emfederin

Here's my bottom line problem:
All 4 cylinders on my 2001 honda civic ex 1.7 have suddenly started misfiring.

Details:
Car is a 5 sp manual with 153K miles on it, and has always run well.

The other day (tuesday evening) I went food shopping and the car suddenly started bucking and hesitating the entire way. This started from the moment I started my car, and persisted whether I was in neutral idle or driving.

When I got to the store I checked my oil (just "because") and it looked about a qt low, so I went and bought a quart and put it in. I then restarted the car, and the yellow "check engine light" came on.

I managed to get home and I parked the car overnight, planning on trying to go to autozone the next day and have my computer read.

Wednesday morning I started the car to go to autozone, and the CEL started blinking. I drove anyway and only got to the end of my street before the blinking unnerved me so bad I went right back home again. About an hour later I came back out and restarted the car, then opened my hood to check for anything I could see or hear. Nothing obvious, so I went to turn the car off - and the CEL was no longer blinking. Classic "WTF" moment...

Cutting to the chase, I managed to get to autozone, and the tech read my computer and informed me that I was having misfires on all 4 cylinders.

I brought the car home and it's been parked since.

Now it's extremely unlikely for the problem to be "muh coil packs" or "muh spark plugs", since as I stated, the car has always run fine and suddenly all 4 of them start misfiring as though I had thrown a switch, which clearly implies the problem lies upstream from the coil paks.

I have a software version of the honda shop manual, but the "engine electrical" section is a bit cheesily laid out. As far as I can tell, the coil packs are fired by the "ECM/PCM" (I'm guessing that's the car's computer?), but I can't figure out how the computer knows when to fire them. How does the computer know this?

So my question is, can any of you guys think of ANY reason for how this could suddenly start happening?

ol Dusty

iTrader: (2)

The car uses a crank position sensor mounted near the crank pulley. It's firewall side kinda hidden by the pulley. You'll see the harness going to it if you look on the right side of the timing belt cover. Usually this sensor and the harness would throw a code it self tho along with anything else that could be causing the miss on all 4. One thing that would really help with pinpointing the actual issue is having the actual code(s) pulled from your ecm.

Many things could be causing your miss, it might not be that your electrical has any issues at all. Maybe your fuel pump is weak/plugged, or the regulator (inside the tank on your car) I can't remember 100% if your car has a fuel filter under the hood or only one in the tank as well, but your car is a returnless fuel supply, and those usually from what I've seen are in tank only.

Potentially you could have issues with things not directly related to the fuel/ignition but throwing things off making the computer dump the wrong amount off fuel to a level that just can't ignite and that will cause a miss. Also hows your coolant level/condition, very unlikely but a head gasket leaking into the cylinders or coolant somehow leaking into the intake side thru your cars EGR system (some 01 civics don't have an EGR) would also be a potential cause.

So again I guess the first thing I'd need to know to better help point you in the right direction is what code(s) exactly were found?

emfederin

Ah, hell! I see you answered this 2 days ago!

I apologize; I'd started checking in with decreasing frequency after not getting any response for a few days. In any event, thank you very much for yours!! :-)

The timing of your question is almost uncanny. Note that I had already had the computer read by autozone who told me I was having "random misfires on all 4 cylinders", but the only codes he actually mentioned by name were 301 and 302.

Now as it happens, just today I *HAD* to go do some food shopping, and the store is maybe a quarter mile from a pep boys who also give free computer readouts. So I stopped in SPECIFICALLY to get the actual codes my computer listed, and in addition to "the usual suspects" which I expected, there was a new code listed today.

The codes the tech read out today are:
300, 301, 302, 303, 304, and 1259

Also odd, aside from the glaring CEL, my car was quite well behaved on the way TO the store, but started getting really cranky on the way back.

Also, thank you SO much for that piece of info about the crank position. I can't believe that I couldn't ascertain that for myself; the best I was able to do was find out that both a crank position sensor and a camshaft position sensor exist, but I couldn't find any "operational theory" on how they're tied into the computer. Back in the old days (read "my days" :-) distributors ran directly off the camshaft, so you can guess where my mind was trying to go...