88 80Q, Runs rough upon starting//possibly resolved

[SJ]

> From: "nick at beol.net" <nick at beol.net>
> Subject: Re: 88 80Q, Runs rough upon starting//possibly resolved
>
> Awhile back a lister had determined a vacuum leak at the brake booster.
> What actually was bad and how was it fixed?
> Nick

**** An easy way to determine if you have a Lean Mix (vacuum leak) is to
hook up a propane line to the air intake.
The boot has enough plugs and air lines going in that you can doohicky
something up.

With engine running, start adding propane (regulator and fine adjust valve
is handy) until idle smooths out.
If propane fixes the rough idle, then you can proceed with locating the
leak.
To locate the leak use propane . . a hose ending in copper tubing. Let
propane flow and poke the tube end near vacuum lines and fittings. Dont
forget the fuel injection inserts area.
When you hit the leak, the idle will smooth out.

A more sensitive test is to do the above and use a voltmeter attached to
disconnected oxygen sensor. The O2 sensor will react dramatically to changes
in air fuel mixture ratios. Lot easier doing this than listening/feeling for
a smoother idle.
Also, disconnect the FPR to keep the computer out of the loop --> eliminate
as many variables as possible.

SJ
85 Dodge PU, D-250, 318, auto
85 Audi 4k - - sold but still on the road
88 Audi 5kq
90 Audi 100q




-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.409 / Virus Database: 268.15.21/589 - Release Date: 12/15/2006