1979-1993 & 94 Conv [Subscribe to Daily Digest] |
Members do not see ads below this line. - Help Keep This Site Online - Signup
I recently bought my first Saab, a '90 900S. I had it checked out by a mechanic, no big problems detected.
The first thing I did was try to get it smogged. The 2500-rpm numbers were like so:
HC 40ppm
CO 0.11%
At idle:
HC 18ppm
CO 0.00%
Passing numbers, to be sure, but it didn't finish because the idle was around 1200-1300 rpm. The lean mixture at idle made me think something important was going on, so I bought a Bentley manual and started digging in. Here's what I did:
-Cleaned throttle body with Berryman B-12 carb cleaner (it was pretty clean to start with).
-Cleaned AIC valve with same
-Replaced AIC valve with new one just in case
-Tested O2 sensor output (a little iffy - sometimes it would oscillate, sometimes not)
-Replaced O2 sensor
-Tested operation of fuel pressure regulator (although I couldn't pressure test fuel system - no pressure guage)
-Checked for vacuum leaks until I was blue in the face
-Checked inputs/outputs to/from ECU
-Pulled a bunch of LH diagnostic codes, like so:
12223 - lean mixture
12241 - mixture fault
12225 - O2 sensor output fault
12112 - O2 sensor loop fault at idle
12111 - O2 sensor loop fault while driving
-Got fed up, took it to a mechanic
Here's what the mechanic has done so far:
-Swapped AMM for known good ones (three of them)
-Swapped AIC valve for known good one (just in case my new one was faulty)
-Swapped O2 sensor for known good one (just in case my new one was faulty)
-Swapped ECU for known good one
-Checked for vacuum leaks until he was blue in the face
As we speak, he is now tracing fuel injection electrical connections one by one.
For reference, the previous owner had it tuned up about six months ago (new plugs, rotor, cap, wires, filters, etc.) It runs and idles smoothly, has no problems with power, acceleration, backfiring, missing, or anything else.
Does anyone have any ideas?
-Tom Young
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
