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Old 04-04-2019, 10:51 PM   #16
Jaxx_
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I can almost guarantee that your cold start issues are not from having 42lb injectors vs 30lb/hr. You just need to spend more time tuning your cold start settings. To be fair, it's one of the harder/longer things to tweak on any megasquirt install.
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Old 04-05-2019, 10:53 AM   #17
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that and maybe get more modern injectors when u upgrade because they'll max it soon i'm sure. Ford green bois right?
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Old 04-10-2019, 02:21 PM   #18
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that and maybe get more modern injectors when u upgrade because they'll max it soon i'm sure. Ford green bois right?
No, Bosch- but I'm sure you're right, I don't think anyone would consider them modern...

I also agree with the cold start tuning stuff, I need to keep working on the tune.
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Old 04-10-2019, 09:08 PM   #19
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Make sure your injector constants are correct and lean it out. Sounds like you're running super rich. If your injectors are still close to tapped out once you've got your AFR around 12.5 instead of 10, you may be having fuel pressure issues. If fuel pressure drops, your tune will have unnecessarily large duty cycle because less pressure means more open time for the same amount of fuel. If your wear parts (fuel filter, pump, regulator) aren't in good order, you could have insufficient fuel pressure under boost.

FWIW, duty cycle is the percentage of time the injector is open vs time to complete one cycle. Incorrect injector constants wouldn't really skew the duty cycle since it only cares about open time, they'd just make your tune look goofy.

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I can almost guarantee that your cold start issues are not from having 42lb injectors vs 30lb/hr. You just need to spend more time tuning your cold start settings. To be fair, it's one of the harder/longer things to tweak on any megasquirt install.
Yeah, he's having tuning issues. Tuning is tricky to teach yourself to do. Strictly speaking, even properly tuned he could have some limitations based on injector oversize. 42lb/hr isn't huge but it's big enough that he could run into minimum pulsewidth instability at idle, especially considering altitude. Most injectors don't like to go below 1.5ms, and the bigger the injector, the more likely you are to wind up with a rich idle because the injectors are up against their minimum pulsewidth and don't fuel consistently below it. It's a little better with sequential injection than the batch/alternating batch we run on M20s.
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Old 04-11-2019, 10:21 AM   #20
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Thanks again for all your help Varg. I've got this pretty well under control at this point. Haven't had much time to drive the car or work on the tune, but I now have a solid grasp on what needs to happen- the higher boost squares are simply way too rich, I just need to spend some time getting them dialed in.

The cold start tune is also improving the more I work on it, it's tolerable right now but not great. I do think the 42# injectors and living at 7500 feet aren't a great combination. I regularly have to cold start it around 11k feet elevation and it's particularly cranky. But what do I expect.

Thanks for all your input everyone!
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Old 04-11-2019, 11:07 AM   #21
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He is running rich, VE's are too high. I was working with the tune, just haven't had much time lately to help more - we have a 14hr enduro in the e30 this weekend and blew the motor at the last event, so kinda been scrambling - also had one of our regular sprint racing clients blow 2 s52's int he last month (seems like there's something going around ). Got it squared away for lower boost, tracking down an issue, since then the boost was increased and hasn't been compensated up there yet.

Last log I looked over was only at 65% duty at ~8psi.

Fraser, you can use the auto tune feature for cold starts. There's another tab in the function "warm up enrichment 1". Start the car on a cold day (of course with the engine cold), and turn on the auto tune - it does a decent job of ironing out the cold starts.
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Old 04-13-2019, 07:08 AM   #22
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[QUOTE=

Fraser, you can use the auto tune feature for cold starts. There's another tab in the function "warm up enrichment 1". Start the car on a cold day (of course with the engine cold), and turn on the auto tune - it does a decent job of ironing out the cold starts.[/QUOTE]

probably another new guy question here but... do you have to have an idle control valve to make use of this function?
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Old 04-14-2019, 09:34 PM   #23
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You don't have to, but it certainly makes controlling idle speed (hot or cold) a lot easier if you have one.

Honestly, not using an ICV is just a hack anyway. If you tried to name one single fuel injected car that didn't implement a closed lop idle speed, I don't think you'd find even one going all the way to the 1959 Corvette..
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Old 04-14-2019, 11:22 PM   #24
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How about the L-jetronic m20 from a 323i E30, made until 1985. Fuel injected with a coolant operated wax auxiliary air valve. Though i guess it closed loop of sorts, mechanical closed loop. I have two and both are jammed shut.

Once i put a proper electronic idle control valve and dialed in the settings in mega squirt it made a world of different to how the engine runs. Even when its hot it helps it idle very well and "catch" the engine as it comes down. The PID settings are key to getting it to work well.
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Old 04-15-2019, 07:15 AM   #25
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yeah, it's still closed loop technically. Like those heated coils used for automatic chokes on carbureted cars from the 1960's. It's just not very reliable or easy to adjust. I'd rather have a manual choke.
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Old 04-15-2019, 09:06 AM   #26
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do u guys use the stock valve?
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Old 04-15-2019, 10:09 AM   #27
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I do, yes.
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Old 04-15-2019, 10:17 AM   #28
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The stock IAC works great for MS. I know back in my GM days and MS had just come out, it didn't support the GM stepper IAC, so we would use either Ford or BMW PWM IAC's.
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Old 04-15-2019, 03:08 PM   #29
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Since mine was L- Jet M20b23 i didn't have an idle control valve. I used one from an AU Ford Falcon. Not really sure if you have the engine in the states. Not the neatest looking, but the valve cost me zero dollars from the wreckers and works perfect with the MS2 on closed loop. This way i didn't need to get a different rubber intake boot. Also im not sure the m20b25 intake boot would fit.
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Old 04-15-2019, 08:06 PM   #30
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dumb question but have you guys boost tested the stock valve? leaks?
i have acouple but they are kinda bulky.
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