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Old 07-22-2015, 12:58 PM   #1
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Default NB turbo - Difficult to start

1999 Miata, t2 turbo setup, MSPNP2. Ever since I installed the turbo setup, I've been having issues getting the car to start. Mostly on cold starts but also on restarts/hot starts. It will crank but I have to give it some throttle to get it to turn over. Once it starts, the idle will fluctuate a bit, I'll still have to give it some slight throttle & then about 5 seconds later it will idle perfect. I've got the car running fairly well now with solid AFR's. It's just the starting I'm having some trouble with. The only thing I've adjusted is the cranking RPM. I've posted some screenshots of several graphs as far as startup. These have not been adjusted. I'm still getting the hang of TS so bare with me.





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Old 07-22-2015, 01:31 PM   #2
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Images are broken, but priming pulse and cranking pulse as well as ASE are good places to start.
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Old 07-22-2015, 01:55 PM   #3
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Attached Thumbnails
NB turbo - Difficult to start-80-ms_cranking_page_001_339d24c4fdee8d4d0a1da98cc81792867c2ad4cf.jpg  
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Old 07-22-2015, 01:58 PM   #4
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^Thank you! That looks like some helpful info. I'll have a shot at it once I get off work
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Old 07-22-2015, 04:12 PM   #5
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Still no luck. I tried increasing several startup tables then decreasing. Same result.
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Old 07-22-2015, 04:29 PM   #6
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The engine won't 'turn over' without some throttle? Or will it actually crank/turn, but you don't get it to start without throttle?
If you need throttle for the engine to start, even though it's turning over, increase 'idle cranking duty'.
If you get something that feels like a backfire and the engine stalls while cranking, try and reduce your 'idle cranking duty'. It's likely too high.
Needing some throttle after startup would point to AFRs being off, or idle valve setting too low.
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Old 07-23-2015, 05:27 AM   #7
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what injectors are you using? priming pulsewidth table should be adjusted according to how big your injectors are. Most people with larger injectors have WAY too much fuel for their priming pulsewidth table. Hard starts are actually a result of too much fuel


The following hints are assuming that your VE fuel table is at least in the ballpark of where it should be, along with corrected priming pulsewidths

adjust cranking pulse if the car doesn't even sound like it's wanting to start

adjust ASE if the car starts but dies immediately or even after a few seconds

idle cranking duty for the idle valve should be adjusted after you get your idle valve percentages (open/closed) dialed in, which you'd do in test mode with the car idling. In my experience, usually 35-50 % is just fine for helping the engine get enough air during cranking
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Old 07-23-2015, 04:32 PM   #8
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Default NB turbo - Difficult to start

You've got to figure out whether it's too much/too little air or too much/too little fuel. It's probably not a spark issue based on what you've said.

Remember that after the ASE turns off you have water temperature correction. I've seen engines die as they roll off ASE because the water temp correction wasn't right (usually too lean for a cold engine).

Also, this is sequential fire right? use batch fire for cranking.

The IAC duty should be maxed for cranking as your initial setting and then adjusted if needed. You also should set your iac initial duty table to have an MAT axis and tune that. There was a recent thread talking about that. When it gets hot you want more initial duty usually.
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Old 07-23-2015, 05:49 PM   #9
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After adjusting some tables, the car starts up fine but it still has a lumpy/up&down idle right after it starts for about 5 seconds. Then idles fine. Here's some more screenshots of some ASE & cranking tables




Attached Thumbnails
NB turbo - Difficult to start-80-w0foplx_e1d22da9342ed7fb157e8645f7d8031f21db1b37.png   NB turbo - Difficult to start-80-cl5ymcb_2c13ac6d67e41b440a051709446d051568449640.png   NB turbo - Difficult to start-80-bnomqvs_4582a9e767761a307cdea2336b056a6939d9f48b.png  
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Old 07-25-2015, 01:35 PM   #10
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So what ended up fixing it? What tables did you end up adjusting? Mine does the same thing as well. Starts, but has a lumpy idle for a bit then settles. I don't know if it's an issue with my CL Idle tables or not. But it settles on it's own.

Keep in mind that you will not have perfection with stand alone. It's very unfortunate, but if you can get it working 90% then you should try to live with it.
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Old 07-25-2015, 02:37 PM   #11
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^Increasing the idle cranking duty & smoothing out the other tables helped a lot.
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