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Hard to start when cold

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Old 02-06-2016 | 11:52 PM
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Default Hard to start when cold

Hello everyone, I am having a heck of a timing getting my 2001 to start when the engine is cold, and I'm completely at a loss. If I manage to get the car to start and run, it runs perfect. Better than ever. AND once it is warmed up, it will start up immediately. So first off, let me tell you what I have done to get it to run well:
  • New igintion wires, sparkplugs, and coilpacks
  • New fuel pump, and ~10k old fuel filter
  • <10,000mi old rebuilt engine
  • Stock ECU
  • timing is perfect
  • New crank angle sensor and Intake air temp sensor

CEL reads P0102 Mass Air Flow, P0113 Intake Air Temperature circuit high input, Multiple Misfire.

Any advice or help would be much appreciated!!
Old 02-07-2016 | 02:15 AM
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Hook a scanner up and look at the realtime data.

With the key on, engine off, your MAF sensor should show 0.00 grams/sec, and temp should be whatever ambient is.

Then crank it and observe what happens.

Once it cranks, let it idle. IIRC, 3.00 grams/sec is normal on a miata at idle once warmed up. A search would tell you what the normal amount is, but I believe it's 3.00 from memory.
Old 02-07-2016 | 12:36 PM
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Originally Posted by patsmx5
Hook a scanner up and look at the realtime data.

With the key on, engine off, your MAF sensor should show 0.00 grams/sec, and temp should be whatever ambient is.

Then crank it and observe what happens.

Once it cranks, let it idle. IIRC, 3.00 grams/sec is normal on a miata at idle once warmed up. A search would tell you what the normal amount is, but I believe it's 3.00 from memory.
Thanks Pat, you're the man. I'll give it a look. I have a friend who also has an NB, so I'll just try his.

I'd also like to add that the car will turn over cold if you spray starting fluid into the intake.
Old 02-08-2016 | 10:42 PM
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Ok, it is not the MAF. I removed it, swapped it with a friend's, and cleaned mine to no avail. I'm almost certain the issue is something electrical, like a sensor or something. The car is such a pain to start, and it runs horribly until it warms up. Every time I get it to start, it misfires. Oddly enough it only throws the code for cylinder 4 misfire at start up. Once the codes are cleared when the car is up to temperature, it doesn't throw any codes or misfire. Anyone have any ideas?
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