Help heavy misfire !

[Turbo_scotty]

Hi all I'm hopeing someone can shed some light in this as im getting to the point of giving up :arms:

I have a 2004 260 8

Basically the car misfires on any load it started off by getting worse and worse and now it won't let you put the car on boost at all or even accelerate at all just bogs down almost feels like car is flooding itself or blowing the spark out

The car has also been awful on petrol lately

Mods are

2.5" downpipe into 3" decat and full system ( decat fitted after this fault due to cat rattleing thought it might be blocked )
Evo 9 intake and air filter
Forge dump valve

Standard map .

Car was smokeing black (over fuel) on idle before I changed lambda and airflow meter

I've changed air flow meter, spark plugs (iridium 0.60) coil packs, injector resistor, lambda and the car is still doin it I get code p0505 but I've changed throttle body for an evo 9 one due to 260 sticky problems so just need to be plugged in

I've also did a boost leak test and couldn't find anything

I recently bought evoscan is there anything I can check as I'm unsure how to use it .

 

[DDS789]

Where are you based?

It sounds like you need to get it to someone for a remap and a good check over.

 

[Andy6]

Did it get worse when you put the injectors, resistor, lamber and MAF etc? If so I'd start putting the old ones back on one by one and see if it improves it, that could hone in on your problem then.
What did you do specifically to check for boost/vac leaks?
Is there a condition that it runs correctly? I.E Slow constant speed?

 

[Turbo_scotty]

I did a boost leak test with a compressor mate . At the moment the engine is in 300 bits dues to a compresson test of about 60psi across the cylinders then with oil in the bore shot up to 110 roughly across the cylinders so gonna change the rings altho the rings all look spot on no wear ect bores all look ace little confused now what would cause the compresson loss