There is a page on the net that talks about testing for vacuum leaks using the instant MPG of the trip computer while decelerating.

It goes something like speed up to 60mph let your foot off the gas. While doing so, if the reading jumps to 99mpg for a second or so, the vacuum system has no leaks.

I tried this on my SIII and could only get 66mph.

Just wondering if this test is valid or not?

 

Wow, a little stroll down memory lane!

I don't know if the test is valid....I can't remember the entire rationale and variables.... but umpteen years ago a bunch of guys on Jag-lovers were trying to get their cars up to 99mpg while chasing rough idle problems and only a few suceeded.

Cheers
DD

 

Is the computer hooked up directly to engine vacuum? If so, where are the vacuum line(s) routed between the two? I have not replaces these lines yet.

 

No.

Cheers
DD

 

At this point I have replaced all the original vacuum lines except the two that run through the center and center-right of the firewall.

Although I can easily see these two hoses on the engine side I have no visabily on the interior side. Is there some clever way to get behind the center dash area easily without having to pull the whole dash apart from the inside?