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Still Lean & Poor Idle, About to just order ECMlink.....


Well-known member
I have a few threads already about my issues and I'm sorry, but I'm bringing all my info on my car and my situation here in hopes of someone seeing my problem. I also posted this on DSMtuners and I'm sorry if that's a no-no, but I really can't take this anymore.

I have been running lean for quite a while and just about 2 months ago I did a few upgrades and all of a sudden I couldn't idle properly. I found my capacitors leaked and shorted my ISC drivers, but I now have a different ECU from my friends car and it solved my ISC issue, but I'm still not able to get my idle perfect.

Before recent upgrades, I had only a 3" exhaust and a crushed 1g BOV on my car for mods and my fuel trims were all maxed at 139% and my exhaust would pop on deceleration.

All these upgrades were at the same time, and after doing them my idle went to shit:
~Fidanza Aluminum Flywheel
~ACT 2600 Clutch setup
~2g ported Exhaust Manifold
~Megan Racing Tubular O2 Housing
~1g Intake Pipe
~Relocated my battery to the intake canister position
~1g Alternator
~Evo 3 16G
~EGT gauge
~Miata Battery

I found one of my caps leaked and shorted my ISC driver and my MAF was throwing a CEL , so I replaced the ECU and it helped dramatically, but replacing the MAF did nothing really.

Now It doesn't matter where I adjust my idle, it will never sit steady at any rpm. It will move up a little, then down a little, like between 812-906 rpms. Then sometimes it will even stall. Most of the time my O2 doesn't cycle at idle either.

Other things I have checked:
~No exhaust leaks
~All boost leaks fixed
~New Denso O2 sensor
~Idle switch it working properly
~TPS is set at 10% at idle
~No extra slack or tension on throttle cable
~Ground strap is attached to downpipe
~Removed all vacuum lines & blocked off EGR
~Bypassed FIAV
~Resistances are good on ISC
~Set my base timing correctly

As to the fuel, I recently swapped in a Fuel Lab AFPR and set the pressure with the hose plugged to 38 psi. I also put in a walbro 255 hp pump and replaced my fuel filter.

I don't know what else could be causing my idle to not behave properly. The only thing I can think of for my fuel trims is that my injectors are clogged. My friend is telling my everyday that all I need is ECMlink(he managed to fixed his idle this way) and I will be problem free. I do intend on getting it, but not until January when I get some more funds.
Any help is appreciated. Thanks


Well-known member
Only one thing on my mind is that when the ECU shorted, did you check any wires at the ECU plugs to see if it melted any wires? Mine melted some wires and then some! so I had to replace sections of wires one at a time! some wires might not melt through, but you could tell that it is burnt and has yellowish tint to it. Might look like nothing, but when opened up with a razor you could see the discoloration of the copper wire and I bet the resistance also changed due to burnt wires.


Well-known member
I will definitely check that out. Thank you.


Well-known member
I know you've troubleshot a good bit, and have had a good bit of upgrades since, but have you checked your sparkplugs, as well as the plug wires that could cause some issues? I reread your posts twice making sure I didn't miss it just in case. Good luck!

You should try to get your gvr4 alt rebuilt. The 1g alt is 75amps while the gvr4 is 90amps.


Well-known member
Yes I am currently on a stock setup besides a 3" exhaust and the items I listed earlier.. I have a boost controller and am only running 11-12psi, but it does creep in 3rd gear. For that reason I don't really get on it too much.

I'm sorry I did forget to mention that I did replace the spark plugs with NGK bpr7es. All of the plug tips did look tannish in color. I haven't checked the wires though, I'm not quite sure how to check them. Maybe I should just buy some new ones.

Yeah I seen that the amps were lower on the 1g alternators, but my idol(Mark Pontarolo) said at one point he was running a 1g alt and had no issues, so I hoped it would be the same for me since I had a space one. I will have to look into getting it rebuilt, its full of gunk and looks terrible. I would only see 14V on the logger half the time and rarely ever when I was idling, and it was smoking a little bit too. I have had bad luck with autozone alternator going bad within weeks of putting them on too. I will have to get a GVR4 alternator on as soon as I can.

Thank you all for your help so far.
Last edited:

I'm not sure if you did this, run direct current to the alt & see if it helps.


Well-known member
I haven't tried that yet. I googled it, but I can't seem to find out how I would go about doing that.

Run a wire directly from the positive side of the battery to the power on the alt.