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EFI in Cold Weather

BulldogBronco

Full Member
Joined
Nov 13, 2018
Messages
155
I have a 1972 Bronco with a 302 with the Holley Sniper setup. The weather in NC/SC is just starting to get colder and I installed the Sniper this year so it’s only been in warm weather. I drove it last night in about 45 degree weather and on my trip home it acted like it was skipping or stuttering a little on acceleration. I know these things are self learning so my question is, is it normal for there to be some adjustment when the weather gets colder or is something else potentially going on? There was nothing abnormal going on with the handheld unit and the numbers they were registering.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,353
Don't know, so am following. But it seems like you'll need to adjust some cold-start enrichment for starters. Even though it sounds as if it was starting fine?
Maybe just general enrichment (accelerator pump-ish)?

What was the coolant temp at the time? Maybe when it goes below a certain parameter it goes back into closed-loop and so only knows what it was programmed to know during setup.

good luck. Curious what the experts determine.

Paul
 
OP
OP
BulldogBronco

BulldogBronco

Full Member
Joined
Nov 13, 2018
Messages
155
Yep started right up on both legs of the short trip. The closed loop deal would make sense, the engine temp was low so that could make sense.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
The Sniper I installed this spring is seeing its first cool weather. I had to add a little to the cold enrichment to keep it happy. I really want to do a little data log and see what it really is doing. The wide band is heated so you can get fairly quick A/F ratios even when cold. Key on and wait a minute for heat to build before starting will get faster readings.

I don't think the cold start is self learn.
 

unimogger

Full Member
Joined
Aug 7, 2019
Messages
214
Loc.
Philthadelphia
Will the Sniper data log? If so you will see pretty quickly what is going on..
I have set up and tuned several megasquirt systems and even as a closed loop system, you ave to give them some guidance to run well. I wouldn't be surprised if the Sniper was similar
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
Sniper will data log with either the hand held controller (add the memory card) or the laptop adaptor.
 

pcf_mark

Bronco Guru
Joined
Jun 11, 2010
Messages
3,574
There should be a intake air temperature compensation table in your fuel enrichment table. See Air Temperature Enrichment % table. Move it toward rich a few % at a time. When you have it working nice at your current temperature then extrapolate the % at lower temperatures.
 

harleyabarton

Jr. Member
Joined
Mar 23, 2019
Messages
64
Loc.
Jupiter
depending on your set up your engine may want to be more rich then they sniper allows. when first tuning was it warm weather? almost all EFI systems have a built in fail-safe to allow for O2 sensor failures. meaning it has a set map it will not go lets say 10 maybe 20% richer or leaner then that map that you tuned it for (self tuning included) so lets say you have it set to 302 cubic inches and maybe a street cam. well now that its becoming to lean to run right. it might be way to lean right? well the computer is putting more fuel but then believes there to be a O2 failure and will compensate by going back to its normal set fuel MAP instead of using the O2 readings to determiner its map in real time... it may be that in cold weather or even normal every day use you may need to reset the tune and set it to something like 334 cubic inches or maybe go to a mild or race cam depending on your set up... but remember that cam settings can actually lean out your map if you have a heavy high RPM cam then it will be leaner at idle and rich up top. so just be mindful of what cam you have. if youre heads are ported and want more air then you might need to set your cubic inches higher then your actual engine...

like i said before there are failsafes to try to save your engine from dying but if its out of its range it will sometimes basically bottleneck your engine.

i have a 460 in my 78 bronco that i did a edlebrock pro flo 4 in and i was having the same issue because my 460 i built to make 500+ hp and it wanted a lot more fuel then a stock 460. so when I set the cubic inches to 460 it had a pre determend map close to what you might need for a stock 460... and wouldnt allow the self tuner to actually make it rich enough to run properly... i had to call edlebrock and have them show me how to install a race version of the 460 map that allowed it to be much richer then a stock 460... that ended up fixing my whole issue.
 

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