fueling problems
Thread Starter
Instructor
Joined: Jul 2001
Posts: 108
Likes: 0
From: Cincinnati Ohio
fueling problems
Hi,
I have a 2002 C5 with a 427 stroker. Recently took a 1,000 mile trip. At the first fuel up, I believe I got some bad gas. The car ran terrible. I put in some "Sea Foam" which seemed to help me get home.
Once home I changed the fuel filter and replaced the fuel pump with a high flow racetronics fuel pump. The car still seems to be low on "seat of the pants" power. Using EFIlive to collect some LTFT numbers, I found that bank #1 was a -8.5 and bank #2 was a positive 25. What in the world does that mean? Why should there be such a huge difference between banks of injectors? Does this mean I have some bad injectors on one side, or is my fuel rail clogged? If anyone can help me with this issue I would be most grateful.
Thanks for your help
Tony
Cincinnati, Ohio
I have a 2002 C5 with a 427 stroker. Recently took a 1,000 mile trip. At the first fuel up, I believe I got some bad gas. The car ran terrible. I put in some "Sea Foam" which seemed to help me get home.
Once home I changed the fuel filter and replaced the fuel pump with a high flow racetronics fuel pump. The car still seems to be low on "seat of the pants" power. Using EFIlive to collect some LTFT numbers, I found that bank #1 was a -8.5 and bank #2 was a positive 25. What in the world does that mean? Why should there be such a huge difference between banks of injectors? Does this mean I have some bad injectors on one side, or is my fuel rail clogged? If anyone can help me with this issue I would be most grateful.
Thanks for your help
Tony
Cincinnati, Ohio
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
Generally you should get a code when your fuel trims go beyond - or +
around 20% for a long time---A huge split from right to left like yours indicates a problem ---DON"T DRIVE it hard----as the +25 % means it's pegged at the max and is adding fuel for an extreme LEAN condition--
Do the fuel trims both right/left fluctuate when giving it some throttle ?? Is the +25% side pegged all the time ??
Check 1st to see if the Injector connectors are plugged in correctly
Check your 02 voltages---Both sides should bounce around rapidly from about .150 to .950 millivolts--If the 25% side is flatlined near .450 then that side's sensor is BAD---
Check your fuel rail--if you have an aftermarket rail--make sure the hose isn't pinched or plugged
Clean your MAF wires with brakeclean--
Check for a vacuum leak on the intake manifold by spraying brake-clean or WD40 or starting fluid near the mating surfaces---If the engine trys to die or if the RPM flares up--you have a leak---
around 20% for a long time---A huge split from right to left like yours indicates a problem ---DON"T DRIVE it hard----as the +25 % means it's pegged at the max and is adding fuel for an extreme LEAN condition--
Do the fuel trims both right/left fluctuate when giving it some throttle ?? Is the +25% side pegged all the time ??
Check 1st to see if the Injector connectors are plugged in correctly
Check your 02 voltages---Both sides should bounce around rapidly from about .150 to .950 millivolts--If the 25% side is flatlined near .450 then that side's sensor is BAD---
Check your fuel rail--if you have an aftermarket rail--make sure the hose isn't pinched or plugged
Clean your MAF wires with brakeclean--
Check for a vacuum leak on the intake manifold by spraying brake-clean or WD40 or starting fluid near the mating surfaces---If the engine trys to die or if the RPM flares up--you have a leak---
Tech Contributor
Joined: Aug 2008
Posts: 2,902
Likes: 21
From: Oak Hill Virginia
Free bump.
Im interested to see what you find as I'm chasing something similar. Both banks on my car are pegged at +25%... So far I've eliminated O2 sensors, grounds, and the O2 circuit fuse as potential culprits so I'm thinking I must have a vacuum leak somewhere....
Im interested to see what you find as I'm chasing something similar. Both banks on my car are pegged at +25%... So far I've eliminated O2 sensors, grounds, and the O2 circuit fuse as potential culprits so I'm thinking I must have a vacuum leak somewhere....
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
Another thing that cause large LTFT swings is an EXHAUST leak--The side with the way positive side has the leak---A +25% would be a major leak--
and would make the car run horribly in losed loop (P/T)
and would make the car run horribly in losed loop (P/T)
