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2G idle surging issue when warm

Edis_99Gsx

Probationary Member
3
0
Dec 20, 2019
West Fargo, North_Dakota
i have a 98 GSX and the car runs & drives fine when its cold but once it gets to operating temp it starts idle surging and the car will die if you dont keep reving it up
any ideas on where to start or what it could be?
 

JeffGS-T97

Supporting Member
691
422
Mar 22, 2019
Muncie, Indiana
-Fast Idle air valve malfunction.
-Idle Air Control malfunction.
-Biss screw out of adjustment or leaking
-Throttle Position sensor malfunction (had this issue just a couple weeks ago theres a good multimeter test you can perform to check this sensor.)
-And just like JK said before me a boost leak test would be a good place to start.
 

TK's9d2TSi

Supporting Member
5,250
2,383
Sep 11, 2017
Cincinnati, Ohio
+1 blt first

So it idle surges when it gets hot. How hot are we talking? A minute of driving, 30 minutes of driving? Just want to know about where the coolant temp is when it starts acting up. Does the car have fiav? That can be stuck open causing air to bypass the throttle plate.
 

jpmxrider489

Supporting VIP
2,339
100
Apr 4, 2010
pittsburgh, Pennsylvania
As mentioned above do a blt. Check this link below for more guidance. I had the same issue. The problem was my fiav. I actually removed mine but wouldn't recommend on a daily for winter reasons. The isc can be bad or going bad. You can test with a multimeter. Another time I had it was when my coil pack was going bad. I replace the plugs and wires. It might not be necessary but couldn't hurt anything.

 

Edis_99Gsx

Probationary Member
3
0
Dec 20, 2019
West Fargo, North_Dakota
So on cold start it runs fine but at operating temp it surges? Any codes?
I’d start with a boost leak test but that is just shotgunning it without a better description or video
yeah itll misfire and wanting to die if your not on the gas itll die out and the only code that comes up just says random misfires
 

Edis_99Gsx

Probationary Member
3
0
Dec 20, 2019
West Fargo, North_Dakota
+1 blt first

So it idle surges when it gets hot. How hot are we talking? A minute of driving, 30 minutes of driving? Just want to know about where the coolant temp is when it starts acting up. Does the car have fiav? That can be stuck open causing air to bypass the throttle plate.
like 5 mins of driving soon as it reaches the middle normal operating temp then it starts acting up
 

TK's9d2TSi

Supporting Member
5,250
2,383
Sep 11, 2017
Cincinnati, Ohio
like 5 mins of driving soon as it reaches the middle normal operating temp then it starts acting up
It doesn’t take much for the fiav to fully close. Running it under hot water through the faucet will get it fully closed so I think you can rule out the fiav.
 

jpmxrider489

Supporting VIP
2,339
100
Apr 4, 2010
pittsburgh, Pennsylvania
I don't think I would rule out the fiav. I personally seen them stuck that you cant even remove turn it manually after removing the freeze plug. Something you can try is, while cold, loop the fiav lines. That way the water in it is colder. Then drive the car, if it still surges then you can rule out the fiav. That doesn't mean the fiav cant cause it still, but would be a good test.

Replace the wires and plugs. If you clear the code, does it come right back? I remember I had a misfire but once I cleared the code, it ran better until it came back on. The links that are posted above is great info to learn.
 

TK's9d2TSi

Supporting Member
5,250
2,383
Sep 11, 2017
Cincinnati, Ohio
I don't think I would rule out the fiav. I personally seen them stuck that you cant even remove turn it manually after removing the freeze plug. Something you can try is, while cold, loop the fiav lines. That way the water in it is colder. Then drive the car, if it still surges then you can rule out the fiav. That doesn't mean the fiav cant cause it still, but would be a good test.
Won’t it still surge since the fiav isn’t closing?
 

jpmxrider489

Supporting VIP
2,339
100
Apr 4, 2010
pittsburgh, Pennsylvania
Won’t it still surge since the fiav isn’t closing?
When this happened to me, I had surge issue right after start up and kind of went away after it got warmer. So looped the lines when it was cold. The surge went away but caused really high idle. When I took out my freeze plug to turn the valve manually, it was so sticky I couldn't turn it. Its just plastic. A matter a fact, this issue bothered me to the point where I just deleted the fiav and chose to help the car warm up fully before I drive. If you tired of dealing with the fiav, you can turn it manually and then loop the lines. But you'll have to adjust idle accordingly. Its tedious.

So my theory here is is somewhat the same. If it is stuck or really slow moving/binding. Maybe looping the lines would cause a different effect. Maybe not solve the issue but at least show a different symptom to rule out. There's a chance it is closing but not well enough or to slow. Im hoping without the heat changing the valve, it would cause a different outcome. Im guessing he will have a high idle all the time. However your theory is still very possible. Remember, were just looking for a change with this test. Please let me know if you think I have the wrong approach.

There is also a chance that his throttle body just needs rebuilt to.
 

TK's9d2TSi

Supporting Member
5,250
2,383
Sep 11, 2017
Cincinnati, Ohio
When this happened to me, I had surge issue right after start up and kind of went away after it got warmer. So looped the lines when it was cold. The surge went away but caused really high idle. When I took out my freeze plug to turn the valve manually, it was so sticky I couldn't turn it. Its just plastic. A matter a fact, this issue bothered me to the point where I just deleted the fiav and chose to help the car warm up fully before I drive. If you tired of dealing with the fiav, you can turn it manually and then loop the lines. But you'll have to adjust idle accordingly. Its tedious.

So my theory here is is somewhat the same. If it is stuck or really slow moving/binding. Maybe looping the lines would cause a different effect. Maybe not solve the issue but at least show a different symptom to rule out. There's a chance it is closing but not well enough or to slow. Im hoping without the heat changing the valve, it would cause a different outcome. Im guessing he will have a high idle all the time. However your theory is still very possible. Remember, were just looking for a change with this test. Please let me know if you think I have the wrong approach.

There is also a chance that his throttle body just needs rebuilt to.
I’ve had a stuck open fiav recently as well. Got a used one and ran both under hot faucet water. Mine moved but not that much and the replacement fully closed. Just looked up what hot faucet water temp is and it’s between 130-140. That temp on a dsm doesn’t take much, probably a minute or two of driving these days. That’s why I’m ruling out the fiav but I could be wrong. I’m thinking that if op’s fiav was bad it would surge/high idle before it reaches full temp.

I can’t clearly remember my symptom that caused me to look into the fiav.

Regardless the op has to start with a blt.
 

jpmxrider489

Supporting VIP
2,339
100
Apr 4, 2010
pittsburgh, Pennsylvania
Yeah I understand but I also saw a post about this guy saying he got his engine blown up by the guy dyno tuning his car an I was like hell nah LOL

Who told you I wasn’t a 4g63 owner ? Just because I dont have anything on my profile but my 1995 eagle talon esi doesn't mean I don't have a gsx

I’ve had a stuck open fiav recently as well. Got a used one and ran both under hot faucet water. Mine moved but not that much and the replacement fully closed. Just looked up what hot faucet water temp is and it’s between 130-140. That temp on a dsm doesn’t take much, probably a minute or two of driving these days. That’s why I’m ruling out the fiav but I could be wrong. I’m thinking that if op’s fiav was bad it would surge/high idle before it reaches full temp.

I can’t clearly remember my symptom that caused me to look into the fiav.

Regardless the op has to start with a blt.

I just know I had surge then when I looped it the sure went away and got high idle. All good info in both posts.

A BLT is critical. Not sure if he is all factory or not. Plus unsure of the health of the matience.
 
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