Random Idle surge!!! Help! (d15b7)

Technical Topics specific to the 4 dr. Sedan body - NOT where you post pics/build specs of your car.
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Random Idle surge!!! Help! (d15b7)

By egsedanMAN
- Mon Jan 21, 2013 3:53 am #324522 Hey guys. So i was on my home from work when suddenly my d15b7 started idling at around 1600 up to 1800 rpms. The weather is fairly cold. About 15 degrees maybe 20. idk if that has anything to do with it or not, but i havent experienced the wacky idle ever before. car burns a decent amount of oil, and a while ago pulled a CEL (43) fuel. reset it, hasnt come on since. has been about three quarters of a year since CEL, so i would like to think that doesnt have anything to do with the wacky idle. PLease help ! any advice at all would help.! im not so savy when it comes to cars, still learning the ropes here!!
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By 92egdxhatch
- Mon Jan 21, 2013 4:09 am #324527 IACV or FITV

By egsedanMAN
- Mon Jan 21, 2013 6:03 pm #324569 Ok so ihave yet to toubleshoot iacv or fitv. But i had a buddy tell me that i might need to get the air out of the coolant system, so i did. it seemed to have helped. brought idle down to a grand, went for a drive, it was up to 1500 midway thru the drive. came back. beld the system once more, let idle with heat on and fan off for 15 min, idle is now at a grand. have yet to test drive a second time. does this sound like a possible bad radiator?
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By teal_dx
- Mon Jan 21, 2013 6:14 pm #324570 There are a few ways air can get into the cooling system.
1. leaking radiator
2. leaking heater core (passenger foot area would be wet if so)
3. bad hose/clamp
4. bad radiator cap
5. leaking head gasket

I would check the radiator & hoses for physical leaks first and replace if bad.
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By mitch6
- Mon Jan 21, 2013 7:40 pm #324575 most likely something to do with the cooling system, but I had the same problem before on my B16A and it was not the cooling system. I cleaned the IDCV, FITV, re-bleed the coolant, everything was good.

Turns out all I had to do was slightly adjust the idle position screw. This screw was out by maybe half a turn and caused my motor to have an RPM surge from 700 - 1500 RPM...
(screw is located on the throttle body, here is a picture I found on the web, http://thelic.org/users/tomo/IACV/Image%2023-2.png)

check the screw, play around with it while your engine is running at optional temperature.

MAKE SURE YOUR TROUBLE SHOOT EVERYTHING ELSE FIRST so you do not mess around with your idle position before the possible real problem was solved.

hope this helps :thumb: :thumb:
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By Apexracing
- Tue Jan 22, 2013 6:11 am #324606
teal_dx wrote:There are a few ways air can get into the cooling system.
1. leaking radiator
2. leaking heater core (passenger foot area would be wet if so)
3. bad hose/clamp
4. bad radiator cap
5. leaking head gasket

I would check the radiator & hoses for physical leaks first and replace if bad.


If the the intake manifold around the coolant port on the head is torn this will cause air to get into the coolant as well. Any vacuum leak will also cause idle surge. Air in coolant, fitv, iacv, and a torn throttle body/intake manifold gasket. Let us know how it goes.

By egsedanMAN
- Tue Jan 22, 2013 5:10 pm #324657 Thanks guys. im looking for any possible leaks. I took the intake off and plugged the fitv hole and it had suction, so that might not be to blame. the coolant bleed was a success but idle is still kind of high. i have an iacv gasket so i might just clean the iacv. any tips on how to do so? will i have to bleed again afterwards?

also, while i was running with the intake off it ran around a grand, cold.
i notice a slight idle surge, very faint

By egsedanMAN
- Tue Jan 22, 2013 5:13 pm #324658 Oh and i have been messing with the screw, i had it to the lowest position, idling around 1300. The temp outside is roughly 7 degrees with wind chill

By egsedanMAN
- Tue Jan 22, 2013 5:15 pm #324659 woops! so i guess the suction in the fitv hole is bad and means something is wrong with it! sorry for the confusion!
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By Apexracing
- Tue Jan 22, 2013 5:21 pm #324660
egsedanMAN wrote:woops! so i guess the suction in the fitv hole is bad and means something is wrong with it! sorry for the confusion!


Yup pull it apart and spray it with throttle body cleaner.

By egsedanMAN
- Tue Jan 22, 2013 5:24 pm #324661 the fitv on my d15 seems really hard to get to. is it possible that i coud take it off without taking the im off?
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By Apexracing
- Tue Jan 22, 2013 5:27 pm #324662
egsedanMAN wrote:the fitv on my d15 seems really hard to get to. is it possible that i coud take it off without taking the im off?


should be on the bottom of the throttle body

By egsedanMAN
- Tue Jan 22, 2013 5:33 pm #324663 ok right on, im looking at it and it looks like i have to undo the throttle cable. like i said im new at this, is this hard to undo and put back on after the cleaning?
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By Apexracing
- Tue Jan 22, 2013 5:34 pm #324664 Should be just a couple bolts, you shouldnt have to remove the throttle body or the intake manifold.
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