Code 32 and Code 44

[gregory5000]

I have a 1990 K1500 with a 5.7, all stock. It runs rough and I noticed tonight when I got off work it seems to smell funny when you first start it. I pulled the codes last night and I am getting a 32 and a 44. The 32 is a EGR and the 44 is O2 sensor. I looked around the internet today and noticed this a common set of codes. It does not seem to be just swap the parts and all is good. The truck sat for about a year with not being driven but maybe 10 miles or so. What should I look at first? Thanks for all the help in advance.

[ChevyTech]

The code 44 is for a lean condition. The most likely cause is low fuel pressure.

If the exhaust smells rich to you and it is setting a code 44 then bad information from the oxygen sensor could be the cause.

Exhaust leaks:
Air getting in the exhaust system can affect the o2 reading. In open loop operation (cold) the ECM ignores the o2 sensor reading, but in closed loop (warm) the ECM uses the o2 reading to determine if the engine is running lean or rich. If the exhaust system leaks ahead of the o2 sensor, (or just behind it), the pulses in the exhaust will draw in air and cause the o2 sensor to get an incorrect reading. A vehicle with an A.I.R. will have the same problem if the air management valve allows air to be injected in the exhaust manifolds during closed loop operation.
Exhaust flow moves forward and backward in the exhaust system more then many people realize. A term used in discussion of this is “exhaust scavenging”.


This is the first test you should do of the EGR
Most vacuum operated EGR valves that are the GM original equipment valve have large openings below the diaphragm area. If you lift the EGR diaphragm with your fingers, with the engine idling, (being careful not to burn yourself or get your fingers caught in the EGR valve) you should hear a definite difference in the way it runs and the engine will most likely stall. If there is no difference you should look for plugged passages.

Here is a post with some EGR information:
http://67-72chevytrucks.com/vboard/s...3&postcount=21

Here is the thread that post is from and the thread has a lot of discussion on EGR.
http://67-72chevytrucks.com/vboard/s...ea+foam&page=2

[gregory5000]

Thanks ChevyTech. I was around the truck this morning and I smelled gas. I looked under it and it is leaking at the gas tank. It is hard to tell if is from the tank or coming from the top. I will tackle that first and then the other issues. It is summer shutdown at work so we are working 12 hours days till the 14th. I did get the 4th off though. Thanks again for the info.

[gregory5000]

ChevyTech, when I lift the diaphragm, should the truck be completely warmed up? I looked at it last night and the EGR solenoid valve wire was disconnected.

[ChevyTech]

Originally Posted by gregory5000

ChevyTech, when I lift the diaphragm, should the truck be completely warmed up?

I would not let it get to hot, so I have less chance of getting burned fingers.

I would just run it a few moments so the IAC has a little time to bring the idle down off fast idle.

Originally Posted by gregory5000

I looked at it last night and the EGR solenoid valve wire was disconnected.

That's a sure way to keep the EGR from working.

[gregory5000]

I plugged it up and drove it to town today(40 miles round trip) and it idled perfect when I started it and the check engine light stayed off. That must be a normally open valve and when it is cold power keeps it off. Thanks for the help ChevyTech.

Also a FYI, I got 17.8 MPG on my first tank of gas since I started driving it again. That is back and forth to work, driving 60-65 MPH.

[ChevyTech]

The EGR should not open until the engine reaches operating temp.

How you are guessing it works is kind of the opposite of they it does work.

Here are two threads you can do some reading on how the EGR should function:
http://67-72chevytrucks.com/vboard/s...light=sea+foam

http://67-72chevytrucks.com/vboard/s...d.php?t=348308

[gregory5000]

Thanks again ChevyTech. I read those and it really helps. I experienced some of the bucking and jerking when I was going up a long grade. So I may have a bad EGR valve. I am going to clean up out good when I have a chance. Thanks again for all the time you spend on this forum.

[ChevyTech]

You're welcome! A thank you is always appreciated.

I'm glad you could understand what I wrote in my last post with the errors I made.

It would be a good idea to clear the codes so if the light comes on again we know which code is still getting set. My guess is there is still a problem that caused the code 44.

[gregory5000]

I am going to clear the codes right now. I drove it this morning to work and it still runs rough when it is cold. It was not as bad this afternoon so that leads me to think it will horrible this winter. It also quit on me when I stopped to get breakfast. In reading the other posts, I am going to get a way to check the fuel pressure and I am going to check the gasket. Also I am going to change the fuel filter. The gas was stolen out it when I went to my mothers to pick it up, so I am thinking it may have sucked a lot of trash up. What is the best way to check the gasket without pulling the throttle body or is that the only way? Thanks again.

[ChevyTech]

A vacuum leak should cause it to idle to fast and is unlikely to set a lean code.

Many people spray carb cleaner around to base of the TBI to check for leaks. Carb cleaner can damage the TPS switch so I don't not suggest this method. I listen for a leak with a 3 foot long piece of heater hose held to my ear. Slowly moving the other end around where I think a leak could be.

Anything that causes it to run to lean, or causes the ECM to detect that it is running to lean, will set the code 44.

A dirty fuel filter.

Low fuel pressure.

Melted or damage insulation, allowing the o2 sensor wire to come in contact with metal, grounding the circuit.

Exhaust system leaks ahead of or near the o2 sensor can allow extra air to reach the O2 sensor causing the code.

A.I.R. Air Injection Reaction (smog pump) system valve failure – on vehicles with this equipment.

A bad O2 sensor can cause a code 44, but usually a bad o2 sensor will set a code 13.

[gregory5000]

I am not getting any more codes since I plugged the EGR valve back up. I still have the rough idle when cold, but it doesn't run perfect. I am going to try and see if I have a throttle body gasket leak. I my just replace it if I have time.

[ChevyTech]

If it does not have the faster idle when cold, the IAC could be the problem.

When you first start it cold it should have a fast idle then begins to slow down right away.