Fuel Trims Trouble Shooting
Fuel Trims Trouble Shooting 88 TransAm with 98 LS1. Just finished up this motor swap in February and just got HP Tuners last week. By the way support from HPT has been great. I've had a couple of issues and they've responded very quickly when I email support.
Bank 1 LTFT is maxing out at 25 and STFT is still adding a little (between 0 and 5) at idle and low RPMS. Appears during moderate driving LTFT are still adding fuel (15 +/-) but not maxed out.
Can't find any exhaust leaks, plan to switch O2s between bank 1/2 tonight and try to listen to injectors with a stethascope to make sure all four are working. Another thing I thought of but wasn't sure if it could be an issue. On drivers side manifold the O2 sensor wouldn't fit in existing bung (clearance issue) so we capped it and put a new bung about 6 inches lower (in the down tube). Would moving the O2 create this kind of problem?
Bank 1 LTFT is maxing out at 25 and STFT is still adding a little (between 0 and 5) at idle and low RPMS. Appears during moderate driving LTFT are still adding fuel (15 +/-) but not maxed out.
Can't find any exhaust leaks, plan to switch O2s between bank 1/2 tonight and try to listen to injectors with a stethascope to make sure all four are working. Another thing I thought of but wasn't sure if it could be an issue. On drivers side manifold the O2 sensor wouldn't fit in existing bung (clearance issue) so we capped it and put a new bung about 6 inches lower (in the down tube). Would moving the O2 create this kind of problem?
If the LTs are 25 then you defiantly have a leak somewhere. I would try the intake, TB, MAP sensor, etc for leaks. Its sucking ari somewhere. Just had this problem with my FAST intake couple weekends ago. I found that one of the intake gaskets came out of the intake on the top of one of the ports causing it to suck air. I wouldnt think that moving the O2 6in would cause that problem, but then agian your working on an ls1 so anything is possible.
Thanks for the response, I had been looking for an exhaust leak but guess it makes sense to be looking on the intake side too. I did switch the O2s side to side last night with no affect. The bank 1 sensor was nasty black though which I assume means I'm getting way to much fuel in that bank. Injectors are all ticking so for now assuming they are putting fuel out too.
What's the best way to check for leaks on the intake side? I've heard of spraying starting fluid around intake but not sure that's the best way.
Any other suggestions are appreciated!
Tony
What's the best way to check for leaks on the intake side? I've heard of spraying starting fluid around intake but not sure that's the best way.
Any other suggestions are appreciated!
Tony
Originally Posted by crewchef
Thanks for the response, I had been looking for an exhaust leak but guess it makes sense to be looking on the intake side too. I did switch the O2s side to side last night with no affect. The bank 1 sensor was nasty black though which I assume means I'm getting way to much fuel in that bank. Injectors are all ticking so for now assuming they are putting fuel out too.
What's the best way to check for leaks on the intake side? I've heard of spraying starting fluid around intake but not sure that's the best way.
Any other suggestions are appreciated!
Tony
What's the best way to check for leaks on the intake side? I've heard of spraying starting fluid around intake but not sure that's the best way.
Any other suggestions are appreciated!
Tony
Thanks for the responses. Put together a listening device, short piece of thin copper tube and then some vacumn hose. Listened all around the intake, TB, etc for a leak, nothing found. Checked all the vacumn lines too, no leaks. Friend recommended doing a balance test (remove one injector connection at a time) as soon as we touched the connector on number six the idle changed. Wiggled it around and discovered that connector was loose. When we checked it the prongs were spread apart. It was firing but not all the time so basically that one cyl was causing the problem. The others were really fat thus the nasty black O2 sensor after only about 40 miles on the car.
Anyway, problem fixed. LTFT reset and while they're still adding fuel both banks are consistent with a range of 10 to 12 between idle and about 3K. Now we can disconnect the MAF and start trying to get the VE dialed in.
Thanks again for the suggestions!
Anyway, problem fixed. LTFT reset and while they're still adding fuel both banks are consistent with a range of 10 to 12 between idle and about 3K. Now we can disconnect the MAF and start trying to get the VE dialed in.
Thanks again for the suggestions!
Originally Posted by crewchef
Thanks for the responses. Put together a listening device, short piece of thin copper tube and then some vacumn hose. Listened all around the intake, TB, etc for a leak, nothing found. Checked all the vacumn lines too, no leaks. Friend recommended doing a balance test (remove one injector connection at a time) as soon as we touched the connector on number six the idle changed. Wiggled it around and discovered that connector was loose. When we checked it the prongs were spread apart. It was firing but not all the time so basically that one cyl was causing the problem. The others were really fat thus the nasty black O2 sensor after only about 40 miles on the car.
Anyway, problem fixed. LTFT reset and while they're still adding fuel both banks are consistent with a range of 10 to 12 between idle and about 3K. Now we can disconnect the MAF and start trying to get the VE dialed in.
Thanks again for the suggestions!
Anyway, problem fixed. LTFT reset and while they're still adding fuel both banks are consistent with a range of 10 to 12 between idle and about 3K. Now we can disconnect the MAF and start trying to get the VE dialed in.
Thanks again for the suggestions!
