Hi, I've got a '91 with 133K on it. Just started acting up. Looking for answers... I've just replaced the fuel filter, recently replaced the coils and have checked the wires. The problem seems to be fuel related... When the car has been sitting overnight and I start it , she runs smooth, After 5 minutes of warming she starts to sputter and run rich. Driving: If i put it in overdrive, normal position, and stepp on the gas she bucks and stutters and sounds like she's running on 4 or 5 cylinders. If i back off the gas and gradually increase she runs fine. More telling is if i put it in (auto) 1st and wind it up she runs better, then shift to second, then drive compared to letting it do it by itself. It somehow seems the higher rpms under load help resolve the problem... Bad fuel injectors????? Help!!!!

 

Check your EGR valve, on mine a spring keep the valve closed and a
multi-position coil open the valve to control the amount of exhaust gas
that will be returned to the motor. In my case the spring was broken
and the back pressure of exaust keep the valve open after it was
activated the first time. When you give more gas or load your
motor more fresh air come in the intake, the mixe betwen returned
exhaust gaz and fresh air change and your motor goes better. This
valve often cause trouble and nobody think to check it. You can
unplugged it to verified, it will solve a big part of trouble.

 

Egr valve can also be held open by carbon depsoits so unpluging them can make no diffrence . Hate to sound like a broken record but check the pressure reglator for leakage on the vacume side or catolitc converter for blockage. Just had one in my shop with these two problems the pressure regulator digaphram ruptured allowing raw fuel in to the intake stream witch in turn allowed raw fuel into the exaust mealting the substrate in side the converter presto pluged exhaust.

 

One other thing to check is the air flow meter. Tapping on the meter while the engine runs at idle may show stuttering, stalling or backfiring, indicative of a problem here. I have made this statement frequently on this forum, maybe to extreme, but these problems were very large in the '80's and '90's. I cannot stress this enough. Overlooking the possibility here can lead to hair pulling, changes in language, and countless replaced parts. Ray

 

Hi. I'm new to this site. I ended up here 'cause my Dad just got a 2002 LeSabre.


Anyway, I read this thread and had to respond for anyone with a similar problem.


I had a 91 Bonneville with the 3.8L, and had a similar problem. It seem to occasionaly run rich, sputter, etc. I took it to the dealer twice. I finally figured it out after it was parked for about 4 days, and the battery went dead. That's right, it had a weak battery. After I replaced the battery, the problem was gone forever. The lesson here is that these cars can be very sensitive to voltage and power supply. The first step in diagnosing an engine problem; check the battery and charging system. I think most Car parts places will check them for free. I hope this helps someone?