I have a 78 with a TPI installed. Once in a while after the car is warmed up a get a SES light and the car runs really sluggish. It has absolutely no power and seems like it is about to bog out. I have noticed it seems to not get very good gas mileage. I check the code and it comes up 44 - lean. Has any one else had this issue? I check the vacuum lines and they seem ok. I was going to change the O2 sensor. Is there any way to know if the O2 sensor is bad? like measuring it or ohming it out? any help is appreciated.

 

you may have an exhaust leak, is your exhaust modified at all ? do you have any modifications ? if your computer is not tuned properly it may not be injecting enough fuel

 

It has dual exhaust with no cats and headers. beyond that i dont know many of the mods, i bought it from a dealer with no history. there is a cold intake and a coil for the ingition. it seems to run fine most of the time, but sometimes on the highway or heavy cruising i get the code 44 problem. the o2 is at the bottom of one of the headers.

 

you may need to upgrade to a heated 4 wire 02 sensor.because since the o2 sensor is moved to the bottom of the header(instead of being on top of the exhaust manifold itself) it does get the same heat as it used to which is contributting to you running lean

 

if i only have 1 wire running to the o2 sensor now, how do i convert? do i need to run 4 new wires to the ecm? will my ecm support that? thanks.

 

yes youre ecm will support it.

http://www.fastbirdperf.com/93-97F-Body/93HeatedO2.htm

it says it works on 93s, so im pretty sure it will work on yours since its pretty similar

 

The one thing I checked today was the fuel pressure. under idle conditions it was like 35 psi. when i rev'd the engine it went up to about 45 psi? Is that too low? Also, with the high pressure fuel system, i didnt see a fuel filter, are they usually in the pump? do you need special kinds because of the high pressure?

 

the fuel filter should be under the car by one of the rear wheels.im not sure what the exact fuel pressure for your engine should be,but being fuel injected that does sound pretty low

 

So I have been at this quite a while and still no luck. I have changed the fuel pump. Pressure is solid at 45 psi. I changed the O2 sensor to a heated version. I took it in to my local guy and had him check it over and he had me swap out the MAF sensor. Still no luck. The same thing seems to happen and more frequently now. I run for about 15 minutes and then the engine bogs down. I get a lean exhaust code 44 and it idles really rough. Little to now power when this happens. It seems to go away after it cools down and sits a couple of days. No vacuum leaks that I can tell. I am at a loss, even my local mechanic can not seem to figure this out. Should I just swap out all the sensors common things until it goes away? EGR next? Knock sensor? Any help and suggestions would be appreciated.