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Discussion Starter #1
As some of you know, had to change the head gasket on my new-ish 02 EX.

I cranked it up, it went up to high idle, then started dropping towards a lower idle. After about 10-15 seconds, the idle started bouncing between 1500 and 2500 rpm. I let it run like that for about a minute, to see if it would stabilize, which it didn't.

I shut it off, let it sit for about two minutes, while I popped off the cruise control cable (which seemed a little too tight, although it was at the same adjustment as when I took it off).

I started it back up, and the idle was holding steady just over 1k, when I bumped the pedal getting out of the car, and the idle started bouncing again...


So, to everyone here, I'm picking your brains, as I'm not entirely where to start looking. Maybe vacuum leak? I'm a little confused about this one. And I don't like troubleshooting with all these damned sensors on the newer cars...
 

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Brokedick Millionaire
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Coolant levels will NOT effect idle.

try driving a D15B7 with a cracked head for 20k miles...idle was never an issue.
 

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Discussion Starter #5
Coolant levels will NOT effect idle.

try driving a D15B7 with a cracked head for 20k miles...idle was never an issue.
I agree with you on that, but I did have an issue with my B2 when a coolant line burst on the throttle body. That was just a very rough idle, though.

Idle is smooth sounding, everything sounds good, just bouncing.
 

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Discussion Starter #7
Check the bolts on the intake manifold. Happened to me once and the middle bolt under the manifold was a little loose... Tightened it up and voila fixed the idle.
That's what I'm thinking, especially since it has that plastic intake manifold with the o-ring seals. I'll check it out when I'm done with work.
 

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Coolant levels will NOT effect idle.

try driving a D15B7 with a cracked head for 20k miles...idle was never an issue.
umm air in the cooling system will give an erratic idle from the iacv not working properly. happens every time i take my head off and numerous times ive done head gaskets.
 

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When I replaced the b2 in my CRX, I had EXACTLY the same symptoms... they went away after tinkering with the IACV.
 

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Meat Popsicle
91 CRX Si
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umm air in the cooling system will give an erratic idle from the iacv not working properly. happens every time i take my head off and numerous times ive done head gaskets.
Looking at my FSM, there's nothing that mentions engine temperature.






I was under the impression that the coolant lines are only there to prevent it from sticking in cold conditions.
 

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Discussion Starter #11
umm air in the cooling system will give an erratic idle from the iacv not working properly. happens every time i take my head off and numerous times ive done head gaskets.
Well,I most definitely don't have the cooling system full, yet. These engines are a pain in the ass to bleed air out of. Not too sure if I'm going to work on it tonight, though. I've had too many nights of working late and not sleeping...

When I replaced the b2 in my CRX, I had EXACTLY the same symptoms... they went away after tinkering with the IACV.
Very good point.
 

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Discussion Starter #13 (Edited)
Ok, car finally threw a CEL at me. About damned time, too, because I can't seem to find any issues with it. The codes are confusing me a little, though.

The one that makes sense is:
P0122- TPS low input

I unplugged the TPS while it was running to see what would happen (before I borrowed the scanner), assuming that had something to do with it. It didn't. Revved to about 3k rpm's, and stayed there until I shut the car off.

The other four are confusing, though, as the thing seems to be running very smoothly, aside from the bouncing idle.

P0300- Random/multiple misfire (x2)
P0302- Cyl 2 misfire
P0303- Cyl 3 misfire (x2)
P0304- Cyl 4 misfire (x2)

And, the 300, 303, and 304 were all listed twice....?

I can't figure out why I'd have a misfire, unless some other sensor is fucking up, and it's just showing up as a misfire, instead of a sensor fault/failure.

I did clear the codes, then started the car a few times to see if they came back. So far, not yet, but it took quite a few times of trying just to get a CEL to begin with...


EDIT: As a side note, when I first started it earlier today, before the CEL came on, it ran very nicely for about a half minute, and then started bouncing.
 

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Discussion Starter #15
That's what doesn't make any sense. When I put the head on, I triple checked (against the pics I took) to make sure the head was at Cyl 1 TDC on compression, which is exactly where it was when I removed it.

Once I put the timing belt on, I rotated the engine over many times, not only to tension the belt, and check that it was lined up, but also to check my valve lash.

Everything was lined up dead-on after rolling over the engine at least four or five full revolutions. Checked all the timing marks.

That's why I can't figure out the misfire issue. Especially since I'm getting cylinders 2, 3, and 4, but not 1.
 

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Civic turbo Hx/Ex
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Theres a can of worms that I don't know much about. But if your running misfires on those cylinders make sure the coil pack is sporting the correct cylinder. I'm sure your all over that, but thats about all I know when it comes to COP. Also double check and make sure all your grounds are solid!
 

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Discussion Starter #19
Yeah, it's definitely a pain right now.

I got the CEL to come back up. Now it only shows p0300, p0303, and p0304.

Interestingly, those two coils were much newer looking compared to the other two...

I don't know if that's got anything to do with it or not, and I'm hoping someone more familiar with the COP and 7th gens could chime in, but I'm going to keep poking around.
 
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