LeSabre Running Rich

Hi all, been a while since I posted but I’ve got a problem that stumping me pretty good. First, some specs:

-1989 Buick LeSabre T Type with a little over 200k on the chassis
-Vin C motor with about 70k miles on it (V6, fuel injected FWD)
-2.79 ratio transmission with about 150k miles on it

Here are my symptoms:

-Sulfur smell after a quick acceleration
-Rich gas smell on startup
-Occasional puff of smoke
-Slow acceleration
-Idles at around 550-650 RPMs but its rough-smooth-rough-smooth-rough-rough-ro… after the motor warms up
-Car seems to have better throttle response after resetting the ECM but the problem comes back after its had enough time for a learning cycle

Here are some facts and parts that I’ve eliminated:

-Flowmaster muffler about 8k miles ago
-High flow cat converter about 15k miles ago (CarSound Magnaflow)
-Belden wires wrapped in loom
-Type II ignition swap (blue on the underside of the coils)
-NGK Iridium plugs (overkill I know now but not at the time I got them)
-NTK (division of NGK) O2 sensor, less than 10k miles on it
-FWI with K&N filter (system worked great on my ’88)
-JB welded cam magnet from a code 41 about 10k miles ago
-No codes/SES light
-Correct ECM programmed for 2.79 trans and it is known to be good
-Adjustable vacuum modulator
-“fresh” rubber on the vacuum lines
-No squaling or clunking from the engine
-very slight damage to MAF screen but it has a known good MAF sensor
-I have cleaned the intake recently but the first time 20k miles back or so I did it I used carb cleaner (d’oh!) and since then the MAF has been replaced
-IAC has been swapped out with a known good one
-I don’t smell fuel in the FPR and the idle doesn’t change when I spray WD40 into it (checking for a pinhole leak)

I think the next step is to check the TPS but otherwise I’m stumped. As far as I can tell it should be running right but its not.

Suggestions would be greatly appreciated as I’m going nuts trying to fix this

I just pulled the FPR off and there was a lot of pressure behind it as it sprayed a ton of fuel everywhere… I did have a hose handy to keep anything “exciting” from happening though. I swapped in a spare and it sees better but still not quite 100%. I think I’m going to try a new one tomorrow and see what happens.

Answers for The Question

  1. richard m
  2. baldie
  3. Jeffrey M
  4. biff
  5. [email protected]
  6. mdk68gto