Rep Power: 0

Hi all,

I tried searching different forums, but I can't seem to find one that matches the issue I'm seeing with my 2003 Honda Civic EX ( auto trans)

THe engine idles smooth and runs well at 1st and 2nd gear, sometimes 3rd gear, depending on the speed. I notice that once I reach cruising speed of more than ~45 mph, the engine misfires and hesitates a lot. I have CEL and the codes are random misfire on all cylinders.

P0301
P0302
P0303
P0304
P0300

I've already tried changing the spark plugs using OE Denso. It works good for a few, but then issues comes back again.

I'm on a tight budget and I was hoping someone can share tips on what can be checked or replaced first.

THanks,

 
Rep Power: 517

Mileage on car?


Erase fault codes.
Unplug the EGR valve and drive it.
See if misfire codes return under the same driving conditions.
(It will set code for EGR because it is unplugged, ignore for now and pay attention for misfire codes.)

 
Rep Power: 0

Mileage right now is around 153K. I'll try to erase code and unplugging the EGR and drive it.

Will report back..

 
Rep Power: 132

I think ezone is hinting at a faulty EGR valve OR restricted EGR valve and EGR ports with carbon. Most likely the latter.


Here is a relevant post: https://www.civicforums.com/forums/1...r-misfire.html

 
Rep Power: 0

Hey guys!

Good news, I think I fixed the issue. Thanks for the tips about the possibility of a clogged EGR valve. I followed a tutorial in youtube on how to remove and clean the EGR valve. I took out the EGR valve and dosed it with carb cleaner. I did noticed that the valve was a bit sticking before I cleaned it, and after cleaning the ports and the valve, the valve moves more freely.

While the EGR valve was out, I also removed and cleaned out the old gasket and put a new one in. I also replaced that crappy plastic cam cover that was leaking like a b*tch.

The engine now runs smooth at cruising speed of higher than 45 mph! So far so good, no more CEL, no misfire or hesistation and also got rid of that pesky leaking cam cover.

One question though... I can't find the correct torque specs for the nut that hold the EGR valve. Anyone knows what it is?
I found some spec for the EGR valve but it was from the Acura forum. I used the same spec, 16 lb-ft.. hope that's right.

 
Rep Power: 132

That torque spec is fine I believe. Thanks for posting the outcome as it will help others in the future.


I had a similar EGR experience with an Odyssey. No misfires but hesitation trying to maintain cruising speeds at around 80 km/h. There was a TSB on this issue that included new EGR valve, reaming and cleaning of ports to make bigger and the insertion of a Teflon sleeve so no more carbon sticking.


Your good for another 150K miles...

 
Rep Power: 517

Agree on torque



Since you mentioned the Odyssey....V6
Those kits with the EGR valve and sleeve insert were intended to address at least a couple different issues related to the system.

That sleeve was made of stainless. (I've got a couple in the toolbox, they make a good hole punch)
It's ID is slightly smaller than 3/8" drill bit.

Several of those V6 engines eventually clogged the EGR passage again later on, even with the sleeve installed.

I even saw some of those engines come in with the passage just plain hogged out to the max with about a 1/2" hole, yet it still clogged up.


Might be drive habits, might be fuel, IDK....Some people have to repeat the cleaning every 50k, others every 150k. But yea, however many miles it took to clog it up the first time is about how far it goes before it clogs up the next time (assuming driving habits remain the same)

 
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Are there Teflon inserts or sleeves available also for civic EX (7th gen)

 
Rep Power: 517

Not possible. Completely different passage design.

 
Rep Power: 0

Hey guys, bad news.. the misfiring / hesitation on my 2003 civic EX came back again after I cleaned the EGR valve. Same CEL code, misfiring on all cylinders. The engine idles smooth and runs well on 1st, 2nd and sometimes 3rd gear, but once i hit cruising speed of more than 40-45 mph, it starts misfiring and hesistating, or under load like going uphill.

This time I replaced the EGR valve ($130!) hoping that will fix the issue. I also regularly put chevron fuel system cleaning additive. It helped a bit, but still hesitates and misfires. Very annoying on freeway.

Any other tips on what I can do to fix the issue? THanks!

 
Rep Power: 132

Dang, I thought we had this solved.
Sure did sound like the EGR system was the culprit by your description. OEM EGR valve installed right?
Timing belt timing off? Are you due for a TB service (every 7 years or 105k miles)?

 
Rep Power: 132

Please tell me you had the timing belt service done within your 153K miles.

 
Rep Power: 517

You never confirmed any specific results regarding my check in post #2.
You only said, "Good news, I think I fixed the issue".....

Right now I can only speculate, because you never really gave detailed information.


EGR valve itself is rarely a problem.
I'm guessing you did not remove the intake manifold to clean carbon buildup out of the EGR distribution channels?

 
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Hey NDNV, no thats another thing i need to do soon. I bought EGR valve from Allied auto parts, not from Honda dealer.

 
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Hey Ezone, my daughter has been using the civic a lot.. maybe this weekend I'll try the steps you mentioned in post #2. Its just that when I initially cleaned the EGR valve I thought that fixed the issue so I did not do that test you mentioned.. but unfortunately the problem came back so I'll try to do that troubleshooting test this time.

 
Rep Power: 132

I know you said money is tight but 1) I would have used an OEM EGR valve and 2) get that timing belt/water pump/tensioner service done ASAP if you have not done it in 2010 or at 105,000 miles whichever came first - a broken timing belt will ruin this engine fast.