Bouncing Idle
 

Alright so I just had my timing and TPS checked this weekend but the past couple days when I took out my car the idle has been bouncing like nuts for at least the first 10 minutes of driving. When I start it up it goes to high idle, then drops down to about 1500. Then as soon as I start driving, then next stop I come to "idle" consists of bouncing between like 1400 and 1800 (vroom vroom style).

Yesterday after about 10 minutes of driving it finally settled down (though was still a somewhat high idle ~1500). Today I didn't drive as far so it never settled down but I tried to mess w/ a few things after I got home- put the idle screw all the way in and no change in the idle, took it a ways out and got it to idle at ~1900.

Wondering if it would just be a vacuum leak somewhere in the intake that just seals itself as the car heats up? Or is it a sign of my sign of low compression or something maybe (motor has 155k)? Of course this weekend I drove about an hour before getting the timing and TPS worked on so this issue didn't show up at all and we got it to idle perfectly.

I'm having the same issue....I set the timing, pulled the jspec BAC and replaced it with a USDM...set the TPS....and it's running a little better...

Now I gotta swap the jspec TB out and replace it with a USDM....hopefully that helps...

You check the idle adjust screw? Cause that idle is way too high. Your thermowax might also be bad. That could cause the high idle, and maybe the idle problems.

Car at normal operating temp. Ground the initial set connector and adjust the idle speed.
Make sure the timing is set correctly. I know you said the TPS was adjusted, but go back and verify the "one light lit" condition. Remove the electrical connector to the BAC. Test it to see if it is working. Ground and 12V to the terminals. You should hear a click. You still might want to take it off and give it a good cleaning. If it sticks, it will cause idle problems.

my car does the same, when the engine finally warms up (which takes about ten minutes) it stops. maybe its a natural thing, i'm not sure, but your not alone.

My car did something silimilar, althought not as severe as yours. Mine would bounce between 400 and 800 rpm's. I just redid all my vacuum hoses this past weekend and changed the UIM to LIM gasket and the UIM to dynamic chamber gasket. Now my idle is a puuurfect 800 rpm :)

Mine does the EXACT same fucking thing. Still havent solved it.

Vacuum, ground wires, tps, emissions. I will put my money on vacuum

Funkspectrum - JDM and USDM are the same thing no different.

Janus - The high idle steps are normal operation to the stock AWS system. You have a VAC leak is you are unable to adjust your idle down to specs and the thermal wax is working properly. You cannot adjust the idle until the system is fully warmed up is the AWS system is still in tacked as it sounds yours is. Try unplugging your TPS and hunt for VAC leaks. Your car has to be idling properly at 750ish to adjust the timing or the timing will be off.

BinaryRotary – Read reply to Janus

mine does the same thing...i'm pretty sure its a vac leak

cprx7 - are you in hoboken? I never see your car around

well im going to have to go with the majority here i just read one of my many tear down and rebuild manuals and it is 90% chance a vacume leak .... lucky for u not to rediculous on the wallette

Well looks like I'll be hunting vacuum leaks tomorrow morning. Any alternatives to the starter fluid or w/e method?

Thanks for all the replies guys...

You spray carb cleaner around the motor and see if the idle changes. DO NOT USE STARTER FLUID! You will blow yourself up

Use NON-CHLORINATED Brake clean.

LOL! Whoops, I think i was a little tired last night...

Vacuum leaks...........You're motor goes through the start up procedure just fine and idles just fine until the heat builds up and the old "hard as cement" vacuum lines heat up and expand allowing a vac leak and...............................


Idle bouncing/hunting.

Rather than hunting for a vac leak this week and then devloping one again in two weeks. Take off your Intakes and buy new gasket for them and buy about three feet of the smaller vac hose and two feet of the larger diameter and replace all that shit with nice new supple vacuum hose........Your 7 will love you for it and won't leave you stranded. and becuase you didn't get stranded your girl will give you some lovin' as well.

Wow, you don't even know how true that is. Well I already got some carb cleaner and such so I think I might try out some hunting tomorrow and hopefully I can find it quick just to fix it for Sevenstock. I'm not sure I'll have enough time to replace all the hoses tomorrow... Unless... Oohhh maybe rx7doc will be free friday!
*runs off to PM the doc*

That job of replacing all the vac lines is a Saturday Morning until Sunday afternoon type of job. DO NOT start it if you are attempting to go to 7Stock. You'll try to rush and mess up something and I'll have to come pick you up outside of Bakersfield.

Just do the carb cleaner thing to get you by for 7 stock and NEXT weekend take that stuff apart and replace each line.

My first time removing the intake manifold and I had it off in 30 minutes, took my time replacing all the hoses and had it all back on and working the next morning. Took me about 4 to 5 total time I guess if you add it all up. Like I said, my first time doing it and I took my time.


Yeah, Hoboken.. it's my daily driver too.. weird how you haven't seen it. Unless you go to SIT and the only part of hoboken you know is the walk to blockbuster or to bagels on the hudson :D

YOU can tell him to tear all that stuff out Friday afternoon before SS8, but I won't.

Actually, I am not telling him to do anything. I am merely sharing my last weekend's experience.

jdm and usdm UIM are not the same the JDM bac valve don't have idle adjust screw hence the JDM UIM doesn't have the appropriate holes

I put up thread asking someon to take a pic of thier USDM s5 UIM so i can confirm this information and if it true drill the appropraite hole in my JDM S5 uim

Tell that to the one in my gerage with a big fat allen screw on the face of it.

Well that is just odd i went and looked at 5 turbo S5 JDM UIM and not one of them bac valves has screw in them

and i saw two turbo S5 usdm uim and the bac valves have star shapped screw in them

can u post a pic up

Mine is S4 maybe they changed them.