2G Idle heat surge

[Velmin hu]

Greetings, so I notice when I drive temp is normal, when I come to stop after long driving the idle would drop around 700-800. And the temp would start to rise then the fan turns on then the temp will drop back to normal. Is this normal or an issue? Thanks it’s 96 gst with also my a/f gauge would go above ———- or 17. when this happen and no reading. But when I drive cruise it around 14.6-15.2. When I hit gas it goes down towards 13, or 12. So basically when I stop at light or idle for long time it will do this. After drive around normally.

 

[Evolving_sti]

The only time your af should read --- is when ur decelerating in gear. If your in neutral or at dead stop you should have a reading. And if at open throttle your seeing 13 or 12 that's way to lean for a turbo car.

 

[motomattx]

Your actual factory temperature gauge should never go above half way, if it is then something is wrong.

 

[609DSM]

Have you checked the quality of your coolant and if it is filled all the way? Any small leaks of coolant that might not be visible at first glance? Usually overheating is pretty straight forward. As far as the afr have you checked for any exhaust leaks or boost leaks at all that could be interfering with normal operations?

 

[Velmin hu]

Have you checked the quality of your coolant and if it is filled all the way? Any small leaks of coolant that might not be visible at first glance? Usually overheating is pretty straight forward. As far as the afr have you checked for any exhaust leaks or boost leaks at all that could be interfering with normal operations?

The reservoir is half way filled should I fill it to the top?

 

[2g2slow97]

Greetings, so I notice when I drive temp is normal, when I come to stop after long driving the idle would drop around 700-800. And the temp would start to rise then the fan turns on then the temp will drop back to normal. Is this normal or an issue? Thanks it’s 96 gst with also my a/f gauge would go above ———- or 17. when this happen and no reading. But when I drive cruise it around 14.6-15.2. When I hit gas it goes down towards 13, or 12. So basically when I stop at light or idle for long time it will do this. After drive around normally.

It sounds like you have air in your system. I’ve had that happen before.
Make sure the sucker tube going to your reservoir doesn’t have cracks/dry rot.

Now for your wide band, if you’re idling it should read 14.7 or around that fluctuating.
Any thing higher than 15.5 consistently I recommend looking at what vac you’re pulling and do a boost leak. You might be pulling air from somewhere causing it to run lean.

 

[609DSM]

The reservoir is half way filled should I fill it to the top?

The resivior isnt what will fill your coolant. You need to open the radiator cap to see if there is coolant in there and if it has gone bad. Coolant doesnt stay good forever.

 

[motomattx]

Check under the radiator cap for cracked rubber where it seals, if its an original cap you should just go ahead and replace it anyway at this point.