High idle and surging problem.

[Bubbas Garage]

Hey, I have a 1991 Talon ( 1992 engine ). We just swapped the car from auto to manual, and while doing so we took off all the intercooler piping to get easier access. ( my throttle body had a fiav block off plate or what ever that is where the ISC goes) So while we had the IC piping off i thought i might as well put an ISC on. But instead of putting on just that, we put a whole different throttle body on that had the isc attached ( made sure it was all clean). Got everything done and tight. Started it up and now i have a high idle and big idle surge. Idled around 2500-3000 up and down. Checked the ISC with the volt meter and they all read around 40. So the ISC should be good. Throttle pos. on the ecmlink 2.5 read 0 when idleing so that should be good. Sprayed some carb cleaner around the throttle body and hoses and no change in idle. So, i went to the biss, adjusted it a little and idk if it actually changed cause of that or cause it just got warmer and it started idling around 1500-2000. Still big surge. Also When i have the clutch in and a tiny gas it would idle arond 3000. And even if im at an idle i will tap the gas and say it goes to like 4000 rpms, it will stay there for a few seconds before it goes down? The car is not Fully tuned. Could that cause this? ANY help would be greatly appreciated. ( hopefully that wasnt to confusing) Thanks!
Jordan

Fuel pressure is at 45psi if that has anything to do with it.
Runs on e85

Mods-
Ross Pistons
Eagle Rods
SBR Stage 5 ported and polished head
FP 2 cams
Magnus Sheetmetal Intake Manifold w/ bungs for direct port N2O

Trans: Shep Stage 3
Short shifter
act 2600 clutch

Mods:
VRSF FMIC short route piping
FORGE recirculated BOV
Dejon Tool Intake
Evo 8 MAF
DSMlink V2.5
LC1 Wideband
Buschur Racing 3in turbo back exahust
2.5in O2 housing with external dump
Turbonetics t3 manifold
HY35 turbo
-4 an feed ( no restrictor yet)
-12 return line 2g cut
Dual Piston Front Calipers
Manual Rack and Pinion Steering
Battery relocated to the hatch
Fuel System:
PTE 1000cc injectors
Aeromotive FPR
Walbro 255 fuel pump

 

[92AWDHX40]

http://www.dsmtuners.com/forums/articles-engine-fuel/191137-how-fix-your-idle-surge-problem.html

start here.

 

[Funfettie]

Im having the same issue on a built engine. I came to the conclusion that its my front o2 sensor not relaying data to the ECU. Maybe check yours to see if its cycling properly? check for boost leaks too, that could do it.

 

[Bubbas Garage]

Alright i just went out and started the car, i once again spray EVERYTHING that i could think of that would have air flowing through it with carb cleaner and NO Changes what so ever. After i let the car war, up it DID lower to 1500-2000 but still surged badly. just lowered down. I see in this Thread- http://www.dsmtuners.com/forums/articles-engine-fuel/191137-how-fix-your-idle-surge-problem.html They say to GLOB the selected areas in the fiav if you blocked off your coolent lines. I DO NOT have any coolant lines going to the 2 hoses on the fiav. Do you think that Would cause a full 500 rpm idle surge? If so, i will go glob and much jb weld in there as i can! I am not sure how to test my 02 sensor but i will go google it Thank you for the speedy fast replies!
Thanks
Jordan

Heres an idle log that i just made. Feel free to check it out.

 

[92AWDHX40]

DO a boost leak test in the entire intake system, intercooler system.

 

[Rock2610d]

You might try adjusting the throttle, accelerator, and throttle body linkage first. My OEM manual shows how to do this on a 2G. The linkage tolerances are very sensitive. The IAC cannot get where it wants if these 3 items are not right.

For instance the throttle body linkage/cable MUST be adjusted with the IAC activated and engine warm, accessories off and no pressure on steering wheel. Otherwise the IAC will adjust with a too tight cable and cause high Idle. This in turn confuses the ECU as engine rpm is too high and ECU tells the IAC to adjust but the tension resists and hunting resumes.

The 2G throttle(1)and accelerator(2) cables need to be adjusted so the link is 0 to 1mm and 1 to 2 mm from the link stop respectfully.

REMEMBER, the IAC MUST be activated and engine warm for the correct throttle body cable sag.

 

[Bubbas Garage]

I am going to first block the not needed holes in the fiav since i knoe this is not done.. wether iy gixes it or not it should be done.. ill test it out tomorrow and let you all know. 1 step at a time. Thanks

PLugging the 2 holes on the fiav fixed it! Thanks for the links and everyone that posted... On to the next... bigger problem i have found out. New thread coming up haha.