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Discussion Starter #1 (Edited)
UPDATE
Aem's repair shop informed me ALL idle circuits are burned out and they cannot repair it, so a ~ $500 (plus shipping) replacement board from AEM is the only fix. Years ago, I let a supraforums member borrow my ecu to help them diagnose an issue with their Supra and as a result it damaged my AEM EMS v1. Sadly, the lesson learned is to never let someone from Supraforums borrow your ECU to "test" their car. Being a good Samaritan cost me ~$600 (with shipping) or ~$1,500 if I upgrade to Aem Infinity 506. :(


Hi Supraforum'ers,

Has anyone experienced a high idle 2500 rpm + (that keeps increasing) after you converted from distributor to the IS300 coil packs with AEM EMS v1 (or similar engine management system)? I set the base ignition timing with AEMPower's wizard, and made sure the throttle body fully closes in the off position, and I replaced the idle air control valve too. Any ideas?
 

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you have to change the idle settings, happens all the time.
 

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Discussion Starter #3
After setting the throttle position sensor to above 0% (per Kurt’s advice), I zero’s out the ignition-idle-offset table and that fixed the problem.

Now, I have to tune that ignition idle offset table. Are there any graph shapes or strategies you recommend for Aem V1?
 

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Discussion Starter #4 (Edited)
I thought that fixed the problem, but I appear to be wrong. In order for me to achieve a steady and lower rpm idle, I have to retard the ignition timing so much in the ignition map, that my headers glow red.

What could cause a 2JZ-GE to keep increasing rpm’s at idle unless the ignition timing is severly retarded (less than base timing)? I also tried the idle % and base target tables, but it does not respond to my inputs even after the +/- 3000 rpm preset.
 

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Discussion Starter #6 (Edited)
Are you running an IACV?
Yes, car is a 1995 2JZ-GE and I bought a used oem iacv because my previous one was not working (confirmed by failing ohms test + position wasn’t responding to my inputs in AemPower software). This used replacement iacv passed the Toyota ohms test and I see it in AemPower software reducing % until it is 0. So, it appears to be working.

As it reduces idle position %, it stops the rpms from increasing. But once the iacv hits 0% (fully closed position??), the rpms continue to slowly increase.

So, I’m wondering how is this extra air entering the engine as the rpms increase (as engine gets hotter) with throttle in closed position? I cannot find any vacuum leaks. Although, I notice the throttle is always a smidgen open against the stopper..from what i read this the normal oem setup we’re not supposed to have the throttle plate 100% fully closed?

Can the flapper valve in the intake manifold cause this problem if it’s in the wrong position?
 

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Discussion Starter #7
Update: After fixing a minor vacuum leak, rpms’s start lower, but keep creeping up.

I put my hand over the IACV opening in the throttle inlet pipe and it dropped rpms to the point of almost killing the engine before I unblocked the hole. It does this with and without the iacv plugged into the harness. So, the IACV must not be moving the plunger enough inside despite the AemPower settings.

Although this replacement used IACV passes the Toyota ohm test, is it possible it will not move the plunger inside? My old IACV fails the ohm test, so that’s why I replaced it with this used one.

Is there anyway to fix this IACV without replacing it?

252221
 

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Discussion Starter #8 (Edited)
This used replacement IACV passes the power test after I added that missing 3-pronged base spring.

The ground signals coming from the harness connector appear to not be sufficient to pass a strong enough current to activate the IACV with the ignition key ON. All 4 S ground terminals on the harness connector work fine to activate the IACV with the ignition key OFF while using direct +12v battery as power.

I’m using Aem’s recommended settings for the IACV too. What is causing this IACV not to get the sufficient ground signals from the ECU?

252274
 
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