Help Troubleshooting Fuel Trims

[TJ Baker]

At 25%, you have a leak, on whatever side says 25%.

Maybe so, but an hour of driving in one fuel trim cell is not what you are going to read at idle later in a different fuel trim cell.

I think knowing what trim cells are higher and what trim cells are lower can sometimes help to narrow down the possibilities.

 

[GregBunney]

At 25%, you have a leak, on whatever side says 25%.

Reading 25% both sides for some reason. When I’m back home I’ll double check with carb cleaner and probably just to the intake gaskets.

 

[Fless]

You might think about trying a smoke machine before doing the intake gaskets. You can also use a propane torch (unlit) instead of carb cleaner.

If you have vacuum brakes pinch off or plug the hose connection to the brake booster to see if it makes a difference. Inspect all vacuum hoses and connections. The PCV hose connection on the driver's side is prone to split and leak.

 

[mhaywoodcz]

I ran into a similar issue years back. Not the same but had high fuel trim issues. My long term trims were high after a 2+ hour road trip. After the MAF and MAP sensor replacement without changes, I found it to be a fuel pump issue. The previous owner had had the pump replaced but they didn't crimp the new electrical wires together. They twisted the ends together and taped them up. After the replacement and proper crimping of the wires, better trims and no issues since.
Again maybe not the same but just thinking it could be a pump issue.