OMGWTFBBQ!

Well I've got a tiny problem with my car, 97 Civic EX, JDM 98+ B18C R-Spec, all stock with CAI and Apexi Exhaust. I've narrowed the problem down to one of two things.

First, the problem: When cruising on the interstate for extended periods of time (more than 30minutes) the car will start to surge and buck very slightly under very very little throttle. It almost seems like the ECU can't tell if the throttle is open or closed, and it just goes back and forth adding and cutting fuel. I also have an issue with startup idle, every 10th or so time I start the car, the idle will wander around a little bit. This problem I was going to write off to a dirty IACV, but the weird thing is, if I rev the car to its rev limiter, the revs will drop and the car will idle perfectly at 1500 till it warms up, when the idle drops perfectly to 700. I can also fix the problem with surging on the interstate if I drop into 3rd and do a full throttle pull to 9000rpm.

This makes me think that the problem is not with my TPS or my IACV respectively, but stems instead from buildup on my 02 sensor. My question is, will a gunked up 02 sensor cause a wandering idle, or is the IACV to blame? And does this indicate an 02 sensor on its last leg of life, or is it merely carbon buildup? I have no CELs at all.

austinkli

could very easily be the o2 sensor. also, make sure all your spark plugs are getting spark. i've seen similiar things happen when people had only 3 cylinders firing. check the cap and rotor button to make sure they have good contact.

OMGWTFBBQ!

I wouldn't think it was a misfire, I've had a cylinder off and the damn thing sounded like big diesel truck, it would backfire through the intake if you opened the throttle at all.

All my plugs have less than 3000 miles on them, wires are only a month old. I'll check the dizzy, which I haven't done at all since the motor was swapped in back in march. I would also think a bad dizzy would mean a more regular problem, these issues are very intermittent, maybe once a week the idle will wander at start up.

austinkli

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by OMGWTFBBQ! &raquo;</TD></TR><TR><TD CLASS="quote">I wouldn't think it was a misfire, I've had a cylinder off and the damn thing sounded like big diesel truck, it would backfire through the intake if you opened the throttle at all.

All my plugs have less than 3000 miles on them, wires are only a month old. I'll check the dizzy, which I haven't done at all since the motor was swapped in back in march. I would also think a bad dizzy would mean a more regular problem, these issues are very intermittent, maybe once a week the idle will wander at start up. </TD></TR></TABLE>

just basing it off my experiences, once my rotor button was loose, the screw wasnt holding it in tightly somehow, and every once in a while a plug wouldn't fire because it would miss contact. i thought the same thing and never checked it. after much agonizing as it got worse, replacing all kinds of parts, i finally found it was just a $13 rotor button.

Vindicator9000

I had this exact same problem. I took off my throttle body and cleaned it really good with brake cleaner. Think it was possibly TPS. Other thought was that my butterfly seemed to be sticking closed at light throttle, and cleaning up around it made it open much smoother.

Try that.

OMGWTFBBQ!

I didn't think about the TB. I'll clean that and check the dizzy and see if that doesn't clear things up a bit.

OMGWTFBBQ!

Well today was an interesting day. I cleaned up the throttle return spring and all that. Then I got to the dizzy. I took the three bolts out, pulled the cover, and immediately noticed everything was covered in a brown colored dust, seen below is the dust that was under the cover.



This kinda stumped me, since I've never seen a dizzy full of dust before. I figured that was causing my interment problems, so I clean the dust off the rotor and the contacts. As I clean the rotor, I notice it has a fair bit of play, which is very odd. I push it back and it moves about an 1/8th of an inch, then I give it a tug, and it pops right off. Well I notice immediately that the set screw is obviously missing, then I notice the rotor has wear damage around its base.



I set the rotor aside, and pulled off the plastic cover that shields the internals. Low and behold I have now found the rotor set screw. It has apparently backed out of the rotor, and eaten itself into the plastic shield, becoming stuck and wearing the base of the rotor.

EL Vap133

Wow, how long were you possibly driving like this for approx.?

OMGWTFBBQ!

This problem has only existed for 2 months or so.

I reassembled everything and fired it up, it was running exactly the same as it always does when it doesn't hunt for idle.

If it starts hunting again then I'll go through the hassle of taking apart the IACV and cleaning that.

But when I fired it up I did notice a little bit of white smoke and I'm not loosing any oil, but I am loosing some coolant I'm praying to every god that the coolant is solely being lost from the lower coolant line and that I don't have any problems with my head gasket

austinkli

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by OMGWTFBBQ! &raquo;</TD></TR><TR><TD CLASS="quote">This problem has only existed for 2 months or so.

I reassembled everything and fired it up, it was running exactly the same as it always does when it doesn't hunt for idle.

If it starts hunting again then I'll go through the hassle of taking apart the IACV and cleaning that.

But when I fired it up I did notice a little bit of white smoke and I'm not loosing any oil, but I am loosing some coolant I'm praying to every god that the coolant is solely being lost from the lower coolant line and that I don't have any problems with my head gasket </TD></TR></TABLE>

go ahead, ask me how I knew exactly what the problem was.

OMGWTFBBQ!

lol, we'll see if the problem is fixed or not. Remember, the hunting idle was only about once every ten starts.

austinkli

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by OMGWTFBBQ! &raquo;</TD></TR><TR><TD CLASS="quote">lol, we'll see if the problem is fixed or not. Remember, the hunting idle was only about once every ten starts. </TD></TR></TABLE>

True, perhaps it just hadn't gotten that bad yet. lets hope so that you don't have to fix anything else yet. I didn't figure that problem out until almost $200 later. on me for not checking the simple things. Of course, i never though that a bad dizzy cap would make my idle hunt, then again, i also never thought that my screw would come out allowing it to sometimes make contact and sometimes not.