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Old 06-02-2010, 11:13 PM   #1
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Default Idle issues - 460CC RX7 injectors, AEM EMS

So I've lived with a crappy idle for quite some time now, and I'm hoping you folks can help me figure it out. Here's the important stuff:

97 motor
M-tuned dual feed rail
RX7 460CC injectors
AEM EMS ECU
Unknown Walbro fuel pump

My problem is that I can't get the car to idle any leaner then 12.5 to 1 fuel ratio. If I try to lean it out farther then that, the car starts sputtering and stumbling all over the place. When the car is in motion, running 14.5 to 1 is not a problem, it's only at idle that I have this issue. When the fuel ratio is 12.5 to 1 the car idles perfectly, but I'd be a lot happier with a leaner idle.

Now is it possible that a huge walbro fuel pump could cause me to have problems making the injectors idle any leaner? Several years ago (2003 I believe), my fuel pump failed and my mechanic went and put some expensive Walbro pump in. Ever since then my gas mileage has been the *****, but the car has always run fine. Could it be the pump is overloading the stock regulator and thereby limiting the injectors to be leaned out enough to idle at a proper value, or are the injectors just piles of crap that need to be replaced? I'm tempted to order a stock fuel pump, but also worried that my car is suddenly going to be crazy lean after.

Thanks for the help folks
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Old 06-02-2010, 11:16 PM   #2
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Im running on stock pump, Id imagine you could get a stock pump if you wanted and just adjust the fuel accordingly, maybe remove the vacuum line on the FPR and see if it changes with what should be a higher fuel psi rate? Hint of maybe a bad regulator? Sorry I couldnt be of much help on this.
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Old 06-02-2010, 11:23 PM   #3
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try adding some timing while pulling fuel.


you have sync'd timing with the ems right?
when i used your map and modded it for me... this is what i had to do...

i dont have my current ECU tune on my computer to compare to yours that you sent me, but i will get it this weekend.
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Old 06-02-2010, 11:26 PM   #4
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Quote:
Originally Posted by shlammed View Post
try adding some timing while pulling fuel.


you have sync'd timing with the ems right?
when i used your map and modded it for me... this is what i had to do...

i dont have my current ECU tune on my computer to compare to yours that you sent me, but i will get it this weekend.
I hate to say it but no I haven't synched my timing. I'll do it tonight. I totally forgot to do that with this new motor...

Last edited by dustinb; 06-02-2010 at 11:45 PM.
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Old 06-03-2010, 10:23 AM   #5
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I've got the same problem with my RX7 550's
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Old 06-03-2010, 08:06 PM   #6
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Timing didn't fix it. I'll probably just save up for a new set of injectors.
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Old 06-03-2010, 08:23 PM   #7
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Quote:
Originally Posted by dustinb View Post
Timing didn't fix it. I'll probably just save up for a new set of injectors.
That won't help your issue either. I have 550cc injectors with a Walbro 255 and my idle is pretty good. It sure took me a long time to get there!

Post your cal. Let me see your idle settings and I'll suggest some changes.

BTW, my car idles at 14.7 to 15 without issues. My biggest problem used to be the a/c and I finally licked that too.
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Old 06-03-2010, 09:48 PM   #8
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Quote:
Originally Posted by Rafa View Post
That won't help your issue either. I have 550cc injectors with a Walbro 255 and my idle is pretty good. It sure took me a long time to get there!

Post your cal. Let me see your idle settings and I'll suggest some changes.

BTW, my car idles at 14.7 to 15 without issues. My biggest problem used to be the a/c and I finally licked that too.
Thanks Rafa, I don't have AC so don't worry about that
http://www.dbmiata.com/miataturbo/2010-06-03.V1.19.cal

Should also mention I have no idle motor hooked up.
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Old 06-03-2010, 10:43 PM   #9
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Why do I get a message saying: "invalid file" when I try to attach the cal file?
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Old 06-03-2010, 10:44 PM   #10
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the board probably won't let you attach it as it is. Maybe compress it as a zip file and then it will work.
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Old 06-03-2010, 10:51 PM   #11
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Let's see if it works now.
Attached Files
File Type: rar 2010-06-03 idle test.V1.19.rar (1.7 KB, 36 views)
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Old 06-03-2010, 10:52 PM   #12
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Dustin, I only messed with some of the idle options and the "Idle vs Target Base" table.
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Old 06-03-2010, 11:05 PM   #13
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Dustin, this is the final one (some settings were not corrected in the other one):
Attached Files
File Type: rar 2010-06-03 idle test.V1.19.rar (1.7 KB, 31 views)
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