Startup/Idle Issue DIYPNP, Miata 90 N/A 1.6L - Miata Turbo Forum - Boost cars, acquire cats.

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Old 09-22-2012, 06:35 PM   #1
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Default Startup/Idle Issue DIYPNP, Miata 90 N/A 1.6L

Oh hai!

First post MT.net and this is stressful lol..

For the past few weeks I've been reading a lot on MT.net about MS and all the turbo stuff. I thought I would be able to fix my issue only by reading but It looks I'm missing something.

I got myself a custom turbo kit with a DIYPNP. As suggested by MT, I installed my DIYPNP without the turbo so I could learn and tune my MS properly.

Whats installed in the car (Miata 1990 1.6L N/A) :

- GM IAT
- AEM UEGO
- TPS unplugged (VTPS soon to be installed)

My main issues are with the startup/idle.

So here's the problem :

After 4-5 cranks, the engine starts. It goes up to 1600rpm, tries to idle at 1200rpm and half a second later, dies.

I have to help the car to start by pressing a little bit on the gaz pedal. Once it reaches 2000rpm it will idle between 1100 and 800rpm depending if its a cold start or not.

Once the car has started and reached normal temp it will idle around 1000-1100rpm and runs like a charm.

I don't have A/C or P/S and I use PWM Warmup has idle algorithm.

I think I may also have a problem with the IAC. I can't get the car to idle like I want by turnin the IAC. I think it has no impact since I'm using PWM idle, am I right?

I read and played around all idle/cranking settings with no result.

I attached a log file and my tune.



Cheers!
Attached Thumbnails
Startup/Idle Issue DIYPNP, Miata 90 N/A 1.6L-zqr5o.jpg  
Attached Files
File Type: msq 2012-09-22_16.42.32.msq (83.5 KB, 87 views)
File Type: msl 2012-09-22_17.07.19.msl (1.66 MB, 87 views)
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Old 09-22-2012, 08:07 PM   #2
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Sounds like u need to tune fuel better. Ill look at stuff tomorrow but first thought is a poor cranking table, after start table, warmup table, and ve fuel table.
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Old 09-23-2012, 11:51 AM   #3
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Quote:
Originally Posted by Braineack View Post
Sounds like u need to tune fuel better. Ill look at stuff tomorrow but first thought is a poor cranking table, after start table, warmup table, and ve fuel table.
Thanks a lot Braineack... let me know if you need any info.

I'll see what I can do based on your first thought.
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Old 09-23-2012, 01:19 PM   #4
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It looks like your idle is controlled by "PWM Warmup" right now. This is the "band-aid" idle strategy, it can work kinda, but it's not very good.

If you want to just make this work for now, go into "Idle PWM Duty Cycle" and raise the "Idle PW..." values to something like 35 for all values of coolant temp.
Right now at 110+ coolant temps you're requesting between 2-8 PWM duty cycle, which isn't enough to idle the engine with no load.

Once you get things more or less running, you'll want to venture into "PWM Closed-Loop" to control your idle settings. There's tons of info about getting that setup available.

If I'm wrong on any of this someone please correct me.
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Old 09-25-2012, 01:00 AM   #5
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Thanks for your help

Unfortunatly I'll be in L.A. for the whole week so I can't work on my car.

I'll give it a shot when I'll get back home
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