AEM FI/C idle issues - Miata Turbo Forum - Boost cars, acquire cats.

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Old 04-22-2010, 11:59 PM   #1
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Default AEM FI/C idle issues

Hello All

Well, I had no issues for awhile, thought I post my fuel map for those who know better than me, see if there's any problems with this map...

FM GT2560 Turbo, 9 psi
460 RX7 injectors

Name:  kyriiansfuelmap.jpg
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The car was idling with A/F of 12-13... Cruise was fine, cruise is around 14. I haven't done much WOT runs yet to really see, but I'd say around 11-12, so i might add a tiny bit more fuel at WOT to ensure it is safe.

Anyways, the idle is really bad and it just turned even worse. Here is two issues that I am aware of so far

1) Whenever any heavy load is turned on, like the fan or even fog lights. The A/F drops and idle drops badly, especially the fan, when the fan turns on at idle, it'd even at times stall the engine. This has been relatively consistent all through since the turbo and AEM was tuned

2) This is very recent, and its very sudden. I have a feeling these two issues are not tuning related but car related, so if you know the reason or possible reason, do let me know

Recently, it was running so well, then just several days ago, driving home, the car changed again, from idling at 12-13, to idling back to 18+, on every stop, the reaction of the motor seems sluggish too, the a/f takes an eternity to drop back down to 14 from off throttle, whereas before would react in about 1-2 seconds, now it drops slowly from 18 to 16, then back to 14 at cruise

I had not made any changes to the map since friday, the car was running perfectly for 4 days before this change. Since then,
-The car idles badly 90% of the time, cold start up, hot start up, doesn't make any changes
-The 10% of the time just happened as I went out to examine... it idles back to normal, 12-14, I made some changes to the map and it was idling perfectly for about 10 minutes before it returned to idling badly
-This maybe un-related, coming to a stop, when I clutch in, the motor holds at 1500 rpm for about 5-6 seconds, not drop to idle right away, after 5-6 seconds, the idle returns to 750-800 and idles badly again.

Sorry for the long post. I am an absolute stickler for details... If anyone can help, tune or not, please do!

Yes, I am a
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Old 05-06-2010, 12:21 PM   #2
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kyriian, I have no clue how the AEM fic works but in the case of the regular AEM ems you can change some settings. I think your variations in afr readings may have to do with AIT sensor heatsoak. Where is yours located?

In the case of the AEM, there's a setting to add additional voltage when the voltage readings are too low. Does the fic have anything like that?

Let's hope one of the AEM gurus chimes in with some suggestion.

Sorry but I'm mechanically challenged
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Old 05-06-2010, 12:32 PM   #3
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TPS callibration? or IAC valve? maybe
do you have a MAF
What year?
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Old 05-06-2010, 03:29 PM   #4
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Use a good scan tool to see what is going on in the engine sensor department, esp. MAF & O2 outputs. Do you have a resistor on the FICs MAF IN to MAF sensor gnd line? Or just start with the simple stuff, all solder, connectors, wire chafes & pinches... Even more simple, check all your grounds in the engine bay... OK check this stuff in the reverse order that I typed it...

Last edited by secretsquirrel; 05-06-2010 at 04:08 PM. Reason: additional thoughts...
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Old 05-06-2010, 09:16 PM   #5
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I used the f/ic for a short time. It's pretty basic, just lets you add & remove fuel and remove timing. You can also use it to delete your MAF - have you done this? If so that could be one of your problems. If your car is idling really badly when anything electric is coming on, then I might check out your alternator & battery....
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Old 05-07-2010, 10:32 AM   #6
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well the good news is, we fixed the motor dying when an accessory comes on issue, it was a faulty IAC valve, we put one my tech had from his spare motor and all is well...

The slow return to idle traced to a throttle cable and a dirty throttle body. This one is also resolved. Though I lost my damn allan key in the process!

We tweaked the map a bit and now its running well.. I don't want to open a can of worms now, but the last remaining issue is, after changing out the IAC valve, we are now ADDING fuel into the map at idle... with 460s i'd imagine i should be pulling fuel but we are adding fuel... wtf?

I am gonna get my injectors cleaned on the car, let's see if that helps... I am guessing I should've had the 460s inspected before putting them on, but its too late now, might pull them anyways for e-testing and going to get them flow tested when that happens

MAF is not ran on the FI/C, too many variables and I know someone who ran FIC and could never get it running right with the FI/C running the MAF
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Old 05-15-2010, 10:56 PM   #7
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I don't understand how you map can look like it does with 460's. My map starts off at -44.5 when the system is under 13.5psia. You don't list what year you car is but I think 94-01 have 256cc injectors so you should have allot of negative numbers.

Then again I just installed high imp RX-7 460's fresh back from Witchhunter and it's skipping idle and I don't know why yet. Could be the duty cycle it too low for the injectors.

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Old 06-30-2010, 09:44 AM   #8
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Can you post your settings, with 460cc injectors you should be pulling at least -30% fuel at idle... I dont see how you only have 3%.

If your MAF is connected may be you dont have the +13% in all cells in the table.
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Old 06-30-2010, 12:04 PM   #9
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Quote:
Originally Posted by kingofl337 View Post
I don't understand how you map can look like it does with 460's. My map starts off at -44.5 when the system is under 13.5psia. You don't list what year you car is but I think 94-01 have 256cc injectors so you should have allot of negative numbers.

Then again I just installed high imp RX-7 460's fresh back from Witchhunter and it's skipping idle and I don't know why yet. Could be the duty cycle it too low for the injectors.

For the record, its an 03, at peak its at 9.5 psi

MAF is not ran by the FIC, its handled by the stock ECU, don't want more problems

seeing your map makes me think mine defenitely isn't correct... car runs fine with a 3% at idle (in fact, we are ADDING 3% at idle now..) yet no one seems to be able to give me an answer, those who are smart just tells me to throw in a standalone and waste $$$

I had to shut the idle air valve completely to get it to idle properly

Car constantly throws engine light with engine running rich (i can see why...)

I am seeing other behaviours...
AFR changes as I drive, if i drive lots of highway, then idle stays at about 12-13, but a few minutes of city driving it creeps closer to 14

if im stuck in traffic, AFR starts to run leaner and leaner, a one hour commute home at stop and go traffic, AFR on start up is about 11, by the time I got home, it was around 15

I tried a can of strong injector cleaner (the stuff that's actually hooked into the fuel line, not the stuff off the shelf) on the motor last weekend, didn't really do much...

The cruise and the WOT AFR is fine, had it on the track several times now and its not been any issues with that... its ALWAYS the bloody idle

Plan is to have the car back to the tuner by the winter... its tracking season and it's already far too short here in Toronto
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Old 07-01-2010, 08:22 PM   #10
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I have a 99 and have the same problem with the 460's at cruise and slightly at idle. It's not real bad but noticable . I have my maf hooked up to the fic and everything and absolutletly no problems under load and WOT running 11 psi on a 30R. Haven't messed with the tune in a while but I'm pretty sure I'm around -33 at idle and the fuel pressure I think but don't quote me at around 50 psi, it's been a while since I messed with that too.
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Old 07-06-2010, 12:41 PM   #11
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Probably a wiring or firmware issue...

If you by pass the FIC will your car idle? Rich? It should with 460cc injectors.

Second make sure that you are using the 110.hex slave firmware. Check all your wiring connections and make sure that you dont have the resistor on the MAF still installed on the boomslang harness.

The AEM FIC doesnt have alot you can mess up so I would suspect bad wiring or bad injectors.
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