Engine Running too lean? (VR6)

[mattwelcer 0]

Just taken the engine apart due to a big end bearing failure and noticed that the valves on the cylinder head were quite white and the inside of the exhaust manifold was also white. Is this a sign of the engine running too lean and therefore running too hot?

 

 

The car was originally a 2.8 which has been bored out to 2.9, it also has Schimmel 263 cams, a CNC Cylinderhead with larger inlet valves (41mm), a Schrick VGI intake and a K&N 57i intake and its a OBD2 model/ECU. I don't think those modifications would be so significant to make it run that lean. Or i am wrong and it really needs remapping ASAP to avoid any further damage? Or should i check the fuel system to see if it really is getting enough petrol?

 

Additionally before this i had problems with a new oil cooler, where the oil and coolant were mixing. More oil getting into the coolant than the other way around. After changing the cooler to my old one it solved the problem but could this also have lead to it eventually running too hot? As with the "broken" oil cooler i had oil temps of around 108C but with the old working one the temps were around 96/98C

[Kevin Bacon 5]

Yep, defo lean. A 'Normal' engine will exhibit exhaust valves with cardboard coloured deposits on them and the intake valves and manifold will be quite black and sooty.

 

Bigger valves + porting + cams is definitely enough for it to run a bit lean at wide open throttle. Defo needs a remap imo.

 

If the valves are the same colour across all cylinders I don't think you have an injector or spark issue, but for the sake of a £100, it might be worth dropping in a new fuel pump as a precautionary measure.

[mattwelcer 0]

Cheers Kev, with regards to a fuel pump new from VAG or else where i.e. third party?

Also how much of a difference can the fuel pressure regulator make? As mine was originally a 2.8 engine (3 bar) are the later 2.9 engines the same (3 bar)or do they use a different one (4 bar)? Could this be the cause of it potentially running lean as i haven't changed this?