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Omega Help Area => Omega General Help => Topic started by: olm on 11 June 2019, 20:00:12

Title: Omega 2.6 runs better without MAF
Post by: olm on 11 June 2019, 20:00:12
Hi, if my car runs better with MAF sensor disconnected, does that mean it's wrong? The car runs like a plane!
Title: Re: Omega 2.6 runs better without MAF
Post by: dave the builder on 11 June 2019, 20:08:26
What prompted you to remove the Maf ?
was it running rough or lacking throttle response  :-\
did you read the ECM fault codes before hand or since ?
removing the MAF defaults to a substitute value map for air intake temperature and flow IIRC 
Title: Re: Omega 2.6 runs better without MAF
Post by: STEMO on 11 June 2019, 20:14:05
Remove some other bits....you never know.  ;D
Title: Re: Omega 2.6 runs better without MAF
Post by: dave the builder on 11 June 2019, 20:21:28
Remove some other bits....you never know.  ;D
what is your school of thought uncle Stemo  :-\
weight reduction = better fuel economy  ;D

pretty sure GM would not have fitted parts if they where not needed  ::)
Title: Re: Omega 2.6 runs better without MAF
Post by: STEMO on 11 June 2019, 20:37:35
Remove some other bits....you never know.  ;D
what is your school of thought uncle Stemo  :-\
weight reduction = better fuel economy  ;D

pretty sure GM would not have fitted parts if they where not needed  ::)
Remove the air filter......more air.....more oooomph.   Seemples  :)
Title: Re: Omega 2.6 runs better without MAF
Post by: dave the builder on 11 June 2019, 20:47:10
Remove some other bits....you never know.  ;D
what is your school of thought uncle Stemo  :-\
weight reduction = better fuel economy  ;D

pretty sure GM would not have fitted parts if they where not needed  ::)
Remove the air filter......more air.....more oooomph.   Seemples  :)
without a MAF, the engine won't know it's getting more air
without an air filter, BIG chunks of rusty subframe and failing front suspension parts will be sucked into the engine  ;D
Title: Re: Omega 2.6 runs better without MAF
Post by: STEMO on 11 June 2019, 20:53:35
Remove some other bits....you never know.  ;D
what is your school of thought uncle Stemo  :-\
weight reduction = better fuel economy  ;D

pretty sure GM would not have fitted parts if they where not needed  ::)
Remove the air filter......more air.....more oooomph.   Seemples  :)
without a MAF, the engine won't know it's getting more air
without an air filter, BIG chunks of rusty subframe and failing front suspension parts will be sucked into the engine  ;D
Yes.....euthanasia. You know it makes sense.  ;D
Title: Re: Omega 2.6 runs better without MAF
Post by: dave the builder on 11 June 2019, 20:57:10
Remove some other bits....you never know.  ;D
what is your school of thought uncle Stemo  :-\
weight reduction = better fuel economy  ;D

pretty sure GM would not have fitted parts if they where not needed  ::)
Remove the air filter......more air.....more oooomph.   Seemples  :)
without a MAF, the engine won't know it's getting more air
without an air filter, BIG chunks of rusty subframe and failing front suspension parts will be sucked into the engine  ;D
Yes.....euthanasia. You know it makes sense.  ;D

 ;D :D
It would save me loads of money off the petrol bill

I'll ask Terry to find me a nice astra  :y
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 11 June 2019, 20:57:40
What prompted you to remove the Maf ?
was it running rough or lacking throttle response  :-\
did you read the ECM fault codes before hand or since ?
removing the MAF defaults to a substitute value map for air intake temperature and flow IIRC

I have dtc p0173, fuel trim. I have already changed the lambda probes and it remains the same. The MAF can also give that breakdown, that's why I try it
Title: Re: Omega 2.6 runs better without MAF
Post by: dave the builder on 11 June 2019, 21:08:31
What prompted you to remove the Maf ?
was it running rough or lacking throttle response  :-\
did you read the ECM fault codes before hand or since ?
removing the MAF defaults to a substitute value map for air intake temperature and flow IIRC

I have dtc p0173, fuel trim. I have already changed the lambda probes and it remains the same. The MAF can also give that breakdown, that's why I try it
check for air leaks and exhaust leaks
have you got access to a code reader or computer to give live engine data ?
that way you could look at bank 1 fuel trims etc to see if they are close to throwing a code, or if it is just a bank 2 specific problem
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 11 June 2019, 21:48:03
What prompted you to remove the Maf ?
was it running rough or lacking throttle response  :-\
did you read the ECM fault codes before hand or since ?
removing the MAF defaults to a substitute value map for air intake temperature and flow IIRC

I have dtc p0173, fuel trim. I have already changed the lambda probes and it remains the same. The MAF can also give that breakdown, that's why I try it
check for air leaks and exhaust leaks
have you got access to a code reader or computer to give live engine data ?
that way you could look at bank 1 fuel trims etc to see if they are close to throwing a code, or if it is just a bank 2 specific problem

Yes, I have. The problem is in bank 2  but the bank 1 also does not work well, although better than 2. But the question is, why does it go much better with the MAF disconnected.  do not see air intakes and the emissions got perfect on itv (mot) so the exhaust does not leak
Title: Re: Omega 2.6 runs better without MAF
Post by: dave the builder on 11 June 2019, 22:15:18
What prompted you to remove the Maf ?
was it running rough or lacking throttle response  :-\
did you read the ECM fault codes before hand or since ?
removing the MAF defaults to a substitute value map for air intake temperature and flow IIRC

I have dtc p0173, fuel trim. I have already changed the lambda probes and it remains the same. The MAF can also give that breakdown, that's why I try it
check for air leaks and exhaust leaks
have you got access to a code reader or computer to give live engine data ?
that way you could look at bank 1 fuel trims etc to see if they are close to throwing a code, or if it is just a bank 2 specific problem

Yes, I have. The problem is in bank 2  but the bank 1 also does not work well, although better than 2. But the question is, why does it go much better with the MAF disconnected.  do not see air intakes and the emissions got perfect on itv (mot) so the exhaust does not leak
obviously something has failed since ITV / MOT test for the code to be present
once cleared, how long before the code comes back ?
Title: Re: Omega 2.6 runs better without MAF
Post by: Doctor Gollum on 11 June 2019, 22:25:27
Unplugging MAF forces it to run on a fixed set of assumptions. That it runs better unplugged points to the MAF being faulty ;)
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 12 June 2019, 05:14:49
What prompted you to remove the Maf ?
was it running rough or lacking throttle response  :-\
did you read the ECM fault codes before hand or since ?
removing the MAF defaults to a substitute value map for air intake temperature and flow IIRC

I have dtc p0173, fuel trim. I have already changed the lambda probes and it remains the same. The MAF can also give that breakdown, that's why I try it
check for air leaks and exhaust leaks
have you got access to a code reader or computer to give live engine data ?
that way you could look at bank 1 fuel trims etc to see if they are close to throwing a code, or if it is just a bank 2 specific problem

Yes, I have. The problem is in bank 2  but the bank 1 also does not work well, although better than 2. But the question is, why does it go much better with the MAF disconnected.  do not see air intakes and the emissions got perfect on itv (mot) so the exhaust does not leak
obviously something has failed since ITV / MOT test for the code to be present
once cleared, how long before the code comes back ?

Around 30-50 milles
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 12 June 2019, 05:19:16
Unplugging MAF forces it to run on a fixed set of assumptions. That it runs better unplugged points to the MAF being faulty ;)

Yes right? Is what I imagine, with the MAF unplugged can not go better, right?

Title: Re: Omega 2.6 runs better without MAF
Post by: TheBoy on 12 June 2019, 08:53:20
Are both banks showing a fair bit of LTFT?  What is the MAF reading (when plugged in), should be in region of 14kg/hr.

That is how you diagnose stuff, not willy nilly replacement ;)
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 12 June 2019, 09:06:50
Are both banks showing a fair bit of LTFT?  What is the MAF reading (when plugged in), should be in region of 14kg/hr.

That is how you diagnose stuff, not willy nilly replacement ;)


I need more info for more revs and conditions to diagnose
Title: Re: Omega 2.6 runs better without MAF
Post by: biggriffin on 12 June 2019, 09:42:28
I had this problem, after looking at maf, it turned out to be the. 135 coil pack.
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 12 June 2019, 09:55:59
I had this problem, after looking at maf, it turned out to be the. 135 coil pack.

Is the last option to cause a p0173 code. If it's not the MAF, I'll try it  :y
Title: Re: Omega 2.6 runs better without MAF
Post by: TheBoy on 13 June 2019, 11:00:28
I had this problem, after looking at maf, it turned out to be the. 135 coil pack.

Is the last option to cause a p0173 code. If it's not the MAF, I'll try it  :y
Look at the live data readings. Not just randomly change parts. The codes are only a small part of the jigsaw in most cases, not the end diagnostic (unless you are a dealer or garage, and thus thick as two short planks)
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 13 June 2019, 11:59:03
I had this problem, after looking at maf, it turned out to be the. 135 coil pack.

Is the last option to cause a p0173 code. If it's not the MAF, I'll try it  :y
Look at the live data readings. Not just randomly change parts. The codes are only a small part of the jigsaw in most cases, not the end diagnostic (unless you are a dealer or garage, and thus thick as two short planks)

You can see values, but if you do not have a sample to compare  at different rpm, load, etc... If you know where those values ​​are, I'd appreciate it if you told me
Title: Re: Omega 2.6 runs better without MAF
Post by: Kevin Wood on 13 June 2019, 13:06:51
I had this problem, after looking at maf, it turned out to be the. 135 coil pack.

Is the last option to cause a p0173 code. If it's not the MAF, I'll try it  :y
Look at the live data readings. Not just randomly change parts. The codes are only a small part of the jigsaw in most cases, not the end diagnostic (unless you are a dealer or garage, and thus thick as two short planks)

You can see values, but if you do not have a sample to compare  at different rpm, load, etc... If you know where those values ​​are, I'd appreciate it if you told me

Long term fuel trims are stored by the ECU over a period of time, so they don't depend on the current engine operating conditions. You can check them with the engine stopped or running and it makes no difference.

Nominally, the long term fuel trims should be zero. They start to depart from zero as the fuel delivery gets less accurate due to engine wear and changes in other items as they age. It's normal for them to wander a few percent from zero in a healthy car. What you're looking for is a value that has shifted more than, say, 10%.

You also need to compare the two banks. If the LTFT for both banks has drifted in the same direction, i.e. they are both at +15%, then the fault is something like the MAF sensor which is common to both banks. If only one has drifted off, or they have gone in different directions, then the diagonsis is very different (e.g. air leak that is affecting just one bank).
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 13 June 2019, 13:45:59
I had this problem, after looking at maf, it turned out to be the. 135 coil pack.

Is the last option to cause a p0173 code. If it's not the MAF, I'll try it  :y
Look at the live data readings. Not just randomly change parts. The codes are only a small part of the jigsaw in most cases, not the end diagnostic (unless you are a dealer or garage, and thus thick as two short planks)

You can see values, but if you do not have a sample to compare  at different rpm, load, etc... If you know where those values ​​are, I'd appreciate it if you told me

Long term fuel trims are stored by the ECU over a period of time, so they don't depend on the current engine operating conditions. You can check them with the engine stopped or running and it makes no difference.

Nominally, the long term fuel trims should be zero. They start to depart from zero as the fuel delivery gets less accurate due to engine wear and changes in other items as they age. It's normal for them to wander a few percent from zero in a healthy car. What you're looking for is a value that has shifted more than, say, 10%.

You also need to compare the two banks. If the LTFT for both banks has drifted in the same direction, i.e. they are both at +15%, then the fault is something like the MAF sensor which is common to both banks. If only one has drifted off, or they have gone in different directions, then the diagonsis is very different (e.g. air leak that is affecting just one bank).

The problem is I have a 3.0 block with 2.6 electronic....  :(
Title: Re: Omega 2.6 runs better without MAF
Post by: Kevin Wood on 13 June 2019, 17:02:01
That doesn't matter. It's the electronics that matters, not the oily bits! You should still get a sane LTFT reading if you use an OBDII code reader because the metered air into the engine should match the fuel required for the correct mixture.
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 15 June 2019, 14:21:51
That doesn't matter. It's the electronics that matters, not the oily bits! You should still get a sane LTFT reading if you use an OBDII code reader because the metered air into the engine should match the fuel required for the correct mixture.

The failure looks like an air intake, but as much as I've reviewed everything, including o-rings to inatke manifold, everything looks good. Is there something that can escape me? Something common that usually fails?
Title: Re: Omega 2.6 runs better without MAF
Post by: Doctor Gollum on 15 June 2019, 14:26:21
That doesn't matter. It's the electronics that matters, not the oily bits! You should still get a sane LTFT reading if you use an OBDII code reader because the metered air into the engine should match the fuel required for the correct mixture.

The failure looks like an air intake, but as much as I've reviewed everything, including o-rings to inatke manifold, everything looks good. Is there something that can escape me? Something common that usually fails?
Besides the MAF you mean?  ::)

When was the airfilter changed last? Anything in the intake plumbing... Leaves/rags etc :-\
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 15 June 2019, 15:13:11
That doesn't matter. It's the electronics that matters, not the oily bits! You should still get a sane LTFT reading if you use an OBDII code reader because the metered air into the engine should match the fuel required for the correct mixture.

The failure looks like an air intake, but as much as I've reviewed everything, including o-rings to inatke manifold, everything looks good. Is there something that can escape me? Something common that usually fails?
Besides the MAF you mean?  ::)

When was the airfilter changed last? Anything in the intake plumbing... Leaves/rags etc :-\

The maf can make the banks work differently? The truth is that it's strange for me to go better with the MAF disconnected ...The air filter, spark plugs, oil, etc are new with around 3000 miles
Title: Re: Omega 2.6 runs better without MAF
Post by: TheBoy on 15 June 2019, 15:41:53
I'll ask one more time before ignoring this thread.

Post up the live data readings for LTFTs and MAF
Title: Re: Omega 2.6 runs better without MAF
Post by: Nick W on 15 June 2019, 19:25:19


The maf can make the banks work differently? The truth is that it's strange for me to go better with the MAF disconnected ...The air filter, spark plugs, oil, etc are new with around 3000 miles


It's typical, not strange!


Even without the correct procedure of looking at the live data rather than just disconnecting the sensor, a good quality replacement MAF would be a sensible way of fixing the fault.
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 16 June 2019, 21:41:02


The maf can make the banks work differently? The truth is that it's strange for me to go better with the MAF disconnected ...The air filter, spark plugs, oil, etc are new with around 3000 miles


It's typical, not strange!


Even without the correct procedure of looking at the live data rather than just disconnecting the sensor, a good quality replacement MAF would be a sensible way of fixing the fault.

Really? You give me some hope!
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 16 June 2019, 21:43:39
I'll ask one more time before ignoring this thread.

Post up the live data readings for LTFTs and MAF

The LTFT of bank 2 is 25%, bank 1 around 14%. Sorry but I do not remember the values ​​of the MAF. Anyway, I'll try to look at them tomorrow, could you tell me what values  have to give at different rpm or speed?
Also say that the injection times are irregular, typical air intake, but for more than looking I do not see it
Title: Re: Omega 2.6 runs better without MAF
Post by: TheBoy on 17 June 2019, 17:40:17
could you tell me what values  have to give at different rpm or speed?
Report the figure at idle, AC off.
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 20 June 2019, 10:26:03
Well, these are the logs at 120 km/h

(http://i63.tinypic.com/10pough.png)
(http://i68.tinypic.com/11j1zbp.png)
(http://i65.tinypic.com/if32md.png)
(http://i64.tinypic.com/96krb7.png)

In order, LTFT bank 1-2 and STFT 1-2.
Title: Re: Omega 2.6 runs better without MAF
Post by: TheBoy on 20 June 2019, 17:33:14
I wonder why I suggested idle ;). Nothing to do with the fact that we don't know engine load when moving ;)
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 20 June 2019, 19:05:09
I wonder why I suggested idle ;). Nothing to do with the fact that we don't know engine load when moving ;)

The load have it down on the riht
Title: Re: Omega 2.6 runs better without MAF
Post by: Doctor Gollum on 20 June 2019, 19:31:21
To save TBs bath water... The readings MUST BE TAKEN AT IDLE :y
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 20 June 2019, 20:51:26
To save TBs bath water... The readings MUST BE TAKEN AT IDLE :y

But at idle the maf can run ok while on hihgway wrong. Nevertheless tomorrow I do readings at idle
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 14 July 2019, 11:58:21
Well, after some good LTFT data after changing lambda sensors yesterday it came back on check engine light for p0170 and p0173. These are the values ​​that it gives me

(http://i66.tinypic.com/2v3n89i.png)
(http://i67.tinypic.com/1zzm1ip.png)
(http://i67.tinypic.com/hrdder.png)

The probes are new, spark plugs, revised air intakes, I've even tried a new MAF sensor, I do not know what else to look. Why does the LTFT go to 25% if the STFT works well?
Title: Re: Omega 2.6 runs better without MAF
Post by: TheBoy on 14 July 2019, 16:31:09
It helps if you stop changing shit randomly.

So, assuming I'm reading your graph right, LTFT for Bank1 is 4%, and Bank2 is 25%? Is that at idle, following a reset - might take 20mins to creep that far.


If so, thats suggesting lean running on Bank1, so its correcting by adding more fuel (but hard to tell with your diagnosis kit).  That lean running points to additional air getting in (airleak, some prat adjusting the throttle butterflies etc), or insufficient fuel (injector).
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 14 July 2019, 17:14:56
It helps if you stop changing shit randomly.

So, assuming I'm reading your graph right, LTFT for Bank1 is 4%, and Bank2 is 25%? Is that at idle, following a reset - might take 20mins to creep that far.


If so, thats suggesting lean running on Bank1, so its correcting by adding more fuel (but hard to tell with your diagnosis kit).  That lean running points to additional air getting in (airleak, some prat adjusting the throttle butterflies etc), or insufficient fuel (injector).

Yes, LTFT is 4% bank1 and 25%bank2. The values ​​are maintained from the reset at the most time. I have checked vacuum lines and even rings fron intake manifold. I will run longer on gasoline but the problem persists in both petrol and glp.
Title: Re: Omega 2.6 runs better without MAF
Post by: Doctor Gollum on 14 July 2019, 17:27:15
Injector loom wiring fault :-\
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 14 July 2019, 18:19:53
Injector loom wiring fault :-\

And would not something strange be noticed in the driving? The car runs perfectly fine
Title: Re: Omega 2.6 runs better without MAF
Post by: TheBoy on 15 July 2019, 10:39:18
Injector loom wiring fault :-\

And would not something strange be noticed in the driving? The car runs perfectly fine
Assuming its running on 6 still, anything up to +/- 25% LTFT the ECU can compensate for. But its shows there is an issue. On a petrol car with no LPG, it LTFT for both banks isn't 0% you have an issue.

And exhaust leak can also cause drifts, so don't rule that out either.
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 21 July 2019, 12:12:47
Injector loom wiring fault :-\

And would not something strange be noticed in the driving? The car runs perfectly fine
Assuming its running on 6 still, anything up to +/- 25% LTFT the ECU can compensate for. But its shows there is an issue. On a petrol car with no LPG, it LTFT for both banks isn't 0% you have an issue.

And exhaust leak can also cause drifts, so don't rule that out either.

Thanks!
now I can not put photos, but I tell you results. With petrol LTFT bank 1 is 0%, bank 2 0,78%. STFT is around +-3%. In LPG is the problem, LTFT bank 1 is around 8% and bank 2 go to 25% and turn the check light, STFT is +-3% too

What I do not understand is that if the STFT value is correct, why the LTFT goes to +25%, what explanation does he have? Logically I will tell my LPG installer, but I would like to know what can be done
Title: Re: Omega 2.6 runs better without MAF
Post by: TheBoy on 21 July 2019, 12:55:33
Ignore STFT values.

So, on petrol, LTFT remains at 0% on both banks? But drifts on LPG (or similar)?  That shows the fuelling on the lpg is out.  If its a piggybank ECU, it probably just needs the map adjusted *AFTER* you have checked the filters and injectors.  If its a mixer system, then you'll always be chasing your arse I'm afraid.
Title: Re: Omega 2.6 runs better without MAF
Post by: olm on 21 July 2019, 20:23:07
Ignore STFT values.

So, on petrol, LTFT remains at 0% on both banks? But drifts on LPG (or similar)?  That shows the fuelling on the lpg is out.  If its a piggybank ECU, it probably just needs the map adjusted *AFTER* you have checked the filters and injectors.  If its a mixer system, then you'll always be chasing your arse I'm afraid.

Yes, in petrol is 0% in bank 1, bank 2 0,78-1,5%. The lpg kit is EuropeGas, is new with around 3000 miles. I don't know if is mixer sistem
Title: Re: Omega 2.6 runs better without MAF
Post by: Doctor Gollum on 21 July 2019, 21:45:21
Looks like they only do sequential systems :y
Title: Re: Omega 2.6 runs better without MAF
Post by: TheBoy on 22 July 2019, 18:53:37
In which case, it sounds like the LPG needs mapping properly.