Ok, so I have a 1992 LT1. It's currently has the check engine light on and is showing trouble codes on the ECM of C44 and C55.

44 is- DTC 44 – Bank 1 (Left Front) Heated Oxygen Sensor (HO2S) #1 Circuit (Lean Exhaust Indicated)

55 is- DTC 55 – Fuel Lean Monitor

Looking for advice on exactly what could be causing these codes and a starting point for fixing whatever is wrong.

 

Take your time, and carefully read through the entire site. There
are several pages:

http://www.corvettephotographs.com/c4vettes/ecm.htm

 

Thank you, that is a very useful link.

 

Time to check fuel pressure. Make sure the filter is good. Pressure at idle, engine off and cruising

 

it's getting a new fuel filter and fuel pump today. 119k miles, it definitely won't hurt even if it's not the cause of the codes being thrown.

 

Well I got the fuel filter done today (that has got to be the hardest fuel filter change I have ever done), figured I'd hold off on the pump until I see what the filter does. Nothing is what it did. Still throwing the C55 code after taking the car for a drive. Looks like tomorrow it's the fuel pump's turn.

 

If o2 sensors are orginal they get tierd change them together did mine on my 94 big differance

 

What were the fuel pressure readings?

 

Code 55 = ECM detected a lean oxygen sensor voltage for 3 seconds during the power enrichment modes of operation.

 

Ok, haven't gotten anything done since changing the fuel filter. Car does seem to run a little better, but they may be placebo.

I have a friend going by the auto parts store as I type this and picking up a fuel pressure gauge now. I'll post back when I get the readings. What exactly should I check? idle, ignition on engine off, and .....

Also, one thing I didn't mention. The car is very hard to start on cold mornings. The colder, the harder it is. Temperature seems to be a major factor in this. On cold mornings (sub-35'f), it takes about 5 minutes to get the car to start. On warm mornings (+65'f), the car starts right up as if it's already been driven that day.

This morning (39'f currently)it took several minutes to get the car to start, but not quite 5. More like 3-4 minutes. But the difference with today is that I was out of the car with the hood up when I started the car (remote start). I noticed that when the ignition turned on, I heard what sounded like the gas being pumped through the fuel lines going into the fuel rail. When I first started trying to start the car, it sounded like the lines were not completely full of fuel. As I continued to try to start the car, it sounded like the fuel lines were getting filled, and as it started to sound like the lines were getting filled, the car started to fire until it eventually started up. The car will start to run without issue for the rest of the day.

Anyone experience this before?

 

Turn the key on run do not start and let the fuel pump stop see what your pressure is then start and drive watching the pressure and let us know what you see

 

The pump should stop after a second or two if not bad pump or a leaky line and if your not stepping in it it is in the tank

 

Can't check the pressure when driving. Guage's hose is only 16" long

 

Go to harbor frieght they have one that will work cheap or get a longer hose

 

I ended up skipping on the fuel pressure gauge and just went and bought a new pump and screen. C55 code is now gone and car is throwing no codes and is running better than it ever has. Probably real close if not exactly what she is suppose to do.

Thing is though, the service engine soon light is still on even though the car is giving no codes. It comes on about 8-10 secs after starting the car. Advice?

 

Try clearing the codes and reset

 

If the o2 are original I would replace

 

Did that right after changing the pump. Guess I'll look into changing the O2 sensors next unless someone has a better idea.

 

While your under there pull your knock sensors and give it a good flushing

 

After driving the car for a few more hours, it started throwing the 44 and 55 codes again. Went to Harbor Freight, got a fuel pressure gauge, and checked my fuel pressure.

turn key on- jumps to around 35 PSI and then drops to 10 PSI in about 5-7 secs

start car and drive- still unable to actually drive the car as Harbor Freight also didn't have a fuel pressure gauge with a long enough hose, but on idle and putting the car in gear and giving gas, 35-36 PSI.

IIRC, my fuel pressure should be around 43-45 PSI. What could be causing this? Car has a new fuel filter and pump. No kind of damage to the fuel lines that I can see. My racing season starts in 5 weeks, practice in 3. PLEASE HELP