Backfires when cold under load.

[jrotten67]

Good afternoon,

I have a 300 Ford in a 78 F150 that I installed a TBI on a couple of years ago. Runs great as long as the weather and the engine are warm. Now that it is winter the truck will backfire under load before it warms up. It only does this when it is COLD, like single digit cold. I tune using TunerPro, I am ok at it, still have a long way to go. I got it running good except for the cold weather start and run. Starts fine and will idle great. Once driving if i get in it a little bit it will backfire, soon as it warms up it is perfect. What scalar or table do I need to inspect to be able to try some things to smooth it out. Any info will be appreciated. Thank you.

[dave w]

What TBI computer are you using? 1227747?

[jrotten67]

1227747 yes that is the one

[dave w]

1227747 yes that is the one

TunerPro RT is a good tuning tool.

Gearhead-efi link for 1227747 Tuning Information: https://www.gearhead-efi.com/Fuel-In...Information-42

[dave w]

1227747 yes that is the one

Screenshot samples of information available from a 1227747 using TunerPro RT.

TunerPro RT Dash.jpg

TunerPro RT Monitors.jpg

TunerPro RT BLM History (Fuel).jpg

TunerPro RT Spark Advance.jpg

[scooterwrench]

Good afternoon,

I have a 300 Ford in a 78 F150 that I installed a TBI on a couple of years ago. Runs great as long as the weather and the engine are warm. Now that it is winter the truck will backfire under load before it warms up. It only does this when it is COLD, like single digit cold. I tune using TunerPro, I am ok at it, still have a long way to go. I got it running good except for the cold weather start and run. Starts fine and will idle great. Once driving if i get in it a little bit it will backfire, soon as it warms up it is perfect. What scalar or table do I need to inspect to be able to try some things to smooth it out. Any info will be appreciated. Thank you.

Try lowering your PE on temp in scalars.

[bennettcvcu]

A couple questions come to mind -

1. Are you running the THERMAC? If the air cleaner temperature isnt accelerated to operating temperatures during open loop, this condition could happen.

2. What's your base timing?

3. Have you checked all the vacuum lines, like really check them (i.e. check that all the connections are tight and all components are operating as they were intended.

Just a few thoughts that come to mind hearing cold run issues with a TBI.

[jrotten67]

No Thermac, timing is set at 0 ,12 in ECM. Vacuum lines are fine. Truck runs fine unless its super cold. Runs fine after it warms up

[1project2many]

Tuning really is a matter of using all available data to determine which adjustments need to be changed and how much to change them.

Cold engines tend to like additional fuel and additional spark advance. Use Tunerpro to watch the Block Learn and Iintegrator values both cool and warm to see if the ecm is adding or removing fuel. Use the results as a guide to adjust cold operation. Try to determine if the problem happens under steady throttle or when you are pressing the throttle to help isolate the accelerator pump enrichment from VE values and corrections.

[jrotten67]

Thank you ...I will look into that.