Pre-ignition, detonation at wot in 3rd & 4th gear

[Hoffbrohaus]

Ordered a stock chip from a R3ver so we'll see what that does. In the meantime I checked my ICV based on the Bentley. It buzzes in the on position. But when the car is running the idle does not change when I disconnect it. The resistance is 24ohms when Bentley says 9-10. What does that mean? Should I clean it out or just replace?

[Hoffbrohaus]

Update. I have put in a stock chip and eliminated the detonation. However....

Cold starts now are ridiculous. I need to give it some gas as I'm starting, sometimes it stalls right away. Once the car is warmed up it idles ok, a little lumpy. Took it to a trusted mechanic for a smoke test and he said he wouldn't do it because he knows it's not a vacuum problem since my AFRs are good.

I put in some stock 14# injectors recently cleaned by MEPEH, and still have the starting problem with lumpy idle.

Just to recap:
New wires, plugs, coil, dizzy looked fine
Put in Stock chip, injectors
Valve adjustment
New fuel filter
Tested fuel pump flow was ok
Fuel pressure is right, although it doesn't hold after pump turns off
ICV is buzzing but resistance is not per bentley manual and when I disconnect it nothing happens to idle

[6SPD]

Good read but few solutions.

I've had a similar issue on my m20... A 2.8L 10:1 build with a 272 cam.

Nothing has seemed to work for me except looking running a standalone or bumping the octane using octane booster

[DesertBMW]

I have tried a bunch of different gas stations Shell, Chevron, Texaco, all 91 octane all result in same issue. I have tried 3 different chips, tuned by 2 different people same results.

I have lots of experience tuning stock engine management and after all these years the best tune that I have found is stock tune. You and me live in hot dry climate, chips made somewhere in humid and cold states will simply ping here in AZ.

There is no power increase with bigger injectors at all, no power with bigger TB, it is just waste of time and money. Best mod that I have found is running M50 injectors with 2.5bar regulator, this makes the fuel spray better at the same exact rate and stock so you can run stock chip. Adjust valves slightly loser than recommended spec, old valve springs and worn valve guides will sometimes make the valve float and engine misfire with up to stock spec valve adjustment.