The integral cat on the '96+ HX (and other models like DX & LX) is the exact reason that nearly every Civic out there will experience a catastrophic cracked manifold and failed primary O2 sensor. Rare for a Honda, it was a terrible design due to the massive heat build-up caused by the cat being a few inches off the head therefore plugging up the exhaust stream. This is why I installed a stout cast manifold & downpipe from a '95 DX on my '98 HX and then relocated a new cat and second O2 sensor beneath the car (between the driver's & passenger seats).

With a new primary O2 sensor ($170 from eBay), it has run very well ever since. I have been popping a few CEL's due to the ECM update issue. Now that I know about the relevant TSB, I'm not worried about the CEL at all. I just carry a code reader around and erase the P1163 & P1165 codes when they pop up. I have driven thousands of miles with no sign of the codes. However, when the stars are aligned with a full moon, for some unexplained reason, the CEL will pop up.

 

The cel is not as unexplained as you might think. I have been testing it on my own to see what causes it and have come to a very simple conclusion. If you shift too soon, the car just does not like it. If you drive the car like the manual says to, I can go hundreds of miles without problems, but as soon as I try to 'hypermile' by shifting as soon as possible, the light comes on everytime (or if I just rag the car out by driving too hard). Try some experiments to see what might cause it on yours.

 

That actually sounds quite familiar. I drive my '98 HX over 200 miles per day on my commute to & from work (been doing it for 18 months...thank God the commute is coming to an end in two weeks!).

Logically, I try to achieve the best mileage possible by listening closely to the sound of the engine and upshifting as quickly as possible. I have noticed that if the CEL is going to come on it will light up within the first 10 mins of driving and typically at low speeds and/or RPM.

I noticed that the replacement ECM's are somewhere around $700. In my mind, it's cheaper to just pull over and erase the CEL and continue on my journey. I've become pretty adept at erasing the code(s) in a minute or less.

 

They are more than $700, because you have to get them 'rekeyed' (don't exactly know what that entails, but they charge about 200 for it at the dealership). I just hope more people find this thread so they don't have to spend the kind of money I did, just to find out it is all in the driving style, especially considering the Honda certified shop took 3 visits before they figured it out. Let me know if you find any other stupid quirks in these cars.

 

How about a completely inadequate clutch release fork? Somewhere around 180k, mine broke in half and the clutch pedal went to the floor. This had nothing to do with driving style or a strong pressure plate...as you know, even when new, the clutch on an HX/DX/LX is so weak it can be actuated with a child's pinkie finger.

Basically what I found is that, over time, any lubrication that was once present between the clutch release fork and pivot bolt disappears. This is normal and happens to every manual trans car. The trouble is that Honda did not account for the added friction that would occur after the lube wears away. The clutch release fork is made from steel that is so thin that the head of the pivot bolt actually wore through the fork. After a while, the fork broke in half. A really bad way to end your day!

Of course, the symptoms (clutch pedal to the floor) pointed to a failed master or slave cylinder so I replaced them both (unnecessarily) thinking this was gonna be an easy fix. When that didn't work, I started looking at the clutch fork and found that it was pretty floppy...not good! In the end, I had to pull the tranny and replace the clutch fork and pivot bolt along with a new clutch set. I even rebuilt the tranny with new bearings & seals while I had it off the car.

Word to the wise. I bought an OEM spec replacement clutch set from Advanced Auto. Do not buy this set or any other OEM set. They are as limp feeling as the original clutch was due to weak pressure plate clamping force. Take my advice...spend a few more dollars and get an Exedy Stage 1 performance spec clutch.

After putting my Civic back together, I was most unhappy to find that my new clutch was weaker & more vague than the (presumably stock) clutch I took off. Sure, you can drive it but finding the friction point in the clutch pedal travel is a lost cause. I honestly think you could drop the clutch in first gear and the car would just drive away like you did nothing wrong.

 

The other quirk that really bothers me is the overhead cabin light. As soon as I removed the stock radio in favor of an aftermarket unit, I have no door actuated overhead light. Actually, I can turn the overhead light on manually, but it's as if the door pin switches were routed through the OEM radio. Maybe for some kind of lame security system (that the car didn't have anyway).

 

The keyless receiver unit of 96-98 Civics is located inside of the stock radio. In this case, the ceiling light circuit that includes the door switches is routed through the keyless receiver unit. By discarding the stock radio, you lose the function of both the keyless remote and door-switch-activated ceiling light. To retain these functions, the stock radio can remain wired and tucked behind a replacement aftermarket radio. You could also regain the lost functions by purchasing and reinstalling/tucking a 96-98 Civic radio that contains a keyless unit.

 

Is this clutch issue specific to the HX model? I have owned a 97 Civic DX since it was new, and the clutch seems just fine. Nonetheless, your experience reminds me that I really need to re-grease my squeaky clutch release fork as soon as possible.

 

RonJ - this applies to any Civic using the S40 tranny (incl yours). The clutch fork part# is: 22821-P20-010. It is terribly weak and susceptible to breakage due to corrosion & metal fatigue. If your fork is squeaking, then you've been etching away the thin metal in the pivot bolt recess of the fork as well as wearing down the head of the pivot bolt.

 

I understand the wear issue, but again my clutch performance is fine rather than weak and hypersensitive like the description of your clutch. In the latter case, I think the problem may not be general.

Thanks for the heads up on the clutch fork. I'll include it among parts to replace when I do a clutch job in about 50K miles (I have 112K now).