E30 M42 itb misfire issues

[Froos]

Hi all,

After putting on 535i engine rubbers its time to test the engine. For safety issues i disconnect the battery after fiddleling with the car. Does the ecu loose data on tps when i disconnect? So it sounds like the engine is running really rough and on 3(ish) cylinders with the occassional load poff of misfire when i try to hold the engine at 1500 rpms, when i let it idle at 1000 it poffs more. I used to own a 750i and after every battery disconnect the ecu had to learn every parameter for about 15 min.
Also since my car started life as a 318i it doesnt have an check engine light. When i repaired the si board it was apperant i dont have that feature so i guess i cant do a stomp test? I google every threat on misfires caused by foulty lead wires and o2 sensors cam sensors and tps but rather that buying all those new i would like to discover which is faulty. Also in th old days you could use a screwdriver to ground a plug to check which cilinder is misfiring. I wont pull a plug wire from a running engine but will i damage a coil if i try to run with 1 coil disconnected? Also did anybody try a noid light for injector signal testing with the m42 injector signal rail on?
Many thx

[Froos]

I guess my story is incoherent.....my questions are:
- does the stock ecu loose any data when i disconect the batt?
- is there a way to self diagnose (like stomp test) on a car without "check engine" light?
- what low tech way is there to check which plugs fire?

Thx

[1998ccc]

AFAIK the cluster will support the check light if the bulb is present and the wire from DME to cluster is installed.

Plug out attached to spark plug wire.  Alligator clip attached to metal base of plug, other end to ground.  Pull fuel pump relay.  Crank engine, look for blue spark.

Good luck

[Froos]

For everybody that needs closure. Turned out to be that the cables going to the coils 3&4 where switched around, car idles and revs good now.