P0307 Cylinder 7 Misfire, '96 Ls400

[stanls400]

The maintenance that was done recently, was the changing of the power steering fluid. I used a hand pump to suck out the old fluid. Unfortunately some PS fluid squirted out and I ended up wiping the excess, spraying a degreaser (simply green), and hosing it off. The PS is another story, which I will save for another search / thread.

The symptom that I feel is a "rough idle" (yes, the 'check engine light came on' and the p0307 code). Also, on the freeway, sometimes there would be a vibration that felt like my alignment was out.

So, it's possible that something did get wet. However, that was about 1-2 weeks before the P0307 appeared. Yes, I am fairly new to the LS family and forum. So, the things I should check or is there a sequence that these items should be checked:

1. clean and/or replace spark plug 7 - done

2. clean the MAF - done

3. clean and/or replace coil #7 - NA for my year.

4. changed oil & filter - done.

5. check / test or replace spark plug wire - done.

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(inserting result)

For my issue, after replacing the spark plug and wire that resolved the P0307.

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Or maybe my question should be 'what causes a P0307?'

I use 91 gas.

Thanks.

[SRK]

I think you're on the right track. However the 96 has got distributors and ignition wires. For sure pull the number seven plug connector as the deep well it sits in may have water in it, and pull the plug to check it. That's more than likely all it is.

The 98 engines with VVTi had coil on plug.

[landar]

It could also be as simple as a worn distributor cap/rotor. If due for maintenance(ie tuneup) in that area, perhaps consider R&R of both caps/rotors. For that matter, it may be time for a general replacement of plugs, wires, caps and rotors. When was that stuff last done?

[stanls400]

FYI - I just added the symptom comment to the original post - feels like a 'rough idle.'

The receipt that I have (from the previous owner) shows the plugs (and other items) were replaced at 125k (now at 141k). It does not say anything re: the distributor cap. So, I will keep this in mind as well. But I will start with plug #7.

Thanks.

[stanls400]

Since I found this diagram on the site, I just want to confirm the spark plug order. When I am standing in front of the car, looking at the engine:

- driver side, starting in the front, the spark plug numbers are 1, 3, 5, 7

- passenger side, from the front, the numbers are 2, 4, 6, 8

Is that the correct spark plug sequence?

[Daniel091]

Yes, thats correct.

[stanls400]

I replaced spark plug #7. But I still get P0307. Other suggestions?

if the wire got wet, would that eventually dry out or still cause P0307?

Could an air vacuum leak "somewhere" cause a P0307?

[Daniel091]

Test the resistance of the wire. Hook a spark tester up and see what kind of spark ya get. Is it weak? Also check the wire fore damage. When I bought mine the last owner had routed one of the wires so it was rubbing the timing belt.

[stanls400]

Thank you everyone for your input (and info from the other related threads). The P0307 issue is resoved. I updated the 1st post with the result as well.

After replacing the spark plug and wire, that resolved the issue.