I have a 91 Camaro rs swaped 305 with 350 long block used Manifolds, TBI, Engine programmer all from original 305. Car ran great for 1st 25k miles. Now the SES light comes on code 44 and the cars missing big time. fuel pump presser good Changed fuel filter, wires, plugs, cap and rotor no change. Replaced injectors and presser regulator no change. engine programmer is next on the list .


Any suggestions

 

You're using a fuel curve intended for a 305 on a 350? Of course it's lean.

SCAN TOOL: What is the data stream showing for short- and long-term fuel trim; coolant temperature, engine vacuum, EGR, etc?




Mind you, I chased a false "lean" condition on my TBI truck that turned out to be a defective O2 sensor, but that was a 350 fuel curve on a 350 engine.

 

Code 44 may indicate dying or cold O2 sensor - get a scan tool or WinALDL to see if your O2 voltage swings once engine enters close loop CL. A good O2 sensor should show rich condition during cold start around 700 to 850 mV and then start oscillating between 200 to 800mV in CL.

//RF

 

It was the fuel pump. Checked pressure it was 10lbs which should have been enough However I pinched off the return hose that should of raised the pressure and it didn't so changed the pump now I got 15 lbs it run great again. thanks for your reply

 

Even a STOCK TBI engine needs ~13 psi of fuel pressure to run well.

 

Mine threw that code once when my o2 sensor was loose