I tuned a guys car 2 years ago ran perfect untill last week. He brought me the car to see what i could do. Trying to convince people that its not the tune is one of the hardest things ever. The car runs lean and skips like crazy. I would have never driven it like that. He put a new fuel filter, plug wires, plugs and coil. still runs like crap. I keep telling him it has to be the fuel pump or something in the fuel system becuase i have to add 20% more fuel just to get it to run. the more i tune it the worst i gets also. I just want to know if you think it can be the fuel pump also. My guess is the fuel pressure is fine at idle but the pump dont got enough to handle a load.

 

When does it lean out, is it only @ higher RPM and under load?

First place I would look would be the fuel pressure regulator, along with the overall fuel pressure (pump). Then I would look at the injectors and make sure they are all operating properly and that they are not dirty. They have little filter baskets, in the fuel rail end, that can be removed and cleaned/replaced.

 

ok we checked the fuel pressure has 40 psi all the time, cleaned the injectors, then put in some injectors out of a good running engine, changed ecu car still runs lean all the time. it not getting fuel the car dont skip just runs lean. I can add fuel to make it richen up but has no power. Compression shows 220 psi alway across

 

What are the AFR's that you are seeing?

Your saying it's not getting fuel but when you add fuel it runs poorly. Are you sure the Wideband O2 is calibrated. What do the spark plugs look like, do they show a lean burn as well?

Just wondering if he has changed spark plugs or any part of ignition system? Maybe the coil is going south or the plugs are bad. In your first post you said it's running lean and skipping..... is it not skipping anymore after the injector swap?

 

after i added fuel its not skipping, afr are dead on but dont have any power.I wander if one cyliner is running lean.

 

Read the spark plugs. I would buy a new set of spark plugs, do a 3rd gear pull and give them a read.

 

jumped timing?

 

it has the power of a car that has jumped timing, but its dead on