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Hello...new to your forum...thanks in advance for all of your insight. I have a '98 Civic HX, it's a D16Y5 VTEC-E. I have stumble/hesitation on acceleration, and I'm getting only about 15 MPG, although that's harsh summer city driving. I got close to 30MPG in the past. I had changed my timing belt and H2O pump near the time this started, I made double sure the valve timing was correct (& not off 1 tooth). Its ignition timing, on the other hand, needed to be adjusted from about the middle of the distributors range of rotation, to nearly all the way toward the front of the car. This was many months post timing belt change, but it is timed now. Other things I have done:

-New cap/rotor/plug wires/plugs (gapped, but I skimped and bought autolite plugs)
-New OEM pre-cat ("broadband") and post-cat O2 sensors (when it was throwing code p1167 6-months ago)
-New air and fuel filters
-Oil/oil filter/PCV valve change
-It does have 190k miles and uses 2 quarts oil a month, but its compression is good in all 4 cylinders to this day
-Its oil, however, would turn dark black in just a matter of days after an oil change
-Cleaned it's intake/throttle body with Chemtool


Where I am at now is speculating its catalytic converter (??) When I shine an IR thermometer on the precat exhaust pipe (not flange) I get about 350 deg. F. Postcat the exhaust temp is lower at about 250 deg. I see descriptions of every other temperature configuration scenario, except mine. How should I proceed? If it is the catalytic converter, does anyone have advice on replacement? Could I get by spending less on one than OEM?

Thanks for any help...

 
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you will not get by on less than oem. spend the money on a real cat that actually does its job.

 
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WHY? WHY?
Sorry! I may be wrong but...I don't believe your "timing" is good. Your distributor is mechanically tied to your camshaft so it can rotate at half crank speed (4 stroke) . There is no reason , other than "mechanical" failure... that your timing would be off and need that much adjustment unless (I would be willing to bet) your timing belt has jumped a tooth. If that still checks out ok...check your valve adjustment

Here is the simplified explanation:

your timing belt jumped a tooth , your camshaft is now one tooth behind your crank (usually around 8-10 deg). So therefore so is your ignition timing (ditributor) most motors can still run.... however.... ignition timing is more dependent on piston position than valve timing. You re-timed (ignition) your engine by advancing your distributor. Which is now timed with your crank.....but your camshaft is still off! put back the distributor to it's proper position and recheck your crank/camshaft timing... i'm sure your going to find your cam is one tooth behind.

Only after checking this... then...

for your cat... a blocked cat will cause lack of power...yes ....but rarely misfires. You'll have a very deep hoooowl from the intake on full throttle. How to test: Short of installing a backpressure guage, you can do a test by creating an exhaust leak pre catalytic (remove o2 sensor, or loosen catalytic from front. Make sure exhaust leak will not hit anything heat sensitive/ flamable .... there can be flames!!! roadtest (short... couple WOT accelerations --- will be very loud...; don't be fooled by "the illusion" of power from the noise. You will then know if your cat is blocked.

 
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be sure your using the proper TDC mark on your pulley (there is a whole bunch of notches.) marks under crank pulley = woodruff key up . (timing Mark on cogged crank timing belt pulley is off 1 notch to match mark on block). Make sure you didn't snap woodruff and pulleys slipped on crank!

 
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Wrencher,
I changed a timing belt on a 1988 Civic 1.5 and now have these problems, stumble/hesitation on acceleration, and I'm getting only about 15 MPG,
Yes I need to move the timing belt a notch, but can you tell me which direction to move the belt in relation to the Cam Pulley? Sounds like the belt needs to go one notch CLOCKWISE in relation to the cam pulley?
If you could be specific it would same me loads of time.

THANKS!!!
(head was rebuilt due to burned valve and head face was shaved enough to clean up surface, will this matter much?)