Question about 1994 Honda Civic

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HIGH HC ( 15mph- MEAS 182ppm,25mph-MEAS 72pp

CO%15mph MEAS:0.81,25mph MEAS:0.74, NO (PPM )MEAS:3016ppm-15mph,MEAS:1618ppm-25mph

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What is the engine code for this Civic? Open the hood, It will be on the engine block proper, to the left of the exhaust manifold, on a small flat tab just below the cylinder head where the transmission and engine bolt together. I need that before anything else...

To put it simply, if this is a D15B7 or a D16Z6 (the two most common D-Blocks in the United States from the OBD1 era), then everyone who's talking about EGR valve operation should be ignored. Because 95% of ALL global OBD1 Honda D-blocks don't have EGR valves, or ports, or even the thought of an exhaust gas re-circulation system. 1994 is too early for EGR Honda's, and most of the up-to model year 2000 Honda D-Blocks were simple exhaust port drill holes with no valves, such as on the D16Y8 and Y7's.

Are there any modifications? Hot rod parts? If so, what. Exactly what, not "a one of these, a one of those", I need to know exactly what. Are you running a stock ECM chip? If not, what fuel MAP and who wrote it? Are you even sure the ECM is original? If it's ever been owned by a kid, the odds are slim that it's running an OEM fuel and timing MAP today. How any miles on the engine? Does it burn oil? What is the overall maintenance condition of the engine? Most recent valve adjustment? And recent major work, such as head gasket, etc?
My best guess is that you're dealing with a missing CAT (knocked out), a clogged or ineffective CAT, or simply a worn out and wiped out major rotating component in the engine (valve seals, rings, pistons, etc). If you had a complaint of a running condition, such as idle surge, stalling, no power, check engine light, etc, then you've got another issue. Fix that first and move on from there. But if all you've got is a failed emissions test with no other symptoms, you've got a bad/missing CAT, or a bad engine. Period.

The early to mid 90's Honda's are flat out the best engines designed and built by man in my opinion. The D16Z6 is one of the marvels to modern engineering. These things ran so good, for so long, everyone who owned one either forgot to take care of it, or drove it till it died. Or, raced it till it died. And now these poor D-Blocks are showing up like rats to the piper at my shop asking if "The Guru of D Series" can breathe any new life into a 250,000 to 350,000 lower ends. I had a D15B7 show it's head last week with 325,000 on it. It was actually the old engine I pulled from one of my del Sol race cars in 1997 with 150,000 on it then (in favor of a B18C) and installed it in this customer's car. Here it is, 325,000 on her today, still kicking. Original head gasket and valve seals, blowing smoke like a diesel past the valve seals and guides, yet still pulling like a freight train still getting rubber when you grab third. But there's NO WAY that 'ol 325,000 mile bird could pass emissions, than god we're in Michigan She's just too old, and too worn out.

Posted on Mar 21, 2014


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Posted on Jan 02, 2017

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SOURCE: 1991 Honda Accord LX failed EVAP test. The ASM

Things to consider or replace...

If you are getting a Check engine Light let me know, it will make things easier to diagnose.

Catalytic Converter
Oxygen Sensor
EGR Valve

Posted on May 17, 2010

  • 834 Answers

SOURCE: failed smog check

How well does the vehicle run?

Assuming that the engine did pass the EGR function test on the emission test results, and the MIL (Malfunction Indicator Light) or check engine light is not on when the engine is running, and if you are not sure when the last time it was that the engine had a complete tune-up, with distributor cap, ignition rotor, spark plugs, spark plug wires, air and fuel filters, then a complete tune-up would certainly help, and if the engine oil and oil filter have not been changed in a while, then they should also be changed before an emission test because long used engine oil traps carbon and it will show up as higher CO on the emission test because the emission analyzer will be able detect the higher CO from the engine oil through the PCV valve.

However, it would seem from those HC readings that there is a vacuum leak, and carefully inspect all of the vacuum lines for any cracks or damage, (especially the vacuum line to the fuel pressure regulator) because cracks in the vacuum lines seem to like to hide underneath the lines.

The emission label under the hood should have the vacuum line routing diagram printed on it, and the vacuum lines should all be checked to be certain that they are all connected correctly.

Here is the firing order diagram for that vehicle to help assist you tune-up the vehicle.


Posted on Jul 10, 2010

  • 158 Answers

SOURCE: My 1997 Honda Civic failed

Jose, I don't know if this will give you the answer you are looking for because there are many things to consider here. The exhaust gas recirculation valve (EGR) is one of the main things involved in reducing NO emissions. This valve is controled by the power control module. (PCM) This is your vehicles computer. The PCM monitors the vehicles speed and will command the EGR to open when the vehicle attains a certain speed, which is why the ASM test being done is recorded at two different speeds. At 25 MPH your vehicle failed the hydrocarbon (HC) emissions limit and this could be for a number of reasons. When is the last time you car was tuned up? Old spark plugs, wires, clogged air filters, oxygen sensors, leaking injectors (personal experience) or the PCV valve could be contributing to the results of the test. I guess that the easiest way to go is to tune up the engine replacing the spark plugs, wires, air filter and the PCV valve and don't forget to have the oil changed at the same time. Only then should have the vehicle retested and see what the results are. Should it fail again you may have to consider having the EGR or the catalytic converter replaced depending on what portion of the test fails. If the NO fails I would consider the EGR. If the HC fails then I would consider the catalytic converter. Good luck with this.

Posted on Apr 05, 2011

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2: bad engine. runs like junk and does not burn all its fuel.

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