: Can I get some help with my '91 LeSabre?

10-05-12, 12:35 AM
Hey everyone,

Got a question for you. With my recently acquired '91 Buick LeSabre, the car will stumble when I accelerate from a stop. It seems to happen more when the engine is cold, but that's not always the case. If the car sits for more than 24 hours, it can die when the engine is cold and when I'm accelerating from a stop, I.E. at a stoplight or stop sign. It has yet to stall on me when the engine is warm, only cold. It seems that this will happen a lot during one ignition cycle, then the next ignition cycle, it will be smooth as glass.

I did some experimenting tonight. It will stumble for a bit when I accelerate from a stop, but by 5 mph, it's smooth. If I accelerate from a roll, it's smooth, only from a stop does it stumble. HOWEVER, if I'm at a stop and I load up the engine before I take my foot off the brake, it's smooth as glass.

The SES light is on, but it's a code 27, which means something about an error with 2nd or 4th gear, which isn't a problem- the transmission upshifts & downshifts just fine.

My thoughts are EGR valve is inop, or perhaps the IAC is messed up or lastly maybe the mass airflow sensor.

This problem does not affect my fuel economy. I'm averaging between 21 & 23 MPG.

Any ideas? Thanks!

10-05-12, 12:48 AM
Has it had a tune up lately? Could be a bad distributor, bad distributor cap, bad spark plug wires. Clean the throttle body too. That could be it. Far as it dying when it's cold, maybe the throttle positioning sensor?

But to me it just sounds like it needs a full tune up.

10-05-12, 01:13 AM
No distributor on the 3800's, coil packs. The wires were replaced, but I'm not sure how long ago.

I'm bringing it over to my uncle's place on Saturday to have him take a look at it, he worked at a local Chevy dealer from '84-95, so he worked on 3800s like this when they were new.

10-05-12, 11:24 AM
These pre-Series 3800's were real pieces of work - they were plagued with timing set and cam/crank sensor issues. Many times the early symptoms match yours.

The only good thing about it is that everything fails around the same time - generally right between 120k and 130k miles, like clockwork. The problem with the timing set is the nylon/plastic timing gear, and for the cam sensor, the magnet likes to work itself loose and disappear.

10-07-12, 07:33 AM
It's a faulty camshaft sensor. My uncle diagnosed it yesterday and is replacing it today. $26 for the part and $17 for a bottle of Captain Morgan for him. :)

10-07-12, 07:57 AM
If you have the common problem and the magnet ends up being bad rather than the sensor itself (you won't be able to tell until you have it apart), the entire timing cover has to be removed... It attaches to the timing gear from the back side. You're getting a good deal if it comes down to that and a single bottle of booze covers it!

10-07-12, 10:21 AM
I gave my mother in law a 3.8 riviera, the ignition imploded at 138,000 miles. I remember it needed coil packs. TPS and major tune. To the scrapyard it went.