Thanks both of you for educating me. I'm still not sure what to do although
when I get a moment I am going to try to test the TPS Voltage -- if my
limited technical skill and analog tester allow. In the meantime, let me
pose a question that I've had for months:
At some point during warm-up, the ECU changes its outgoing instructions from
"warm-up mode" to "operate normally." This is the exact moment my problem
always starts. What is going on in the sensor communication to make that
change happen? Which component can do its job just fine and idle at exactly
1K during warm-up, but drops the ball and falters below 750 when the
instructions change? In my non-tech interpretation, that's the culprit I'm
after. It seems so clear cut because when I'm having the problem it always
plays out exactly the same way.
Any ideas? Thanks again for taking time on my problem.
if it's only at idle, it's not the igniter - igniter would be all across
the rev range. describe again the exact symptoms and how they show
themselves. if it's the idle control system, it's relatively easy to fix.
99 Accord 4 cyl 5 speed, 184,000 mi.
Long drive at high speeds produces the following condition:
Car warms up normally at full, steady idle.
When at operating temperature, car starts to falter at low idle speeds.
Often kills engine when slowing down to a stop.
At it's worst, it died every time you stopped. Since replacing various
items (coolant, PCV, spark plugs, wires, distributor cap, rotor, coil) I
thought I had it beat.
The problem reappeared after a few months of short (less than 50 miles)
trips with no problems. Brought on by a drive on the highway lasting over
Currently the car falters at low idle after slowing down, but usually
"catches itself" and resumes a normal idle.
I would like to do more highway driving in a few weeks and would love to
solve this riddle.
Your help is appreciated very much.
here's what i'd do.
1. check the iacv, idle air control valve. they have a wire mesh filter
in them, and they tend to get caked with soot and grime. clean that
screen and it'll make it easier for the valve to kick in sufficient air
for the motor to idle properly. reset hot idle speed per the book [or
google this group]. also, make sure there's no gotchas like timing
being out, etc.
2. check the valve lash. unlike a lot of other vehicles, the gap on
hondas closes, not opens, so valves stay open longer, and this
interferes with idle behavior. if they close too much, a valve can
burn, and this /definitely/ affects idle behavior! you'll need to
replace gaskets when doing this.
3. once you've eliminated those, and checked the throttle body, vacuum
hoses, throttle linkages, etc, go back to the ignition system.
for ignition, only use honda parts for the distributor cap, rotor and
coil. plugs and leads we discussed before. [you used ngk or denso
plugs, right?] make sure there's no fingerprints from sweaty fingers on
anything electrical, and that there's no cracking or tracking marks
inside the cap or on the rotor. i've had a brand new rotor cap be
defective before, so while unlikely, bear that in mind.
let us know how that turned out. also, there's no codes in the
computer, correct? if there are any, report back.
Thanks, Jim. That's a lot to think over. And, yes - there are no trouble
light codes associated with this problem.
My book doesn't cover the iacv, so I'll google around and see what I can
find. Any hints where to find that mesh filter? Thanks again, I will let
you know what happens.
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