Hey everybody,

About two weeks ago, I was driving along (always very conservative, I drive for MPG). All of a sudden, the engine misfires...not bad, but starts doing it pretty consistently over the next few miles.

Now, whenever I drive it, the misfiring is so bad that the CEL light starts blinking.

I have not put but maybe 30 minutes of driving on the car since this started. I've pulled the timing belt cover because I wasn't sure if the belt might be going bad...just bought the civic in July, 188,000 miles on her, and the prior owner couldn't tell me if/when the belt had ever been changed as he only had it for a couple of years.

I had Autozone pull codes. They are:

P0401 - EGR valve (on since August)
P1300 - Multiple Cylinder Misfire (new)
P1399 - Random Cylinder Misfire (new)
P0420 - Catalyst System Effeciency below threshold bank 1 (on since August)
P0301 - Cylinder number 1 misfire (I did not ask for them to print out the other cylinder codes, but there were at least two others that came up...cylinder 2 and 4 I believe) (also new)

Now, there is a hairline crack in the exhaust manifold that I discovered in August, and the P0420 has existed since then with the engine running perfectly...so I don't think that is a cause...

Also, the EGR code has been there since August as well. I've spent the last couple months tracking down oil leaks and a handful of other issues, so I wasnt' in a hurry to do the EGR since the engine ran so good. Got 42mpg last tank...

After having the codes pulled that nite, I bought a new cap and rotor and replaced them...still no luck...lots of misfiring.

I had purchased all the injector o-rings, and the gaskets for the EGR chamber and valve this summer. So, i went ahead and pulled everything and cleaned it all...and yes, it was completely blocked.

Still, the engine isn't running any better than before.

Please help. I have been riding my motorcycle to work for the last week...3 hours and 140miles on the road per day...and would be fine going forward...if the temps weren't about to drop. I've gotta get this figured out as soon as I can.

Any assistance would be HUGELY appreciated.

Thank you.

 

have you had any coolant issues before? Sounds like a possible head gasket leak. Maybe try some stop leak and see if the misfire chills out a bit. Have you checked your plugs and wires to see if they are good?

 

Oh, yes, sorry. I actually did pull all the plugs and re-gapped them as well. They all looked great, and were only slightly out of gap. I'm really concerned about running the engine very much as long as its misfiring so bad. I'm borrowing a timing light and compression tester tonite, so I was going to try to check that out without running the engine too long. I've still got coolant in the reserve tank, and have no smoke or such in the exhaust. However, when I got home from driving it last, I did notice an unusual amount of smoke in the engine compartment...

 

Update: I had changed the fuel filter when I did the EGR cleaning. So, the codes were cleared when I had the battery disconnected. I just finished running the engine long enough to get it up to operating temp, and pulled the codes afterward.

Currently, the only codes coming up are 71, 72, and 74 (random misfires on cylinders 1,2, and 4). No EGR codes or O2 codes came up.

Thanks.

 

I had the same problem on my HX. Did you clean out the throttle body? My was quite dirty.

 

No, I haven't checked the throttle body. I will take a look. Thanks. Is there a how to on the topic ?

Thanks again.

 

Well, I kept reading how everybody says aftermarket wires and cap/rotors are crap, so I figured what the heck...its just another $125. So, here it is...the engine is running without a hiccup after putting on new cap/rotor/wires from Honda.

I'll let you know if anything changes, but as of right now, its back to running great, and no CEL for once in a good while.

 

yeah def. use oem wires for sure, ngk makes a set too and I've heard good things about them but never used them and only used oem honda. For the plugs you are running ngk ZFR4F-11 correct? other plugs will work as long as they are the same type and heat range but ngk's are the best and also what what honda calls for which I run in my 97 hx. Also it seems like that you could check/replace the air filter and clean the throttle body. Just get some throttle body cleaner it comes in a can then pull the intake hose off. You can spray the cleaner either with the car running or off, when it's running you can't spray near as much in there since the engine bogs down and wants to die. You will get a cel so you'll have to clear them afterwards.