'94 Accord. Engine Surging

94 Accord 2.0i. Engine is surging between 1000rpm and 2000rpm when
stationary or the clutch is dipped when driving. Engine light has not
come on and there appear to be no fault codes present. Otherwise, the
car drives perfectly ok.

Any suggestions? Failing lambda sensor perhaps?

Please help....this is the mother in law's car and it would make my
life much more peaceful as well as earning major brownie points with
the wife!!

Matt
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How about you take that advertisement crap out of the bottom of your
post?

And it sounds to be your IACV (Idle Air Control Valve) located on the
back of throttle body, extending onto the intake manifold. When those
go bad, the idle tends to surge like you're speaking of. If that's not
it, try bleeding the coolant.

This has happened to me quite a few times, and everytime it has been
either the IACV, or coolant needed bleeding.

Good luck with it.

-Wes

 

Just a thought. Older Accords (86-89) had what I think was called a
fast idle control mechanism that was basically thermostatic in nature
and ran on coolant temp with one sensor, I think. In failure (as a
thermostat fails) it would make the engine race at idle and with the
clutch depressed in the same RPM as you described. BUT not sure if
this/these cars have the same set-up. $40-50 bucks at salvage yard and
a DIY job if this is the case. Just a thought, but not sure of the
specifics.

KL

 

Why bleeding the coolant? Are you saying air in the coolant would
make
engine stalling or rough idling? why?

 

If you have air in your coolant system, gaps in the coolant if you will,
when that air flows through the IACV, it causes the idle to drop. When I
had my IACV not attached to anything when I had ITBs (Individual
Throttle Bodies) on the Civic, the idle was horrible. We made a plate
to bolt it to that sealed it off properly, and the idle returned to
normal.

When we reinstalled the normal manifold (ITBs aren't too good for daily
driver, I learned this the hard way.) and we had everything back to how
it should be, the idle was still sparatic. After about 10 seconds of
bleeding, the idle returned to normal idle.

Hope that answers your question.

-Wes

 

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The temp sensors all have to be immersed in coolant or they convey a
wrong reading to the computer. If there's ANY air in the system it will
confuse the computer at some time in the warm-up cycle. Filling the
reservoir is the first place to start after topping up the rad. Air
can't leave if there's no 'spare' coolant to replace it. Fill the
reservoir to MAX before driving, two or three times. Tap water is called
HONDACIDE.

'Curly'