Thread: The $800 GPSE resurrection.

How's it going?
So last week, for $800 I picked up a 1996 Grand Prix SE as a second vehicle for my wife and I, and also as a project I could spend time on over the weekends. The car is in kinda rough shape as would be expected of an 18 year old car with almost 190,000 miles. The engine and trans are both in great shape, and the intake mani gaskets were changed recently, which on a 3.1 is definitely a bonus in my mind.
When I picked up the car, it was throwing code P0420 (inefficient catalyst...) so I replaced the O2 sensors and checked all the wiring and now that I have eliminated all the variables, I have decided to just go ahead and drop $300+ on a California approved replacement catalytic converter, which should be the fix that takes care of the trouble code. The new problem (created by me) is that one of the bolts from the cat to the manifold snapped and is broken off in the flange on the manifold. So...the next plan of action is to remove the rear manifold and extract the bolt, or just replace with a new part. I've gotten about 3/4 through the removal process and should be able to have the mani off by tonight.
My main goal of this build is to bring this car back to life, I'm not looking for impressive hp numbers or for this to be a head turning show car, just keeping a log here of what's been done. This may be a good reference point as I move forward with this project and maybe I can help some others through some of the problems I work through.
This is not my first and will probably not be my last 3.1 GM sedan, but I plan to do a little more than just drive this one to work.
So stay tuned if this thread doesn't bore the hell out of you, I'll add a few pics here and there when i think they might be useful.



Thanks,
Tim


Sent from my Windows Phone.

I have already replaced the alternator due to the headlights pulsating at idle, that along with cleaning the MAF and throttle body has made this car run 100% better than it did the day I brought it home.
I do have a checklist I'm working my way through, and once I have it a bit more organized and concise, I'll post that here too. Once the manifold and cat are finished, I'll be working my way from front to rear and repairing or replacing anything that is in need.

Thanks,
Tim


Sent from my Windows Phone.

So... I got the rear manifold removed and had no trouble extracting the sheared bolt. I used a method I had heard of previously but never tried; I welded a washer and nut to the broken bolt and backed it out with a rachet and socket (and a liberal application of liquid wrench). After the bolt was removed and the holes all re-tapped, I put everything back together and now, I'm just waiting for payday to order the ~$350 CA legal catalytic converter, then this $800 heap will be roadworthy, and ready for smog.
I will say, removing the rear manifold was much easier than I had expected after reading all the info online. I was even able to do it all without unbolting the suspension sub frame.
The longer I have this car, the happier I am with my $800 "investment". It runs better than my '94 Buick Century ever did, and I got that car with only 89,000 miles on it (the Grand Prix just turned over 189,000).
Once I get the cat and have the car smogged and ready to go, my next plan of action will be to go through the suspension and replace the front struts and all the bushings front and rear and from there this car that was bound for the scrap yard will be my daily driver and I can keep my low mileage Mazda b2300 low mileage.

Thanks,
Tim


Sent from my Windows Phone.

Some good news today.
So I went ahead and put the exhaust back together so I could drive the car to and from until I have the cash to buy a new catalytic converter. I ran the car with the downstream O2 sensor out until the SES light kicked on so I would know that the ecm was logging data, then I installed the O2 sensor and drove the car to work today (17 miles each way), and just before I got to work the SES light clicked off. And now after about 30 more miles of driving, still no light. I know this is not a guarantee that the problem has been fixed, but several things that could possibly trigger code P0420 (namely replacing the alternator giving a steady flow of voltage to O2 sensors, replacing both O2 sensors, and repairing a cracked PCV tube) were addressed over the last few days and could very well have been the root of the problem after all.
I never take the word of someone telling me what's wrong with a car, even though they are generally right, but this time my diligence may have saved me from wasting $350 on an unnecessary part. Smog check will happen sometime around the 10th, until then I will just keep cruising in this car and see what happens.

Thanks,
Tim

Sent from my Windows Phone.