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Tuning for Dummies: e85 & Cold Start

 
Old 03-03-2019, 07:43 AM
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Default Tuning for Dummies: e85 & Cold Start

If this has been beaten to death, please post appropriate search terms to help me find it! Not 100% sure this belongs in MS thread or elsewhere.

Car in Question: 2018 built CSP car.
Problem: early / late season cold starts suck

Before starting the build I was told by a well-known (and top performing) CSP racer "The car won't start on e85 if its below 50 out" and just accepted it.

My car is e85, ms2, stock 1.6 coils and battery shark etx9 battery. As the registration chief, I need to be able to start my car and get it off the trailer when I arrive, which is usually early by autocross standards. That also means some cold mornings. I've gotten as high as e91 at my local pump, so we're not working with the watered down e50 garbage a lot of people are stuck with.

Mechanical Changes Coming Soon: Moving to a Braille battery (poopy knock off has 120 CCA, Braille is 210.) Then LS2 coils and eventually MS3. Presumably more CCA / fatter spark will help, but I also suspect there's a lot in the tune.

Question 1: Mechanically, am I on the right track?

Question 2: I've seen that cold start tuning requires lots of "get it to start on a cold day," followed by "try again tomorrow." Where can I find a detailed walk through on how to get the car to cold start (what parameters to change, what to watch) for dummies? I've read some discussions but only half follow it and want to make sure I'm not monkeying with things I shouldn't be in the actual tune. My first experience street tuning was plagued with all kinds of issues resulting in pig rich conditions, and I'm short on "car time" with a toddler at home and another on-the-way.

Should I even bother working on the startup tune before making the other mechanical changes?
Should I even bother starting with the MS2 knowing that its getting switched to MS3 in about 6 weeks? (And then re-tuned anyway).
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Old 03-03-2019, 07:49 AM
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Ted75zcar has had some experience with E85 and cold starts, using cranking pulse taper, but I don’t know if that is an option with MS2.
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Old 03-03-2019, 10:43 AM
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I don't remember if crank taper is available on MS2 or not. I would say tune it on MS2, the value of learning to fish is way higher than the fish itself. You oppotunities to tune the first start event are limited, so you want to get as many sessions in as possible.

Couple notes:
- due to science, e85 requires much more fuel than ULG.
- the cranking pulse is based on req fuel, not the output of the fuel equation. If you are running flex you need to tune the blend option. If req fuel is based on e85 stoich, the numbers will be roughly similar to ULG for crank, if using ULG stoich for req fuel and a multiplier based on an ethanol content sensor, the flex curve will be ~40% longer than the ULG curve.
- cranking RPM is important, set it high enough for the engine to actually be starting to run before switching over to ASE and fueling based on the fuel equation/table timing
- EAE is in play here, big time. I would turn it off for inital tuning if you aren't super familiar with how it works
- ~MAY ONLY APPLY TO MS3~I have had the most success with having the primary timing map tuned in idle regions for maximum TQ. On high compression with e85, this is probably ~20-25 degrees or more. Cold start idle targets in the 1500RPM range may be upwards of 35 degrees or more. Use idle advance (may only be on MS3) to get more retard at idle when warm.
- tune the cranking IAC
- crank to run tapers 10-20 seconds
- I personally set all ase taper targets to the same number, based on time. This number is equal to the EGO delay or slightly longer than EGO delay.
- AFR should go from ~lambda = 0.8 at t=0 to 1 at t=ego delay
- ASE is tuned soley with the ASE adder curve.
- long priming pulse delay to purge the entire fuel system. Returnless setups will require longer priming pulses. Return style can have a shorter priming pulse. I use crank taper to provide a prime pulse that correlates with cranking. This is a bit more advanced, so hold off on it until you don't need to ask questions to use it

- BIG ONE - for initial tuning, hook the car up to another running car with jumper cables. The first crank event is the one that is the hardest, but you can do a ton of tuning after the inital start by turning the car off and restarting multiple times till warm. The other huge advantage is that the MS doesn't lose comms with TS while cranking, which allows you to log the whole process. MS2 doesn't do SD, so you will have to make due with the low speed logging. Look at the logs carefully when making changes.

I am mobile and don't have my tuning CPU, so that is what I remember

Edit: if it doesn't start, add more cranking pulse
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Old 03-03-2019, 03:51 PM
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Ted75, I like the thought of setting ASE taper to time. I realized that I look at my AFR and set my cycles of taper to match needed time anyway.

How on do you “tune cranking IAC” before you get cranking going?

Yes EAE is indeed active big time.

Thanks for your response.
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Old 03-04-2019, 08:23 PM
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Well I don't do everything exactly as suggested above. The one thing I will add that 18psi once said to me, not in so many words but, you can choke some with your IAC valve. I have no problem cold starting with e85 running a relatively low IAC duty, also increased cranking pulse over petrol of course. It never really gets below freezing around here though, at least not when I have to drive anywhere.
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Old 03-05-2019, 08:33 PM
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I wouldn't call this a great start, the car has been sitting for quite a while. It should be colder in the morning, I may grab another video then.

As far as the IAC is concerned, I carefully tuned the initial value table, then used values that matched the idle target. Right or wrong, it seems to work for me.



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Old 03-05-2019, 08:40 PM
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Sounds right to me. IAC duty is pretty low when cold from my experience, like a choke.
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Old 03-05-2019, 08:48 PM
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Originally Posted by sonofthehill View Post
Sounds right to me. IAC duty is pretty low when cold from my experience, like a choke.
Not sure what choking an EFI engine does, but maybe I will give it a shot and see what happens.
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Old 03-05-2019, 08:58 PM
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Reduces the amount of cranking pulse needed. You might need to adjust cranking pulse some too. Helped me with fuel economy a little too(I think ) I guess being EFI, we could just spray as much fuel as needed if we want to, but it gets excessive with cold e85.

I never considered it until trying to start e85 cold.
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Old 03-05-2019, 09:31 PM
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Originally Posted by sonofthehill View Post
Sounds right to me. IAC duty is pretty low when cold from my experience, like a choke.
Possibly by lowering MAP, vaporization is enhanced?
See what you find when you try it.

As to how you tuned Cranking IAC Duty that does make sense. Basically what I have done. It only creates a slight gut reduction in MAP during cranking.
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Old 03-05-2019, 10:02 PM
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Originally Posted by DNMakinson View Post
Possibly by lowering MAP, vaporization is enhanced?
See what you find when you try it.

As to how you tuned Cranking IAC Duty that does make sense. Basically what I have done. It only creates a slight gut reduction in MAP during cranking.
Possibly. For really cold starts, I found the period between the crank-to-run and hitting cold idle target is really important. This is where the alternator kicks in, you see a big swing in spark advance, the pw has a big swing, EAE integrates to a stable wall fuel .... slewing the IAC seemed to be counterproductive to having it fire up and stay fired up.

We will probably get at least 1 more cold spell yet this year where the temps in the mornings are low (like 10F or lower), I may try it. Anything over about 30F won't really provide useful information.
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Old 03-06-2019, 12:06 PM
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I don't have much to add but here's how I tune cold start ignition timing. If it cranks and cranks with weak or no booms then advance the timing a bit. If it starts up briefly and then kicks back and dies then retard the timing.
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Old 03-07-2019, 07:38 PM
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Snagged a 38F start, I would call it OK, could probably tweak in some improvement

I did try various idle cranking settings the other day. I did not conduct the test formally, so I did not capture proper data, but from a perception standpoint, the higher IAC DCs produce a better start, most notably in the period of time between the crank to run transition and the cold idle target.

I my still hook it up with jumper cables to the DD and run a proper set of experiments with high speed data to be sure.

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Old 04-02-2019, 12:32 PM
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impressive starts Ted. I've got my e85 system up and running and at freaking 60deg garage temps I don't have a start that nice. Got some work to do!

Thanks for posting the previous video - that helps a lot.

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Old 04-02-2019, 08:54 PM
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Thanks man, glad the video helped!
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