Idle Surge(Ground terminals)

[tjohn23]

OK, Well at some point we are plagued with the dreaded idle surge not only does it cause MPG to decrease, it is probably the most annoying thing that you can experience at a stop light.Well I had a cold idle surge for years then it was finally fix ( after thousands of forums) by using a by blocking the FIAV with a bypass plate so that the ISC could still be used.

Recently I "slapped" a turbo on my 1g 6bolt n/t and I was getting cold start idle problems so i kept playing with the BISS screw eventually I played with the CAS, long story short, My idle surge returned

I fixed the surge. It would only happen when warm on a 2g ecu.

This my help 1g ecu user also but from all the tips which included ISC, Low coolant, boost leaks, vacuum leaks, BISS O-ring, BAD ECU, Coolant Temp sensor etc.All was ok still had a surge this was from the BISS being adjusted without properly grounding what needed to be ground for the adjustments. For 2g using scantool, or in my case, using evoscan to turned on the speed adjustment screw mode to adjust the BISS and adjusting the CAS by using the IG 5deg actuator magically no more idle surge. (also unplugged the ISC, its worthless)

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so follow vfaqs for adjusting the BISS on 1Gs and 2Gs fix the surge.
Oh i fixed the cold start problem with a new coolant temperature sensor

I know its long and not much info but if got the surge any insight helps

 

[tjohn23]

idle surge is an SOB. Just block the ISC along with the fiav , terrible cold start but a little warm up in phoenix weather no problems no surge magic