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PostPosted: Thu Dec 04, 2014 1:13 am 
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Spends Too Much Time Under The Hood
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Location: Seattle, WA
So I have about 8 miles and 2 hours of run time on my fresh rebuild engine, the idle is surging bad from 1200-1700 RPMS. I've checked everything!!
-ISC is good
- throttle body shaft seals just replaced
-TB Hasnew gaskets on both sides
- on SD V3 lite with the base SD map
- no wide band, just need to weld on the bung
- no boost leaks at all! I checked up to 15psi until my tester shot off like a bullet
- FPR set at 42.5 psi with Evo 8 550cc
- BISS is grounded out and doesnt change anything
- TPS set at .63V
-All settings in link are cherry and i have tried adding dead time to no availe
- I even hooked back up my 2G MAF and adjusted the airflow sliders and its the SAME outcome as SD

On SD at idle revs are rising and dropping bad, regardless of this surging AIRflowper rev is between .24-.26 and Fuel trims are -3% to +4% during surgeing, if i start decreasing airflow numbers it runs lean and the O2 goes from 0.00-0.02 and doesnt cycle at all. I f i raise airflow fuel trims go to +17% and revs raise, O2 cycles good but the surgeing gets faster and worse and airflowperrev goes to .30-.38.

This throttle body is off my talon, I swapped them because it would never idle no matter what we did. The only thing i havent checked is the FIAV, does anyone have any experience with high idle surgeing while warm before closing the FIAV... Could this work? I'm F'in stumped and feel like burning it haha

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95 Mirage S Sedan- Evo III Project {In Process}
91 Talon TSi AWD- SOLD
91 Mirage 4dr 4G63T -Daily
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Last edited by modicaUSMC on Fri Dec 05, 2014 9:03 pm, edited 1 time in total.

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PostPosted: Thu Dec 04, 2014 2:49 am 
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Spends Too Much Time Under The Hood
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Location: Tacoma, WA
There are many things that can contribute to idle surge, especially when messing with the tune via Link. If I understand you right, you took that TB off of another car because it wouldn't idle no matter what you did? If so that certainly makes it suspect. The FIAV could be bypassing air but I'd make sure the surge isn't caused by improper settings in Link. If your VE table isn't right you can still get the car to run what might seem good by changes to global inj and deadtime. However what you end up with is several adjustments that are all technically incorrect and although you might be able to get it to drive ok there will be some areas that just seem impossible to "fix" with the tune. Idle can be one of them.

If you're positive there are no vacuum leaks, you can screw the FIAV closed and see if that helps. That's easy to do and free.

In the meantime, if you can't correct the idle surge and you need to drive the car, just disable the Idle Position Switch so the ECU thinks the TB is never at idle. The engine will run fine and won't surge however the ECU won't turn the injectors off during decel.

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'91 Talon AWD w/bigger than stock turbo
'05 Dodge diesel w/bigger than stock turbo


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PostPosted: Thu Dec 04, 2014 3:07 am 
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In the meantime, if you can't correct the idle surge and you need to drive the car, just disable the Idle Position Switch so the ECU thinks the TB is never at idle. The engine will run fine and won't surge however the ECU won't turn the injectors off during decel.[/quote]


I already did that is the revs shoot to 2000RPMS. Tried messing with global and everything, set timing to 1500 rpms at 5*. It helps steady idle but then the O2 won't cycle, I am under the impression it's the throttle body because when we switched it out it idled GREAT and we didn't change anything else. I'm assuming the FIAV is corroded inside and not closing when hot. The Talon before me and my friend owned it was not taken care of at all!! We fixed SOOO many problems

_________________
95 Mirage S Sedan- Evo III Project {In Process}
91 Talon TSi AWD- SOLD
91 Mirage 4dr 4G63T -Daily
2016 Ford Edge Titanium -2L.0T AWD Wife
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PostPosted: Thu Dec 04, 2014 5:18 am 
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The happy administrator
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Did you unplug the fiav? For as much work as you've done, just delete the FIAV with a plate. I did this and I used a half a cut up can slipped in between the throttle blade, then poured jb weld into the opening. This left it a straight smooth tb with no fiav holes.

Does it run alright otherwise? Can build and hold boost?

_________________
Had a:
1991 Eagle Summit ES Hatchback - 4g15 12v 5spd
1991 Dodge Colt -4g15 12v 4spd
Have a:
1978 Oldsmobile Cutlass - 468BBO TH350
Round 3:
1990 Dodge Colt-4G63T 5spd


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PostPosted: Thu Dec 04, 2014 6:53 am 
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FIAV still has coolant passages hooked up. Don't want to spend any more money since Xmas needs my money, that's why I was considering closing it all the way since it will have the same effect. Car has 8 miles on it. Not gotten on boost yet. Car runs and drives great! Fuel trims and airflow are great it's just the damn idle that's keeping me from driving her daily and racking up the break in miles

_________________
95 Mirage S Sedan- Evo III Project {In Process}
91 Talon TSi AWD- SOLD
91 Mirage 4dr 4G63T -Daily
2016 Ford Edge Titanium -2L.0T AWD Wife
facebook.com/modicausmc


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PostPosted: Thu Dec 04, 2014 9:17 am 
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I may have missed it but did you try adjusting the throttle stop switch?

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PostPosted: Thu Dec 04, 2014 10:53 am 
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That's what I was thinking. You're supposed to loosen it until it doesn't make contact. Hook up an ohm meter and screw it in little by little until it displays a reading. From there tighten it almost one full turn (15/16 of a turn in the manual I think) and lock the adjusting nut down.

With the ohm meter you put one probe on the base and the other on the little tab on top.

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93 Mitsubishi Expo LRV 1.8/manual
95 Eagle Summit DL Coupe 1.5/manual
01 Mitsubishi Mirage ES Sedan 1.8/manual


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PostPosted: Thu Dec 04, 2014 3:04 pm 
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^Yeah, that cured my issue after I went through a similar run-around. It's funny I never see the throttle stop switch mentioned in idle problem posts, I'm sure it causes more issues than people think.

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89 Mirage Billet 20g 63t 12.4@120 417whp 400wtq @ English Racing.
89 Colt GT E316g
06 Silverado SS
07 ZX6R


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PostPosted: Thu Dec 04, 2014 5:34 pm 
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Spends Too Much Time Under The Hood
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You know what... I haven't messed with the idle stop... Figured I was simulating the idle switch and didn't need to worry but that's not its only job. I'll check soon

_________________
95 Mirage S Sedan- Evo III Project {In Process}
91 Talon TSi AWD- SOLD
91 Mirage 4dr 4G63T -Daily
2016 Ford Edge Titanium -2L.0T AWD Wife
facebook.com/modicausmc


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PostPosted: Fri Dec 05, 2014 9:02 pm 
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So I closed the FIAV and BOOM! Perfect steady idle. Everything in link looks good other than some slightly ligh airflowperrev
Numbers. But she drives beautifully

_________________
95 Mirage S Sedan- Evo III Project {In Process}
91 Talon TSi AWD- SOLD
91 Mirage 4dr 4G63T -Daily
2016 Ford Edge Titanium -2L.0T AWD Wife
facebook.com/modicausmc


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PostPosted: Fri Dec 05, 2014 9:08 pm 
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The happy administrator
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Probably a junk stepper motor for the idle air control. You could unplug it with the car off for it to stay closed.

_________________
Had a:
1991 Eagle Summit ES Hatchback - 4g15 12v 5spd
1991 Dodge Colt -4g15 12v 4spd
Have a:
1978 Oldsmobile Cutlass - 468BBO TH350
Round 3:
1990 Dodge Colt-4G63T 5spd


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PostPosted: Wed Dec 24, 2014 12:08 pm 
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Location: malta
i dont have surging anymore but got a a stall when mines warmed up.....do you think blocking off the fiav could solve my problem, isc is working fine and there are no boost leaks i know of,all though not 100 0/0 sure.
Ive been struggling with this for over a year.Another thingis im getting a barometic pressure sensor fault and i replaced the maf twice allready,it went away when i replaced it but came back a month and a half later.
If anyone has some new insight into this it would be a great help .
cheers


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PostPosted: Wed Dec 24, 2014 12:18 pm 
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I would check the condition of your ecu as well. Every time I've ever thrown a code for the barometric pressure sensor the ecu was on the way out.

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93 Mitsubishi Expo LRV 1.8/manual
95 Eagle Summit DL Coupe 1.5/manual
01 Mitsubishi Mirage ES Sedan 1.8/manual


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