2000 Civic SiR low, rough idle

Hey, I was wondering if anyone could shed some light on what would be
causing this:
2000 civic sir with 120000km on it.
Intermittently idles low, like 150rpm, with a rough feel to it. If I tap
the gas rpms jump then just drop right back down to 150rpm or so (the line
just above the very bottom line on the tach). It slowly comes back up to
750rpm or so but if you tap the pedal it drops right back down again. It
can do it once or 4 to 5 times in a row this way. Oil changes done
regularly and according to the user manual the plugs don't need to be done
until 160000km.

thanks for any advice
dave

 

Forgot to mention... it has a Short ram air intake as the only engine mod.

 

I'm not at all familiar with your model, but most modern cars do that when
the throttle body and/or idle air control valve (when it exists) gets gunked
up.

Mike

 

Ding ding ding! Aftermarket parts!

Remove, reinstall original parts and see if problem goes away.

 

extremely doubtful an intake would cause this problem, its about as likely
as having a flat spare tire would cause this issue

 

I can see how faults in an air intake could affect idle. If there is a
flapper (intentional or otherwise) in the intake and it is giving any sort
of trouble, it could certainly choke the engine at low air flow (idle).

An important first step in troubleshooting is to make everything right, then
see what problems you have.

Mike

 

yes, but gathering from what he said, the issue didn't start from adding the
intake, in which case there is nothing that could cause the issue, its a
piece of mandrel bent pipe, hard to have something go wrong there

 

He never said when it started.

First step in a proper diagnosis: Install original parts.

If problem disappears, you know his "short ram" is causing the problem. If
the problem recurs, then you know it's not.

The OP also has provided very little other information. What would help
here is:
1) Does he have EGR?
2) How does the car start? OK? Lots of cranking needed?
3) How's his gas mileage?
4) How is the car off-idle? Any hesitation?
5) When does the low idle start happening? Cold? Warming up? Full warm?
6) Does it happen in the wet and dry, or just in the wet?
7) Does the temperature gauge go up all the way to the middle within 5 or 6
minutes of driving?
8) How new are the ignition wires, cap and rotor? Are they aftermarket too?

 

When? Cold? Warming up? Full-warm?

Has the MIL lit up?

That's 500rpm, not 150.

Does the car warm up so the temp gauge goes to the middle within 5 minutes
of driving?

Did the problem start soon after you installed the "short ram"?

Does it happen even on dry days?

Your EACV is attempting to adjust the idle speed to where it should be, so
that part of the system is working. How clean was the throttle body when
you installed the ram? Did you reset the idle speed properly?

 

The root of the problem is that aftermarket parts introduce unknown issues
into the system. The customer can spend an enormous amount of money to find,
say, mice have built a nest in the ram. Since the problem doesn't appear in
the unmodified car because of a nuance of design (possibly learned the hard
way by the OEM) it is overlooked.

I once spent $900 to have a dealer fix a problem in our Volvo. The problem
turned out to be aftermarket injectors I'd put in - they tested perfectly,
but for some reason didn't work in the car. Drove me crazy.

Mike

 

OK first off thanks everyone for the replies.... sorry it took me so long
to repost.

This does the same with the OEM intake back on the car.

1. I am not sure if I have EGR...
2. Starts well most times but sometimes will turn over more then normal (say
3 to 4 turns I chaulked that up to low fuel)
3. Gas mileage... 300km to 370 per tank... It has been cold her lately and I
do 90% city driving, seems low but I used to drive a Civic DX getting 500
to550km per tank.
4. Off-idle... no hesitation, but seems maybe slugish sometimes... but
wouldn't be noticable to anyone but me... sometimes i think its just me :0)
5. Idle problem starts happening once it is warmed up. Never when it is
cold and idling high to get warm. When started it revs around 1500rpm then
once warm it is down to 750rpm and once stable at 750rpm, with a few stop
and starts in traffic it drops down to 150 or 200rpm (if you look at the
tach it shows a Large white line as 0rpm and then another Large white line
that is shorter and the gauge is reading just above that short Large white
line. Round 200rpm. Engine sometimes shakes then slowly comes back up to
750rpm. There has been times that if I don't wait for it to come back up
and try to take off it sounds like when you dont give the car enough gas
before you let the clutch out.
6. Wet dry? doesn't mater if it is wet, dry, warm, cold, does it in all
conditions.
7. Temp gauge does go up to the middle like it always has within a few mins
of driving.... depending on how cold it is.
8. Ignition wires and plugs are OEM, never changed (platnum plugs changed at
160km I do believe) The plugs + rotor have been "serviced" 2 times by the
dealership. Once at 46000km then again at 96000km... (it has 120000km now)

It does go down to 150 or 200. Sometimes when comming off of the
mechanical idle and the ecu takes over it will drop to 500rpm for a spit
second then quickly come back to 750rpm, but this is different then what i
am talking about.

MIL has not lit up.

I didn't notice any gunk in the throtle body when the SR was installed but
then again .. i am not really shore of what I should be looking for?
buildup? Blackened areas?
How do I reset the Idle speed properly? Leaving the battery off for 20 or
30min?

thanks again!

 

Have a look at the sticker under the hood. It will list some things on one
line, like SFI, HO2S, TWC, that sort of thing. If EGR is listed, you've got
it. If not, then you don't.

Been a while since I looked at the tach on your generation, but is there
not
1) a zero line
2) two lines above that, unevenly spaced, and
3) a 1000rpm line?

You've got an air leak somewhere, I'm sure. The ECU sees this and is trying
to force the idle back up to where it ought to be.

Carefully check any and all vacuum connections to the intake plenum. Make
sure none are disconnected, pinched, split or misrouted.

 

Thanks I'll check sticker, tach and vac lines when i get a chance and post
back.

 

Been a while since I looked at the tach on your generation, but is there

It is pouring down rain today.. so I can't check for the air leak or the
sticker but i did look at the tach today. There is a zero line then 5
small lines between the zero and the 1000 line all evenly spaced. The one
closest to the zero line is thicker like the zero line. Rpms drop to just
above the thick 1st line.

 

That's 500 rpm. Count up.
"thick 1st line": 500
2nd line: 600
3rd line: 700
4th line: 800
5th line: 900
1000rpm.

The tach does not reliably read below 500.

 

Man I should have looked closer! Your right TeGGer, so that means that when
it idles low it drops down to 500rpm or a little above that.

 

If that's the case, you may simply need an idle speed adjustment.

Make sure that throttle body has no soot or gunk, then see these files:
www.tegger.com/hondafaq/misc/11-111.pdf
and
www.tegger.com/hondafaq/misc/11-112.pdf

They're from this site:
http://www.hondahookup.com/manuals/

They are actually for the '98-'01 Integra, which has the B18C engine.
You've probably got a B16A3, but the procedures and settings can't be a lot
different.

Have a poke around and see if the hardware looks the same. If so, perform
the idle speed adjustment as specified and see if the problem goes away.

If the base idle is far off enough, the car won't even idle at all until
fully warm. And you'll probably get the MIL lighting up. Don't worry about
that. It will go off again once the IAC and EVAP are reconnected.

I find it best the disconnect the IAC and EVAP when the engine is cold. It
gets pretty hot.


Good luck.

 

2 Kings 9:20?

:^)

 

Would I still need an idle speed adjustment if it didn't happen all the
time?

I checked for Vac leaks... I didn't notice any cracks.. but I am not really
sure how to really check for a vac leak.

I probably should have mentioned this before but I have taken it into a
honda dealership and on 3 occations they have told me 1st time. it is your
intake system causing it
2nd time. we couldn't find anything
3rd time. we adjusted your base idle (basically found nothing again)

thanks again!

 

I hunt them with a stethoscope with a slender tube for a probe.


Tom Willmon
near Mountainair, (mid) New Mexico, USA

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