Help!! 1994 E34 530 erratic performance - BMW Forum

OWarrior · 10-13-2007, 03:21 AM

Hi Guys, I have (as described below) a very Angry 1994 530 V8 Automatic tourer, it moves rather well when it starts. idle is rough, around 450-480rpm, with a working MAF connected it runs sometimes and cuts off sometimes at whatever speed. the last time that happened, i was overtaking at 170kph (yeah i know its not exactly legal to dricve that fast here in Nigeria) engine just lost power suddenly, i pulled to the slow lane, took my foot off the gas, and it stumbled a bit and fired up again. when i start (cold or hot) it cranks and starts the first time most times. if it does not start the first time, it takes continuous cranking with flat out accelerator to start! cabled accelerator, i did a diagnosis which came out with MAF faulty, i changed the MAF and the same thing. i checked the plugs and it is very black (running rich) yes that will happen if the MAF does not work or is not connected, but it runs well without the MAF (no cut-offs in motion) i concluded i have an air leak, which is not allowing the fuel pressure regulator return fuel. BUT what is the cause of the intermittent cut-off? ECU failure? i recently did a 400km trip and burned 40ltrs of fuel (20ltrs/100km) THATS A LOT FOR HIGHWAY TRAVEL!! if thats the normal fuel consumption, so be it.. but why are the plugs black then? DESPITE THE BRILLIANT ENGINE RESPONSE AT ALL TIMES? Thanks In Advance

d3ity · 10-13-2007, 12:09 PM

Plugs being black usually means burning oil. It could be running too rich and that's causing it to stall.

Torque · 10-13-2007, 02:02 PM

Leaking injectors flooding the engine?

OWarrior · 10-14-2007, 08:34 AM

injectors not leaking... already checked. thanks. today, i disconnected the air intake temp sensor, drove the car around a bit (not good performance) plugged it back with my MAF and it drove like a dream, 5 minutes later after switching off to get a bite, the whole madness started again!!! the strange thing is.... i disconnected the Camshaft position sensor and the car does not miss it at all (ie like it was not doing anything) should the car start at all without it?

Bently says:

"If the hot him breaks or if there is no output from the air flow
sensor, the ECM automatically SWitches to a "limp-horne"
mode and turns on the Check Engine light."

when i disconnect my MAF i do not get a 'bong' neither does my car turn on the MIL light ( i doubt if i have one as i have never seen it) and my car can still kick ass!! JUst takes a lot of gas!!! i get the same fuel consumption either in town or on the open highway!! something MUST be wrong. i can afford the fuel, its just not running properly. the ONLY authorised BMW workshop in Abuja, (BMW NIGERIA) wants me to pay the cost of the car to "diagnose" and asked me to leave the car for about a month because "intermittent problems on cars this old take more time" i felt like shoving my foot in his mouth!!

OWarrior · 10-29-2007, 04:22 PM

Changes the MAF (again) and lousy fuel consumption becomes dramatically better like double my former MPG!!! ONLY issue unsolved is erratic idle. thanks Guys

AlpineSixAndSeven · 10-29-2007, 04:32 PM

Quote:

Originally Posted by OWarrior

Changes the MAF (again) and lousy fuel consumption becomes dramatically better like double my former MPG!!! ONLY issue unsolved is erratic idle. thanks Guys

Check all the vacuum lines and intake boot all the rubber hoses and tighten all the clamps. what about the cam pos. sensor that didn't sount right it might be on its way out... run some Seafoam engine cleaner through it. what till you have like 1/8 or a tank and put it in. drive it till almost empty the fill with pre. fuel and drive till empty again