Engine Mechanical problem
1990 BMW 525 6 cyl Two Wheel Drive Manual
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Hi, for the last week or so my car will sometimes take 1 or 2 times to start,it turns over but wont start.Then yesterday all it would do was to turn over but wouldnt ignite,i put STP complete system cleaner in the fuel tank. it took maybe 5 times more start ups before the engine caught.
I drove back home but found that if i tried to accelerate i felt i was loosing power.
Today im back to square 1, i can turn the engine but it wont start

The issue might be in the wiring harness connector that is directly below the throttle body, it is round and is through a bracket that is attached to the engine block. The individual pins in the connector and the wires themselves can corrode and cause the issue of which you speak. The remedy is either a thorough cleaning of the pins or cutting and splicing the wires if the corrosion has metastasized into the harness. Inspect the connector and look for corrosion. If the connector is free of corrosion then the next thing to do would be to scan for faults through the 20 pin diagnostic plug that is at the front of the intake manifold with the proprietary BMW software the dealer and some independent shops use and repost for further diagnostic directions.