unplug the spark-plug: error code or not?
Hi,
To make sure all 4 cylinders are running, I unplugged the high voltage wire from each spark plug (one a a time, not all at once). Each time the idle RPM dropped a little bit, so I said "OK, each cylinder must be firing properly". However, I drove later to AutoZone and asked them to check the error codes, and there were NONE! not a single error code. So why there were no error codes? Also, with one wire unplugged, the Check Engine light did not come on (the lamp is OK, it comes on at start-up). All this is for a 97 Civic LX by the way. Thanks |
"chibitul" > wrote in
oups.com: > Hi, > > To make sure all 4 cylinders are running, I unplugged the high voltage > wire from each spark plug (one a a time, not all at once). Each time > the idle RPM dropped a little bit, so I said "OK, each cylinder must be > firing properly". > > However, I drove later to AutoZone and asked them to check the error > codes, and there were NONE! not a single error code. So why there were > no error codes? Also, with one wire unplugged, the Check Engine light > did not come on (the lamp is OK, it comes on at start-up). > > All this is for a 97 Civic LX by the way. > Why would there be any error codes in the first place? Were you experiencing a misfire or something? -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
no, I wanted to *cause* an error code... if I pull the plug, the
cylinder does not fire, so it should generate an error code, I would think just trying to understand what the OBD-II does. thanks. |
chibitul wrote:
> Hi, > > To make sure all 4 cylinders are running, I unplugged the high voltage > wire from each spark plug (one a a time, not all at once). Each time > the idle RPM dropped a little bit, so I said "OK, each cylinder must be > firing properly". > > However, I drove later to AutoZone and asked them to check the error > codes, and there were NONE! not a single error code. So why there were > no error codes? Also, with one wire unplugged, the Check Engine light > did not come on (the lamp is OK, it comes on at start-up). > > All this is for a 97 Civic LX by the way. > > Thanks > what problem are you trying to diagnose? plugs are so cheap, if you have any doubts, just replace them. regarding codes, fwiu, you /should/ get a code from a "misfire". it's detected by registering a change in the angular velocity of the crankshaft and should indicate /which/ plug is misfiring. but the ecu may not trigger a misfire code below certain revs or maybe if it's not misfiring for very long - just guessing because idle can give erratic crank rotation speeds hence the need to not be too sensitive and plugs self-clean when hot, hence the need to ignore any misfire when still warming up... if anyone knows for sure, please post. |
"chibitul" > wrote in
oups.com: > no, I wanted to *cause* an error code... if I pull the plug, the > cylinder does not fire, so it should generate an error code, I would > think > > just trying to understand what the OBD-II does. thanks. > > If I remember correctly, the MIL will illuminate if the ECM determines that the engine has exceeded Federal emissions limits by 150% on at least TWO consecutive "drive cycles". You'd need to pull the plug, let it misfire fifteen seconds or so, plug it back in and drive the car to full-warm. Then shut it off and let it cool completely (overnight is good), then repeat the whole thing the next day. That ought to set the MIL. But 15 seconds misfire may not be enough (about 188 revs at 750rpm), and leaving the plug off for longer risks damaging your coil. -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
good points Jim.
Regarding your question: I think the car is not as powerfuls as my wife's car (i know, mileage, age, 1.6 vs 1.7 L engine), but still, I think it's missing a few horses. So I wanted to make sure all 4 cylinders fire properly. I was just wondering why I didn't get error codes. Thanks. |
chibitul wrote:
> good points Jim. > > Regarding your question: I think the car is not as powerfuls as my > wife's car (i know, mileage, age, 1.6 vs 1.7 L engine), but still, I > think it's missing a few horses. So I wanted to make sure all 4 > cylinders fire properly. I was just wondering why I didn't get error > codes. > > Thanks. > replace plugs, leads, distributor cap & rotor arm. |
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