I recently purchased a 92 Bonneville with 165K on it. While trying to merge on to the highway my oil pressure spiked from ~65 to 120 and I lost all ability to accelerate. I was nearly hit from behind by a semi because of this.

After pulling over to the side of the road for 30 seconds the car would accelerate as normal. However this happened 3 times again in the span of 15 minutes while driving on the highway (no other semis involved). Needless to say I would like to figure out what is causing this so another inopportune moment does not occur and leave me without a car and in the hospital.

Does anyone have any ideas what could cause this? (My oil is due for a change in about 1000 to 1500 miles too)

Possibly a restriction in your oil filter? What type of oil filter did you use?

shadowcat,

1. How much gas was in the tank?
2. Were you merging while traveling clockwise around a ramp, or just coming out of a curving ramp?
3. I double your oil pressure reading is related to loss of power. If so, I would think your other gauges would have done something weird too. Did you notice?

Another thought. How many tanks of gas have you had in your "new" car? What I am getting at is, do you have any reason to believe your gas gauge is not accurately registering fuel amt.?

I still think you have 2 unrelated problems?

1. Electrical
2. Fuel related

Ok.

1. As for the oil filter type, I don't know the brand. I just bought the car and it is not parked where I can check right now.
2. The tank was registering between 3/8 and a 1/4 tank. I have put a full tank of gas now in the car and now my check gages light is on. This is the first time I have filled the tank since purchase too.
3. I was merging traveling clockwise up a ramp when the first power loss occured. The other 3 times were on straight sections of highway.
4. None of my other gages moved when the oil pressure buried and I lost acceleration control. Battery charge was at nominal, Temp was between 1/2 and 3/4 of the gage (it is a little warm in Des Moines), Gas was jumping a little but it has been doing that since I bought the car.

Sounds like what happens to my '92 SSE supercharged. I bought it in 1999.

On mine, if the fuel level is less than 1/4 tank or so, beware when making right turns or it'll stumble and lose power. If I let the tank go to that level or less, I have to slow down when making turns. So I always try to fill it at 1/2 tank or so. Yes, this is dangerous, and from what I've read, the fix is to replace the fuel pump and sending unit...but it'* inside the fuel tank so I haven't done that to mine.

My fuel gage also sometimes reads empty when I fill the tank, and the "check gages" light turns on. The light will turn off and the gage will read full after you drive a while and the fuel level drops a bit. Annoying, isn't it? GM issued a service bulletin about this, and it involves adding a 2000 Ohm resistor to wires under the carpet on the left passenger side. It'* documented in the tech info section.

By the way, I also learned about both of these problems just as you did...the hard way! The previous owner didn't say anything about them to me...

shadowcat,

Here is my guess:

1. You have a faulty voltage regulator module in your dash. Means dash "cluster" needs to be replaced. You should be able to find the "part" for about $110 rebuild/exchange. Install yourself with our help.

2. Faulty module = inaccurate fuel readings, oil pressure. Seldom effects voltage and water temp readings.

3. Inaccurate fuel readings = fuel starvation due to you having less fuel in your tank than you think. Try this: the next time you show about 1/4- 1/8 tank, try that sweeping right-hand turn again. I'll bet she stalls out again, or sputters like a fool then catches again if you get out of the turn soon enough. Also, DO NOT COME TO A STOP WITH THE NOSE POINTING DOWN (AS ON A SLIGHT GRADE). Your fuel pickup screen, in the tank, will not pick up fuel and you probably will not start until you get her off that grade. Parking with the nose uphill = no probs.

4. Final clarification. Replacing the module will make your gauges read more accurately and more stable. It will not correct your problems when you are prox. 3/8ths tank or lower.

shadowcat,

In my previous reply I stated, "You should be able to find the "part" for about $110 rebuild/exchange". I forgot. My bro got me a "professional" auto mechanic'* discount. A dealer will charge you $300 for a rebuild w/ exchange. Have a buddy who is a mechanic authorized for dealer discount when he orders? If so, you'll save big bucks.

Well here is the situation thus far.

1. I have replaced the oil filter and put new oil in it. The gage remains buried at 120+.
2. The check gages light is off, guess the fuel settled in the tank and fixed that.

The engine sounds fine, runs well too. The oil pressure gage still fluctuates while driving. Although it seems to happen more when I am in reverse. Guess I'll be driving her until she goes goofy again. Hopefully not on a highway again. Thanks to everyone who helped.