petr0lb0mb

D16Y7 5-speed, misfires with power loss. Throws CEL with codes 71-74 (misfires).

Just bought the car with 120k miles on it. Can't seem to get any info out of the previous owner.
When cold, the car seems to function normally. Then after about 5 minutes, it will stumble and misfire in low (below 3000) RPMs. In higher RPM's the problem seems to go away. After a long drive the car becomes almost undriveable. I have to rev the engine to about 3k and feather the clutch to get the car moving. This seems to be a common problem but I have yet to see the common solution.

Compression test:
#1 - 175
#2 - 172
#3 - 185
#4 - 187

Spark plugs:
Electrodes are more white then I would like them to be. (Have pic but cannot post attachments).

California smog test passed, but just barely.
The smog guy said that the ignition timing was too advanced. He adjusted it to the TDC mark using a variable degree timing light set for 14 deg. BTDC. I asked him if I could take a look with his timing light. I set the light to 0 deg and noticed that the engine was slightly out of range based on the timing marks on the flywheel. I didn't want to argue with him since he was just about to pass my car through the emissions test. Anyway, changing the timing didn't seem to affect the problem. One thing I noticed is that the distributor was initially set to the factory alignment mark. After he set the timing the mark was misaligned by about 4 mm which seemed like a lot to me.

Mechanical timing:
With the pulley TDC mark precisely aligned to the pointers on the belt cover, the cam pulley marks align perfectly with the aluminum surface of the head, NOT WITH THE ARROWS ON THE PLASTIC. However, it seems that if I adjust the timing by a tooth, it will be even more off than it is now. (Would love to post pics but cannot due to being forum newbie).

On the web, many suggest that the mechanical timing might be off by a tooth and so I'm hoping that this might be the problem. But, I can't tell if this is out or not. Help please.

Also, was thinking that the EGR passages could be clogged but it turns out the D16Y7 doesn't have EGR. Haha!

Former User

When you buy a used Civic, the first thing you should do is replace the plugs, wires, cap, rotor, and fuel filter. Use NGK plugs and Honda plug wires. Then go from there.

petr0lb0mb

I'm very particular about using Honda fluids and parts. I've replaced the plugs with NGK already and air filter with Fram. I haven't bought any other parts yet as I want those to be Honda. Somehow, I suspect that these things are not the cause of the problem, though as I've seen many threads where sufferers of this problem have changed all the usual parts and even distributors, and various sensors.

Former User

It's unlikely that you have any idea how old those parts are. Replacing them all is part of basic car maintenance 101 (tune up). Issues with the ignition system are the most common cause of engine misfiring. Until you do a full tune up on this newly purchased car, there's not much to discuss in my opinion.

tony_2018

Learn to post pics and than show us the TDC mark you are talking about.

petr0lb0mb

Okay, so I've just learned that non-vtec motors such as my D16y7 are to ignore these arrows in the plastic and align the cam gear timing marks to the valve cover surface of the head. In other words--my mechanical timing is fine.
Changing the plugs and air filter (that filter was derty), has alleviated 98% of the problem. The car runs MUCH better now. Doesn't stumble but still has an occasional misfire. I'm going to go through and do a tune up replacing all the usual stuff and see if it fixes the misfire. At least the car is driveable now.
Attaching pics just for reference. Again, D16y7 cam gear marks should align with the top surface of the head as seen in photos, NOT THE ARROWS on the plastic.

petr0lb0mb

You were right, RonJ@HT. I am happy to report that the car runs perfectly after changing cap & rotor, plug wires, PCV valve and fuel filter. I threw everything on at once and so I can't tell you which one was the culprit. If I had to guess, I would say it was the PCV valve but it's just a guess. Thanks for the help.

Former User