two Bad 3100's need help [Archive] - Forum


View Full Version : two Bad 3100's need help

10-17-2006, 06:32 PM
Hey guys i know its long but any help is appreciated,

I own 2 grand ams the first a 1997 grand am se 4 door auto with the 3100v6. wich is where the problem begins. This car has about 260 000kms on it but is still in great condition. One day while backing out of a local burger king there was a wierd knocking noise. not just a valve tick or an exhaust leak but a loud almost banging noise contiuiously. Living at home and my dad being a mechanic owning his own shop i thought id drive home and see what he thought.

Well on the way home it got louder and wierd things started to happen. My check engine light had come on about 3 weeks before this happened but there was no problems when we checked the car over so i just assumed where i had a bad muffler maybe it was the exhaust sensor. so i ignored it. so im driving down the road and all of the sudden i feel like im losing power its taking a while to accelerate then i get almost to 40 and it abrubtly stops accelerating but the engine revs higher. i let off the gas and my speed drops, then i push the gas again it goes to 40 then just starts reving like crazy.

so on the highway i get it going to just about 60 then it did the exact same thing. parked it. After letting someone hear it running i was told that something had happened to the connecting rod bearing. but in an emergency i drove it again and it had that very loud banging noise and didnt have an accelerating problem if you accelerated slowly. so i bought a 1996 grand am se 4 door auto wich is where my 2nd engine came from.

I got this car strictly for parts. i drove it about a 20 minute drive to my house with no problems except the loud rotted out exhaust. engine ran smooth and only had a small exhaust leak. so the 97 engine came out and the 96 went in.But not so simple. had to change the coil pack,and plug wires,and a few censors that had different connectors. so i put the 96 engine and tranny in with the coil pack plug wires and mass air of the 97. the engine ran like crap. kept dropping revs and quitting , it was chugging enough to shake the whole car.

So i started swapping parts. in went a good idle air flow sensor and a good egr valve checked the mass air and still the problem persisted. the engine had new motomaster formula 1 oil and a can of "wynn's engine tune" additive in it. and still it wasnt working right but the rev dropping only happened when the car first started and it would only do it once. but it would idle around 750 rpm and still chugged. I also found that the lights would dim when the engine was running at idle and dropping revs or when the car was at one set rpm no matter how high or low and it had a good battery and alternator.

then while bleeding the brakes, i was pumping up the brake pedal when the car was running and the engine would drop revs to the tempo at which i was depressing the petal. I checked all the vacuum hoses had a lose hose fixed it problem still remained. then it all randomly stopped my check engine light went off even though i took out my cat and resinator and exhaust oxygen sensor and put in a straight pipe to muffler exhaust from the down pipe on. it was running fine then i took it out for a drive and then i got to almost 70 and the abrubt stop of accelerartion came on again. back to the shop.

thought it might be the computer so i switched it up for the 96 computer. Once that was in, the car wouldnt even start. back in goes the old 97 computer. magically car works fine now. put on new brakes and down the road i went to lunch. all was good then 5 minutes down the highway the car stopped accelerating at just before 100kmh so being in a 110kmh zone i put the petal slowly to the floor and the car did nothing then randomly quit but just before it did my battery and oil light came on, go check the oil and its good.

But the engine was kind of hot. got back in and started to drive well the car wouldnt go past 40 then 60 like the first one so i got off at the next exit then stopped at a stop sign. there was a driveway to a cemetary right across the 2 lane road that i decided to cross, to go check the engine. it took about 30 seconds for the car to cross the road. turned it off. tryed to start it again and only a "click" no starter motion. I checked all the starter wires they were good it was a new starter. so i got my dad to come boost me. hooked up the booster cables and"click". Darn. he checked over a lot but it was torential downpour weather and just wanted to go home so i tryed the key again and it started right up.

But then i heard the death sound. the all to familiar loud rapid banging of a piston or a connecting rod inside the engine but it was 2 times as loud as the first motor that had this problem. tryed to drive it home on flat i could achive about 40 kmh with the petal to the floor on up hill i got to 20kmh and down hill i was up to 60 but it was revving really high one second then dropping to nothing the next with me still having the petal at the same point almost like it was randomly changing gears. took it hoke parked it. this all happened within a month of each other sorry its soo long but ive been racking my brain trying to figure this out and im hopeing someone here can help me out. Any insights are appreiciated.