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Old 11-04-2009, 04:00 PM   #1
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Default Car won't restart after running more than a few minutes.

Over the past couple of weeks I've noticed an issue building. If I drive the car for any period of time, then I turn it off the car has to sit for a while before I will restart. The three most recent changes to the car have been more boost. Deleted the charcoal canister, and washed the engine bay.

When I washed the engine bay, because of the COP conversion I ended up with water in the spark plug wells, and I didn't realize this until I was left sitting at a Walgreens for a hour or so. When I got home I pulled the plugs, used a heatgun, and finally turned engine over to make sure any water inside came out. "Although I know water should not have made it past the plugs. I reagapped the plugs to .035, and the car seemed to be ok. This was a couple of weeks ago.

I did the charcoal canister delete almost a month ago, but this issue sort of reminds me of something like vapor lock, so I thought maybe it could be the culprit.

I also upped the boost recently, and I wonder if maybe the additional fuel is getting unburned, and fouling he plugs.

The first thing I want to do is go get a new plug set, but that requires me to hang out at the auto store for an hour. This wouldn't be an issue, but I can only do it at lunch and that just doesn't work well until the weekend.

Does anyone have an idea if any of these might cause the issue, or something else completely different could be the problem.

BTW I seemed to have spiked to 17psi today on the way to work, and it scared the **** out of me once I saw the trail on tuner studio. I haven't seen the log yet, but I can't imagine my 460's weren't doing well at that level.
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Old 11-04-2009, 04:07 PM   #2
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blame your heatsoaked AIT and your non-tuned AIT corrections table.
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Old 11-04-2009, 05:07 PM   #3
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If we are talking about the sensor I added to the intake piping, last night it was actually really cool, the intake temp never got over 80deg. In fact when I went to lunch today, it happen as well, intake temp below 90 this time. I let the car sit while I had lunch, and 40 minutes later it started fine.
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Old 11-04-2009, 05:31 PM   #4
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but what do the temperatures read just before you try to restart it and it fails?
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Old 11-04-2009, 06:23 PM   #5
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When it runs, do you have a rough idle as well?

You might have an exhaust leak...

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Old 11-04-2009, 07:08 PM   #6
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The idle is a bit crazy at times but I'm not sure of the temp when this happens, but I'll check it tonight.
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Old 11-05-2009, 02:33 AM   #7
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Under Coolant corrected Air Density I see -
Air Density Correction: Corrected
Correction based on: IAT Corrected
Start to reduce correction at:(RPM) 2000
End Correction at:(RPM) 3000

But the help file says this should be set to Normal Correction. Which one is correct?
When I turned the car off the coolant temp was 189, the intake temp was listed as 86. When I tried to restart the car the Intake temp had risen to 91. This is pretty frustrating, since this is a completely new phenomenon.

Last edited by apariah; 11-05-2009 at 03:10 AM.
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Old 11-05-2009, 03:22 AM   #8
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Default Log/Msq

Just incase someone ask attached are a log and MSQ taken just before I shut the car off.
Attached Files
File Type: msq 2009-11-05_01.01.59.msq (31.7 KB, 106 views)
File Type: zip 2009-11-05_00.53.40IAT_Idle.zip (7.6 KB, 42 views)
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Old 11-05-2009, 09:43 AM   #9
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Since you have a turbo, you might benefit from redoing that table. That table it great for a stock miata that can see well over 150*F AITs at idle, but it's not great for a turboed setup where you really only see those temps if the sensor heatsoaks.

Something like this may be beneficial to you:


But you'll have to rework the idle cells on your VE table. This way you're only adding fuel at idle when the AITs get artificially higher. Give it a shot and report back.
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Old 11-05-2009, 02:11 PM   #10
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So I should reduce the offset at 120, or is the thought I need to rescale the entire table?
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Old 11-05-2009, 02:27 PM   #11
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This should only effect your idle cells. In your log the Gammae is completely pegged. the Gair is 90% of the enrichment, so it's trying to dump in 57% more fuel than your VE table just to sustain your AFR at idle based solely off your AIT corrections.

If you zero off all the enrichment and only use them when you have real heatsoak you should be able to not only have a smooth idle, but solve the hot start issue.

Tuning your fuel map in the first place would also help, that thing is a mess and i cringed when i looked at it. As well as turning baro corrections off, since you have none.

Try this attach fuel table with the AIT corrections table I posted....this should give you a much better starting point.
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File Type: vex veBins1_200911051325.vex (1.6 KB, 134 views)
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Old 11-05-2009, 06:08 PM   #12
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I reflashed the firmware, and made the changes, the results were the same, but I just realized I did not turn off baro correction. I'll give that a try when I get home tonight. With the new tables, and turning off barometric correction do you think that might fix this issue. The manifold temp was 91 deg, and rising when I tried to start the car this time.
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Old 11-05-2009, 06:54 PM   #13
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the baro is probably the main issue, but that fuel map i provided is a great start compared to your current fuel map.
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Old 11-05-2009, 07:26 PM   #14
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Cool, I'll make the change after I get back home, and update. Thanks for the help.
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Old 11-06-2009, 11:20 AM   #15
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This has to be one of the stranger issues I've had with my miata. The hot start issue is still going on, but it takes a lot less time for it to restart. I also noticed that turning off Baro Correction seems to make idle at startup a little iffy, but over all your map is super smooth.

Could anything else cause the hot start problem.
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Old 11-06-2009, 03:43 PM   #16
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Default Hot and Cold Start Logs

The attached files are the hot and cold start logs, I don't really see anything that stick out like a sore thumb, but I also love British Comedy.
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File Type: zip 2009-11-06_11.09.58_Cold_Start_log.zip (30.6 KB, 40 views)
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Old 11-06-2009, 04:10 PM   #17
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does your wb restart during cranking? its pegging rich when you're trying, plus your battery looks to be holding a strong 10v....
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Old 11-06-2009, 04:22 PM   #18
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That doesn't actually look like heat soak you're having, as much as needing to adjust the hot cranking pulse width. It doesn't seem to get above cranking RPM, and below cranking RPM the IAT is ignored.
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Old 11-06-2009, 04:59 PM   #19
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The wide band doesn't restart until I switch the key to off. The battery voltage is right around 10.3v or so when I flash the firmware, and its always been that way. I don't know if thats positive or negative .

As far as adjusting the hot cranking pulse width. Are you thinking it might be related to the new injectors.

This is what I have under Cranking and Priming, is that what you were referring too?

-40 - 5.5
-20 - 5.2
0 - 5.0
20 - 5.0
40 - 4.0
60 - 4.4
80 - 4.2
100 - 3.6
130 - 3.4
160 - 2.0

Under More Cranking Stuff, Extra fuel for cranking is off, but at this point I don't think I need more fuel, if anything maybe less.
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Old 11-09-2009, 04:13 PM   #20
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The final nail is in the coffin, thanks to Matt. I adjusted my PW @ 160 up to 2.5, and the cars staring great. I thought it was way to rich, and it was the exact opposite.
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