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97 GP GT wont start, need some help

A

armyguy1027

New member
Hello first to everyone, Im new on this forum and have been searching quite a bit to no avail. Anyways the problem Im having is with my wifes 97 Grand Prix GT 3800 series II motor. The last couple weeks its been acting funny and dieing on its own. The tach would go to 0 then back up and die. I was able to restart it it most times. After doing some searching I came up with the idea that the Crank Position sensor was bad so I replaced both the Crank and cam sensors. Seemed to run ok after and the next day she drove it to school but said it died three times on her. On her way home she stopped and shut it off and that was the last time it started. Had to have towed home. I did some more troubleshooting and found the upper intake was cracked and the cylinders had antifreeze in them so i replaced the upper intake and all the gaskets. Im getting fuel and air now but seems i have no spark. I tried cranking over the car and it cranks ok except while cranking it, the mufflers exploded and it backfired something awful. I have checked and cleaned all the grounds as well as checked for codes. I use a Matco Md 1052 scan tool with ABS. Also the traction and abs lights have been on for sometime. Not sure if thats related or not.I also tried unplugging the MAF with no change. Engine just cranks but will not fire. Im thinking of changing the ICM next but want some input as Im all out of ideas. Any help is appreciated Thanks.
 


Do you have spark? Do you have fuel? If you have a scanner, do you have codes pending or stored?
 
What I meant was that while i was cranking it, it backfired and blew the sides out of both mufflers. I have 12v on the one side of the ICm but not sure if the command side has voltage yet. Still trouble shooting it.

I do have fuel and no codes are popping up as well
 


Hey just an update. Im not sure how I did it but I went ahead and cleaned up all grounds and the coil pack connections and then the car started up for me. Its getting late so I wasnt thinking about it to much when I said no spark yet backfiring. I been trying to get this thing started for about ten hours now. Anyways runs ok now except the big holes in the mufflers. Still not sure what caused that. Thanks to this forum I have found tons of valueable info that helped me through this thing. I still have the ABS and Traction thing to deal with but Ill start that another day. Anyways Thanks for all the help guys. This is the first Grand Prix i ever messed with and have learned alot in the last few days. I would have never known why I had Antifreeze in my cylinders if I hadnt read it on here. I would have thought head gaskets first. But like I said the upper intake was bad and definalty had a hole in it. Good info I found in one of the post on here made that job pretty easy.
 
TAKE PICTURES of anything that exploded or cracked and upload them here.

This engine has some mad squabbles my friend... Cracked intake AND exploding mufflers, that's intense.

The sensors were an excellent place to start based on the strange tach. behavior. Kudos to you for searching old threads. Can you tell us more about exactly what the tach. did before/after the sensor replacement?

Did you do anything to get the water out of the engine?

Exactly what did you take off and replace when you say you "replaced all gaskets". At the moment I'm assuming you replaced the plenum and the plenum gasket and then fired it up. What make/set/model is the new plenum? Did you replace the throttle body gasket too? Check and re-check that all mating surfaces are sealed and if you can you should verify torque specs on all fasteners for anything you removed or re-installed.

Unfortunately, an explosion concussive enough to 'blow the sides out of both mufflers' is something worth taking pictures of, I doubt many forum members (including myself) have ever seen or heard of this. Did the old plenum merely crack or did it 'explode' as well? You MUST have had fuel and/or massive concussive air pressure where it was not welcome.

This is a long shot and I'm not a mechanic but my best shot-in-the-dark would be to suggest the fuel pressure regulator (or something with your fuel system) is severely effed in the ay.
 
sure will post some pics up. I did replace all gaskets on the plenum and trottle body. I bought the Dorson kit that came with all the gaskets for everything including injector o rings and PCV valve. I Pulled plugs and rotaed engine to blow all the anitifreeze out that i coudlnt get with rags and shop vac. Not sure why the Mufflers exploded like that but both of them have the whole inside sides of them blown out. Car runs but is loud as hell now. Also i work full time for the Army as a mechanic so im only used to diesiel engines and what not as well as am a Eclipse enthusits so I work on my 2G Eclipse on my own as well. Im a big beliver in tourqe specs though so I looked all those up when it came to this job. Been turning wreches now about fifteen years Anyways Thanks again guys and Ill post some Pics up of that. They are pretty impressive holes even though it sucks to have to replace those as well.
 
In all the cranking..you had raw fuel in the exhaust. When a spark headed down the pipes.. it ignited the fuel. Simple muffler bomb.. fix the muffies and you should be set.
 
Off topic, but I've done that to a delivery van that had a 454 in it. Replaced the disp cap and wires and goofed the firing order. Crank Crank Crank BOOM! That muffler didn't stand a chance, lol..
 


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