Intermittent Code 44.

[Gander]

First off, no scanner, no ALDL cable, no Windows 7 or Windows 10 laptop and I won’t be able to have any of that stuff anytime soon. Wish I had that stuff because it sure would be easier to figure this stuff out.

OK, so random code 44. Only seems to do it if I’ve shut the truck off hot like at a gas station or a store if I haven’t been in very long. I’ll start it back up, drive off, and as I’m driving off the SES light would come on. Just did it again today and as it happened it felt like I was pressing the gas pedal but it was hardly feeding the motor any fuel. Fuel pressure regulator and spring is new, injectors are reconditioned, TPS is new. Checked the voltages there. IAC is new and so is the connector. I don’t think it’s a fuel pump issue since this happens regardless of which fuel tank I’m using and each tank has its own pump. Fuel filter is new. Any ideas? Tell me where to look and how and I’ll start checking. BTW, when I shut it off and turn it back on the light is gone though the code is stored, I can pull it up when I jump A&B on the ALDL. This is an intermittent thing. I can go a week without it happening and then have a week where it happens once a day. Just can’t figure it out.

 

[gmbellew]

If it is intermittent, I would guess the O2 sensor is flaking out. 44 is lean condition, closed loop (O2 voltage low for too long). Or something that is causing the O2 to read low in closed loop.

 

[YakkoWarner]

I get this too but not in the same conditions you describe, mine happens when I'm driving either up a long gradual hill or on a highway with a speed limit 70 or more. I had the data log running the last time it happened and saw an anomoly - right before the error triggered both the MAP and TPS readings went very high much quicker than could be achieved with pedal manipulation.

In your case, I would almost suspect a partial vapor lock since it only happens when you shut down the truck while hot and then restart. Some of these trucks had an extra fuel "hot start" pump control module that would run the fuel pump longer before cranking in order to circulate cooler fuel into the throttle body before startup. An experiment to try would be to turn your key on for 10 seconds, then off, then on again for 10 seconds 3 or 4 times before actually starting - that would do the same thing in terms of moving cooler fuel thru the lines. Is your truck a small block or big block? I have that hot start thing but I have a BBC, I don't know what caused some trucks to get it and others not but maybe they didn't put it in SBC trucks?

 

[Gander]

I get this too but not in the same conditions you describe, mine happens when I'm driving either up a long gradual hill or on a highway with a speed limit 70 or more. I had the data log running the last time it happened and saw an anomoly - right before the error triggered both the MAP and TPS readings went very high much quicker than could be achieved with pedal manipulation.

In your case, I would almost suspect a partial vapor lock since it only happens when you shut down the truck while hot and then restart. Some of these trucks had an extra fuel "hot start" pump control module that would run the fuel pump longer before cranking in order to circulate cooler fuel into the throttle body before startup. An experiment to try would be to turn your key on for 10 seconds, then off, then on again for 10 seconds 3 or 4 times before actually starting - that would do the same thing in terms of moving cooler fuel thru the lines. Is your truck a small block or big block? I have that hot start thing but I have a BBC, I don't know what caused some trucks to get it and others not but maybe they didn't put it in SBC trucks?

5.7tbi. I’ll try the 10 sec trick on hot startup and looking forward to any other ideas. Thanks!

 

[gmbellew]

code 44 will only set in closed loop. so it shouldn't set immediately after a start, hot or cold. in addition to the temp and O2 fluctuations to kick it to closed loop, there is also a time component of some sort.

the only time I had a code 44, I looked at the ALDLDroid data and my O2 was randomly reporting all sorts of values that didn't make sense. it would go high, low, stay constant, etc all at just flat cruising. and the BLM fuel trims were trying to match it and also going haywire. new O2 sensor was the ticket that time.

 

[YakkoWarner]

Last night it occured to me another thing that could cause the mixture to go excessive lean when the truck is hot could be an out of spec coolant sensor. The engine gets heat soak when turned off (turn the key on and watch the temp gauge before starting, it will be higher than expected until the engine runs and circulates thu the radiator) - if the coolant temp sensor is reading higher than actual (no way to tell without the computer data - its not the same sensor that feeds the dash gauge) it could cause the computer to pull back too much on the fuel flow.

 

[Gander]

CTS and O2 are 9 months old, doesn’t mean anything these days with low quality Chinese junk but it is what it it. I’m going to get an ALDL cable next paycheck and get some real data.

It’s not an immediate code 44 but almost immediate. When it happens, I’ve just started the truck hot, backed out of the parking space and headed towards the street, by the time I get to the street the SES light is on. Again, it’s not all the time, didn’t do it at all today, I’m going to wait until it cools down and check under the truck tonight and see if maybe the O2 sensor wire is shorting out or melted or something. If not then I’m going to wait for that ALDL cable unless I get impatient and swap out the CTS and O2, those are both easy to do. Of course, who’s to say any replacement I buy isn’t out of spec right out of the box. I know the last TPS sensor I bought was out of spec right out of the box plus the connector I bought wouldn’t fit either the old or new one. The connector was the correct type, but had a flaw in the injection molded plastic which made it impossible to slide on. Total junk. Standard Motor Products BTW.