1995 Buick Regal - stalls, poor gas mileage, tach. jumps

1995 BUICK REGAL
135,000 MILES • 6 CYL • FWD • AUTOMATIC
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JLOSEY
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I've been having some problems with my 1995 Buick Regal Gran Sport (3.8L) for quite some time now, and I was hoping someone might have some suggestions on what I can replace to fix them. The reason I'm asking this is because I can't get a reading from the OBD-I connector (according to people at Autozone and a local repair shop); therefore, I have no idea what's happening. Also, I had the EGR valve replaced (about a year ago), then replaced the spark plug wires - both didn't seem to do anything.


Always does the following:

- smells like gasoline outside the car, but only when it's running (coming from exhaust)
- gets terrible gas mileage compared to several years ago


Intermittently does the following:

- "Service Engine Soon" light isn't always on - it randomly comes on after awhile and stays on until car is shut off
- stalls out when coming to a stop or after being put in neutral, but after being put in park, it often starts back up easily
- car "hiccups" (for lack of a better term) almost as if the pistons weren't firing correctly
- violently shakes up and down (whole car and tachometer) while idling, especially right after the first start-up that day
- tachometer sporadically jumps around while I'm driving at highway speeds, causing the car to change speeds (to clarify, if I take my foot off the gas pedal, the needle jumps down to 800-1000 rpm's and slows down almost as if I lightly applied the brakes; from that point, I need to press the gas pedal much more than typically needed, and it jerks the car up to 1500-2000 rpm's)


I'll keep searching the forums in the meantime - If you have any suggestions, they'd be greatly appreciated...
Nov 11, 2009 at 3:47 AM
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DOCFIXIT
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Try this find DLC underdash see diagram jumper from A to B paper clip works. Turn key on count flashes on MIL. So flash, flash pause flash, flash,flash = 23 Let me know


https://images.2carpros.com/forum/automotive_pictures/198357_Graphic_237.jpg

Nov 11, 2009 at 1:10 PM
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JLOSEY
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Based on your posted diagram image and one I found at this site https://www.2carpros.com/articles/mitchell1eautorepair-car-repair-manuals, my OBD-I connector has no B wire run to it, but only 3 at the locations of A, M, and J. I've been unable to find any information online about such a setup. Thanks for the info so far - please get back to me.
Nov 12, 2009 at 12:59 PM
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DOCFIXIT
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Car has pre OBDII 16 pin and needs scanner to get codes. That site has what you need you may check with local GM dealer they may have an old scanner.
Other option is check basics compression, vacuum, fuel pressure, ignition coils and EI module, crank and cam sensors and MAF
Nov 12, 2009 at 2:36 PM
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JLOSEY
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I've considered that it may be the OBD 1.5 hybrid, which uses a 16-pin plug, but I am positive that it is a 12-pin connector.. Thank you for the suggestions - I guess I'll need to find a new mechanic with better tools sometime soon...
Nov 13, 2009 at 1:48 PM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.