Civic VX miss under load

[wehrd1]

Originally Posted by edgolla

I have had an intermittent miss in my VX for some months now. I tried various things to fix it, such as Oxygen sensor, distribuator, fuel filter etc. and nothing seemed to help except that the problem only seem to occur after the engine was warm, so I sent the ECU false information by replaceing the temperature sensor with a 1 k ohm resistor. This helped a great deal but I didn't know why. I also found that if I removed the lead from the throttle angle sensor the miss would go away. I have finally discovered the source of the problem. There was an arc occuring across the end of the rubber boot that extends the plug wire down through the head. This happened on two of my boots. You could just barely see a very faint light gray trace across the bottom of the boot. I scraped this trace clean and then coated the end of the boot with a light coating of silicone grease. This complete eliminated the miss that I was having. It only seemed to happened when the engine was warm, because the car goes into lean burn only when it is heated up to operating temperature and I believe that under the lean burn condition the plug is harder to fire and that causes the spark to bypass the plug and arc to the metal wall by way of the rubber boot. Disconnecting the throttle angle sensor gave a CEL and also kept the ECU from going into lean burn. Let me know if this helps you. egolla@airtesting.com

did this increase your mpgs? my mpg's SUCK on my VX, and they seem to be getting worse. I was maybe at its BEST, getting 42mpg, and it's down to 35-38 now, under same driving conditions. I posted back in May 2007 in this thread as to what was happening. I still have a stumble and the idle speed goes WAY LOW when i stop @ a light or am not under throttle.

Way back then, I changed the spark plugs to the type indicated in the Haynes service manual for this lean burn engine. When I initially bought the car, it was throwing a couple CEL codes, that indicated the TDC sensor & the O2 sensor...both of which I replaced with a used dizzy & a new sensor for this engine.

I'm wondering if you could contact me via email as to the exact steps & procedures used (and where these parts are actually located) to see if I can improve my VX's performance.
Thanks

[XyKo]

You might need a new o2 sensor.

[add|ct]

I thought I'd bring this back from the grave, again, for all VX owners.

After going through my experience of the VX having these symptoms I'm convinced that its prone to these symptoms because it is a lean burn engine. If you look through this thread you'll see everyone having problems from CKP Sensor > to distributor/igniter > to a plug wire causing a miss at operating temp when lean burn is being implemented, causing an arc along one of the wires to the plug.

In all such scenarios, lean burn, going in/out of this 'mode', all monitored by the ECU, creates a great deal of potential culprits and until a code is thrown it seems to interfere with lean burn mode FIRST, if anything...and yet, when the car is under full load why would the stumble still occur? I believe its related to the drawn out affects of parts 'wear'/sensitivity from being in a lean burn engine and being subject to all that implies, that when its time for VTEC-e/full load/WOT etc. it shows up slightly finicky. Thus, making one think the timing had skipped/retarded, misfiring(s?) somewhere, valve problems etc.

I'd be curious to know if others eventually get the CKP sensor code thrown like the one poster.

Maybe I'm reading into it farther than is possible, but it leaves me wondering why the VX is prone to these problems and not the CX etc...lean burn engine is all I can come up with.

[Farlander]

I've read a lot of stuff on this post that is completely irrelevant.

Barring the usual dumb butts such as spark plug wire arc (please this one is simple my 17 year old sister can do it, spray the dam wires with some water in the dark and see the arc or not) there are 2 things nobody else mentioned.

A! On the Vx and all the other 1.5/1.6 engines, the distributor timing is manually adjustable. Rotating left as your facing the distributor advances the spark all the way - on my vx it completely smoothed out my engine stumble. I suspect poor fuel econ however.
Rotate right (watch the alternator belt and note the engine rotates counter clockwise) and you retard the timing all the way. In an ideal world, the most efficient combustion would be ignition at TDC, but our own imperfections, namely VALVE ADJUSTMENT, carbon, need for more power, and weak ignition systems mean that we have to advance the spark before TDC, so the combustion actually starts when the piston is still on it's way up. The peak horsepower is generated when the spark advance is mated to the greatest combustion at the greatest compression.

MY ADVICE: ADJUST YOUR VALVES THEN SET YOUR SPARK ADVANCE BY TEST DRIVING UNTIL YOU FIND A SPARK ADVANCE SETTING YOU LIKE. REMEMBER TO CLEAR THE COMPUTER MEM EACH TIME TO CORRECTLY RELEARN INJECTOR PULSE DURATION.

[msweatherhead]

i have an vtec-E also in the HX model civic my misfires have been caused by the EGR ports being pluged with carbon deposits ,need to be cleaned every 100k or so.I don't have anymore problems since i do this,97 hx 366,500 and counting 47-50mpg