I just fixed my random misfire with a buddy this weekend... best part -- FREE!

I was having the misfire on all cylinders and the random codes. Before this weekend I had already replaced plugs and coil packs, no luck. I was planning on buying some new injectors as my next step but a friends suggested that we just clean them. Pulled the fuel rail, got some throttle body cleaner and went to town. Cleaned the injector tips and all the cracks we could get to with qtips. The tips get pretty gunky and the part that I thought was the worst was the hole where the injector sits. After the cleaning... I'm at ~150 miles and 2 days with no codes.

I should mention that I have an AP1.

Please check this before spending money like I did... It might just save you the trouble too!

edited - fyi, This has worked on 2 other AP1s that are in our PNW group.

 

Might want to check that last bit of info. A majority of autozones ignition/engine management items are made by Wells. Only time I've seen non wells items in autozone packaging at a store is an employee "hooking up" their friends by swapping worn oem for new aftermarket parts.

 

 

I wasnt hooked up as far as I know as I didn't know the guy behind the counter. Maybe it was mid packaged, but I do know that the new one I got has "Denso" emblazoned on it and matched the ones in the car in every detail

 

No misfires here. I have been reading through everyones nightmares so I know what to do when I do. Then, I felt suddenly stupid. 3 years ago, I was doing some research for an automotive publisher attempting to predict the probable cause for a trouble code. During my research the most common solution for misfire codes was to clean the injectors, followed by bad plugs/plug wires, followed by the TPS and then throttle body followed by valves. As much as we like to think our car is unique, these will be the most common source of the problem. Where the s2000 is unique is the abuse we give our valves. I am the type of mechanic who seems to always have parts left over and less skin when I am done. So, I limit myself to the top two solutions. Most of the techniques suggested appear to be haphazard. There are techniques to test all electrical components and sensors. You can go a long way with a simple code puller and digital multimeter. The cost of the simple tools would probably save you money and hours experimental replacement. Me, I will just take it to my mechanic .

 

Been wrestling with a a P0304 for a while now. Haven't checked compression or leak down, and i swapped coils (still misfire cylinder 4). Plugs are relatively new (less than 5000 miles, about a year old), when I pulled them they looked nice and brown. I've re-set valve lash and checked it a couple of times, and unless i'm completely incompetent with a feeler gauge, i'm in spec. Will do compression and leakdown next. Have a friend who services injectors who says he'll clean and flow test them for me so if comp/leak down show up good, that'll be my next step.

Since the misfire is consistently cylinder 4, is it safe to say that the problem is either with the #4 valves or #4 injector at this point (coil and plug are ruled out)? I did misshift (4th - 3rd money shift) at the track and caught it pretty quickly. I didn't notice anything off with the valves when i re-checked lash after the overrev, but i may have missed it.

Car runs strong. even with CEL lit i'm in VTEC with no issues. thoughts?

 

I'm getting a misfire code and shop is recommending a complete new engine. I started this thread in case I can catch some advice...

 

Just thought I'd chime in here. Recently diagnosed a misfire on another member's car. Codes came up for misfire on cylinders 1,2,3,random.

I ended up swapping coil packs and spark plugs from a good working car but immediately continued to hear misfires on idle. Swapping injectors is what solves the problem.

FWIF: This was a 2004 AP2 with 125k and excellent compression.

 

Struggled with random misfires on 05 for a long time. It was, in the end, failing WIRES by the map sensor. Couldn't tell by looking, but the wires inside the insulation had failed . New wiring harness solved the problem. Hope this helps.

 

Just fixed my misfiring issues. 2 bad coil packs.