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Old 08-31-2012, 06:50 PM   #1
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Default FIC Frustration

Hey,
1991 Miata 460cc injectors.

I'm really starting to get frustrated with my FIC. I thought I had it figured out, but I guess not. I was over on the AEM forum asking questions, then realized that my car is not OBD II.

Long story short,
I was trying to lean out the idle to get it to near 14.7 and noticed it wouldn't go... kept going down. So, after asking questions, I connected the o2 sensor and played with the map. It seems like the AFR is all over the place. I'm under the assumption that the ECU and the FIC are fighting each other. I was running the FIC for a few months without the o2 connected, and everything was pretty OK, except for the rich idle. What's the deal? Does an OBD I car have the same issues as an OBD II as far as tuning goes?

Almost starting to think I should have saved and gotten the MegaSquirt EMS.

-Fred

Last edited by generalfred; 08-31-2012 at 09:45 PM.
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Old 08-31-2012, 07:53 PM   #2
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Old 09-02-2012, 05:43 PM   #3
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Those of you with OBD 1 cars (89-95).... What are you guys using with the FIC to tune it? Scanner? What type?
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Old 09-16-2012, 06:45 PM   #4
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I'm using an FIC6 on my stockish 1.6 and had no trouble tuning the base fuel curve, even for E85. I found the FIC-6 to be a little finicky but ultimately very capable for the simple job of dialing in the fuel and spark. I did all my calibrating on the road first. Took only an hour on the dyno to confirm the fuel was right on and make final small tweaks to the spark.

If you're using the stock AFM and TPS switch then use the TPS fuel map to adjust for the injector size change and WOT fuel requirements. Use the MAF modifier table to trim the AFM signal for all loads other than WOT. This needs to be done with the O2 sensor disconnected but keep in mind that the ECU will periodically swing its fuel trim looking for a signal from the sensor. Letting the engine idle a few seconds prior to the run will probably avoid that issue. Some of the time the MIL may be illuminated for an O2 sensor fault. Log and review the AFM, rpm, WOT and AFR signals (from a wideband meter).

From a low speed in third gear gradually add throttle until you get to WOT. Then review the data on an excel sheet and decide on the AFM adjustments needed. For WOT fuel just mat the throttle at 2000 rpm in second gear to the redline while logging. Review AFR and RPM and the adjustments should be easy in the fuel map. BTW my TPS load point to switch to WOT is 20%. Noise on the signal caused some grief when I tried to use 50%.

For idle just idle the engine and adjust the AFM signal via the MAF map while idling.

If you're not using the stock AFM and TPS switch then tell me what you're using and how you're wired.
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Old 09-16-2012, 06:47 PM   #5
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Quote:
Originally Posted by generalfred View Post
Those of you with OBD 1 cars (89-95).... What are you guys using with the FIC to tune it? Scanner? What type?
Not sure what you mean. I just logged the AFR along with the FIC values and made adjustments based on the data.
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Old 09-16-2012, 08:24 PM   #6
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The problem is at idle. The ECU is either trimming or adding fuel. I've got it pretty close with the o2 map... it's not perfect, but about as good as I can get it. It still "hunts" and tries to trim fuel, but if I dial down the o2 map just one point, it goes rich (12 AFR).
At this point, I've had success running off just the fuel map and using the o2 table just for idle control purposes. I haven't used the MAF or TPS tables at all. I was under the impression, to use the TPS function, I had to get a TPS from an auto and wire it in?

Maybe I should start my tune over.... Would be nice to see inside the ECU to figure out what's going on.
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Old 09-17-2012, 12:56 AM   #7
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The O2 sensor is not hot enough to work at idle so the ecu gives up on it pretty quickly making the O2 trim pretty useless for idle. I left the O2 sensor connected to the ecu but don't connect it to the FIC. If you're not boosted this is what I'd recommend. If you are boosted then you may need to use it to fake out the ecu but this is a feature I have no experience with.

I wired the WOT signal to the TPS lead. Watch the load and it will just toggle from high to low when you hit WOT. Just set up the left hand axis to work with this and it basically splits the fuel map in two. This is important because when the ecu sees a WOT signal it will ignore the AFM totally and uses a look up table so all WOT fuel adjustments will be on this map. When not at WOT the only value you want in the fuel map is that needed to account for the injector change.

Intercept the AFM signal into the MAF lead. After you've put the injector size factor into the fuel map use this MAF map for all idle and part throttle adjustments. I used this opportunity to unwind the clock spring in the AFM several more teeth. Now it barely shuts off the fuel pump when the car isn't running but it opens as wide as possible.

The oem system is pretty simple and crude. You can do all you need with only the MAF and TPS fuel maps.

I did the spark in TPS mode as well since I was only really interested in optimizing at WOT. Again the fact that the TPS is only a switch worked out perfect for this purpose. If you need more resolution (is your's a turbo?) you can probably use the MAP or MAF modes.
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Old 09-17-2012, 04:29 PM   #8
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Yes, it's turbo. I installed it while the car was NA, and only really had issues with idle. I spent some time at AEM forum looking for answers, but I think most of the advice came from OBDII users. When I first changed the injectors, I just used the software features to do it and I've actually not created a base map after that. Then, I just adjusted the fuel map to get it where I wanted it. When the idle became an issue, I used the o2. I also had the FIC ignor the o2 for 5 sec. I have connected everything except the TPS. The AFM is connected to the MAP leads, but the only time I used it was to try a MAF simulation to dump the AFM.
Maybe the ignor feature wasn't long enough? As a result of moving the narrow band o2 10" from the turbo must have made the difference.

Thanks for all the info... I like your methods. I think since I've got a decent tune, I'm gonna play around with it. Awesome!
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Old 09-17-2012, 07:54 PM   #9
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Okay, sounds good. I've not done a turbo so I haven't tackled those challenges. It sounds like you're close though, the solution should be within reach. Good luck and I'll try to keep tuned in.
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Old 09-17-2012, 08:40 PM   #10
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Sounds like you've done your homework on the FIC. I still plan on moving over to the Megasquirt, but for right now, the FIC does the job. I think it's perfect for OBDII cars. I just want the ability to get rid of the AFM (takes up a bunch of room under the hood and is restrictive). Also, there's a ton of Miata MS users to draw knowledge from. You're really the only person I've found that knows what their talking about in regards to using the FIC on an OBDI vehicle. I don't think there are many of us. Keep it up! I learned a few things through this conversation. Thanks.
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Old 09-16-2013, 11:08 PM   #11
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Default FIC tuning on 95 STS miata

Sorry to dig this one up but I recently installed an FIC on my STS 95 Miata and am having problems getting the tune right. Car will misfire in the 3-5K range. I have taken it to a tuner with a dyno but they are not familiar really with this piggyback or dealing with the restrictions we have in STS of no added sensors.

Is it possible to look at some maps so that I can compare where I am at? I have searched around and there isn't much info on STS miatas using the FIC

Any help would be greatly appreciated

Thanks
Adrian
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Old 09-17-2013, 08:42 AM   #12
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I suggest you use the logging feature in the FIC to capture some running in this condition. I believe it can be caused by vibration at the TPS causing the load read into the FIC to jump around. I read something similar on the AEM forum and the solution, IIRC, was a resistor at the input to the FIC, like 100 or 1000 ohms I think.

Anyway, if the issue is the FIC the logging should hopefully give you the clues you need to track it down. After that you might call the AEM support line, I've had some success with them.
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Old 09-17-2013, 08:35 PM   #13
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Thanks for the tip. That could be the issue. I have tried to get on the AEM forum but they don't respond well to new registrants. Don't know what's going on there and still waiting to hear back from aem tech 3 days ago. So I do appreciate your input as I said there aren't many threads for the FIC in STS form.

When you speak of vibration is that a defective TPS situation or is it that the signal needs to be massaged with the resistor? I did see that elsewhere but thought they mentioned it for OBD II 96&97.

I will give it a go.

Thanks very much!
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Old 09-17-2013, 08:59 PM   #14
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The TPS may not be defective though a new one may work better. The resistor filters the signal to the FIC but also slows down the signal's response. You have to strike a balance.

Check the logs for erratic load, spark or injector duty values. What sensor are you using for load? An unbalanced I4 engine has a lot of vibration so any sensor bolted directly to it gets shaken hard.
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Old 09-20-2013, 07:10 PM   #15
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Jay - just got car back from the tuner and running better. The car is running without the o2 sensor connected. Would you mind if I send my cal file to you to look at and see if they are in the ballpark with what you have experienced with your STS?
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Old 09-20-2013, 07:13 PM   #16
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Also car pulled 119 whp and 111 tq on a superflow. Should be about right?
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Old 09-21-2013, 01:16 PM   #17
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119/111 sounds good. If it's running well now then the tune must be good. I'm glad to have a look but haven't tuned a 1.8 so wouldn't have much perspective. Hooking the O2 sensor up shouldn't make it run any worse, just cleaner and maybe more efficiently. If it does run poorly with it hooked up the sensor or harness or something has failed.
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