1990 Miata DIYPNP hard to start cold. - Miata Turbo Forum - Boost cars, acquire cats.

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Old 11-23-2011, 07:02 PM   #1
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Default 1990 Miata DIYPNP hard to start cold.

Hey guys first I'll tell you what im working with. Its a turbo'd 1990 1.6l with a MS DIYPNP, Map daddy 4 bar map sensor, BMW tps, runs great. The problem is when the engine is cold i have to crank for around 10 seconds and pedal the gas for it to start. When its warm it fires right up. I feel like it may be related to my IAC... thats also just my guess... i dont have a clue. If anyone could help it would be great! Let me know if i should post anything to help out. Thanks,
Mike
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Old 11-23-2011, 08:06 PM   #2
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Does it seem to run just fine with good AFRs once you finally get it started, or does it run rough until it warms up?
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Old 11-24-2011, 12:09 AM   #3
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Trying increasing the cranking PW% at the temps you are having trouble with.
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Old 11-24-2011, 01:48 PM   #4
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you have to hold the throttle at about 2,500rpm for a few seconds then its fine. If you dont it will stall. Runs great with great AFR's. Ill try increasing the PW either tonight or tomorrow and and see if it changes anything.
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Old 11-24-2011, 02:20 PM   #5
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sounds like the IAC max range may be set too low if you are using closed loop. check your idle valve control. ****, send me your email and i will send you a tune form my diypnp, you can use it to compare.
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Old 11-24-2011, 07:08 PM   #6
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That would be awesome! [email protected]. As for the afr's im actually not 100 percent positive. My wideband sensor is at the end of my downpipe and I don't have an exhaust on the car yet so its not accurate in its current location. When tuning on the dyno I welded a bung further up stream and used an external wideband. My problem seems very similar to the thread that just got posted after mine "cold starts will end me" hopefully one of us figures this out lol.
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Old 11-24-2011, 07:26 PM   #7
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Hmm our problems seem to be a little different actually. You have trouble getting the car to start, mine fires right up but immediately falls on its face, and if I touch the gas it'll stall.

You also use your IAC, I don't.
+1 to taking a second look at your cranking PW's.
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Old 11-24-2011, 08:03 PM   #8
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Ahh I see, miss read your thread , mine has a nasty hesitation also that I didn't mention that's like you described, when you touch the gas after starting it will hesitate and stall if you hold the gas. Problem gets better when the engine is warm. Maybe I can learn something from your thread also!
-Mike
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Old 11-24-2011, 11:36 PM   #9
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also make sure your 4bar map sensor is calibrated in tunerstudio

Edit: check your email
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Old 11-25-2011, 07:01 PM   #10
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Yup just double checked the map sensor, everything looked correct. Got your email im going to do some compairing tomorrow! Thanks a lot!
-Mike
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Old 11-28-2011, 10:04 PM   #11
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Have you checked the cranking rpm threshold? I found that mine had been reset to 200rpm after a firmware update which obviously made it hard to start.
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Old 11-29-2011, 08:48 AM   #12
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yeah cranking rpm needs to be closer to 350rpm.

if the throttle needs to be held, it's obvious you have fueling issues.
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