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2G Need help rpm issue (97 gst)

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DSM NE

Proven Member
88
3
Oct 21, 2020
Omaha, Nebraska
Ok so about 2 months into owning my 97 gst and the car was amazing the first 4 weeks of owning it and the previous owner had done some mods to it you can see them on my profile long story short I wanted to get a new radiator fan from mishimoto got the plug n play and it blew tons of fuses a30,a40 and a50 because the connection is wrong anyway and then the cold weather came around and the car started to idle mind you I unplugged the hose to the radiator to put the new fan on and now I have replaced iac valve cleaned egr valve since I can’t find one tried to adjust tps sensor and adjusted biss screw nothing seems to work it’ll rise in rpm when idle and it will stay at high rpm while driving once I let foot off of the gas pedal like it’s stuck and so I took it to two o Riley’s and one advanced auto parts scanner said it was a o2 sensor b1 sensor 2 I also knew because my car has been running super rich I can smell gas and everything and air fuel ratio gauge can’t seem to find a balance always bouncing between 16 to 28 and just yesterday while car was at idle I disconnected the tps sensor and the rpms slowly were dropping slowly but once I plugged it back it started to rise and my apexi gauge said I was on throttle about 8-2% when my foot wasn’t even on the pedal does this sound right tps and o2 sensor is what is causing my issue? Also checked for leaks nothing boost leak tested 3-4 times nothing and yeah water pump is getting replaced right now so I need help any help hopefully those two sensors once replaced and re adjusted will solve it
 
Its not your tps or o2 sensor, it sounds like your fiav system isn't working right, are your small coolant lines still connected to your fiav?
 
Dang i don’t know to be honest because it’s in the shop getting it’s water pump replaced can you send a picture of what it looks like? Also how much would a new one cost or could I replace it?
 
It’s under the throttle body and has two coolant lines attached to it. It acts like a thermostat letting more air in when the car/coolant is cold. As the coolant warms up, it closes the valve bringing the idle down. Don’t think a new one is available so you’d have to buy a used throttle body.

Seems like your car has a lot of issues from what you’ve been posting. Throwing parts at it isn’t a good idea unless dough isn’t an issue.

Fast Idle Air Valve
https://www.dsmtuners.com/threads/fiav.259300/
 
Hmmmm could I just clean it or do i really need to find another one? How hard is it to replace?
 
Also I don’t understand how this issue started could the cold weather have a play on this because 4 weeks before when I bought the car it was amazing car would pull you could feel the power it would start smooth and nice rpms never went up only thing that was needed was a water pump replacement.

once cold weather hit it started to surge a little bit and it’s been like that ever since mine you it happened when it first snowed in my state like in October and It also blew a lot of fuses because of the mishimoto fan shroud kit and it’s wrong connections
 
Hmmmm could I just clean it or do i really need to find another one? How hard is it to replace?

You have to remove the throttle body and unbolt it. Not difficult at all. Getting the screws off without stripping the head will be the hardest. Use the right size bit and an impact driver will be your friend. If you plan to remove it, it’s not a bad idea to replace the seals as they often leak with time and age.

There’s a good write up on it but I can’t find it. Maybe someone else can’t find it and post
 
Welp bro replaced iac valve cleaned egr valve also replaced tps and harness still same problem don’t know what to do anymore man I’m loosing hope at this point
 
It’s just high it doesn't bounce back and forth nothing it’ll just slowly drop after maybe like 2 minutes.

and if the car does regular speed on a highway like 70 and it’s put into neutral it’ll get stuck at the rpm it was doing and slowly drop also I figured out it mainly happens when the car is in neutral 1st and 2nd gear are fine.
 
How do I close the throttle Body? Also is it a good idea to Try and adjust tps sensor since it’s brand new
 
Ok I’m going to post a video tomorrow and I’ll link you it I bet it’ll be 10 times easier I appreciate you still responding man I really want the car to work like when I first got it 2 months ago
 
No. The throttle cable is connected to it. When you press the accelerator, the cable pulls the plate open and when you release the pedal, it goes back to the closed position. You want to verify the cable isn’t too tight to where it’s causing the throttle to be slightly open AND that it fully closes.
 
Ok tomorrow I’ll make a video and do just that while also showing the rpms on how it acts and also the engine bay just incase something seems odd thanks a lot man you’re a big help as well as everyone else who’s responding to my other posts I’ll link you it tomorrow
 
Here it is as soon as I turned it on
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Yep it settles down to about 1200-1300 also the boost gauge says it’s making boost even thought it’s not
 

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It was idling properly before we tried to replace the radiator fans for mishimoto ones which then kept blowing fuses could it of messed up the tune?
 
That’s why I thought it was the tps I’ve seen people install new ones and it says the same thing
 
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