problems.
The only thing is 7 days ago the engine light came on, so i run my scantool software and the lpg software both at the same time.
The engine light is on because its running too lean. I have noticed that the injection times are different between banks -

injector times m/s -
bank 1 - petrol 3.2-3.4, lpg 4.0-4.2
bank 2 - petrol 3.4-3.5, lpg 4.4-4.5

On the scantool the fuel trims are

bank 1 - oxgyen sensor petrol 0.205-0.765v @ -2.3 % trim, lpg 0.175-0.800v @ +16.2% trim
bank 2 - oxgyen sensor petrol 0.210-0.800v @ +9.4% trim, lpg 0.130 @ +39.8 trim stays as this

The problem being is the injectors times should be the same for both banks of my V6, whichs means bank 2 is being over fueled.
Have cleared all codes from ECU turned off lpg and run for the last days on petrol, checked codes still too lean on bank 2 but no engine light

Have today swapped the oxgyen sensors over, thinking may be bank 2 sensor is playing up but the injectors times/trims are the same! Have also checked for air leaks on the inlet manfolds.

Also then on lpg have a think a missfire at low revs (below 3k), its normal for problems to show up on lpg before petrol due to it being a finer fuel.

What do you think?

[Simon.h]

Is there any way of checking for air leaks down in the V ?
It did have all new inlet manfold gaskets 1-2 years ago.

[Bernard LPG]

Is there any way of checking for air leaks down in the V ?
It did have all new inlet manfold gaskets 1-2 years ago.

You can spray some sort of hydrocarbon spray locally and listen if the engine revs change on tick-over.

[Bernard LPG]

Over fueling on 1 bank -V6?
Hi I have a V6 MG ZT 2.5 with lpg, its been on the car for 1-2 years, with no problems.
The only thing is 7 days ago the engine light came on, so i run my scantool software and the lpg software both at the same time.
The engine light is on because its running too lean. I have noticed that the injection times are different between banks -

injector times m/s -
bank 1 - petrol 3.2-3.4, lpg 4.0-4.2
bank 2 - petrol 3.4-3.5, lpg 4.4-4.5

On the scantool the fuel trims are

bank 1 - oxgyen sensor petrol 0.205-0.765v @ -2.3 % trim, lpg 0.175-0.800v @ +16.2% trim
bank 2 - oxgyen sensor petrol 0.210-0.800v @ +9.4% trim, lpg 0.130 @ +39.8 trim stays as this

The problem being is the injectors times should be the same for both banks of my V6, whichs means bank 2 is being over fueled.
Have cleared all codes from ECU turned off lpg and run for the last days on petrol, checked codes still too lean on bank 2 but no engine light

Have today swapped the oxgyen sensors over, thinking may be bank 2 sensor is playing up but the injectors times/trims are the same! Have also checked for air leaks on the inlet manfolds.

Also then on lpg have a think a missfire at low revs (below 3k), its normal for problems to show up on lpg before petrol due to it being a finer fuel.

What do you think?

My first reaction on looking at the fuel trims is that bank 2 is being under fueled because you have a large +ve trim. That could equally be due to a misfire confusing the oxygen sensor.

Have you changed the spark plugs lately? They are responsible for 95% of all misfires that I see.

Small imbalances should be able to be trimmed out by using the bank offset which is in most setting softwares.

[Simon.h]

Plugs were changed at 40k but im thinking may be a wonky sparkplug though ; bear in mind a cylinder misfire releases unburnt fuel and air into the exhaust ; the oxygen sensor detects the oxygen (as you might expect!) and the engine management misinterprets that as "lean". It cranks up the fuel trims trying to compensate, which will give two cylinders running rich and one running rich with a ignition misfire as well. Well thats one idea!

[Bernard LPG]

Plugs were changed at 40k but im thinking may be a wonky sparkplug though ; bear in mind a cylinder misfire releases unburnt fuel and air into the exhaust ; the oxygen sensor detects the oxygen (as you might expect!) and the engine management misinterprets that as "lean". It cranks up the fuel trims trying to compensate, which will give two cylinders running rich and one running rich with a ignition misfire as well. Well thats one idea!

Unless you have iridium plugs then 40k is an awful lot of miles on LPG.

[Lates]

The spec is lpg plugs get replaced every 12 months. Rather than go round the houses with live data, do the simple checks first.

[Simon.h]

Have ordered some lpg spark plugs from rimmers today.

Thats news to me about plugs only last 12 months.

Cheers
Simon.

[wutang]

Simon,

I have been running on LPG for the last 4 years and 100,000 miles, I change my plugs every service, so twice a year, LPG eats the plugs this will be the cause of the misfire almost certainly.

Richard.

[Bernard LPG]

Iridium is the way to go. NGK BKR6EIX-LPG has been specially developed for Autogas applications. I have fitted lots now in different cars with good results.

[Simon.h]

Hi
Have now got code -
P0300 Random/Multiple Cylinder Misfire Detected.

New lpg plugs have turned up from rimmers so im doing the compression test 1st.
Whats psi should the pistons have?

Cheers
Simon

[chrissyboy]

i"d do a compression test as it sounds to me the misfire and over fuelling is being caused by a lower compression cylinder ,you should be looking for around 10% diffrence if the readings show you have a much lower reading on a cylinder ..

[Simon.h]

Cheers for that, but what psi should i get from a cylinder?

[Simon.h]

Hi, update

Did a compression test

cylinder 1 - 13.5 bar
2 - 14 bar
3 - 13.3 bar
4 - 13.9 bar
5 - 13.0 bar
6 - 13.9 bar

I think these figures are ok for a 107k engine? Fitted new set of spark plugs and drove 50miles on petrol. My bad missfire has now gone then on lpg and its feels 100% on both fuels.

Injector times m/s

bank 1 - petrol 2.6-2.7, lpg 2.1-2.2
bank 2 - petrol 2.6-2.7, lpg 3.0-3.1

bank 1 - oxgyen sensor petrol 0.805v @ S/T 0% trim, lpg S/T -22%, L/T +7.8% trim
bank 2 - oxgyen sensor petrol 0.095v @ S/T 0% trim, lpg S/T +33%. L/T -0.8% trim

The injectors times are now the same for both banks of my V6 on petrol but lpg its different, which still comes up with code for too lean and turning on engine light.

[Bernard LPG]

bank 1 - oxgyen sensor petrol 0.805v @ S/T 0% trim, lpg S/T -22%, L/T +7.8% trim
bank 2 - oxgyen sensor petrol 0.095v @ S/T 0% trim, lpg S/T +33%. L/T -0.8% trim

The injectors times are now the same for both banks of my V6 on petrol but lpg its different, which still comes up with code for too lean and turning on engine light.

You haven't said which make of Autogas kit but I would say the LPG injectors need cleaning and the system resetting up.

[Simon.h]

Sorry ive got a stag 300 set up.
I now understand that due to my plugs missfiring on bank 2 this caused the petrol/lpg to overfuel, but what i cant work out is now the plugs have been changed and run on petrol to get my petrol fuel trims back, that now ive reautocalibration the lpg the lpg injector time are now miles off?

How do i go about cleaning them

Thanks Simon.

[Bernard LPG]

Sorry ive got a stag 300 set up.
I now understand that due to my plugs missfiring on bank 2 this caused the petrol/lpg to overfuel, but what i cant work out is now the plugs have been changed and run on petrol to get my petrol fuel trims back, that now ive reautocalibration the lpg the lpg injector time are now miles off?

How do i go about cleaning them

Thanks Simon.

I don't know the Stag system. What do the injectors look like?
I've got a feeling that they are a copy of the OMVL blocks.

[Simon.h]

Can you view this http://s744.photobucket.com/albums/xx85/simonhouse06/MG%20ZT/?action=view&current=MGZTLPG1.jpg&newest=1

[Greeners]

http://i744.photobucket.com/albums/xx85/simonhouse06/MG%20ZT/MGZTLPG1.jpg

[Simon.h]

I can now, thanks David!

[Bernard LPG]

They look a little bit like the OMVL type. I have no idea what Stag recommend but I would not have mounted them horizontally if they are of the sliding piston variety or they wear badly due to them not being centralised in the bore.
A bit like what happens to Subaru engines.
If this has happened it can cause drag within the mechanism and affect the opening time.
I am speculating somewhat here, you understand. It's just something that I have seen on OMVL.

Probably best not to take them apart at this stage. You could try washing them out with some solvent. Turpentine is best but WD40 seems to work pretty well.

[Simon.h]

Hi,
The injectors are Valtek 1 ohm, ive been through all the paperwork ive got and it does not say any thing about mounting horizontally.
The injectors have always been noisily, with the bonnet up you can hear them 30-40 ft away.
I turned each one off, one by one useing the laptop and by listening useing a stethoscope and found all 3 injectors feeding bank 1 were making a louder metallic clanging noise and 1 on bank 2.
So i think i need to replace both rails or rebuild them (is this poss). Ive had alook on the web for spares, but no luck!


Thanks.

[Greeners]

Hi,
The injectors are Valtek 1 ohm, ive been through all the paperwork ive got and it does not say any thing about mounting horizontally.
The injectors have always been noisily, with the bonnet up you can hear them 30-40 ft away.
I turned each one off, one by one useing the laptop and by listening useing a stethoscope and found all 3 injectors feeding bank 1 were making a louder metallic clanging noise and 1 on bank 2.
So i think i need to replace both rails or rebuild them (is this poss). Ive had alook on the web for spares, but no luck!


Thanks.


Try swapping the rail between banks and see if the fault moves.

[Simon.h]

Then swapped the rails over and the injector times are-

Injector times m/s
bank 1 - 2.1-2.2 changed to 2.0-2.1
bank 2 - 3.1-3.2 " " 2.9-3.0


bank 1 again ended up with 3 noisily injectors and bank 2 one.

Bearing in mind that the injector times are are the same on petrol.

[Bernard LPG]

Can't help you with Valtek, unfortunately. I would suggest that you change or overhaul both banks though or there may still be an imbalance.

[Simon.h]

Hi just ordered 6 off repair kiks for valtek injectors which come new spring,o ring and piston, for £4.50 each.


Thanks

[Bernard LPG]

Hi just ordered 6 off repair kiks for valtek injectors which come new spring,o ring and piston, for £4.50 each.


Thanks

I would be interested to see what sort of pistons they are and the condition of the old ones.
I'll wager that they are worn on one side if they are the type that I think they are and that maybe the 'O' rings have disintegrated.

[Simon.h]

I will take some pics, just for you to see!


Cheers

[Simon.h]

update-

After changeing spark plugs, the car was running fine on lpg/petrol and the injector times were-

Injector times m/s
bank 1 - petrol 2.6-2.7, lpg 2.1-2.2
bank 2 - petrol 2.6-2.7, lpg 3.0-3.1

The injectors times were the same for both banks of my V6 on petrol but lpg its different.
I then fitted 6 off VALTEK-Injector-Rail-Repair-Kit, reautocalibration the lpg and my injectors times are now-

Injector times m/s
bank 1 - petrol 2.6-2.7, lpg 2.6-2.7
bank 2 - petrol 2.6-2.7, lpg 2.6-2.7

After a few days, checked the maps and their a spot on match.
Then its run on petrol there on engine light/fault codes, but then on lpg sometimes i get codes 151- heated 02 sensor bank 2 sensor 1 and 174 system too lean bank 2, but the biggest problem is on lpg it does not wait to pull/hesitates and may be missfires.

Any ideas?


Thanks Simon.

[Bernard LPG]

update-

After changeing spark plugs, the car was running fine on lpg/petrol and the injector times were-

Injector times m/s
bank 1 - petrol 2.6-2.7, lpg 2.1-2.2
bank 2 - petrol 2.6-2.7, lpg 3.0-3.1

The injectors times were the same for both banks of my V6 on petrol but lpg its different.
I then fitted 6 off VALTEK-Injector-Rail-Repair-Kit, reautocalibration the lpg and my injectors times are now-

Injector times m/s
bank 1 - petrol 2.6-2.7, lpg 2.6-2.7
bank 2 - petrol 2.6-2.7, lpg 2.6-2.7

After a few days, checked the maps and their a spot on match.
Then its run on petrol there on engine light/fault codes, but then on lpg sometimes i get codes 151- heated 02 sensor bank 2 sensor 1 and 174 system too lean bank 2, but the biggest problem is on lpg it does not wait to pull/hesitates and may be missfires.

Any ideas?


Thanks Simon.

What do the LTFTs say?

As I've said before, I don't know your system but it suggests to me that a bit of spot adjustment may be necessary or acceleration setting. :shrug:

You need to monitor the O2 sensor during acceleration and make sure that it stays rich all the time, for example.

[chrissyboy]

Over fueling on 1 bank -V6?
Hi I have a V6 MG ZT 2.5 with lpg, its been on the car for 1-2 years, with no problems.
The only thing is 7 days ago the engine light came on, so i run my scantool software and the lpg software both at the same time.
The engine light is on because its running too lean. I have noticed that the injection times are different between banks -

injector times m/s -
bank 1 - petrol 3.2-3.4, lpg 4.0-4.2
bank 2 - petrol 3.4-3.5, lpg 4.4-4.5

On the scantool the fuel trims are

bank 1 - oxgyen sensor petrol 0.205-0.765v @ -2.3 % trim, lpg 0.175-0.800v @ +16.2% trim
bank 2 - oxgyen sensor petrol 0.210-0.800v @ +9.4% trim, lpg 0.130 @ +39.8 trim stays as this

The problem being is the injectors times should be the same for both banks of my V6, whichs means bank 2 is being over fueled.
Have cleared all codes from ECU turned off lpg and run for the last days on petrol, checked codes still too lean on bank 2 but no engine light

Have today swapped the oxgyen sensors over, thinking may be bank 2 sensor is playing up but the injectors times/trims are the same! Have also checked for air leaks on the inlet manfolds.

Also then on lpg have a think a missfire at low revs (below 3k), its normal for problems to show up on lpg before petrol due to it being a finer fuel.

What do you think?


best way to check for air leaks is with a smoke machine .will find a leak in mins .. you could have a weak cylinder and a misfire so eu will over fuel to try to even it out ..

[Bernard LPG]

best way to check for air leaks is with a smoke machine .will find a leak in mins .. you could have a weak cylinder and a misfire so eu will over fuel to try to even it out ..

Your smoke machine is not a panacea for all ills I regret. :shrug:

[Greeners]

http://upload.wikimedia.org/wikipedia/commons/6/6a/Smoke_Machine_engineer.jpg

[chrissyboy]

Your smoke machine is not a panacea for all ills I regret. :shrug:


for most things ,, like today have a stuttering bmw in ,2 mins later found it had a split hose that goes on to the throttle body .. also a x5 exhaust blowing but couldnt see where is was blowing 4 mins later found where it was blowing ...the machine you can use fo almost all systems ..

[Bernard LPG]

for most things ,, like today have a stuttering bmw in ,2 mins later found it had a split hose that goes on to the throttle body .. also a x5 exhaust blowing but couldnt see where is was blowing 4 mins later found where it was blowing ...the machine you can use fo almost all systems ..

Can you explain to me and the OP how it will set up his LPG system then?

I will be intrigued.

[keir1163]

I had a Morelli system on mine and had numerous issues...one being a missfire on number 5.
Turned out to be an exhaust gas leak which was causing the lambda to run wrong signals.
Fixed leak, changed plugs, recalibrated and it still was flat at 3k revs so fine tuned it to give more gas at that point and ......voila! managed to make it run smooth! even got it to 118mph on gas (on the autobahn obviously)

[chrissyboy]

Can you explain to me and the OP how it will set up his LPG system then?

I will be intrigued.

Is there any way of checking for air leaks down in the V ?
It did have all new inlet manfold gaskets 1-2 years ago.
__________________

he asked for a way to check for air leaks .... and a smoke machine is the best way ....

[Bernard LPG]

recalibrated and it still was flat at 3k revs so fine tuned it to give more gas at that point and ......voila! managed to make it run smooth! even got it to 118mph on gas (on the autobahn obviously)

I never cease to be amazed at the number of systems brought to me that have never been set up properly. So many installers seem to believe that the kit is either 'plug and play' or will just auto-calibrate itself.

Before anybody chooses to contradict me, I am aware of a small minority of systems that can do just this. :D

I really deplore the lack of technical know-how within the industry which has not been good for its image in this country.

Sorry to deviate from the thread but the spot adjustment bit may well be relevant. ;)

[Simon.h]

Hi, rechecked maps today, and they are miles out. I took about a hour of driving/stopping/adjustment and now the maps are the same and its running 100% on both fuels, at long last!

Bernard LPG, heres the pic of my old injector, its worn all over.

Thanks for all the help!

[Simon.h]

Sorry the uploading of the pic has failed.

[Bernard LPG]

Hi, rechecked maps today, and they are miles out. I took about a hour of driving/stopping/adjustment and now the maps are the same and its running 100% on both fuels, at long last!

Bernard LPG, heres the pic of my old injector, its worn all over.

Thanks for all the help!

Good to know tou have sorted it. :}