Check engine and traction light at the same time.

My 1996 Buick Riviera has had this intermittent issue going on for a few months now. What usually happens first is the check engine light and traction light both come on at the same time on a startup. After the codes are read the only code in the system is a p0171 which is system to lean. I have not found any vacuum leaks yet. The fuel pump has been recently replaced twice and I have good fuel pressure. Usually the check engine light will leave by itself or if it clears it will stay off for a few days and then randomly come back. The car runs pretty good it doesn't run the best. On some startups it will crank to where it almost wants to die out but then it will eventually stay running and kind of grumble and moan and then clear out to an even idle. This car has almost 400,000 miles on the original motor so I know anything could really be an option. Just wondering if anyone's had similar experiences.
Thanks,
Alex

...no, sounds like just lack of maintenance. My Riv has 390+ thou and I've never had to even think about opening the motor (although I have replaced the valve cover gaskets).

The 'traction' light sounds like a bad wheel sensor or bad pigtail to a sensor. You will need a TechII to see which wheel is the culprit.

The 'system too lean' could be a crack in the exhaust manifold. Because of peculiarities in exhaust flow, such cracks tend to suck wind and dilute the exhaust effluent - resulting in your O2 sensor complaining that things are too lean. The peek-a-boo P0171 sure sounds like a manifold crack (almost certain at this mileage) or gasket failure (rare). Reason manifold crack is almost certain is that they are a cast ferrous alloy and after so so many thermal cycles they crack. Get a younger one at a junkyard and swap them; consider getting new bolts from ZZP for the job (they sell righteous bolts for cheap).

The long crank may be a fuel system leak somewhere, allowing the pressure stored in the fuel system to bleed down (a lot) between starts. Or just a weak battery, you should test it.

FWIW you could also check your brake fluid level. Since you're seeing the traction control light at start up, this may not be your problem, but if it is a little low it will shift back and uncover a sensor when accelerating and cause the traction control alarm to ding.

Alexander Morgavan wrote:

This car has almost 400,000 miles on the original motor so I know anything could really be an option. Just wondering if anyone's had
Alex

Good to know my Riv still has 300,000 miles left to give! I only manage to put about a thousand miles a year on it so I've got at least 300 years to save up for the Riv's replacement!