Hello everyone, Happy New Year!!

As a new years resolution I’m determined to get my 1997 Honda Civic HX 5 speed back on the road, registered and smogged legally after sitting for two years. I do run it every other week though. I have multiple vehicles (all old and showing their age too) so I only work on it occasionally. I’ve been searching this site and the internet off and on for the past two years trying to figure out my issues and this is the first time that I have posted a thread about it.

The car runs and drives but it won’t pass smog because of high hydro carbons. A lot has transpired since the vehicle first failed it’s smog test and was left in the backyard as a learning project for me to understand more about smog components. Before I smogged the vehicle I put on a new distributor and I believe I failed to time it correctly. Now as the car sits using a decent obdII scanner tool that gives live data I have been trying to fix my vehicle kinda throwing parts at it all the while learning how each part effects it and I just can’t get the fuel trims down which from my understanding is causing my issue. At idle the STFT sits around 9-11%.

To break down what I’ve done I’ll list everything with bullet points hoping to give as much information as I can remember.

* 1997 Honda Civic HX 5 speed VTEC-E with around 125,000 miles on it, original as far as I know.
* Got it mid 2014 with 60,000 miles, replaced the clutch and put 65,000 miles on it up until 2020.

* Put in an aftermarket distributor, failed to time it correctly and drove around 5,000 miles that way.
* Set the timing on the vehicle correctly as far as I know, after failing smog
* Cleaned the EGR valve and cleaned out the passage ways which were really clean actually, it seems to function correctly, doesn’t get stuck.
* Checked the fuel injectors and they seem ok, created a stand alone tester using a battery and extra fuel injector connection.
* Checked the compression and it seemed ok.
* Changed the engine coolant temperature sensor
* The fuel filter was replaced within 30,000 mile
* Bought a new fuel pump as the vehicle didn’t start but that was due to a bad ecu
* Replaced the upper wideband O2 sensor
* Replaced the lower O2 sensor
* Replaced the catalytic converter because the old one had a crack above the upper O2 sensor
* Replaced the map sensor
* Replaced the ECU after a capacitor melted and my repair attempt failed. New ECU numbers match and it’s an OEM unit from a used vehicle. The bad ecu caused a lot of weird things to happen, diagnosing that took a while.
* Searched for vacuum leaks but haven’t found one yet.
* Tested the fuel pressure regulator and it seems ok, removed vacuum line and no fuel comes out yet fuel trims go way down.

To do still:

* Replace the valve stem seals
* Test the iacv, still figuring out how to do that.
* Keep searching for vacuum leaks.
* Clean the throttle body
* ??????

Throughout this process I have run across rental tools like the compression testing tool that were faulty as well as getting faulty brand new replacement parts so it’s been a struggle. Getting the car to run and stay running isn’t hard for me yet getting it to run correctly and pass smog is a challenge that I want to learn more about so I welcome any and all advice, suggestions or criticism. Thanks so much!

Included some screen shots of the live data:

 

How did you check the fuel injectors? You could have one that has some trash in the pintle which can cause it to dribble extra fuel when it's supposed to be closed. I recommend sending your four injectors out for cleaning and flow testing.

 

Thanks for the suggestions Dax, I checked the injectors in two different ways, first I pulled the fuel rail off of the intake with the injectors still attached and than cycled the ignition on just to power the system and proceeded to observe the injectors spray patterns. They seemed ok but to my untrained eye I very well could have missed something. The second way I tested them was to hook each one up individually out of the vehicle to a makeshift fuel injector connector that I powered by a 9 volt battery coupled to a can of carb cleaner. I did my best to seal the injector to the carb cleaner nozzle hoping to keep the pressure. I than sprayed the fluid into the injector followed by powering the connector with the battery and the fuel fired out of the injector and looked ok. This was all a rudimentary attempt to check the injectors. I’ll look into having the injectors sent out, it can’t be that expensive, I hope at least.

 

As my memory of what I did returns, I’ll add that I did perform a tune up on the vehicle as well. Put new plug wires in (not oem) and tried two different types of spark plugs.. As I’m writing this I’m wondering if I still have the old plug wires, curious to see what if any change putting them back on will do.
Also is there a possibility that something is wrong with the new aftermarket distributor that I put in? I have the old one but the internal seal leaked a lot and I couldn’t get it to stop, looked like the seal housing was etched, scratched or just damaged. I remember that my year Honda called for two different distributors and I’m pretty sure I got the right one.
I used the stock plugs and a set of colder plugs and really didn’t see any difference.

Spark plugs that I used:

ZFR4F-11 recommended
ZFR5F-11 colder

The HX model is a special beast of an economy vehicle for that era as I’m learning and is very sensitive due to it’s lean burn, wondering if my scanner isn’t reading everything correctly also. If this was my only vehicle I would be stressing but I want to solve this myself and learn along the way; I’ll add it would be great to benefit from the a Honda’s 40mpg again as my truck gets only 10-15 mpg………

 

Double check your distributor timing... make sure it is set correctly. Don't forget to short the service connector when checking the timing at the crank pulley with your timing light. Also, your live data shows that your TPS value is nearly 10% while the car is idling... it should be ZERO. I don't think that a 10% add in short term fuel trim in cold weather would cause issues with passing smog... especially since the long term trim is at 0%. Check your TPS voltage and properly set it to .495-.500v with the key on, engine off.

 

Thankyou for the suggestions, when I set the timing I believe I shorted the service connector correctly but it’s definitely time to check it out again and see if the timing is correct. Your comment about the TPS value interests me because I thought it should be zero as that seemed logical at idle otherwise to much air would be getting into the intake causing a rich condition. When I researched my theory I came across a lot of conflicting info where some people suggested live data showing 9-10% for the TPS at idle was ok, I even went so far as hooking my scanner up to my other vehicles and a 9-10% TPS value was the common factor all with low fuel trims. Now other people were saying it should be at zero because the the iacv allows for what I can only describe as an air intake work around letting a little air in at idle while the butterfly is closed. When I read what I just tried to describe I was confused and honestly didn’t know what to try next. With your suggestion I feel a little more confident to dive into checking the TPS.
I haven’t tried to smog the vehicle since changing all the parts I listed but maybe I should just bite the bullet and pay the money to see where the numbers are now, it sucks failing and paying but maybe just maybe I’ll get lucky. For the most part I’m hesitant to try again because my scanner still shows that the cat, O2 and EGR monitors arn’t ready but there is no check engine light. In California I believe my year Civic can’t have any monitors that are pending so I would fail, whereas my newer truck consistently has one monitor that is problematic but it passes, the EVAP system always acts up on the truck. Back to my civic, I havn’t really driven it much after putting the cat and O2’s in mostly because finding a day to drive over 300 miles has been difficult for some time. I figure the monitors should reset after 300 miles, the cat and O2’s are new and the EGR valve was only disconnected and cleaned so that should be the reason behind it’s monitor not reading, at least I hope.

 

Don't confuse throttle percentage with TPS voltage:

0% TPS (throttle fully closed) should be about 0.4 - 0.5V when measured with a multimeter
100% TPS (wide open throttle) should be about 4.5 - 4.9V when measured with a multimeter

 

I wanted to thank everyone for their help and apologize for not keeping the post updated, I caught COVID and am just trying to feel better. As soon as I feel better I’ll get back to working on my car. Thanks again