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Hello everyone, I’m new here, I’m seriously at a dead end with this issue. Any advice would be greatly appreciated! I have a long story so grab your popcorn.

2004 Civic coupe EX, it’s got the JDM D17A VTEC. Used to have American version D17A2 VTEC. Only thing aftermarket is an AEM cold air intake.



First I noticed a check engine light that indicated “catalyst below threshold efficiency” I cleared the code, drove it for a while, another code came up but this time it was something related to EVAP unfortunately I don’t recall the code. After clearing and driving, the catalyst one came back but shortly cleared itself. I replaced the O2 sensors anyways and the codes never came back. Just a couple weeks later I notice the idle is slightly shaky, which has progressively gotten worse with time. Then I noticed intermittent misfiring on cold start only when idling. I’ve experienced something very similar with the old engine as I explain in much further detail shortly. Because of this knowledge, I check the valve clearances, which seemed to be a bit tight, so I adjusted them. I must have made the gaps too big because it was making a lot of noise. I did it again, after it cooled all night of course, and it was quiet! Shaking still though. Next the misfiring gets worse on cold start idle and now when I give anything more than half throttle it misfires so many times that it effects power a ton! Only in low rpm, and only for the first 5 minutes or so of driving even up to operating temperature. After it goes away it won’t happen again until the next morning. Although it always shakes at idle. I adjusted the valves and every one on the intake side were way tighter than I set them at. I couldn’t even fit a feeler gauge two sizes smaller than what I used. After adjusting unfortunately there was no change in performance like my previous engine. Still the same amount of misfiring. Odd to me that my valves are going out of spec just like the last engine. Here’s the explanation…



I bought the car not knowing it had a blown head gasket. I got it serviced by a mechanic and fixed the problem. A whole year later I started having issues where my car would slowly have more and more misfires until it finally couldn’t start anymore. I got that serviced by a different mechanic who did a valve adjustment and it ran like a top! For about 3k miles… then the same thing happened. I brought it back to the same mechanic who had absolutely no answer for my problem. He did another adjustment for free this time and it ran perfect once again! Next time it was only 1k miles that it went out of adjustment. I researched how to do a valve adjustment, did it myself and it ran great. Not for long. Soon I was doing an adjustment every few days with tons of valve noise even after adjustment and the CEL was always flashing. So I parked it and ordered myself a used engine from Japan bc I had several leaks around the engine and I knew it would never be the same after it got hot more than few times I’m sure. I installed the engine myself with the help of a friend. The engine was in beautiful condition by the way. I swapped over all the parts I had recently replaced or that looked better than the other, like the timing belt, water pump, alternator, coil packs, fuel injectors, thermostat, and the sensors and stuff. It ran so smooth and much quieter than the last for about 1.5k miles or so until this very similar thing (as mentioned in paragraph 2) started happening to the beautiful engine I received from Japan!! Believe me that engine was clean as can be on the inside and I personally cleaned the EGR valve it seemed clean but maybe need a replacement? What is causing this? Please help

 
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check if your cat is not plugged

 
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yes I’ve wondered the same thing! I tried running it and driving it for a while with the down pipe disconnected so the pressure wouldn’t have to go through the cat. Nothing changed. Still same misfiring. I will check valve clearance and try again see what happens. Do you think a clogged cat could cause my valves to go out of spec like that?

 
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Also UPDATE! Today my car will misfire even when completely warm at idle and under acceleration. It’s getting worse

 
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Does anyone think that I may have gotten the timing off by such a small amount that I wouldn’t notice right away? Would this possibly cause my valves to bend over time therefore going out of adjustment? Also I’ve heard cam position sensor or crank position sensor could play a role in wacky misfires. Any feedback would be very helpful

 
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I’m currently doing another valve adjustment because they were noisy I may have just made the gap too wide. I notice a creaking sound coming from the cam wheel area when I’m cranking it by hand can’t seem to figure out where exactly it’s coming from

 
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Here’s a video. Sounds like a floorboard

 
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Is it possible that when you re-installed the cam gear you forgot to tighten the bolt that holds it on? The "alignment pin" on the back of the gear may have sheared slightly when you first started the engine, and now it is shearing more as you drive it throwing the timing off. I did this once, so it comes to mind.

Have you been able to check the compression at all? I would check it and see what results you get. I think the minimum spec is 135 psi, so a timing issue may give you lower readings.

 
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I did check and make sure the bolt was tight yesterday after hearing the noise. Not with a torque wrench or anything but it was very tight. Is this so called “alignment pin” visible? Also timing marks are dead on. Wondering if the sound could be coming from the water pump gear. I’m almost positive the timing belt, tensioner and water pump are not OEM.

After doing the valve adjustment I would spin the engine by hand a bunch of times and re-check clearances until I had them all coming back around the same as I set them. Took about three times because they would always move slightly after cranking the engine over. Seems to run a little smoother but the misfire under heavy acceleration is still there under 2,000 rpm. have not done a compression test yet.

Thankyou so much for the advice.

 
Rep Power: 99

If the timing marks are lined up and the cam bolt is tight, then that's not the issue.

Could be the water pump pulley, but you mentioned that in your other thread.

Only other thing I can think of is the guide behind the crank gear was installed backwards. Would that making a scraping noise against the block as it spins? But you stated the noise is up higher near the cam gear and it came only after a valve adjustment so...??

 
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Will I have to pull off the whole valve train to be able to tell if I’ve sheared the alignment pin you’ve mentioned before? But you’re saying that my timing marks would be off if that were the case? And yes the most odd thing is that this is a new sound but I haven’t touched the timing belt at all since I installed the engine about 3k miles ago. I did have the alternator and power steering belts off at one point shortly after because my alternator bolt wasn’t tightened. Im hearing a “whistling” sound that I think is coming from power steering belt and appeared just a few days ago as well. Maybe that sound goes along with my creaking problem? But I put my ear right next to the sound while someone else cranked for me and it’s definitely coming from the cam gear or the water pump area I can’t quite tell. My timing belt and water pump are aftermarket.

 
Rep Power: 99

No, you'd just pull off the cam gear and look behind it.

Right, because then the cam gear would rotate independently of the camshaft. Or maybe the marks might line up ok (if the pin only sheared partially), but the timing would still be off and you'd have low compression numbers. Have you checked the compression yet?

You could try removing the belts and starting the engine. That can rule out belt or pulley problems causing the noises.

 
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ok so my compression came back really good. Almost exactly the same across all 4 at about 230 psi. Also I have solved the misfiring with a simple fix! I ordered some Denso coil packs and just like that no more misfire. Very happy with this but still concerned that it shakes at idle. It seems to be related to the idle and not the engine mount. Maybe air filter is old? (AEM) It sounds like it’s trying harder than before to draw air in, even after cleaning. Not terribly worried unless it gets worse I guess

This cam gear noise is gonna drive me nuts on the other hand. I can hear more noise while it’s running, coming from maybe the injectors, sounds like a diesel engine. But I don’t think it’s the valve clearances bc I’ve heard that sound plenty times in the last year with this car. when I accelerate I hear what I think is the cam gear making some noise. I can tell it’s not my air filter making the noise although it does make its own sound similar to that of the new sound I’m hearing

Lastly, are you suggesting I could start my vehicle without the timing belt on? I thought that was a huge no no. Or are you just referring to the other two belts? (A/C, power steering)

 
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timing belt off is a no-no

 
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This.

 
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that’s what I thought lol