2G Idle Speed Controller (ISC Motor) Issue

[Sp00lin16g]

My 97 talon is idling like crap. I have replaced many gaskets and it still idles poorly. I swapped the stock T25 turbo because it had blown seals and replaced it with a 16G ... the car idled fine before and now I'm dealing with this ..

Any thoughts on stock talons with blown turbos and swap to a larger turbo -- Need help finding boost leaks?
-When I unplug the ISC motor / Idle air control valve the rpm's don't change and the car doesn't die ???

Help .. thanks guys

 

[Sp00lin16g]

Not sure if you got the boost leak test figured out. When i do a boost leak test i charge the system and spray all joints and conections or any possible leak area down with soapy water and watch for bubbles. Easiest way i know to find a air leak. Hope this helps

Yea I have been doing that and it helped me find the leaks I have listed above ... I'm going to try to compress the system with smoke and see where it leaks out

 

[Maes]

Oh that's a good idea guy. Smoke that turd. I would use a smoke pro if you can get your hands on one

 

[PlanZero]

Here's the deal. If your idle is really that bad it's gotta be a big leak, easily heard during a standard BLT. ISC/IAC are known to go bad, especially if you have the older tan version. The mitsu black version is supposedly revised, also the same one used on 3000gt/Stealths. Most aftermarkets are black as well. So if you still got the tan one replace it ASAP. Both of my Tsis needed replacements. On my 97, I got a cel but no symptoms. On my 96 I got idle surge out of nowhere, but no cel. Both IACs had dead coils. Make sure u don't lose the o ring when u put a new one in.
When the coolant temp sensor goes bad it causes cold start issues and rough idle until she's warmed up. If you replace this do not overtighten! I cracked my thermostat housing in the middle of winter because I saw all the threads remaining on the sensor and thought it went further
On my 97 I have a nice boost leak at the TB seals, but it doesn't affect my idle at all. Just saying.
I know this may sound rudimentary, but your BISS is adjusted properly, correct? Ive had tons of idle issues , but most of the time it's idle surge. The only time I had low idle is when the biss wasn't adjusted following some other repair (replacing IAC, removing egr, replacing tb gaskets, etc), or when my MAF was disconnected, my BOV line wasn't recirculated, or an injector was unplugged.
Just want to give you serious props man. You're definitely following the maintenance /upgrade path to a T. I wish I had the funds to do everything at once and properly when I got my TSIs. Instead its been a gradual process. Good luck.

 

[redfield102j]

I was also having idle surge issues. Had a cel for coolent sensor. I replaced it and problem persisted. Cel still comes on but has no code. I started running the hanes manual test and found the nunber 1 prong on isc was faulty and had no resistance. I also have the tan isc. Ordered a new one threw napa for 80 dollars. Pretty cheap. I have noticed that for some unknown reason the car is changing the ignition timing by 15 degrees. Just wanted to fill you in on all my symptoms. Hope it helps

 

[Sp00lin16g]

Here's the deal. If your idle is really that bad it's gotta be a big leak, easily heard during a standard BLT. ISC/IAC are known to go bad, especially if you have the older tan version. The mitsu black version is supposedly revised, also the same one used on 3000gt/Stealths. Most aftermarkets are black as well. So if you still got the tan one replace it ASAP. Both of my Tsis needed replacements. On my 97, I got a cel but no symptoms. On my 96 I got idle surge out of nowhere, but no cel. Both IACs had dead coils. Make sure u don't lose the o ring when u put a new one in. The only leak I can hear is something behind the intake manifold -- or I think it's just the air passing the throttle body going into the engine? not sure though
When the coolant temp sensor goes bad it causes cold start issues and rough idle until she's warmed up. If you replace this do not overtighten! I cracked my thermostat housing in the middle of winter because I saw all the threads remaining on the sensor and thought it went further Thanks I'll try to be careful
On my 97 I have a nice boost leak at the TB seals, but it doesn't affect my idle at all. Just saying.
I know this may sound rudimentary, but your BISS is adjusted properly, correct? Ive had tons of idle issues , but most of the time it's idle surge. The only time I had low idle is when the biss wasn't adjusted following some other repair (replacing IAC, removing egr, replacing tb gaskets, etc), or when my MAF was disconnected, my BOV line wasn't recirculated, or an injector was unplugged. I will find out when I install the ecmlink -- it currently idles at 1,100ish on my gauge cluster (aftermarket face) but on a obd2 reader it's 900ish and I will set the BISS screw correctly when ecmlink is installed
Just want to give you serious props man. You're definitely following the maintenance /upgrade path to a T. I wish I had the funds to do everything at once and properly when I got my TSIs. Instead its been a gradual process. Good luck. Thanks

 

[Sp00lin16g]

I was also having idle surge issues. Had a cel for coolent sensor. I replaced it and problem persisted. Cel still comes on but has no code. I started running the hanes manual test and found the nunber 1 prong on isc was faulty and had no resistance. I also have the tan isc. Ordered a new one threw napa for 80 dollars. Pretty cheap. I have noticed that for some unknown reason the car is changing the ignition timing by 15 degrees. Just wanted to fill you in on all my symptoms. Hope it helps

Nice and Rockauto has it 60ish .. and thanks ill pay attention to the ignition timing
What's the base timing on the 97 tsi supposed to be -- 5 degrees?

 

[redfield102j]

Nice and Rockauto has it 60ish .. and thanks ill pay attention to the ignition timing
What's the base timing on the 97 tsi supposed to be -- 5 degrees?

Mine is a 91 and base is 5 degrees before tdc. I would think it to be the same but not 100%. You also stated that you could hear air in the back of the intake. The only thing on mine back there that would leak air is the break booster line. Again tho mine is a 91 so may be diffrent. But i would check to be sure it is hooked up

 

[97 eclenger]

just about all engines are setting ignition timing 5* btdc. mechanical should be dead on and ignition 5* btdc. only spot on the back to leak is the brake booster. or an emissions line that isn't blocked off. other than that its fuel pressure regulator on drivers side front and passenger side front for pcv. top has a mdp sensor for emissions. that can leak to

 

[Sp00lin16g]

Mine is a 91 and base is 5 degrees before tdc. I would think it to be the same but not 100%. You also stated that you could hear air in the back of the intake. The only thing on mine back there that would leak air is the break booster line. Again tho mine is a 91 so may be diffrent. But i would check to be sure it is hooked up

Hmm .. i'll check out the brake booster line thanks. I also saw on the forums that there is a evap emission purge solenoid valve ... http://www.dsmtuners.com/threads/boost-leak-behind-intake-manifold.496381/

And I'll find out about the base timing before top dead center

Thanks again brotha

 

[Sp00lin16g]

just about all engines are setting ignition timing 5* btdc. mechanical should be dead on and ignition 5* btdc. only spot on the back to leak is the brake booster. or an emissions line that isn't blocked off. other than that its fuel pressure regulator on drivers side front and passenger side front for pcv. top has a mdp sensor for emissions. that can leak to

Right on thanks man .. I'll make sure to check all those components

 

[97 eclenger]

forgot to mention the throttle shaft to. that can also leak

 

[nastygsx]

any update??? I'm having the same high rough idle problem

 

[nastygsx]

any update on this I'm having the same problems

 

[redfield102j]

any update on this I'm having the same problems

I tested the isc motor it had one bad terminal. I replaced it with new part. That helped the problem slightly. So i went on to a boost leak test. I found that the throttle shaft seal behind the tps was leaking horribly. Bought a new set of seals and installed them. The car started right up no idke surge. It ran for about 2 to 3 min. And had a slight idle surge about 200 rpm for about 1 to 2 min and clears right out with no further issues.

 

[Sp00lin16g]

The only update I have is I ended up tearing the engine apart .. Had valve seal leaks and had to repair the head gasket. I bought ecmlink and that did help dial in the idle prior to the tear down.

I will keep yall up to date.