Your thoughts

[dfb]

Last week I posted a question.. I have two codes, one is Number 3 cylinder is misfiring and the other is HO2 sensor slow to warm up... Here are the symptoms... Car has 200k miles.. When I start it up in the morning or any time for that matter, most of the time there is a miss for about 20 seconds, then it magically smooths out... At times while driving it will miss... I am thinking a bad or weak fuel injector in number 3... It is slow to activate causing a miss... This may cause the HO2 sensor to "not heat up" as quickly as it should..It it were a bad wire, I should see arcing, or it would not just magically smooth out is the same amount time... 20 seconds...If it were a bad fuel filter, all cylinders could or would miss...same with pump...It it were a defective sensor, this would NOT cause just ONE cylinder to act up... I changed the plug to no avail... What do you all think???

 

[96eb96]

Last week I posted a question.. I have two codes, one is Number 3 cylinder is misfiring and the other is HO2 sensor slow to warm up... Here are the symptoms... Car has 200k miles.. When I start it up in the morning or any time for that matter, most of the time there is a miss for about 20 seconds, then it magically smooths out... At times while driving it will miss... I am thinking a bad or weak fuel injector in number 3... It is slow to activate causing a miss... This may cause the HO2 sensor to "not heat up" as quickly as it should..It it were a bad wire, I should see arcing, or it would not just magically smooth out is the same amount time... 20 seconds...If it were a bad fuel filter, all cylinders could or would miss...same with pump...It it were a defective sensor, this would NOT cause just ONE cylinder to act up... I changed the plug to no avail... What do you all think???

What are the exact codes?
Sensor heats up using an internal heater. Note the 4 wires going into the sensor. 2 for the heater and 2 for the sensor. The heater may be bad.

A miss that magically goes away after startup or intermittent could (among other things) be the intake gasket. It warms up a bit, expands and seals. That could be a lean miss (no pun intended). At 200K on the OHV that is not impossible. It is not a frustrating repair (nice DIY job) and there are pictures on the site.

The other thing is your plug wires. When were they changed last? The max is 100K(tuneup interval), but sometimes they fail sooner.

 

[dfb]

What are the exact codes?
Sensor heats up using an internal heater. Note the 4 wires going into the sensor. 2 for the heater and 2 for the sensor. The heater may be bad.

A miss that magically goes away after startup or intermittent could (among other things) be the intake gasket. It warms up a bit, expands and seals. That could be a lean miss (no pun intended). At 200K on the OHV that is not impossible. It is not a frustrating repair (nice DIY job) and there are pictures on the site.

The other thing is your plug wires. When were they changed last? The max is 100K(tuneup interval), but sometimes they fail sooner.

Today it drove perfectly, except after a long run and a shut down for one half hour, then it DID NOT want to start!!! It would momentarily fire and then shut off... 4x this happened.... I shut the AC (air conditioner off) then it started with a sputtering... On the way home... it drove perfectly... Here is what is happening... I washed the engine and the miss started, the CEL would come on... After several days I reset the computer and no CEL... It starts with a miss.... slight....then smooths out.... Sometimes it misses at hiway or driving speeds or when stopped for a light... Shut it offf, wait a minute then it runs smoothly...I am fairly certain it is NOT mechanical....IE... Compression issues or head or intake gaskets... I can try swapping the plug wires and see if another cylinder misses.... But now it is running OK except for a hard start today... The first time this has happened...

 

[Tbars4]

...either you got water into some electrical which is bad as it will make new grounding/contact points to items that is not suppose to connect with or, you simply blew a vacuum line loose...
...btw, you can still have codes stored with no light ...

 

[Willard]

I had a similar thing happen to mine. It would intermittently miss and then it got worse until it just did it all the time. Found out it was a bad injector. I would just test the injectors and see if one's bad. Test for resistance. There should be specs in any service manual if you have one.

 

[96eb96]

.. I washed the engine and the miss started, .

Uh oh. Thats risky with electronic control engines. Some contact may have taken on water. When you pulled the plug wires did you replace the that dielectric silicon lube? Did you get water around the coil pack? Is there lube in the wires? That stuff is there to resist moisture.

Since it happened after the wash I would lean toward the connectors.

 

[dfb]

Maybe I need to put dielectric grease back in... How in the heck do you get to the plugs... I took one off and that STUPID air pipe almost kept me from getting it back on... As far as the injectors, I CAN"T EVEN SEE THEM>....

 

[Willard]

As far as the injectors, I CAN"T EVEN SEE THEM>....

Didn't think about that, since your probably have the SOHC, and I have the OHV. Mine aren't easy to get to, but are visible (kind of)

 

[dfb]

Na, stupid me. I have sprayed water onto lots of engines and keep them running while I do it till the steam stops... This time I must have gotten stuff wet.... but I do think I may have a bad injector...