i need your professional diagnosis

[///Maybach]

my E30 is turning in to a labor of love.. bought it running but let it sit for about a year and then it wasn't starting..

#1 - replaced the fuel pump, didn't think to check fuse
#2 - replaced the fuel pump fuse, it was blown

car was running well, there was a crack in the intake boot so I ordered a new one.

#3 - replaced intake boot, car was running extremely rough and then ran better after some fresh gas

this car is a major project getting it back in to running condition. after the above steps and repairs, I noticed a leak in the exhaust flex tube ahead of the O2 sensor..

then the car was doing a very strange power thing, it would just lose all power at random RPM's and putting the pedal down wouldn't do a thing.

#4 - replaced air filter
#5 - replaced fuel filter
#5 - cleaned and rebuilt all fuel injectors

the car at this point was running superb, all RMP's it was FLAWLESS (the exhaust leak is very loud, but did not make much difference in the power)

NOW -- at this point is where I need expert advise.. I was driving it down a hill last week behind a car, i put it in 1st gear, letting the engine do the braking for me. When I got to flat ground again, I noticed the engine running REALLY rough, power was sparatic and there was a very strong smell of gas (kind of smelt like bad gas, for sure something with the fuel mixture)

I proceeded in to a parking lot ASAP as the car just had little to no power. I looked under the hood and there was some blue smoke near the exhaust leak, but it kind of looked like it was coming from the front middle of the engine. After letting the car sit for a while (I worked nearby so left it for an hour or so) I went back to start the car, it did its usual few turns of the ignition then suddenly there was a massive BANG, it sounded like metal on metal. I looked to see if a piston shot through the block but that wasn't it. I tried again giving it some gas and it fired up, still running really rough. the smell and blue smoke still were happening as well as the lack of power.

Aside from the items I replaced above, the car needs a new battery so I use a jumper pack (this is a work in progress), it has been in the 90-100 degree temps here, and a hose off the radiator appears to have some tape on it.

so if any of you have experienced this, or know of anything like this, I will greatly appreciate the help! I am considering taking it to a mechanic but since this is more of a project I prefer to do the work myself unless this is going to require some extreme engine work.

thanks for reading!

[crappycoco]

Please check if the replaced injectors are seated properly, and that the seals are not leaking gas. I hope the injectors were flow tested - what you described sounds like a leaking injector to me. However, i can't explain the bang, maybe accumulated fumes from the gas leak.

And you should really start your labor of love with a new battery.

[95BMWIC]

I went back to start the car, it did its usual few turns of the ignition then suddenly there was a massive BANG, it sounded like metal on metal. I looked to see if a piston shot through the block but that wasn't it. I tried again giving it some gas and it fired up, still running really rough. the smell and blue smoke still were happening as well as the lack of power.

First thing that comes to mind is that you had a backfire due to access fuel (blue smoke) or a timing issue..just another thought - after you check to ensure the fuel rail / injectors are seeded properly..