Fuel Trim Values On Bank 2
05-07-2018, 04:10 PM
#1
Three Wheelin'
Thread Starter
Fuel Trim Values On Bank 2
Since I put my Fisters on my exhaust tips get dirtier...and I see ever so slightly more stain on the left pipe. I don't suspect the bore scoring boogeyman but being curious/OCD I wanted to track down the likely reason. The car uses zero oil, zero smoking, zero knocking, zero cold weather, and is 100% fun.
I do typically see more water coming out of the left pipe, particularly after a wash, and suspect that has something to do with it. The staining is on the bottom of the pipe, consistent with dirty water dripping out of the pipe.
I also wanted to track down fuel trim to see if bank 2 was running rich. During my PPI they told me bank 2 was slightly richer (-1) but said totally normal and dont worry about it. They figured it would normalize once the car was driven more.
I took it over to my indy to have them check and they showed bank 2 still running slightly rich. Bank 2 is at -1.6 and bank 1 at -0.65 (I assume this is a percentage). He said that was perfectly in range (I think he said -12% is where you would get a CEL) but also thought it odd that bank 2 was double that of bank 1. He thought maybe it was a clogged injector. He gave me a bottle of "BG 44K Fuel System Cleaner" and told me to report back after I ran down the tank. He said he's seen it do wonders and regularly use it on older 911s to get them to pass California smog.
Anyway...any thoughts from the pros appreciated on the following:
1. Do you think rich fuel trim lead to soot on the pipe?
2. What could be the likely causes of the bank 2 v 1 variation?
3. Is ~1.6 vs -.65 even a material deviation from norm?
4. Any reason you would get more water out of one pipe vs another? Rotation of the earth, moon phasing, etc?
Thx
I do typically see more water coming out of the left pipe, particularly after a wash, and suspect that has something to do with it. The staining is on the bottom of the pipe, consistent with dirty water dripping out of the pipe.
I also wanted to track down fuel trim to see if bank 2 was running rich. During my PPI they told me bank 2 was slightly richer (-1) but said totally normal and dont worry about it. They figured it would normalize once the car was driven more.
I took it over to my indy to have them check and they showed bank 2 still running slightly rich. Bank 2 is at -1.6 and bank 1 at -0.65 (I assume this is a percentage). He said that was perfectly in range (I think he said -12% is where you would get a CEL) but also thought it odd that bank 2 was double that of bank 1. He thought maybe it was a clogged injector. He gave me a bottle of "BG 44K Fuel System Cleaner" and told me to report back after I ran down the tank. He said he's seen it do wonders and regularly use it on older 911s to get them to pass California smog.
Anyway...any thoughts from the pros appreciated on the following:
1. Do you think rich fuel trim lead to soot on the pipe?
2. What could be the likely causes of the bank 2 v 1 variation?
3. Is ~1.6 vs -.65 even a material deviation from norm?
4. Any reason you would get more water out of one pipe vs another? Rotation of the earth, moon phasing, etc?
Thx
05-07-2018, 08:06 PM
#2
Fuel trims do not equal actual air fuel ratio. The air fuel ratio you can look at is measured in lambda. The trims just represent additive or subtractive fuel that was utilized in order to meet that specified lambda and give you ideas of any issues the vehicle may be having. Btw 2% or less is nothing.
The Bosch ECu can trim a heck of a lot before it will actually start deviating from the specified air fuel ratio and when that happens you'd get a soft code and eventually a check engine light anyways. in short if you want a measure your air fuel ratio you need to just measure lambda. You can trim upwards of 25% on some cars before you start deviating from specified lambda
The Bosch ECu can trim a heck of a lot before it will actually start deviating from the specified air fuel ratio and when that happens you'd get a soft code and eventually a check engine light anyways. in short if you want a measure your air fuel ratio you need to just measure lambda. You can trim upwards of 25% on some cars before you start deviating from specified lambda