Problem with 1993 Pontiac Grand Prix

[High Head Blues]

Hello, first a little information about my vehicle. I own a 3.1L 6 cylinder 4 speed automatic 1993 Pontiac Grand Prix with about 180,000 miles on it. Overall (I think!?!?!), it is in pretty good condition.

I recently replaced the water pump on the car because of a leak. After I started it back up, the service engine soon light came on (I did reconnect everything). I took it to an auto store in town to try and run a diagnostics check on it but I think the machine wasn't working properly and I couldn't get a reading.

There are a few 'symptoms' my car displays. First off, on start up, the idle is normal and then it will rev quite a bit higher than normal for 10-15 seconds. Acceleration is lagged but once I am accelerating the light goes off but comes back on once I have settled into a constant

A few months ago I drove through the mountains and I started getting pretty hard knocking at about 60 mph and on uphills. I don't know if the altitude could have turned one of the sensors out of whack or not??? I am not sure whether these two are related or not. I have probably put about 10,000 miles on it since then (changed fuel filter and added injector cleaner which helped a little).

I think it has to be something with the intake system like a bad seal on one of the gaskets, bad O2 sensor... something of that nature. It also seems like I have a significant more amount of condensation coming out of the tail pipe and my gas mileage is less but this might just be the cold weather taking over.

I appreciate any suggestions and how difficult the repair would be for a complete moron. Thanks in advance.

Oh yeah... I own a Haynes Manual too.

[tblake]

I agree. it sounds like a vacuum leak somewhere.

[CrazyHorst]

I would also recheck your electrical connections. If a sensor is loose you would get the instant SES light. I'd double check the ESC sensor which could also lead to unmitigated knock, although a number of other sensors could contribute.