bucking/hesitating

[E30MACK]

so this has been an on going issue for a couple weeks now and I really need to get it addressed. car starts right up and runs like it should (as long as I dont push the accelerator to the floor) for the first like 5 min....or until the engine warms up. then it will buck and the rpms rise and drop rapidly. also, im getting a whiteish gray smoke that I see from my tailpipe in my rear view mirror. so far this is what I have done to try and fix it. plugs,wires,rotor, O2 sensor, air filter replaced,took apart the maf and all connections to verify there are no vaccum leaks, replaced fuel filter and fuel pump, visually there are no leaky injectors, did a seafoam treatment today which seems to have reduced the smoke but still get hesitation.

[E30MACK]

because of the fact that it starts to happen when it is up to temp im thinking a sensor of some type......any guesses?

[Gilroy]

BMW is a good reputed Automobile company. The internal and external features are advanced.

[zxert]

Ban^.

What model/engine do you have?

I'm having the same issue.

I need to test.

Thermo time switch
Cold Start Injector
ICV
AFM
O2 Sensor
Injectors
Fuel pressure regulator

Then see where I'm at.

I have a 84 318i = M10 motor

Car runs PERFECT for 10 minutes, almost exactly.

Then the car won't hold a stead idle. It will die any time I take my foot off the gas. I hold it at 1500rpm at lights and the engine is bouncing roughly 200 to 300 rpm in both directions. Sometimes it can stall while my foot is on the gas, very rarely. When this happens it runs SUPER rich. Smells like someone lit a bucket full of gasoline. When it shuts off it will fail to start the first time, but kick on the second time.

I'm thinking its leaky injectors, bad FPR or something fuel related combined with something temperature sensitive thats causing my problem. Depending on what motor you have we might be able to help eachother.

[zxert]

From bentley

If a cold-start valve fails to inject fuel during starting, it will be
difficult or impossible to start the engine. If the cold-start valve
leaks or stays open too long, the engine may receive extra fuel
at the wrong time and become flooded, especially if the engine
is hot.

[richardkeith97]

i had the exact same problem with my eta. i changed so much stuff and wasted so much money. a bottle of dry gas and the problem was solved. i have to put in a bottle about once a month. the ethanol in the gas attracts water. seriously try it. i know a couple other people who have had the same problem. when my tank was low i put a bottle in and let it sit over night. next morning all way good and i filler it and put in another bottle.

[E30MACK]

dry gas? never heard of it.....but ill research and give it a shot.
88' 325is btw

[E30MACK]

ok guys any other suggestions I need this fixed like 3 weeks ago! now to add to the symptoms my gas gauge is bouncing along with my rps when it freaks out.

[bernzpeed]

have you tried fuel injector cleaner? clean your icv, afm, & intake? replace your air filter? white smoke=burning oil?

[richardkeith97]

did you try the dry gas\gas line antifreeze? I also had the white smoke.

[E30MACK]

put in a seafoam treatment, seems to smoke less now but still getting the hesitation/bucking...

[u3b3rg33k]

dry gas? never heard of it.....but ill research and give it a shot.
88' 325is btw

Alcohol to deal with the water. aka iso-heet.

[zxert]

Happened to be my alternator. I am of no help now.

[E30MACK]

could it be a backed up cat. converter?

[jlevie]

When the car is in gear and moving, if the tach is making large excursions toward zero whenan event occurs the cause could be:

Loss of timing data to the DME
Loss of power, ground or start signal to the DME
Bad DME

If the tach doesn't move during an event but the econometer drives towards zero, look to the fuel system (bad relay, fuse, FPR, filter, pump). If neither the tach nor the econometer react, the coil, wires, or distributor are the likely suspects. In both of those cases a bad DME could be the cause, but go there only after eliminating the other possibilities.