Which injector sizes are available for a 91 TT? I did a search, but can't seem to find the messages that tell you this, although I'm sure they are there somewhere.

 

Was it 440, 550 or 555, 660, 720, 850? Or were some of these for later models only?

 

Is it only around 850 that they affect drivability - and is this just because of less smoothness at low revs?

From what I have heard, any injector which is larger than the CC of each cylinder, will effect the idle. Using that rule 555cc will effect the idle slightly but I have heard people say it doesnt.

 

I have seen threads on TT.net with people who have installed 720CC and they say the idle is really rough because of them.

Idle up to and including 740s can be held nice and steady. After that, the injector duty is so low that it starts to affect the fueling - although someone who is good at mapping should be able to achieve a nice stable idle.

 

Sizes are as follows:

 

370 - stock

440 - not much use

550 - usually bored out 370s

555 - from Nismo etc

720 - bored out stock

740 - nismo?

850 - YUMMY me wants some :D

how are you gonna combat the idle duffer :) would be interesting to know :)

I would guess that rough idle would only be due to poor fueling from an off the shelf chip, maybee proper tuning would help

Yep pretty much what Paul said. Who cares about idle anyway? These cars only idle how they're supposed to for half their lives anyway so whats a bit of roughness between friends.... Erm maybe I should rephrase that :D