Cylinder #2 Misfire & check engine light blinking just when idling

[lmdew]

I thought you had a dollar bill get sucked back into the exhaust tail pipe.  If so you have a bent valve that is not closing all the way.  You may get a little power out of it, but not much.

 

Used 2.2 from a Self Serve yard $200.  

[Fairtax4me]

The blinking light has nothing to do with the O2 sensor.

ECU senses misfires by reading changes in crankshaft speed. Every time there is a misfire there is a change in crankshaft speed because the lack of power from that cylinder causes the crank to slow down slightly on the next cylinders compression stroke.

The ECU counts each percieved misfire (it doesn't always pick them up) And keeps track of how often the misfire occurs, then compares that against engine revolutions.

When a misfire occurs a certain number of times, something like 10 times in 1,000 revolutions, (i dont recall the exact number) the ECU sets a code and turns on the CEL. But if that misfire occurs 40 times in 200 (two hundred) revolutions the ECU sets a code and blinks the CEL to let you know there is a major problem which can quickly turn your cats to glowing red orbs.

 

With a burned valve there is a loss of compression in the cylinder at low engine speed. The engine doesn't spin fast enough for the compression to build to an adequate level in order for there to be combustion. Also add to that, at idle the throttle plate is closed so there is less air available to the engine. When less air is available there is lower compression. These two factors joined together will cause a misfire at idle speed.

When the throttle is opened you get more air, and the engine speed increases, which means there is less time for compression to escape through the burned valve. Now there is enough compression for combustion, though it will not be ideal, the crankshaft speed will not be effected as much as it would be with the misfire.

 

So at idle, the ECU sees more misfires happening because of the lower compression, and the misfire occurs often enough to trigger the blinking CEL.

When engine speed is raised the misfires do not occur as often, the CEL stops blinking, but remains on partly because of the misfire count, but also because when a misfire occurs the CEL remains on until a certain number of engine revolutions has occurred withOUT a misfire.

[Gecko1650]

Wow, that was really helpful. That makes a lot of sense. Thanks for the write up

[ivans imports]

have piles of cly heads if need one

[Wazer]

I have a '06 Baja Turbo with the same issue. Replaced spark plug , coil, fuel injector! NOTHING!!!!! Mine idols like a charm, then when I put it in drive that's when it does it. I rev it up in neutral, it gets worse. Put it in park I can hear a pinging notice but idols good. If I drive it, runs like a top!! Somebody help.

[Wazer]

I have a '06 Baja Turbo with the same issue. Replaced spark plug , coil, fuel injector! NOTHING!!!!! Mine idols like a charm, then when I put it in drive that's when it does it. I rev it up in neutral, it gets worse. Put it in park I can hear a pinging notice but idols good. If I drive it, runs like a top!! Somebody help.

[Wazer]

Also had a compression test. Held consistently at 130,give or take. I think specs are 158>.?????

[ivans imports]

Feul pump low out put pinging is no feul getting to engine check for pluged intank pump screen