Ok, here's the story.... Car is a 2001 with a 04/05 AP2 swap, bone stock motor internals. Modifications are Vortech V2, ID1300's, SOS 3 bar map sensor, AEM FPR, Hardwired AEM 320lph fuel pump, AEM V2 EMS, NGK BR8EIX plugs, High boost pulley. Car is currently on 93 octane running a basemap from Jeff Evans. So, with the basemap the car idles perfect, but once any type of throttle is applied the car sputters and breaks up. The original basemap would break up very bad. Jeff then sent me another basemap adding more fuel/ an actual tune from another supercharged s2000 with the same injectors and map sensor. After this, the car runs slightly better but it still breaks up. Note* Jeff has sent me prior basemaps with no issues. I'm running out of options since my tune date is less than 2 weeks away. Now, this motor was installed in the winter of 2014/15 and the car ran fine until I installed the new injectors (1000's to 1300's). Me, being a dummy, didn't change the tune, compensating for the injector change and the car ran crappy. I then got a basemap for the 1300's and the car ran fine, but then ran into an issue one time where the electrode actually broke off the spark plug in cylinder #4. I then assumed it was a fualty plug or something unfortunate. I replaced the plug and went to tune day (last year). We ran the car well on E85 (made 491whp) then ran into problems where the knock sensor was showing considerable knock. We played with the timing a little and nothing made anything better, another plug on cylinder #4 also broke an electrode. (I don't remember if we broke a plug and then played with the timing to compensate for the knock or vise-versa). We then changed the plug, moved the coilpack and did a compression test. Compression came back a little low in cylinder #4, but nothing crazy. The coilpack wasn't the issue either. We then assumed the E85 was junk since it was still knocking with the timing being set on close to what 93 runs on with considerable knock still. We then dumped the E85 and filled up with 93 and nothing changed. We then came to the conclusion that the new ID1300's might have been faulty (the one installed for cylinder #4 at least). I sent the injectors out and they checked out perfect. I swapped from an AEM V1 to the new V2 and here we stand. I'm not sure if something could trigger this kind of issue with doing a motor swap (wires pinched, etc.), something wrong with the motor internally, shitty fuel, fuel pressure (the AEM FPR is brand new and un-adjusted, not sure what fuel pressure I should be making on my gauge? must it be 43psi and nothing less?), etc.. Not sure and I'm interested in any and all opinions.

Thanks guys!

 

I'd do a leakdown test. My guess is the engine has issues after you've had two electrodes break...

Once a cylinder starts losing compression it can only go downhill from there.

 

What could be wrong with the motor in that case to cause it to break up under any type of throttle movement? Valve adjustment potentially?

 

My rough guess is a problem with your valves and/or scarring on the piston and cylinder walls.

Someone else will probably have a more educated guess but I'd be very surprised if after all that engine has been through there's not some internal damage.

If you've already ruled out bad injectors and a faulty coilpack then that's where my money is at least.

 

I had a SCed car here the other day that ran great but was breaking up bad under load.

4 coilpacks solved the problem. 2 if not 3 of them were all bad. Breaking up under load is typically ignition. Hope this helps a little.

 

Thanks Billman, I'll order up some new ones, do you reccommend the k20 coilpacks over the oem f20/f22 ones?

 

F22c 04-05 denso coil packs #673-2301 are crazy cheap from walmart.com
http://www.walmart.com/ip/DENSO-673-...-Coil/42400838

 

^^
I bought these same ones from Amazon Prime for similar money and they work great in my MY01.

 

Don't just buy one or two coil packs, get the whole set, when one fails the rest follow soon. At least that's my professional experience.

 

^^^x2 right on the money, my experience as well