HELP! 2006 Toyota tundra very high fuel trims

Just to make sure it isn't the fuel pressure regulator, hook up the fuel pressure gauge. At idle, disconnect the vacuum hose. Fuel pressure should go up. Recconect and it should go down again.

 

Ok, I'll have to go rent the one from O'Reilly's. That's how I checked it before. I'll update as soon as I'm able to get the gauge.

 

I see your latest comment about finally checking the exhaust. How dod you check and all did you check….from rear sensors forward ?

Also you mentioned way back when that the ECU is the right one for your truck. Is that the original as far as you know or another from newer to you engine ?

 

I first did a smoke test and pressurized the exhaust to see if i could see anything leaking around either manifold. Then I took both manifold heat shields off and started the truck and felt around for anything. Also looked for soot stain that could guide me to the leak and found nothing. And the ECU seems to be the original from 2006. The last things I have not replaced in this entire mess of diagonistics is the ECU and fuel pump. So it could be a failing ECU but I kinda doubt it but then again I'm out of luck at this point so it could be. Is there any "testing" that could be done to it or is it just replace it?

 

Can the gauge be taped to the windshield?

Check pressure under load (driving). If it's dropping as your ltft rises, it usually means a bad pump. Pressure may be ok at idle but failing pumps sometimes won't provide enough volume.

 

I feel stupid for not checking it under load. I just checked while at idle since I was by myself. What’s funny about that is my fuel trims stayed great at idle but a couple miles down the road doing 50mph and that’s when I noticed they got bad. I’m definitely going to look into that.