Idle Hunting After Hks Twin Power Installed

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does anyone know what cause the car to idle to hunt after installing the HKS Twin Power.

Car is r33 gtst with the usual mods with new splitfire coil pack. With the twin power i can run 1.1mm plug gap and no miss at 23psi and seems to run smooth everywhere except when idling.

any help would be appreciated!

[DVS JEZ]

What afrs at idle? What ecu?

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A/F about 14:1. on my apexi multi check, i will try to lean it out and see how it goes.

ecu is Power FC.

The kit was listed for R34 GTR but was told it's the same for r33 s2 gtst and as listed in HKS web site.

[zebra]

Its probably too lean already,

Mine needed about 13:1 to idle smoothly, an i know of a few others that were the same.

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was your idle hunting or just rough? mine just hunting up/down. I will play with A/F ratio to see how it goes.

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have richen it out to 12.5 to 13.5:1 seem to help a little but still hunting. I also noticed that the hunting starting when the engine operate at 75degree and above.

[Nee-san]

move the idle around a bit, see if that stabilises it, worked with mine.

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what did you mean by move around?

i have rise the rpm - didn't work, but when lowering to 650-700rpm it seem to be better but still hunting. i have even tried to rise to 1000rpm and the hunting seem to be worst.

Thanks

[zebra]

Is there an air leak somewhere on the manifold then?

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I have checked a few times for leaks and seemed to be ok... i will check again over the weekend. I have also plugged back the stock harness last week and it seems to be idling ok but not smooth. Was thinking the hks unit but it seems to run fine to redline with 1.1mm plug gap at 23psi.

[DVS JEZ]

so the stock ecu stops the idle hunting but still has a pop at idle?

check and set all the basics too, like TPS, CAS etc

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sorry, i meant stock coil pack harness. have checked TPS-0.45v, clean the AFM, all the hoses, the only thing i haven't clean is idle air control valve. I have also tried richen the AFR to 12.5:1 and reduce mytiming by 2 degrees and lower myidle rpm to 700rpm, which reduce the hunting by 70%, now only a little hunting which still not smooth.

Thanks for all the input guys.

[DVS JEZ]

is your timing the same in the higher and lower cells that the rpm enters when hunting?

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high cell - 15

lower cell - 17

previously i had the lower cell 20 and it's fine with stock coil pack harness.

[DVS JEZ]

Is the afr fluctuating? Same as above are the inj ms different in high and low cells when fluctuating?

Try smoothing these areas out. Set the timing to 15 in the lower cells. See if it helps.

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Afr is the same for both cells. Will try timing 15 for both and see how it goes. Thanks

[Duncan]

have you tried to adjust the idle screw on the AAC to match the target idle on the PFC?

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have you tried to adjust the idle screw on the AAC to match the target idle on the PFC?

yes. it's already matched, but have also tried to rise/low the idle above/below the PFC and it was worst to go higher than PFC. I will clean the ACC today sometime and set the timing for lower cell to 15 from 17 (as suggested by DVS32R)and see how it go.

[RRob]

What are the 4 idle speed setting's in the rev/idle menu?

[GTRNUR]

I have a slightly different theory.

While I havent seen the twin power CDI before, I have seen this sort of behavior with other CDI's when the ignition triggering is set incorrectly. The AEM CDI's and MSD CDI's have configurable rising or falling edge triggering. If it is set incorrectly, you idle advance will drift by the effect of the dwell angle the ecu is sending to the coils. This is most noticable at idle, and not noticable at all at higher rpms.

Im pretty sure the R34 coil packs contain a dumb ignitor module and are falling edge triggered. If you are triggering the twin power CDI from the output of the R32/R33 ignitor, then that could explain it. Re-wiring to have it trigger from the ecu directly could resolve the issue.

You wont be able to spot this ignition drift with a timing light aimed at the balancer timing marks as the flurry of sparks the CDI delivers at low RPM makes exact timing impossible to read. The AEM CDI's allow you to disable multispark to set the base timing. I have no idea if the twin power allows you to do the same. I'd figure you would just bypass the twinpower to set the base timing and then re-connect it afterwards.