She is 13yrs old...

[samsonevickis]

I have a 93 325is. For the last 5 months I have a multitude of problems with my car, but each time I fix what is appearently the problem one persists through all the repairs. Ok So I stomp the gas to pull out into traffic, it makes a sound similar to misfiring or and air popping, not a hammer, but a pop almost. Now since Nov of 05' I have changed the fuel pressure regulator (myself), Changed the spark plugs 3 times (Currently Bosch double platnum), had the valve gasket replaced at the $tealer, replaced the flex disc. Now with all of the problems affecting performance you'd think I would have solved it by now! but to no avail. Now 2 wks ago I went to a shop a "BMW Specialist" he went for a ride. He said it was 95% the cat converter, so I had it taken care of, From the air filter to exhaust there is NOTHING restricting airflow, so it could be a exhaust problem, the only thing left in there is the resonators - Muffler. Now I have a few suspicousions, but could the fuel filter really be a sparadic problem like this. I implore anyone out there who can help to comment.

Much Thanks

[SiGmA_X]

IF you have this problem, there is currently no cure. If not, that’s good. But to me, it sounds like the same problem.

[samsonevickis]

Yeah that sounds like my exact problem, but that was last year, and no one ever seemed to post a resolve. Surely someone with this problem has corrected it. Hasn't anyone?

[Manolito]

Recapping: We have a popping or misfiring (but not knocking) on hard acceleration.

The mechanic thought it was an obstructed exhaust. That will definitely impact acceleration, but won't cause a popping from the engine until it gets pretty severe. To confirm whether you have an exhaust obstruction, put your hand in front of your exhaust pipe opening. You should be able to feel individual bursts of exhaust. If it is a smooth flow with no pulses, suspect obstruction.

Popping and/or misfire on acceleration would indicate to me that the mixture is not lighting off reliably, which can be dirty injectors or low fuel pressure, but is more likely a weak spark or a spark that is going somewhere other than to the end of the spark plug.

If the problem seemed to be helped, at least temporarily, when you put in fresh plugs, I would look for: 1) cracked plug caps that are allowing the spark to arc over to the head. Cracks can be too small to see, but will have telltale burn marks. 2) Corroded connections in the primary wires to the coils. 3) Failing coils.

If you noticed no difference at all when you replaced the plugs, look again at fuel delivery. Check both static pressure and volume delivery. Dumping a bottle of Techron through it never hurts.

[samsonevickis]

The plugs are brand new twice over, but they did temporarily work like perfectly, I mean I left the house to the Auto Parts store ran like a demon, from the parking lot home, POp, Limp, Hestitation... But the boots are new and are in perfect condition, also if I'm in Neutral I rev up with nothing holding it back, only when I'm drving.

[Lee101315]

IF you think its the exhaust, just loosen the six bolts on the down pipe enough to make a lot of noise, and take it for a spin. If there is a big improvement, youve got an obstruction. Usually in my shop I just heat the bolts with a torch, but if you dont have access to a shop, just drive the shit out of it and try to loosen them up.
If you've checked everything simple on your car, take it to a mechanic THAT KNOWS bmws (like me). Just remember. A good mechanic may charge more for the hour, but is cheaper in the end because he wont fix the car by the famous "process of elimination" technique. It looks something like this.

REPAIR BILL
COMPLAINT: WONT START
PARTS CHANGED:
FUEL PUMP
FUEL RELAY
AIR METER
CRANK SENSOR
CAM SENSOR
O2 SENSOR
DME RELAY
PRICE: $1300

You wanna watch out for those guys. Trust me a specialist is cheaper!!!!
Good luck with that problem. I have 2 friends with the same car, and when something goes wrong they just keep swapping good parts from the good one to the bad one until the other one runs

[sk8wnec]

For that much you could have bought stand alone engine management.

[98M3Convt]

If the problem gets worse as the car warms up, test the coils. I had a problem that sounded very simmilar and it turned out that 2 of my coils were bad.

[Manolito]

The fact that it sometimes runs well tends to rule out the exhaust obstruction as a possibility. The fact that it happened to run well right after you changed the plugs leads me to focus on the ignition.

I hesitate to suggest tests that I have never tried myself, and it would be a chore, but if you want to try another test, you could try pulling the coils and plugs, ground both the plug and the coil so they will fire, and crank the engine to see if you have a good strong blue spark on all six of them. That won't identify every coil problem, but if you see a weak yellow spark anywhere, you know you are on the right track.

The fact that it accelerates smoothly under no load does not rule out much except maybe dirty injectors. No-load acceleration does not demand much fuel flow volume, and it does not create the ultra-high cylinder pressures that cause the spark to go elsewhere.

Does it matter whether the gas tank is full or empty? A leak that causes the fuel delivery system to suck in air when the fuel level is low can cause problems similar to what you describe. Such a leak can be inside the tank.

[x2dg]

have you tryd the ignition wires cause i didnt see you state that you checked or got new ones.

[Dogeeseegod]

put in a set of OEM spec NGK or Bosch plugs and see if that helps. I put the platinum plugs in my car and got reduced gas mileage and power. They were gapped properly, but were not burning all of the fuel for some reason.

[samsonevickis]

Thanks it was the Plugs, put in some NGK perfect better than ever! I would have never geussed until you said something!

[cbouchez]

so it was the spark plugs??