98 honda accord missing-stumped

I have a honda accord lx 4cyl vtec that has 70k miles. It is missing
pretty bad. The check engine light is on and flashing sometimes. The
codes set are 71 (random misfire) and sometimes 72,73,74. I suspected
ignition so changed in sequence the coil, rotor, distributor cap, plug
wires, plugs, ICM and then the distributor assembly (with cam position
sensor) none of the changes made any difference. I have also checked
valve adjustment, compression and pinched the return fuel line and
listened for changes. I have listened to the injectors with
stethescope and they are consistent. I pulled the fuel pump from the
tank and checked for screen clogged etc. None of the above has led
anywhere. I don't know what to try next. Help!

 

Just curious: Have you checked the ignition timing?

 

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If you were looking for screen clogged, does that mean you're only
having high-speed misfire, because luel filter or plugged screen would
only show up at high load / speed.

Whether it's missing at low speed or high speed, I'd run a can of
Techron Injector cleaner through it, or at least a couple tanks of
gasohol, but then I always try the cheapest fixes first.

Does it ever show signs of FLOODED engine first thing in the morning?
(see manual)

'Curly'

 

It could be a number of different things. If you don't have any equipment
needed to check various things, I advise you to take it to a local
mechanic that you trust. Mechanics will hook up a diagnostic computerized
engine tester to your engine and quickly determine the cause of the
problem.

I once had this problem and eventually took it to a local mechanic that
had a great reputation. He determined that the problem was the spark plug
wire that ran from one spark plug to distributor. He said that it could
have been lots of other things but his computerized tester quickly found
the problem.

 

elimnate the simple stuff - is the coolant level ok? and i mean
checking inside the rad, not looking at the level of the expansion
bottle. if the level is not high enough, the engine can get a false
"cool" signal on the head temp sensor. the ecu then injects too much
gas, and when the engine is hot, it will randomly misfire. i had a
civic with this problem and did pretty much all that you did before i
figured it out. _never_ trust the level in the expansion bottle. if
there's the smallest air leak in the coolant system, when the engine
cools, it sucks air back through the leak rather than refills from the
expansion bottle, so the coolant can be significantly low without it
being obvious.

 

I have checked it, I forgot to put it in my description, good catch

 

I just checked the radiator fluid and it is to the top. I wonder if
the sensor you talk about could be bad causing the same thing. I will
see if I can get to it through the computer.

thanks

 

Believe it or not I have had different shops look at it. Both have
hooked it up to computer OB2 and can't find anything. Thanks anyway