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Old 02-08-2008, 07:40 PM   #1
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Default New EMU install, wont start when hot...WTF

You guys have been great so far and have helped me figure out a lot of stuff. I'm almost there but still have a few issues. Main issue. When the car gets hot it wont start. Once it cools off it will start again. The car is a 2004 MSM. Mods consist of 440 CC injectors, FM CAI, FM DP, Magnaflow exhaust, FM O2 modifier, EMU, pressure sensor and AEM wideband O2 sensor. I included a file of my setup. It also runs ritch as hell, need to tame those 460's..any help would be greatly appretiated
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File Type: zip onmywa.zip (1.2 KB, 16 views)

Last edited by msydnor; 02-08-2008 at 08:19 PM.
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Old 02-08-2008, 08:26 PM   #2
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A quick glance at your i/j adjustment map shows you ADDING lots of fuel. I changed it to display in relative pressure because thats how i think. You are adding tons of fuel from 2000 to 3500 rpm from -11.6 to -5.8 My map has negative numbers there. You also have your A/F target map trying to adjust a/f ratio under vacuum. Those cells should all have - in them. If you have an 02 clamp ( i think you do) you should be okay having the EMU adjust the boosted cells. I am not sure, but I think the 02 clamp will keep your ECU from adjusting them, but without it your MSM is probably trying to tune those as well.

Try setting the unboosed cells to -20 or so and see if it starts when warm. You can then adjust the values at idle to around 14.7. Subtracting fuel makes the a/f ration go up.

I suggest you change to display in relative pressure.
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Old 02-08-2008, 08:41 PM   #3
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I'm not sure if this helps but my O2 clamp is set to click over and 03 vac
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Old 02-24-2008, 08:17 PM   #4
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Quote:
Originally Posted by msydnor View Post
You guys have been great so far and have helped me figure out a lot of stuff. I'm almost there but still have a few issues. Main issue. When the car gets hot it wont start. Once it cools off it will start again.
Common issue with the EMU on NB's. Has something to do with latency, min open time or the fact big pintle type injectors designed for RX7's don't work perfectly in Miatas.

Anyay, with NA's you enter whatever stock injector at fuel pressure you are running 205 or 230cc and the bigger inejctor in teh next window, works fine. The NB's you would think would require the 230/270cc injector adjusted for the 55psi they run at. Then you would think that the correct value would be say, 460cc corrected for actual fuel pressure. Doing this in an NB will result in car that has weird auto tune logs and won't start when hot.

With smaller injectors you can just tweak IAC duty, doesn't work with anything much bigger that 350cc though.

Fix is to scale the 460's at 230cc and the stock injectors at half, 135cc in your case. You then adjust off boost fuel maps to run -50%. I never tried this but about two years ago there was a lot of emails being shot around, greece UK and here between NB owners all having the exact same problem, me included. I think Kags1969 discovered the fix. That tweak seemed to fix every car. I had an AEM built and haven't run the EMU since.
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Old 02-24-2008, 08:27 PM   #5
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Originally Posted by emilio700 View Post
Common issue with the EMU on NB's. Has something to do with latency, min open time or the fact big pintle type injectors designed for RX7's don't work perfectly in Miatas.

Anyay, with NA's you enter whatever stock injector at fuel pressure you are running 205 or 230cc and the bigger inejctor in teh next window, works fine. The NB's you would think would require the 230/270cc injector adjusted for the 55psi they run at. Then you would think that the correct value would be say, 460cc corrected for actual fuel pressure. Doing this in an NB will result in car that has weird auto tune logs and won't start when hot.

With smaller injectors you can just tweak IAC duty, doesn't work with anything much bigger that 350cc though.

Fix is to scale the 460's at 230cc and the stock injectors at half, 135cc in your case. You then adjust off boost fuel maps to run -50%. I never tried this but about two years ago there was a lot of emails being shot around, greece UK and here between NB owners all having the exact same problem, me included. I think Kags1969 discovered the fix. That tweak seemed to fix every car. I had an AEM built and haven't run the EMU since.
Not sure what you just said but let me see if I have this right. basically put in half of what my stock injector is? Example, the MSM comes with 265, so I'll input approx 133. And in the box for after input hald of 460 (230)? How do I adjust off bost maps to -50%
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Old 02-24-2008, 09:11 PM   #6
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Originally Posted by msydnor View Post
Not sure what you just said but let me see if I have this right. basically put in half of what my stock injector is? Example, the MSM comes with 265, so I'll input approx 133. And in the box for after input hald of 460 (230)? How do I adjust off bost maps to -50%
I don't have the software loaded anymore but I think you just, um enter -50 if you are using DC and not opening time (MS).

That's about all I remember so its just a suggested starting point. The rest you'll have to figure out on your own. I think there have been many soft and firmware revisions since I used it last so don't consider me an expert!
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Old 02-25-2008, 12:12 AM   #7
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try using the search button

https://www.miataturbo.net/forum/sho...ight=start+hot

this may help.
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