Cold Weather EFI Issues

Engine troubles? Try here.
Post Reply
mdevino
United States of America
Posts: 9
Joined: Thu Jan 15, 2015 2:28 pm

Cold Weather EFI Issues

Post by mdevino » Wed Jan 17, 2018 2:20 pm

Hi All, I have Jim L's EFI setup, and having some trouble with cold weather starting. Ive been driving it in warmer weather for a couple years, and have tuned it pretty well for those conditions. It runs great in the cold too, but only as long as i start it in the garage. i would say it starts pretty much perfectly down to about 0C and then its a no go, but im not sure of the exact temp that the problem starts at.

Now i didnt reach out to Jim directly for help for two reasons: 1. i bugged him way too much getting it all set up and 2. he lives in warm weather. That being said, Jim's comments would certainly be appreciated

my setup is pretty much as per the spec....its an EMS 8860 running sequential with a modded distrib for cam sync. I have IAC, intake temp and oil temp sensors, and a fuelab prodigy pump mounted low on the tank

i have tried all of the following:
adjusted post start fuel up and down
adjusted general fuel compensation for coolant temp up and down
made slight adjustments to timing pct in ign temp comp
tried iac on and off with various changes, and blocked off completely
kept the batteries on charge so i had good power
listened for fuel flowing back to the tank

The best i can get seems to be with about 50-80% extra fuel and everything else the same....i get a few pops of ignition and then nothing. after that it acts as if its flooded, but clear flood mode doesnt help.

Scratching my head on what else i can check....anyone have any ideas?

Thanks,
Mike

User avatar
rmel
United States of America
Posts: 916
Joined: Sun Sep 25, 2011 12:19 pm
Location: Woodside, CA
Contact:

Re: Cold Weather EFI Issues

Post by rmel » Wed Jan 17, 2018 4:30 pm

Choke control and Cold crank increase the amount of fuel over the Map settings vs. temp.
Have you played with these yet? I believe you can tweak these up starting at -20C and
they both go to 0% at 60C with a linear interpolation between.

I run with a SDS controller myself, it's similar in the cold start fuel injection tweaks.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q

User avatar
TechMOGogy
Canada
Posts: 2798
Joined: Wed Feb 01, 2012 11:39 am
Location: Ontario, Canada

Re: Cold Weather EFI Issues

Post by TechMOGogy » Wed Jan 17, 2018 7:24 pm

I had an issue with my crank sensor
Not really sure how the cold affected it, but only had issues when cold.
Replaced and starts right up.
Doubt that is your issue but easy to check, if you see RPMs on the software when cranking it’s fine.
That was at about -5 C. Never started it colder as it goes into winter hibernation
72 Pathfinder | 75 710M 2.7i | 96 350GDT Worker

User avatar
Jimm391730
United States of America
Posts: 1456
Joined: Wed Apr 14, 2004 10:58 pm
Location: Idyllwild, CA

Re: Cold Weather EFI Issues

Post by Jimm391730 » Sat Jan 20, 2018 10:29 pm

In the tuning section, there is a tab for "Air Temp Compensation". I don't remember what mine is set for (I'd have to go fire up the truck computer to see) but IIRC I needed to significantly (like by increases of ten or more for each block) up those fields at the freezing level and below. While I live near Jim L, I am at a much higher elevation where it gets down to single digits occasionally. My truck still doesn't start just by pushing the button, but I can wiggle the gas peddle and the accelerator pump function kicks in for an extra blast of fuel that helps. I've also found that it won't run without opening the throttle more (probably about 2k rpm if it was warmed up) .
Jim M.
712W and 710M

User avatar
TechMOGogy
Canada
Posts: 2798
Joined: Wed Feb 01, 2012 11:39 am
Location: Ontario, Canada

Re: Cold Weather EFI Issues

Post by TechMOGogy » Sun Jan 21, 2018 3:31 pm

If we all have Jim’s EFI we should start a section to share maps/tuning files
Just a thought
72 Pathfinder | 75 710M 2.7i | 96 350GDT Worker

mdevino
United States of America
Posts: 9
Joined: Thu Jan 15, 2015 2:28 pm

Re: Cold Weather EFI Issues

Post by mdevino » Mon Jan 22, 2018 1:06 pm

Now the weather is not cooperating with me to test....but i am going to look into the crank sensor as soon as i get an opportunity. I did have some issues getting it to run early on, and found that the firs sensor i had was bad, but it was also not placed perfectly and i wasnt getting a good signal. it took an oscilloscope to figure that out.

I think sharing our tune files is a good idea....i have a few maps from other peoples projects Jim shared with me when i was trying to get the system tuned initially. mine now looks nothing like any of them. its hard to believe they are all maps for the same engine. Mine is attached if anyone is curious, someone is going to tell me im nuts for sure.
Attachments
20180116.EM8.zip
tune file
(6.02 KiB) Downloaded 33 times
Screen Shot 2018-01-22 at 13.54.07.png
Screen Shot 2018-01-22 at 13.54.07.png (220.62 KiB) Viewed 815 times

User avatar
Jimm391730
United States of America
Posts: 1456
Joined: Wed Apr 14, 2004 10:58 pm
Location: Idyllwild, CA

Re: Cold Weather EFI Issues

Post by Jimm391730 » Mon Jan 22, 2018 1:55 pm

...someone is going to tell me im nuts for sure.
Well, not NUTS, but ? LOL.
Frankly, I've found that with my map (not handy to share at this moment) that the low vacuum (pedal to the metal) end of the fuel map is fairly flat across the rpm range (where yours is quite peaked at lower rpms); this gives roughly a 12:1 fuel/air ratio which is somewhat overly rich but gives the most torque. One or two steps down in vacuum from there the fuel drops to the 13-14 range for better fuel efficiency. Myself, I'm probably nuts as I cut the fuel to zero at the highest couple of vacuum steps at 2000 rpm and above; this kills the "popping" on downhill grades. Yes there is a separate spot to program this in, but I can best see that it is happening by programming it into the fuel map. Maybe by next weekend I can get my map and show you what I mean.

But in general, I set my fuel map based on the fuel/air ratio from a wideband sensor (which you should have, too). As I said, WOT (wide open throttle) should be on the rich side at about 12-13:1. It can be leaned out at less than WOT but typically is still a bit rich for air cooled engines. I found out that if I leaned it out, not only did I loose power but also had to really put my foot into it and actually used more fuel if too lean. Have you looked at what your O2 sensor is saying at different operating points? Honestly, my truck mostly runs either at idle or almost WOT when being driven; hardly ever is it in between those points!
Jim M.
712W and 710M

mdevino
United States of America
Posts: 9
Joined: Thu Jan 15, 2015 2:28 pm

Re: Cold Weather EFI Issues

Post by mdevino » Mon Jan 22, 2018 2:29 pm

Right, i definitely did not tune with efficiency in mind. I used the wideband sensor for tuning and applied adjusments from 20 or so runs through rpm and vacuum ranges with the desired a/f set for somewhere near mean best power, i believe 13.3 or so. then i shaped it by hand a bit to make it smooth and fix some of those errant pops on decel. I run with the o2 sensor off above -70 kpa, and below that i try to keep it at around lambda for the exhaust smell and sake of the plugs. i also used 20% accel enrichment. i get 11 to 12 mpg on the highway averaging about 3800 rpms, whatever that equals in speed, maybe 60ish. i do find there is a huge difference in the power the engine produces in colder weather....wish i had larger valves

mdevino
United States of America
Posts: 9
Joined: Thu Jan 15, 2015 2:28 pm

Re: Cold Weather EFI Issues

Post by mdevino » Wed Feb 07, 2018 5:02 am

In case anyone runs into this in the future, i spoke with EMS and they suggested that the post start adjustments are a percentage, so at the low cranking rpms, the fuel table is providing a rather small amount of fuel. even at 100% post start enrichment, there was probably not enough fuel. sure enough, adding a column for 250 rpms let me increase the 0 rpm column enough that it made starting easy while not affecting the idle once started.i havent tested it in warm weather, but i suspect i could use a negative value for post start in warmer weather if necessary. thanks to all that chimed in here for the suggestions!

Post Reply