Thread: 300tdi Boost compensator banjo connection

The original post describes this line form the turbo to the boost compensator diaphragm as a "vac line" (ie vacuum) It is actually a pressure line. As those who have put a T piece in this line are fully aware, the boost pressure only builds up with when revs and load are up somewhat. The maximum fuel injection rate for the revs are limited until air pressure builds up in the inlet plumbing past the turbocharger When pressure from it increases on this diaphragm, maximum fuel rate is increased as there is extra air to burn the fuel. Note the full boost standard setting allowed by the turbo wastegate on 300Tdi's is 15psi. ie absolute pressure is about 30 psi, double absolute atmospheric pressure of 15psi. However, there is not quite double the quantity of air entering the engine because compressing by the turbocharger heats and expands it. Purpose of the intercooler is to cool this air under pressure.


With this line off, motor is somewhat gutless as fuelling rate cannot increase with increase in load and boost pressure. If you then jammed diaphragm mechanism so maximum fuel could possibly be delivered all the time, power under full boost would be normal. Under low boost it would be increased but lots of black smoke due to insufficient air. Manufacturers settings have to comply with pollution regulations. However, a weaker than standard spring under the diaphragm allows the fuelling rate to increase earlier. Allows better acceleration - if you are not worried about the extra smoke.

Cheers to all!!

Bloke an Enzed yesterday gave me the number for Rosier Diesel Injection Services in Kotara. Gave him a call and he knew straight away what I was after. Just got back and the legend there gave me a bolt and 2 new copper washers for free!!

It's not the exact same as standard as it doesn't have the filter but said shouldn't be a issue. I'll just remove the cover in a month or so to make sure there's not any crap getting in.

Thanks again to all who helped, especially Mike for pulling his pump apart to help out.

Take the rest of the day off. Tell your boss I said so. Haha

Ben