Faster cold starting? Freezing weather!

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Spiffy
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Faster cold starting? Freezing weather!

Post by Spiffy »

Norway is pretty cold in the winter and as it's gotten colder over these past months I've noticed it takes much longer time to crank before it fires(compared to warmer weather).
So I'm thinking it needs more fuel added? But I don't know if I should alter the priming pw or cranking pw setting, where do I start?

Once it catches it runs perfect though. I would just like to try to get it to catch faster...
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Re: Faster cold starting? Freezing weather!

Post by jsmcortina »

Adjust the cranking PW curve.

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Spiffy
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Re: Faster cold starting? Freezing weather!

Post by Spiffy »

Any suggestions as to how much % I should increase to begin with?
elaw
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Re: Faster cold starting? Freezing weather!

Post by elaw »

More? :lol:

The help says the coldest cranking PW should be 200-400% but I've found my car likes a *lot* more than that:
Capture.PNG
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Keep in mind the temps in that image are degrees F not C. It rarely gets below 0 degrees here but I suspect if it ever got really really cold, I'd need even more fuel than I have programmed now.
Eric Law
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Spiffy
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Re: Faster cold starting? Freezing weather!

Post by Spiffy »

I haven't touched the stock settings since it's been starting fine up until now. Gave it 20% more today. Seemed to help, will try a bit more tomorrow

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elaw
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Re: Faster cold starting? Freezing weather!

Post by elaw »

Hey just to circle back on this, we've had a long stretch of 0-degree (F) overnight temps so I've had good opportunity to tune cold starting. It turns out my car likes even more fuel than the images I posted earlier show! The values in these images for temps < 0 technically haven't been tuned, but the 0-degree values are about the minimum needed to have the engine catch quickly and not stall right afterward:
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Capture2.PNG
Capture2.PNG (49.83 KiB) Viewed 1567 times
I should add I'm also using the "batch fire during cranking" feature. On MS3 (and I think MS2 also?) the injector pulse width is limited to about 65 milliseconds, and a single 65 ms pulse per cycle is not enough to get my engine started in temperatures this cold. The batch fire feature effectively allows injection of 5x as much fuel per cycle on my 5-cylinder engine.
Eric Law
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2012 Audi A4 quattro, desperately in need of tweaking

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Re: Faster cold starting? Freezing weather!

Post by DocWalt »

Wow Eric. I've been steadily adding ASE % to prevent the "start then stall short time later" behavior and I was feeling ridiculous at ~75% but I'm apparently not that crazy even with my gigantic cams and such. Today it started and ran until the alternator kicked in then stalled. Clearly not enough fuel yet!
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2cvJasu
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Re: Faster cold starting? Freezing weather!

Post by 2cvJasu »

Spiffy wrote:Any suggestions as to how much % I should increase to begin with?
A lot. Very much. What I have experienced, you wouldn't believe how much fuel is needed to start from really cold...

I have 170cc/min injectors on my 602cc flat twin (Citroen Dyane), and I eas really surprised when I started that on about -30C, those injectors had max duty cycle on 1400 RPM and they were practically squirting constant for a while. But very shortly the duty cycle went down when engine was getting a little warmer (not near to its operating temperature before outside temperature went less freezing...
goodysgotacuda
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Re: Faster cold starting? Freezing weather!

Post by goodysgotacuda »

Are you just adjusting the value, cold starting and testing to see how long it takes to fire reliably?



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2cvJasu
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Re: Faster cold starting? Freezing weather!

Post by 2cvJasu »

goodysgotacuda wrote:Are you just adjusting the value, cold starting and testing to see how long it takes to fire reliably?
Yes. Trial and error. And when the temperature is -20'C...-30'C it won't get long to cool down for new testing, especially with small aircooled engine... :roll:
DaveEFI
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Re: Faster cold starting? Freezing weather!

Post by DaveEFI »

On early EFI systems, it was common to have an extra cold start injector.
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2cvJasu
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Re: Faster cold starting? Freezing weather!

Post by 2cvJasu »

DaveEFI wrote:On early EFI systems, it was common to have an extra cold start injector.
Yes, on D-Jetronic, some early L-Jetronic (Citroen Cx 2400 IE for example) and Rover 3.5 with "flapper" (ECU and cold start parts on my table). Must be more, but those I have experienced myself. Those have "thermo-time -relay" to control cold start injection time, and they inject only when starter motor is operated, pretty clever system on those days...
DaveEFI
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Re: Faster cold starting? Freezing weather!

Post by DaveEFI »

Yes - my RV8 had the flapper system. When I went MS, I removed the cold start valve and thermotime switch. Cold starting is OK - but then it never gets very cold in London.
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2cvJasu
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Re: Faster cold starting? Freezing weather!

Post by 2cvJasu »

Reason why I have those parts at my home, is the plan to remove Strombergs from my -76 Range, and install manifold (and all other parts for a while) fron flapper engine. But not now, weahter must get warmer, and also sunlight what we have about five hours...

Also another plan is to replace Lucas ECU with MS2 what I have waiting...
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Re: Faster cold starting? Freezing weather!

Post by DaveEFI »

Unless you already have the flapper bits, best to start out with a hotwire system from a Rangie. Has Hi-Z injectors and a much better quality wiring loom, which you can adapt for MS. Also has a stepper motor idle valve which MS can drive.
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mrx79
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Re: Faster cold starting? Freezing weather!

Post by mrx79 »

Hi folks,

just doing also some cold start (around 0°C ambient) tuning.
priming pulse: 1ms with 0.5s pump delay
cranking pulse: 190%

time from crank to first engine speed detected: 0,625s (aprox. 1.7rotations)
then it takes another 1,782s in crank mode until it reaches >670rpm (which is my cranking rpm)

I was wondering if an increase in priming pulse can also increase startup. But what i was whinking, because it takes about 2 rotations to sync up, a lot of the priming pulses fuel is pushed thru the engine. So what are your experiences on the effect of higher priming pulses on startup time?

By the way, what are your times from voltage drop to 1st engine speed (sync time)?

Best regards
Honda CRX B16A1 Turbo | MS3 running | pre1.5.1 beta7 Firmware | 24/1 Dual Wheel | COP ignition | 725cc ID injectors
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Re: Faster cold starting? Freezing weather!

Post by turbo conversion »

mrx79 wrote:Hi folks,

just doing also some cold start (around 0°C ambient) tuning.
priming pulse: 1ms with 0.5s pump delay
cranking pulse: 190%

time from crank to first engine speed detected: 0,625s (aprox. 1.7rotations)
then it takes another 1,782s in crank mode until it reaches >670rpm (which is my cranking rpm)

I was wondering if an increase in priming pulse can also increase startup. But what i was whinking, because it takes about 2 rotations to sync up, a lot of the priming pulses fuel is pushed thru the engine. So what are your experiences on the effect of higher priming pulses on startup time?

By the way, what are your times from voltage drop to 1st engine speed (sync time)?

Best regards
Try lowering your cranking rpm to 200 rpm above what the starter is actually spinning the motor when cranking,
670 cranking rpm seems high to me.

David
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Re: Faster cold starting? Freezing weather!

Post by 2swe »

mrx79 wrote: By the way, what are your times from voltage drop to 1st engine speed (sync time)?

Best regards
it depends on engine position before cranking, theoretically you need 2 crank revolutions before cam trigger passes sensor, then additional crank movement until missing tooth passes sensor...
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elaw
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Re: Faster cold starting? Freezing weather!

Post by elaw »

That's not quite right.

If you're using edge triggering for the cam sensor and the ECU "sees" the missing tooth on the crank before the cam edge, the engine could start pretty quickly, probably less than 1/4 revolution. Worst case would be when cranking was started just past the cam sensor so it would have to turn 2 revs to see it again.

If you're using "poll level" for the cam sensor, the engine will be able to fire as soon as the missing tooth on the crank is seen. That can be from nearly zero to one revolution max.
Eric Law
1990 Audi 80 quattro with AAN turbo engine: happily running on MS3+MS3X
2012 Audi A4 quattro, desperately in need of tweaking

Be alert! America needs more lerts.
2swe
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Re: Faster cold starting? Freezing weather!

Post by 2swe »

Well, I'm using edge triggering for the cam sensor and 4 channel full sequential injection/ignition.
So I expect the ECU needs to "see" cam trigger followed by crank missing tooth ( in the worst case it can take 2 crank rotations) , then it is synced.

but that's not all.
#1 tooth angle is roughly 90° before cyl # 1 and 4 TDC.
my cranking injection timing is 320°

So after the ECU is synced,
crank rotates 90°, cyl 1 in TDC, but there is no fuel..
crank rotates 40°, injector on 4th cyl fires (320° bTDC),
crank rotates 314°, cyl 4 is 6° bTDC, spark fires, fuel burns, engine starts...

Am I right ? have I forgotten something ?
1978 vw golf gti 16v itb cop full sequential MS2
1992 vw corrado 16v moonlight blue MS2
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