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Discussion Starter · #1 ·
need to fix this problem so i can sell the car, any ideas? when starting cold the idle will surge up and down in about a 500 rpm variation. Say from 600 to 1100.
I have searched on here and have tried
Idle screw
blue temp
o2 sensor
anyone please help so i can sell the car and fix my other corrado...
 

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Discussion Starter · #4 ·
Re: wandering, surging, unstable idle (whos_your_daddy)

ok i checked the tb and the throttle was connecting to the sensor. So what is next to check?
 

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Re: wandering, surging, unstable idle (whos_your_daddy)

Clean the ISV with carb cleaner, unplug the ECU main connector
for 30 sec. to reset any codes when the isv is reinstalled
start the engine and spary some around the intake manifold and
vacume hosses to check for a leak. then check timing and adjust the
idle screw. if the ECU and ISV are getting the correct voltage then
with the idle screw adjustment and the timing correct it should idle fine.
Good Luck
 

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Re: wandering, surging, unstable idle (REPOMAN)

i'd suggest (key off) unplug the isv.
start car. If the car doesn't idle at target 840-900rpm, then you need to adjust (timing,idle screw) to do so.
If the ISV is constantly correcting a mal-adjusted based idle, it will surge indeed. It is meant for miminal correction, and to help when you let off the gas (clutch in).
if the car does not idle at 840-900rpm without the isv, the isv is working very hard in closed loop to overcorrect and will do just that, surge. Also vacuum leaks can cause some crazy scthuff to happen. Cover the vacuum line bases by going over every vacuum line and its end point to detect any erosion of the line , esp ecu->tb , fpr->intake, and all that octopus of carbon canister and various T'ees . All vacuum lines should be in new shape and i prefer the micro zip ties or metal clamps on all end points. Leaving them unclamped or tied will eventually lead to fall out.

and everyone hates when it falls out.
 

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When you figure this out,please let me know!
I've been having this problem for three years now, only it does it on the random.Cold starts ,warm starts, after an hour of driving,whenever.It makes for a tricky shift for sure.
 

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Re: (CorraddoGirl60)

mine was surging after high rpm.today i cleaned the vdo with card cleaner and adjusted the pot in the sensor connected to my boost tubes and it seems to be better so far.
 
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