Whenever I start my car and look at the fuel trims they are all positive like it is very lean. Once the engine is warmed they are in check. I was wondering if this is normal or if there is a way to correct this with a simple ECT multiplier?
Startup Fuel Trims.hpl
Haven't looked at your log. Injector data that's a smidge off can cause it. A band aid that worked well for me is to utilise the injector tip temp table up to about 40deg. Positive numbers add fuel.
Create a histogram and log fuel trim vs injector tip temp and do a bone cold to warm idle log. That should get you heading in the right direction.
Should add, find your normal injector tip temp cell during cruising first. Example it might sit between 41 to 47deg. If that was the case then the highest injector tip temp cell I would go to for cold compensation is 35deg.
What table are you referring to in the editor, most of my options seem to be based on intake valve temps, not injector temps? General cruising puts the inj tip temp anywhere from 29-44C.Originally Posted by hjtrbo
[ECM] 12303 - Injector Offset vs. Injector Temp
Ah OK, I have that table zero'd out for the time being and was planning on putting the OEM values back in when I was done with tuning (but that is only for hot temps though).
Are you suggesting to add a positive number here for the colder temps? I ask because if I follow the graph trend, I'd expect that colder temps would continue to trend into negative offsets.
Don't follow the graph trend. When finished you'll end up with a V shape, except around operating temps it will be flat at 0.
This next statement assumes at normal operating temp your trims and wideband are dialled in for all driving scenarios...
If you find that it fixes your idle trims but becomes rich when driving when the engine is still warming up then points towards injector data that needs a tweak.
The Aussie falcons have a table called lost fuel that has ect and load as the axis. Around operating temps the table is all 1's but in warm up areas you can dial it to enrich where needed. Very handy table. We don't have that on the GM.
Thank you!
OK I have added some offset and this seems to be the ticket! Thank you!
Reply With Quote