E30 all new- won’t rev past 3-4-5k depending on CKP adjustments

[Rutech13]

Update:
had my buddies mega squirt ecu and e36 tps all connected and got same 3k rpm limit. Also MEgasquirt seeing crank sensor to noisy.
went ahead and changed engine harness-no change .
than I put my oem harness back and noticed that I have new cam and crank screened wires tap in to the harness by someone already and whole harness soft and no corrosion found.
than I went ahead and checked physical timing once again-tried advancing and retarding it by one tooth-no change
have swaped crank sensors around between 520ohm and 920 ohm ones-no change .
than I wanted to check what actually happens at the rev limit and noticed that spark goes erratic to almost to no spark while holding wot ,whit is noisy crank signal would affect it I assume .
i am stumped at this point .
im ready to pay whatever to whoever to get this thing resolved.

[TobyB]

2 thoughts- check your valve springs to make sure they aren't soft

-stick a borescope down each cylinder to make sure the pistons aren't hitting anything.

t

[Rutech13]

How would I check for softness ?
also I did look at they cylinders and didn’t see no marks and it looks super clean
Car came with freshly rebuilt engine and has thick headgasket for some reason.

[TobyB]

That's a good question, if you don't want to tear the head apart.

The big old US V8's had an 'on engine' valve spring checker, but I've never seen that for a rocker- headed BMW.

Digger? any ideas?

t

[digger]

you would need to make a tool to either test directly in situ or a tool that you can remove the spring while in situ and then bench test.

To me the fact that there was a 3000 rpm "limit" you messed around with stuff and then it went to 5000 rpm suggest a valve spring not being the root cause

OP needs scanner danner

[TobyB]

Yeah, sorry, I somehow completely missed the entire first page of 'my crank sensor is noisy'
posts, so ignore the valve springs. As you all know, I'm a dumbass.

I agree, 15 minutes with an oscilloscope can find a multytood of evils.

t

[Rutech13]

What should I scope for ?
im here thinking of crank wooble that could cause it .
help me out on what and how should I check with oscilloscope?