Code 44 91 C1500

[DylChrFla]

I’m been having trouble getting my truck to run correctly. I have an idle surge and it starts rough on cold mornings. I occasionally get code 44 lean exhaust. My fuel pump, fuel filter, O2 sensor, and many other parts are less than a year old. It holds perfect vacuum according to a diagnostic gauge. I also tested my fuel pressure which holds steady at 13psi. Does anyone have any ideas? I do also use an ALDL scanner and could not figure anything out there.

 

[Schurkey]

Define "ALDL scanner". If this is a crappy code-reader, it's no wonder it's not useful.

If that is a REAL scan tool, the answer is almost certainly in the data stream. I'd be looking at the coolant temp sensor, the short- and long-term fuel trims, and the MAP and TPS; but don't ignore any of the other sensor readings.

How old are the cap, rotor, plug wires, plugs? Have you tested coil output using a spark tester calibrated for HEI ignitions?

 

[DylChrFla]

Define "ALDL scanner". If this is a crappy code-reader, it's no wonder it's not useful.

If that is a REAL scan tool, the answer is almost certainly in the data stream. I'd be looking at the coolant temp sensor, the short- and long-term fuel trims, and the MAP and TPS; but don't ignore any of the other sensor readings.

How old are the cap, rotor, plug wires, plugs? Have you tested coil output using a spark tester calibrated for HEI ignitions?

I’m using the reddevilriver scan tool with tunerpro. All of my sensor data seems pretty normal. Fuel trims in closed loop are hanging around 128. My cap, rotor, and plugs, were replaced over the summer. I haven’t tested the coil with a spark tester but my spark seems to be pretty strong. My timing advance with the est disconnected is set to 0-1 btdc.

 

[PlayingWithTBI]

Something else that TunerPro (or any other scanner) won't tell you is if your Ignition Coil and/or ICM are good. While watching your log, and it surges, do you see a weird jump in RPMs? Your ECM is probably a 1227747 (Maybe?) which has a baud rate of 160 (only sampling once or a couple times a second) so, it may not catch it every time but, you may see it occasionally. You can also spray some water on the Coil while idling and see if it stumbles.

A new Coil or ICM doesn't mean it's a good one every time.

 

[1997]

wow, another one.

i posted my scanner info, see how it compares to yours.

1993 k3500 with 350 tbi, issues starting in cold weather (below 35 degrees)

I just purchased this truck back in the spring and it has ran great all summer. but now that it is cooling off it has had issues when trying to warm up. it is idling rough, missing, and sometimes stalls out. to restart i have to throttle it some to open it up. I have replaced fuel filter, fuel...

www.gmt400.com

Surging idle on cold start

Hello everyone, my first post! '94 5.7 TBI with 145,000. Truck is original and last year developed a miss/bad idle in gear. I replaced the IAC, TPS and EGR, plugs, wires, cap, rotor, still had the problem. Checked the fuel pressure, good, 13 psi. No codes. Next, I noticed that the...

www.gmt400.com

randomly had ERROR CODE 45, similar symtoms to your 44

between all of us we should be able to solve,, hopefully.

 

[DylChrFla]

wow, another one.

i posted my scanner info, see how it compares to yours.

1993 k3500 with 350 tbi, issues starting in cold weather (below 35 degrees)

I just purchased this truck back in the spring and it has ran great all summer. but now that it is cooling off it has had issues when trying to warm up. it is idling rough, missing, and sometimes stalls out. to restart i have to throttle it some to open it up. I have replaced fuel filter, fuel...

www.gmt400.com

Surging idle on cold start

Hello everyone, my first post! '94 5.7 TBI with 145,000. Truck is original and last year developed a miss/bad idle in gear. I replaced the IAC, TPS and EGR, plugs, wires, cap, rotor, still had the problem. Checked the fuel pressure, good, 13 psi. No codes. Next, I noticed that the...

www.gmt400.com

randomly had ERROR CODE 45, similar symtoms to your 44

between all of us we should be able to solve,, hopefully.

Would be great, I've been trying to figure it out for some time. I do have a spare ignition coil and ICM I could try. Maybe there will be a difference there. However, everything on my ignition system was replaced just a couple months ago.