Birdi

Hey guys,

New here but needed some help!

Got a honda s2000 2000 year plate. So my brother was driving along and he said he heard a little pop sound and all of a sudden the car lost accelaration and he drove back home in low gears. The car was misfiring, the first thing I thought was the spark plugs have gone. Got the AA out, and they checked and found the code P1399. So took the car to my local garage, and they changed the spark plugs the old ones were completley black and worn out he said and they have never been changed at all, he also changed one coil pack.

When i got the car he did the diagnositic in front of me and it came up as perfectly fine. the only problem is the car is still misfiring at idle. the car mileage is 102,000 miles.

To what I have read up if the car has done that amount of mileage, your meant to do a valve adjustment.

Now reading through the forum, I have gone through a few threads on what it could potentially be, The mechanic has checked alot of things, at first thought it could be the spark plugs that need changing did that car starts fine idles nicely but just misfires, and the Check engine light is on solid. (no flashing at all).

I was thinking it could be a coil fuse but werent sure.

The only thing that keeps coming back to my mind is a valve adjustment i could be wrong but can anyone help at all?

Birdi

randomwalk101

Since you have changed plugs & coil, next step I'd do is valve adjustment and clean the injectors. Good luck.

Chuck S

Got the Service Manual? <--- that's a link to the US model but all markets should be very similar despite what side the steering wheel is placed. Download it and search for P1399 paying attention to possible other codes and to the model year of your car as some codes only apply to certain years. Without the SM you and your mechanic are making wild guesses and wasting time.

Cursory review of P1399 notes trouble shooting starts fuel as in fuel pressure, low compression, poor quality fuel. There seem to be no codes for specific cylinder misfires in the very early cars but someone will have personal experience and post it here.

Good luck. these are pretty robust cars and engine.

-- Chuck

engifineer

If the car is on OBD2 then misfire codes are P0300 for random misfire, P0301 for misfire on cylinder 1, etc. An OBD2 code that starts with a P and a nonzero number should be a mfgr specific code, while P0 codes are generic (all OBD2 cars should support the generic codes). So for some reason, it set the random misfire mfgr specific code (P1399) and did not set one of the generic misfire codes. I believe the mfgr can NOT set a generic code and instead set a mfgr specific code only if the issue is not thought to affect emissions. But a misfire should and thus I would expect it to set at least one of the generic codes. The s2k will set the P030X codes if a misfire is detected. Again this is all assuming this is not an early JDM running OBD1.

That blurb from the service manual does not really help much and is just generic troubleshooting any mechanic should know how to do for a misfire code. So the SM is not often all that helpful for diagnosing codes assuming the person doing the work is experienced in general.

OP, do you have any means of pulling codes yourself? If not, can you verify they actually looked at the full list and no other codes were being set? If it is setting the random misfire code it is telling you that the misfire is moving and not always on the same cylinder or is on multiple cylinders. So barring all the plugs being bad (and you just replaced them) it is not the plugs. Check your valve adjustment as mentioned, but not to confident that will be your issue. Good to get that out of the way though.

Injectors can cause random misfire codes, but since that code means misfires happen on multiple cylinders, you would have to have at least 2 bad injectors I am thinking, so given your mileage that seems a bit odd on these cars.

Coils of course can too, but again, these coils are not known for just going bad often, so having more than one bad at your mileage also would be suspect, but can happen.

Fuel pressure could cause it

Compression issues can cause it

Vacuum leaks can cause random misfires, especially at idle.

There are a lot of causes, so good to check valve adjustment, make sure all vac lines are in good shape and properly connected, you have fresh plugs in already it sounds like. See if the easy things I just mentioned are in order and then go from there.

B serious

what brand of coils and plugs were used?

and is the misfire being caused by the cylinder with the new coil pack? what happens if you put the old one back on?

windhund116

If the spark plugs were never changed, a good guess is the valves have never been adjusted. I'd start there. The OP may want to check compression, after the valves are re-adjusted.

Chuck S

Foot notes in the Service Manual show the P0300 codes don't exist in the very early cars so, if true, misfires aren't tagged to a specific cylinder. Again that's just me looking at the manual. There's at least one other misfire thread running now as well but I think it's a later model car.

-- Chuck

engifineer

I wonder about that in the US. The US mandates that anything affecting emissions must support the use of generic codes (So you do not have to have special hw/sw tool to access things related to emissions). So I wonder if that is referring to the JDM vehicles that did not come to the US? OBD2 has been required as far as I know it since 1996 in the US

Chuck S

I could easily be misreading the Service Manual...

-- Chuck

Birdi

Hey thanks guys,

I'm going to get the mechanic to carry out the valve adjusment first then take it from there. But hopefully fingers crossed that solves the problem.

Birdi