Long term, short term fuel trims and mixture formation percentage
Thread Starter
MBWorld Fanatic!
Joined: Sep 2016
Posts: 1,175
Likes: 130
From: NY
2010 C63 2019 GLA45
Long term, short term fuel trims and mixture formation percentage
I replaced my injectors and watched the trims with my handheld. One bank is over 20% and seems like the short term is pushing it still up, the other bank is at 30% and staying there.
No Codes, no stored codes.
So broke out the Xentry Kit:
No codes, no pending codes, even after re-scan. The idea was to reset the trims.
So what does the xentry think about this?
It doesn't show long or short fuel trims, but Fuel Mixture formation self-adjustments.
And it's kinda in the middle of the range for one of the banks and the range is from -4.5% to +4.5%, the other is a 2.9%.
So the question is, percentages of what? vs trims being percentages of what?
There is clearly a problem with the way a handheld reads the trims for this car.
Being that this is a closed loop car maybe trims are processed differently?
Would be nice to read a word or two by a tech, if you care to provide some info.
No Codes, no stored codes.
So broke out the Xentry Kit:
No codes, no pending codes, even after re-scan. The idea was to reset the trims.
So what does the xentry think about this?
It doesn't show long or short fuel trims, but Fuel Mixture formation self-adjustments.
And it's kinda in the middle of the range for one of the banks and the range is from -4.5% to +4.5%, the other is a 2.9%.
So the question is, percentages of what? vs trims being percentages of what?
There is clearly a problem with the way a handheld reads the trims for this car.
Being that this is a closed loop car maybe trims are processed differently?
Would be nice to read a word or two by a tech, if you care to provide some info.
Last edited by Vladds; Oct 21, 2017 at 10:37 AM.
Thread Starter
MBWorld Fanatic!
Joined: Sep 2016
Posts: 1,175
Likes: 130
From: NY
2010 C63 2019 GLA45
I know they should. But I didn't even think they can go up to 30.
So yes there should have been a code by now and the car should run like crap.
But there is no code and xentry can't find one even upon repeated testing.
Furthermore it says that that trims are fine but in its own weird way.
The car has 4 new oxygen sensors , all new injectors, all new mafs that came with the row boxes, new spark plugs, new one air filters, new oem intake gaskets and bolts.
I am using the innovate ap with the Bluetooth piece.
I think the problem here is not the car but the innovate. The Xentry says it's fine.
But I don't know for sure and I'm trying to learn more about the factory parameters.
But there is even so a significant difference between banks, so I think I only have the exhaust side left to check. I will check the exhaust manifold nuts and converter fastening.
So yes there should have been a code by now and the car should run like crap.
But there is no code and xentry can't find one even upon repeated testing.
Furthermore it says that that trims are fine but in its own weird way.
The car has 4 new oxygen sensors , all new injectors, all new mafs that came with the row boxes, new spark plugs, new one air filters, new oem intake gaskets and bolts.
I am using the innovate ap with the Bluetooth piece.
I think the problem here is not the car but the innovate. The Xentry says it's fine.
But I don't know for sure and I'm trying to learn more about the factory parameters.
But there is even so a significant difference between banks, so I think I only have the exhaust side left to check. I will check the exhaust manifold nuts and converter fastening.
Junior Member
Joined: Aug 2014
Posts: 71
Likes: 2
2008 C63 AMG
I know they should. But I didn't even think they can go up to 30.
So yes there should have been a code by now and the car should run like crap.
But there is no code and xentry can't find one even upon repeated testing.
Furthermore it says that that trims are fine but in its own weird way.
The car has 4 new oxygen sensors , all new injectors, all new mafs that came with the row boxes, new spark plugs, new one air filters, new oem intake gaskets and bolts.
I am using the innovate ap with the Bluetooth piece.
I think the problem here is not the car but the innovate. The Xentry says it's fine.
But I don't know for sure and I'm trying to learn more about the factory parameters.
But there is even so a significant difference between banks, so I think I only have the exhaust side left to check. I will check the exhaust manifold nuts and converter fastening.
So yes there should have been a code by now and the car should run like crap.
But there is no code and xentry can't find one even upon repeated testing.
Furthermore it says that that trims are fine but in its own weird way.
The car has 4 new oxygen sensors , all new injectors, all new mafs that came with the row boxes, new spark plugs, new one air filters, new oem intake gaskets and bolts.
I am using the innovate ap with the Bluetooth piece.
I think the problem here is not the car but the innovate. The Xentry says it's fine.
But I don't know for sure and I'm trying to learn more about the factory parameters.
But there is even so a significant difference between banks, so I think I only have the exhaust side left to check. I will check the exhaust manifold nuts and converter fastening.
