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97 gp one problem after another

V

vermsta

New member
I just bought into the gp world and now i'm stuck. Don't get me wrong i've always loved this car, but I bought the worst one out there. Heres the story I bought it knowing it needed a fuel pump and transmission for 500. I ended up buying a factory fuel pump because a used one was very little savings, then I pulled the trans... I don't even want to tell you about that, so trans back started runs like crap. Cracked front exhaust manifold and It struggles to rev up. Is it a common problem to crack the manifold? I'm leaning towards a plugged cat, but I want to know if the cracked manifold is a common result of a plugged cat, or if I should just junk the car and stop putting money into it.
 


cracked manifold? where?

a plugged cat would make the manifolds glow red hot. that might make a potential situation for one cracking with the heating and cooling, but thats pretty bad. start your car up, let it run and open the hood. if those mani's are glowing then you know whats wrong.

if not, maybe you've just got a screwed up manifold. they are pretty cheap. hell, ill sell you mine that isnt on my car anymore if you really need one. either that or its a great time to upgrade.
 
I can barely get the car to run. Right now it's almost impossible to get it moving and that's with the car on a rack with the wheels off the ground. with no load on the car it can barely get to 60 (by no load i'm talking about wheels in the air off the ground) I'm basically just trying to put a story together to find out why the car runs so horribly since i have no history on it. I'm getting map sensor codes too, is there a map sensor on this vehicle, or is it the mass air flow sensor?
 
you should find a weekend warrior to rebuild the entire engine for a good price. the car was only 500$.
 
if your manifold is really cracked, thats probably why it doesnt run. thats like straight off the heads, dont work that way.
 
I really don't want to go jumping into a engine rebuild till I find out why it's not running correctly. The manifold crack is a hair line crack it's not an actual break the only reason we found it is cuz you could hear the exhaust leak from the front of the engine. I actually removed the engine oil pan cuz it was leaking and it was really clean in there, and visually everything looked good at least from the bottom, if anything I would just pull the heads, but the car isn't showing signs of overheating to be concearned with a blown head gasket at this point.
 


The cat hasn't been checked yet, but when I started it up all kinds of rusted metal shards shot out of the tail pipe, but the car has been sitting for over a year without running so that could just be corrosion. If I floor it in park it won't rev past 2000 rpms
 
I don't know if a cracked manifold is common or not, but the one on my 97 was cracked. It didn't cause the problems that you explain, but it also wasn't cracked as bad as your in that I couldn't hear any exhaust leak at all. But it did run better when I replaced it. Your best bet is to start with replacing the things that you know are wrong. Start with replacing the front manifold and go from there.

It is very hard to diagnose a car when there is something that is bad. The cracked manifold can cause all kinds of problem if bad enough. And it is pretty bad if you can hear the leak. And if you can hear air coming out, then outside air is going into the exhaust, and messing up the reading of the O2 sensor. So change what you know is bad, the manifold and see what happens.

As for the MAP sensor. Yes, these cars have a MAP sensor. One thing though is that you never said what model of grand prix it is. Is it a SE, GT or GTP?

As for the cat, I wouldn't trust a cat that is over 130k miles or so. Sure some people run them for longer. But they get hot and wear out. If it is possible, I would just remove the entire cat (check local regulations first). If not, get a good high flow cat and a larger downpipe, and get rid of the very restrictive u-bend. All of that can be done considerably cheap.
 
ok, I know this sounds like a no brainer..but have you rechecked the spark plug wire routing?

I wouldnt trust the coil pack numbers...as they are easily switched around.....
 
Actually I haven't checked the spark plug wiring, but I will do that just in case. You never know right?? As for the model it's a 97 coupe gt non supercharged. Is the map sesnor the three wire sensor that is plugged into the p.c.v. valve?? Basically right now I'm so fed up with the car I'm leaving it alone for a while since the wrong internal wiring harness is inside the transmission. I don't even know how to feal about that except that the world is out to get me, but I can't think like that. For now I'll walk away from it, but when I get back I'll let you know if you can successfully get a 4t60e to chirp 2nd gear, cuz that's what I was working for.
 


to get it to chirp 2nd gear, is not a hard task. all you would have to do is get a tune with somewhat raised line pressure, or a shift kit. I have my line pressure raised another 5%, and "sometimes" it will bark into 2nd.

just remember...some hard shifting is good to keep the clutchs in tip top shape. but too much...and you will snap internals.
 
i know in my monte when the cat goes the will not go anywhere at all and runs like **** but other than that i don't know sorry cant help ya
 
It does actually have a shift kit installed in it. I just rebuilt the transmission, that's why I got it so cheap it had a bad tranny when I bought it. I don't have an e.p.c. in my trans, so that isn't an option, I do have an adjustable modulator though, so I will mess around with that. As for the 2nd gear clutch pack I just found out alto makes a heavy duty 7 clutch pack to replace the original 6, so I will see if that makes a difference at all. It's the first time I'm trying it out so I'll let you guys know if it is worth installing, that is if i can ever get it on the road. Also I'm not sure how, but the last one I did I got 11 frictions to fit in the 3rd clutch instead of 10. Anyway I'll have to look into that one, maybe they make a thinner pressure plate.
 
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