TTS supercharged misfire issue

Hi guys… So Took my TTS supercharged v8 s5 to MRC (uk) for what I’d hoped would be just a map tweak to for my replacement refurbed engine…


When put on dyno for initial health check it seems I have a misfire at around 5900 revs, had similar misfire on old engine but put that down to low compression on 2 cylinders and blocked cat on bank 2 which was discovered up on engine removal.

MRC tried 8 new coil packs but no change

Collected car yesterday and was told, fuel pressures were bouncing around and would obviously need to be looked at, also it is not running the same exhaust that was fitted when MRC BUILT THE CAR 10 years ago?? Mentioned it could be restrictive.

Running 3" down pipes (decatted) … into x pipe with 100cel welded in.

So decided when home I’d simply remove x pipe to try and rule this out.

X pipe does look quite restrictive where it crosses so had straight pipes welded in , mis fire remains ! it seems me and 2 previous have been chasing this misfire for 3-4years according to the receipts I have in history… this is the dyno graph that compares mine to another s5 they did not long with very similar set up (upgraded impeller wheel in Rotrex).

Need to work out how to attach dyno graph lol…

Also have fuelling logs from MRC if any of you experts could kindly take a look it would be much appreciated
Mrc advised MAF was max ing out and it’s since been discovered I have standard v8 maf in place :see_no_evil:

so got larger MRC maf coming this week to install bud I can’t believe that will solve issues completely :man_shrugging:t2:


If you wish you can load the logs. But the exhaust isn’t the issue. The MAF likely isn’t the issue.

Why has nobody swapped or moved injectors? If you’re getting an issue with just one cylinder move the injector. I know due to the hassle of doing this they don’t want to do that but that would be the first thing I’d do.

It’s not been back to guys who fitted the engine yet as they are on holiday.,. Back this weekend.
I’ll try load logs now, and I’m swapping maf out tommorrow along with new fuel filter.
Am I right in thinking I should disconnect battery for a while while carrying out these jobs?

Regarding injectors, this is their main suspicion.
Injectors were only 3k old in old engine.
I’m little disappointed these were not tested/cleaned before fitment to fresh engine :frowning: :man_shrugging:t2:

Can any of you supercharged guys confirm what Maf sensor you are running please ?