Misfire codes (Honda S2000)

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Mihail Milkov
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Joined: Thu May 15, 2008 11:25 am

Misfire codes (Honda S2000)

Post by Mihail Milkov »

My 2005 Honda S2000 with about 65K miles started getting misfire codes for cylinder 1 (most often), but also sometimes for cylinders 2 and 4. I also get code P0300 (random/multiple cylinder misfire). The interesting thing is that the misfire codes and check engine light don't come on during regular driving, but appear after autocross runs and also when I start the car at a steep driveway at my friends' place. This should give us some clue... Bad fuel pump perhaps? What do you guys think? BTW, I put fuel injector cleaner and HEET in the last gas tank, but last night I reversed on the steep driveway and the misfire code happened again.
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Re: Misfire codes (Honda S2000)

Post by Jonathan Lugod »

Mihail Milkov wrote:My 2005 Honda S2000 with about 65K miles started getting misfire codes for cylinder 1 (most often), but also sometimes for cylinders 2 and 4. I also get code P0300 (random/multiple cylinder misfire). The interesting thing is that the misfire codes and check engine light don't come on during regular driving, but appear after autocross runs and also when I start the car at a steep driveway at my friends' place. This should give us some clue... Bad fuel pump perhaps? What do you guys think? BTW, I put fuel injector cleaner and HEET in the last gas tank, but last night I reversed on the steep driveway and the misfire code happened again.
Hello Mihail,

Did you happen to have a clutch done recently? The knock sensor is a common failure during a clutch job as it is easily broken off. Coil packs are also a common failure (slow failure). I would recommend buying new coils regardless.
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Mihail Milkov
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Re: Misfire codes (Honda S2000)

Post by Mihail Milkov »

Jonathan Lugod wrote:
Hello Mihail,

Did you happen to have a clutch done recently? The knock sensor is a common failure during a clutch job as it is easily broken off. Coil packs are also a common failure (slow failure). I would recommend buying new coils regardless.
Hi Jon,
As a matter of fact, I had the clutch replaced recently. I will check the knock sensor. But I thought misfire is detected by the crankshaft position sensor as variations in the angular velocity? But maybe if the knock sensor is misbehaving, then the CPU reduces spark advance (to prevent knock) so much that it causes a misfire.
Thanks for the useful tips!
Mihail Milkov
Posts: 104
Joined: Thu May 15, 2008 11:25 am

Re: Misfire codes (Honda S2000)

Post by Mihail Milkov »

There is a strong clue what might be causing the misfire code. I did a compression test and here is what I found:
Cylinder 1: 165 psi
Cylinder 2: 238 psi
Cylinder 3: 240 psi
Cylinder 4: 242 psi

The compression of cylinder #1 is substantially lower than that of the rest. Incidentally, this is the cylinder that has been giving me the misfire code most often. The next step is probably to do a leakdown test.
Mihail Milkov
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Re: Misfire codes (Honda S2000)

Post by Mihail Milkov »

Julian and I did the leakdown test yesterday and the results don't look good for cylinder #1:

Cylinder 1: 64%
Cylinder 2: 3%
Cylinder 3: 1%
Cylinder 4: 3%

The cylinder 1 leakage is through the exhaust valve. Can you guys recommend a good S2000 mechanic, especially one experienced in engine rebuilds?
Gsxtasee
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Re: Misfire codes (Honda S2000)

Post by Gsxtasee »

Unless you are doing the full engine rebuild because you want to go through the whole thing and freshen it all up &/or to bump up performance there is reason for a rebuild ESPECIALLY with only 6x,ooo miles on a Honda that's been even remotely reasonably well maintained. that goes for pretty much any car with such low mileage

You should be perfectly fine just pulling the head for a rebuild and maybe a nice 5-angle or even a radius valve job.. perhaps new cams if you want to adjust the power band to Better support your driving needs ie lower end grunt for Auto-X.. then reassemble and rock out..

That's assuming that the testing you performed has been done accurately as the other compression #'s looked healthy and uniform across cylinders excluding #1.. no need to exacerbate the scale or complexity of the issue if you are simply looking for a healthy vehicle that will support an enthusiast owner's demands for reliability and performance..

Good luck either way you go. Personally.. I'd either do the full build for performance (forged everything, higher compression and cams/head work or lower compression and force induce) or just swap in a used unit for ease of procedure, less downtime, and considerably lower cost. I'd do the used engine swap long before I'd do a head job unless I were specifically pulling the head to do full performance build & crazy port work..
Mihail Milkov
Posts: 104
Joined: Thu May 15, 2008 11:25 am

Re: Misfire codes (Honda S2000)

Post by Mihail Milkov »

Gsxtasee wrote:Unless you are doing the full engine rebuild because you want to go through the whole thing and freshen it all up &/or to bump up performance there is reason for a rebuild ESPECIALLY with only 6x,ooo miles on a Honda that's been even remotely reasonably well maintained. that goes for pretty much any car with such low mileage

You should be perfectly fine just pulling the head for a rebuild and maybe a nice 5-angle or even a radius valve job.. perhaps new cams if you want to adjust the power band to Better support your driving needs ie lower end grunt for Auto-X.. then reassemble and rock out..

That's assuming that the testing you performed has been done accurately as the other compression #'s looked healthy and uniform across cylinders excluding #1.. no need to exacerbate the scale or complexity of the issue if you are simply looking for a healthy vehicle that will support an enthusiast owner's demands for reliability and performance..

Good luck either way you go. Personally.. I'd either do the full build for performance (forged everything, higher compression and cams/head work or lower compression and force induce) or just swap in a used unit for ease of procedure, less downtime, and considerably lower cost. I'd do the used engine swap long before I'd do a head job unless I were specifically pulling the head to do full performance build & crazy port work..
Thank you for the detailed reply but by the time I received this I had already had the engine repaired. The mechanic pulled the head out and saw that one of the exhaust valves on cylinder #1 doesn't fully close. Later on, the machine shop he works with replaced both exhaust valves on cylinder number 1 as well as the valve guides and valve seats. I was told that two more valve guides on a different cylinder were replaced as they were going bad even though there was no compression drop for the other cylinders. It was never too clear to me what had caused the damage on a relatively low-mileage (66K) engine. But then I have had the car only for the last 15K miles so I have no idea what the engine had seen before that.
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