Your "OBD-I" scanner is a paper clip.
You short the Service Check connector on top of the ECU with the paper
clip, turn the ignition ON, then read the Check Engine light flashes.
specifically page 15.
Thanks for the pdf. I was hoping for something more substantial, like
hooking up the serial port of a PC, running some OBD tool, to a diagnostic
port of the car and collecting performance data. I must be dreaming.:) I
am specifically interested in learning about which cylinder is misfiring
during engine idle. What other options do I have? There is no problem with
ok, so that's the real issue you're getting at. messing with the ecu
won't fix that. and diagnostics on the obdcII ecu aren't that
in relation to the exhaust, the gas flow dynamics are not optimized for
idling, they're optimized for driving. flow will not be entirely
"smooth". that said, if the flow is worse than normal, it's easily fixed.
yes you can, but it's massively expensive overkill and won't fix this
problem. go to http://boomslang.us/ and read about their conversion
kits if you want to do it the factory ecu way.
getting back to your existing situation, check the ignition system and
oxygen sensor. non-oem sensors are often abysmal and confuse the heck
out of the ecu - don't use them. fresh ignition components help
significantly too because the voltage needed to spark an idle mixture is
greater than that needed to spark a running mixture. weak or failing
insulation on the plug leads means it may run ok on the freeway, but
give weak spark on idle. same for old plugs, worn distributor cap, etc.
lastly, check the ignition timing. when doing it, [with the service
connector on] check to see whether the timing marks are lashing back and
forth. if they are, the timing belt could be loose - the ignition
sensors run off the distributor which runs off the cam. loose belt
means the whole timing for the vehicle is subject to "noise" and again,
that affects smooth idle. correct valve lash helps too.
i did - that's what all the verbage on the oxygen sensor/ignition/timing
system was about.
yes. but don't do it because you'll need a second oxygen sensor, the
obdcII ecu data recorder could be used against you in the event of a
crash investigation, and you'll be speed limited.
yes. with the service connector in place, if the belt is loose, you'll
see the timing marks jumping back and forth. if the belt is tensioned
correctly, they'll be rock solid - assuming the rest of your ignition
system is working well of course.
Interesting that you mention a loose timing belt may cause this
behavior. This problem started after timing belt was replaced.
I will check ignition timing with a light asap and report back what I
Thanks for the advise.
ODB was the original standard SAE-derived system installed from 1988 to
1995 in some California vehicles. The rest of the US (and Canada) used
automakers' own proprietary diagnostics system.
Starting in about 1994, the entire US was forced by US federal law to begin
phasing in an updated version of California's original OBD. This updated
system was known as OBD-II.
After some thought here, I suppose you *could* logically call the original
OBD "OBD-I". World War I was not called that until they had a second war,
so the logic is similar. However, Honda's diag system is not the same thing
as the original OBD.
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