1990 Buick Regal 3.8 problems

[3Bar_Mopar]

This is my cousin's car and I can't figure this thing out. Basically, it can drive fine, then you hit a bump and the dash (digital) will suddenly read "0"s for the speedometer and tach, then the car will sputter badly and have absolutely NO power. She can floor it and it just will not accelerate. The car will also die in this situation. The CEL will flash erratically. Also, you almost always have to keep your foot on the gas or it will die. I replaced all vacuum lines, plugs, wires and the fuel filter. I'm wondering if it's the computer or injectors....I'm thinking maybe something electrical since a good jar will cause it to act up again.
Please help...she's in college and works and needs this car to be reliable.

[turbovanman²]

Get it hot and let it run, tap the computer and see if it dies, common problem on early GM's.

[TurboSedan]

could be a bad ground somewhere. check to see if the battery terminals are tight to begin with.

[TurboSedan]

btw, are you getting any codes? i think you just need to ground pin 'A' and 'B' in the ALDL dianostic connector with a paperclip and the CEL will flash the codes at you. it will start with code '12' then any existing codes will follow then repeat IIRC. GMs don't have a an 'end code' like '55' that our TMs have.

[tsiconquest88]

Could be one of the grounds from engine to body. some gm's have a ground within the harness that is bolted to the body or engine block. Also it could be the thinner wire at the starter. Sounds weird i know, but gm and many manufacturers (although not all cars within those manufacturers) tend to have this wire effect the vehicle running and they corrode and or break/come loose with vibration etc. Usually its a 1 wire connector that slide onto a tab off the starter.

[capev86]

i have an 89 lesabre limited 4 door and can offer you some advice based on mods to my own car:

the 93-95 ac delco ignition module replaces the magnavox unit of the previous several years - the plug socket and mounting plate bolt pattern is the same. you must have a module for the exact size engine you have, but same era ignition coils for the 3.1 will mount to the 3.8 module and vise versa. the ac delco ignition is more dependable and puts out more power and the specs call for a wider plug gap!

92-96 lesabre (and others) have 11" brakes whereas on my 89 the brake rotors only measure 10". the mod made for night and day stopping ability. everything from the knuckle out must be swapped. you can bolt in your old hubs and run the original axles, but i wanted to use the newer parts especially since the threaded ends on the newer axles dont stick out as far (i didn't want to use cheesy buick hubcaps and instead run acorn lugs and trim rings). the inner splines are idental between 89 and 93, but there must have been a change to the right side of the trans. i had a local shop build a hybrid using the inner and middle section of the 89 axle with the outer section of the 93 axle. the middle on the 89 unit is roughly 3 inches longer. the part numbers for 91 vs 92 axles are different (i was trying to see if there was crossover year before i had the hybrid built) but thankfully the cv joints were compatable.

notes: you will need two different sizes of large deep socket to spin the nuts on the axles and the threads/diameter is different too. also....i found out that 89/90 era riviera 15 inch steel rims will not clear the calipers on the 92+ brakes, so i went back and got the 15 inch wheels off the 93 donor car. they look almost identical, but there is a slightly different radius where the wheels curve around the caliper.

i also put on 87-89 lesabre t-type sways, early 90's gm h body strut brace, used u-haul brand class 3 hitch from ebay (no longer produced), and a magnavox 1.5 din cd stereo. future plans are a mild resto job with new paint, poly bushings and general chassis overhaul, and perhaps some day a rebuild and stroker kit on the 3.8 (makes it a 4.2).