My check engine light is sending a 44 code which is Lean Exhaust System.

My 82 is eating gas big time. I am getting about 200 miles to a tank where I used to get about 400.

It is running very rich as can be seen by the black exhaust stain on my concrete garage floor.

So if the ECM thinks the system is running lean, does it then tell the injectors to pump more gas? Is the sensor bad? Because it should certainly see that it is running rich?

Any help appreciated.

Obie

 

I would think your O2 sensor is bad. That would be the first place that I would look.

 

Code 44 in the GM book says the O2 sensor is below 0.3V and will not go above that point. It then sets the car to run in open loop.

Kelso is probably barking up the right tree. Check your O2 sensor wiring and if it looks correct, replace the O2 sensor and see if that takes care of it.

Have fun and get the red GM 1982 Corvette Shop Manual. it will tell you how to trouble shoot each code.

 

i am thinking the coolant sensor in the front by the water pump is bad .

 

I have an O2 sensor on order. I will check back once it is in. Thanks.

MN-Brent,

I have a red shop manual, but the info was pretty weak.


Terry82,

If the coolant sensor were bad, wouldn't the temperature gauge show that?

 

temp gauge sensor and temp sensor are two differant sensors.temp gauge tells you what the temp is .temp sensor tells the computer what temp it is .i dont think the computer is getting the right temp.http://crossfireinjection.net/

 

hi, i have exactly same problem. Driving distance on one tank is 200 miles, black spots on garage concrete, and yesterday i got code 44 on diagnostic. Did new oxygen sensor helped?

 

vette_82,

I replaced both sensors as suggested. I liked the idea, but results are the same. I would get new ones and see what happens. Not that expensive and you know that your sensors are good.

I did not trace or test the wiring. Waiting for spring.

 

The service manual diagnoses the Oxygen sensor and then check for any exhaust leaks allowing air to sucked into the exhaust system. After those two things are proven ok, it begins to diagnose the carb.

Do you have a copy of the service manual diagnostic procedure, I can send them to you if you like.

 

If you replaced the sensor and got no change, the odds are that the sensor wiring is bad preventing the sensor signal from getting to the ECM. It could also be that the connectors at the ECM are not making good contact, yielding the same result. Remove all connectors from the ECM, clean the contacts on ECM and cable, then put some dielectric grease on them to prevent further oxidation (get it at Radio Shack). Hopefully, that will cure your problem.

Oh, make sure to remove the ECM grounding wire from its mounting spot and clean that as well.

 

I can fax you some diagnostic info I printed out from the factory manual. The oxygen sensor reads if the exhaust is rich or lean. When running correctly, car warmed up,thermostat open,it will vary between .1 and 1.0 volts, and should fluctuate constantly. Your problem is most likely caused by a vacuum leak, exhaust leak or a bad vacumm conection to the map sensor. PM me with a fax # and I'd be happy to fax all the info I have.

 

One other possibility is if the air pump is pumping up stream to the exhaust manifold or if there is an exhaust leak near the O2 sensor when the computer is in closed loop the "oxygen" sensor will read extra the air from the air pump or exhaust leak as a lean a/f mixture and then the computer will comand a rich a/f mixture.

I hope this helps Henry @ olescarb

 

I have checked for holes on exhaust system. I have found one hole at the muffler and then one hole at the something, I have no idea how is it called. I tryied to search web and I think it is "air exhaust manifold pipe". I am attaching picture from brochure what I mean. Can this caused code 44?

 

Any extra air from an exhaust leak or if the air pump is pumping (upstream) to the exhaust manifold when the computer is in closed loop will cause the "oxygen" sensor to have a output that will tell the computer that it sees a lean air/fuel mixture. Repair the exhaust leak and check and also check to see if the air pump is pumping air to the check valve when the computers is in closed loop (or just pinch off the air pump hose).

Henry @ olescarb

 

I was checking out air pump and I found out strange thing. On one side is hole in air exhaust manifold pipe like I decsibe earlier, and on other side there is pipe missing at all!!! On the place where air exhaust manifold pipe used to be, there are only four welded points. (probably previous owner did that) Question is, what should I do now? Do the same thing on the side with hole in it? Just remove air exhaust manifold pipe and weld the holes or buy two new manifold exhaust and replace them? Can it cause some problema, if the engine will run with out AIR system at all?

 

you do not need any of the air lines air pumps or the egr .your car will run fine with out them.but you do have to plug them off where you have holes and you do have to block off when you take things off.all those parts are worth money to people who have to get there cars inspected.http://www.crossfire.homeip.net/index.php?act=idx

 

Terry, thanks for help. I was trying to get to that crossfire forum last year, but for some reason I wasnt approved
Now, I have 82 Vette and I feel like a dummie about CFI
I will try my luck again on that forum..

 

http://www.crossfireinjection.net/

 

None of that stuff will cause the lean problem. YOu can take it all off and block it if you don't need it for inspection.

The O2, CTS and MAP send info to the ECM. The ECM adjusts the fuel/air mixture based on these three readings.

If the CTS is bad it tells the ECM the engine is hot or cold it incorrectly it adjusts the fuel/air.

If the 02 is bad it tells the ECM to adjust the fuel air incorrectly.

If the MAP is bad it again tells the ECM to adjust the fuel/air incorreclty.

The injectors control fuel.

The IAC's conntrol air.

The TPS tells the ECM if you are at low RPM idle or excellerating to higher RPM based on the angle of the throttle plate on the rear TBI. Not likely the cause.

Bad ECM can cause all the problems even if all the sensors are good. Maybe the cause.

If you have changed the CTS and 02 and you still have the problem. Next place to look is the MAP. The MAP may not be bad. Lots of possible sources of a vaccum leak. It may be receiving a low mainfold pressure reading because of a vaccum leak in the upper gasket of the intake....the one the TBI's sit on. If you put a guage on the hose from the Manifold to the MAP you should have a constant 20 PSI. If its much less and fluctuating you have a leak in the upper plate gasket. Or some other component may be leaking that needs to be elliminated. You may need to replace the upper gasket. This is the main cause by the way....you must use the correct gasket....no silicon...no liquid gasket....it will fail if you do.

Other sources....I would also plug off the hose that feeds the headlight system to test before and after you put the gauge on the MAP hose. A leak in the vaccum lines of the head light system will reduce mainfold pressure too. Come to think of it the valve on the master cylinder in the front if bad will do the same. Do your headlights and brakes work as the should? Another source could be a leaky PVC or bad EGR. Disconnect the PVC and plug the hose...any change? Push up on the the bottom of the EGR....should be a change....engine will try to stall....no change means its bad and leaking.

You will know if the MAP is being read by ECM if you disconnect the wires to it....ECM should show a code for it.

The three sensors mentioned above are critical to the ECM. What they say determines the fuel/air mixture.

Did you remove the fuse in the battery area for the ECM....you need to erase incorrect perameters set by the previous sensors (CTS and 02).

If all is well with the above. Move on to the IAC's. When bipping the throttle look down where the pins seat for the IAC's both should be moving in sync adjusting the air mixture. If one is not moving or eratic in movement compared to the other that IAC may be bad. A bad IAC will not allow the proper air flow and confuse the ECM which sets of the the 02 code.

Other then this there is not much else to the system.

Jim