CounterSunk

Hey guys just needing some help here. I had nitrous backfire yesterday and discovered when I got home ( when it occured I slowly pulled over and the car slowly died. I thought I blew my motor but I started it right back up and it was fine and I drove it home ) from what I could see their was no real damage or anything under the hood. The only thing I could see was that the top of my intake lid was only being held on by two clips and the air filter inside was kind of messed up. All today it was idling at 1500 RPM at neutral even when warmed up and the rpms kept dipping in neutral from 500-2000. I came home fiddled around with a couple of things pushing vacum hoses in all the way checking for leaks and unplugged and then replugged the battery. It idles fine now at 1000 RPM but the RPM dipping back and forth is becoming intermittent. I drove it around all afternoon with zero problems and then now when I went to start the car again the rpms were dipping back and forth. Any idea what this could be? I need your help guys! From what I can see their are no leaks of any kind on the floor or in the engine bay.

* Note the idle is not rough at all its just dipping from 1500 back to 2000 intermittently (it used to be 500-2000 but since I changed the air filter its dipping now from 1500-2000)

* Update November 20th - I posted a link to a video of the RPMS dipping
- Things Ive changed
- Air Filter, Spark Plugs, Cleaned IACV, Map Whack, Checked for Vacuum Leaks( couldnt find any , Unplugged battery and fuse to ECU so it could re-learn idle.

* Update November 22nd - PROBLEM FIXED!!
- Alright so I took it to the shop and they cleaned the IACV some more and it help with the issue but the RPM dip was still there. They decided to check if it was the Throttle body and when they carefully inspected it it was the problem. Ive included a photo as it was bent. the picture of it is in the closed position and you can still see through it. Enjoy, I upgraded to a blox 68mm tuner series throttle body.

Broken throttle body

stupkid

Does it still drive like usual besides the jumping rpms?


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CounterSunk

Yup besides the RPM jumps, and the jumps only happen sometimes. I drove it for 2 hours today and it didnt do it once but when I parked it for a couple of hours and turned it on it did it again but as soon as I drove it for 10 minutes it stopped. Yesterday it was running lean at around 1700rpm at idle. Todays its idling normal at a 1000rpm and never once went over 1000 the whole day today.

stupkid

Maybe something in your intake manifold (oil, carbon buildup, etc) slowing down air entry and causing heat soak while parked?
Also do you think something got sucked into your intake?
Try cleaning the manifold.

CounterSunk

Thanks for the reply! I will check that tonight right after work

CounterSunk

Update: So I havent replaced the spark plugs yet but I did change the air filter and clean the intake manifold. No more weird idling but the dipping is still there. Instead of dipping from 500-2000RPM this time it did it from 1500-2000RPM. It didnt do it all day except for tonight. So again it still happened "intermitently" but its not as bad as a drop this time. Im changing my spark plugs tomorrow to Denso IK24 and getting the shop I go to to check for any visual leaks that I may have missed.

vividracing.com

I'm going to say it's either a vacuum leak, or IACV (Idle Air Control Valve) issue.

davidc1

My 03 with 145000 just started doing it as well. With several of my old GS-R's, when it would start to do that it was the IACV.

CounterSunk

Thanks guys Im not to familiar with that part? Would it just probably need a cleaning or an entire replacement?

UPDATE:
So I cleaned the IACV and man was it dirty. I took photos as I used some cleaner a rag and Qtips lol.



- Started the car from a cold start after cleaning the IACV and no dipping. I let it idle for about 5 minutes then took it for a drive. No idle dip when sitting at a stop light or stop sign. Came back home turned the car off then about 10 minutes later I came back out to move the car in the garage and still no dip. Hopefully this fixed it! Thanks everyone

CounterSunk

Ahh! It came back... Im really starting to think its a vacume leak somewhere but Ive checked everywhere lol. It only happens to the car within the first couple minutes of starting it and never happens to me when Im actually Im driving. Sorry for doubling posting in advance..

Update: Be a good idea to get it on video so thats what I did. Here it is on video
http://s442.photobucket.com/albums/q...120_144218.mp4