Hey guys!

 

Currently acquiring a RS from my coworker, it came in the shop with a broken belt and he had the cash first, however he's given up after a persistent misfire.

 

car is a 05 RS with ej253 and a manual trans, recent repairs include (history unkown):

rebuilt engine, great leakdown/compression

driverside head is non egr(more on that in a minute)

new: plugs, wires, fuel pump, injectors, front o2, battery, ACT flywheel/clutch, motor mounts, yada yada

 

i've personally swapped, cam/crank sensors, cleaned throttle body, tried spare map sensor/maf, extra grounds, no vacuum leaks.

 

everything appears to be operating correctly. however from an idle if you stab the throttle it will slightly miss and clear up, worst when cold but still there when hot, almost unnoticeable when driving, car is very responsive and quick, revs through the gears fine. just has this slight miss. If you ease in the throttle its fine, and always returns and idles fine. It seems that its loading up with fuel because if you make it miss several times, turn it off and pull the plugs they are wet, doesn't throw codes and if it does its never the same ie:Misfire 1,2,3,4 never the same and never multiples.

 

I'm starting to think either it has a dieing throttle body or the lack of egr is the problem, the codes are turned off via RomRaider but don't know the perimeters for EGR to try to add additional air, I know off throttle around 55-60mph will open the egr but do they also open when you stab the throttle from idle? do I just need to tune out the tip in enrichment? i've gone through everything I can think of so far and was hoping for some more suggestions.

 

Thanks

 

 

 

link to video of the problem, sorry i don't know how to embed it,

EGR is only used when cursing to prevent light throttle lean mixture detonation.

Its never open at idle, acceleration, or during snap throttle.

 

Who tuned it? Or what are you using to tune with?

What kind of plugs are in it? If it's tuned to run a little more rich, it may need hotter plugs to prevent fuel fouling.

Ah, good information thank you!

 

It's not tuned per say. The codes have simply been turned off with romraider and a tatrix cable.

 

Plugs are standard NGK. I can try hotter plugs and see where that gets me.

Is the flywheel a lightweight? Those can cause stumble/roughness when engaging the clutch due to the loss of momentum.

 

If you have Romraider start logging some data. O2 / AF sensors, injector pulse, spark timing, knock correction, etc.