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1G Idle surge...

a7xinsane

Proven Member
49
4
Oct 5, 2013
clarence, Pennsylvania
I know this has been covered thousands of times on here but ive gone down the checklists and nothing really seems to be working...

91 talon tsi awd

Haveing really bad idle surge issues. Performed boost leak test and fixed leaks but it hasnt changed the idle a bit. Changed tps, isc, and even the throttle body/gaskets... I'm at a loss at this point. I have a data log I took on ecmlink of startup if that would help. Only mods are 560cc injectors, 2g maf, vac line delete and a 16g with manifold. Thank you in advance if anyone has a suggestion I'm all ears. Ive been beating my head against a wall with this thing....
 

Cherry

Proven Member
277
60
Jun 16, 2019
Hull, Georgia
The FIAV could be stuck open and wouldnt show up in a boost leak test. The IPS could of been adjusted in place of the BISS screw unless the idle surge is new and you know it hasnt been touched.

It could also be the ETC(ecu) that isnt sending the right temperature to the ECU so it thinks it is colder than it is and the ISC is letting in more air than there should be since the ECU is trying to get the engine to operating temps.

I dont know if the timing would cause a surge but it can make it a nightmare to get things set right if it isnt set properly though again if you are the only one touching your car then it probably isnt out but its still good to check it when dealing with an idle issue.

If it is the FIAV however when trying to find the part you probably wont find it under the Eclipse when looking up parts, I found mine under a 3000gt vr4 at Autozone.

Im currently trying to find a leak and I hope its my tester not sealed well somewhere.
 

AWD-Tony

Supporting Member
6,802
3,690
Sep 11, 2017
Cincinnati, Ohio
You have 3 dtc's.

Log ISC Position.
Set your tps to .63 volts with the car off.
Zero out your fuel and maf sliders.
Select stock IM under MAF clamp (I don't think this matters but I just set it)
Under ecu input, I think you have to assign the front O2 (not 100% sure since I run separate sensor). This might be why your O2 isn't cycling???

Inspect the wires on your ISC connector.
 
Last edited by a moderator:

a7xinsane

Proven Member
49
4
Oct 5, 2013
clarence, Pennsylvania
Wow thank you guys so much. I will go through these posts and try everything today after work. Thank you guys again! Trying to restore someone elses molestation...
 

a7xinsane

Proven Member
49
4
Oct 5, 2013
clarence, Pennsylvania
Well after messing with settings and soapy water I figured I'll try throwing more parts at it. Swapped my throttle body again to another used one with bad shaft seals and.... No surge... I'm going to send my tb out to be rebuilt. I would imagine it was the fiav since it had 0 boost leaks.
 

Cherry

Proven Member
277
60
Jun 16, 2019
Hull, Georgia
Thats good, at least you figured out what it possibly could be, still working on mine to get the leaks out and then my lower thermostat housing broke so 93 dollars gone.

Im going to have a whole new engine by the time im done with this thing, could of just bought an 4g63t AWD trans with wiring harness and ECU for what I have spent trying to fix this mess of an engine that the previous owners butchered.
 

a7xinsane

Proven Member
49
4
Oct 5, 2013
clarence, Pennsylvania
Thats good, at least you figured out what it possibly could be, still working on mine to get the leaks out and then my lower thermostat housing broke so 93 dollars gone.

Im going to have a whole new engine by the time im done with this thing, could of just bought an 4g63t AWD trans with wiring harness and ECU for what I have spent trying to fix this mess of an engine that the previous owners butchered.
I am in the exact same situation. The amount of money i have in axles, seals, parts etc. Could have bought a decent awd...
 

Cherry

Proven Member
277
60
Jun 16, 2019
Hull, Georgia
2500 for an engine trans wiring harness and ECU apparently out of a running car. Cant remember from what company though. But all those engines were all around that much, even for a new Evo VIII its around 2500.
 

Vegas Smith

20+ Year Contributor
5,035
2,905
Dec 2, 2002
Houston, Texas
Well after messing with settings and soapy water I figured I'll try throwing more parts at it. Swapped my throttle body again to another used one with bad shaft seals and.... No surge... I'm going to send my tb out to be rebuilt. I would imagine it was the fiav since it had 0 boost leaks.
FIAV leaks/improper bypassing can cause a vacuum/boost leak that isn't detectable on a BLT. I drove around for 2 years with one of those leaks and never knew it.
 

a7xinsane

Proven Member
49
4
Oct 5, 2013
clarence, Pennsylvania
So I ended up sending the throttle body out to be rebuilt and have been doing some other restoration work to the car. (it started as a full resto/300-350hp daily project) Doing some electrical work I may have found a huge clue as to what may be causing all of my issues beyond boost leaks... The entire chassis from front to back is putting out 2.3 volts constantly... Every single ground location besides battery has voltage to it... This has been fun. Disconnected all of the engine and lighting harness and still showing voltage. Had to give up for tonight but i will be back at it again tomorrow gents. If anyone wants to chime in and has a good starting point from experience it would be much appreciated. Either way me and my power probe are going to be best buddies tomorrow.
 

Vegas Smith

20+ Year Contributor
5,035
2,905
Dec 2, 2002
Houston, Texas
So I ended up sending the throttle body out to be rebuilt and have been doing some other restoration work to the car. (it started as a full resto/300-350hp daily project) Doing some electrical work I may have found a huge clue as to what may be causing all of my issues beyond boost leaks... The entire chassis from front to back is putting out 2.3 volts constantly... Every single ground location besides battery has voltage to it... This has been fun. Disconnected all of the engine and lighting harness and still showing voltage. Had to give up for tonight but i will be back at it again tomorrow gents. If anyone wants to chime in and has a good starting point from experience it would be much appreciated. Either way me and my power probe are going to be best buddies tomorrow.
Damn, let us know what you find...
 

a7xinsane

Proven Member
49
4
Oct 5, 2013
clarence, Pennsylvania
Pulled out dash, console, seats, carpeting, both bumpers, and engine/trans/tcase. unplugged every single connector one at a time while power probing ground... Nothing! There is still voltage... Pulled both wiring harnesses apart completely and laid out. Nothing is bare, shorting, or corroded... Who wouldve thought that turn signals could screw ya this hard... Only the lighting connector on the battery terminal makes this happen... Unplug it and ground is ground again... I'm at the end of my ropes on this thing but i cant let the thousands ive already dumped into it go to waste because of (most likely) one effing wire.
 
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