E30 M50 swap not starting: cold start issue?

[th3gentlegiant]

Hey guys, new here. I picked up my e30 with a m50 swap a few months back and it didnt give me any issues besides rpm hop on cold starts (jumping between 1.5k and 3k). on random days it wouldnt happen and the CEL would light up, but after running for a minute or so the light would go out, and the rpm hop would come back. there arent any codes showing up and whenever the CEL comes on and the rpms are stable on cold starts, i dont have access to a code reader. the car ran great otherwise. since then the fuel pump died on me, so i replaced it, and now the car wont start. the engine is getting flooded. i cant source the problem. i did a ecu reset (disconnected the DME overnight) and the car started and ran with the CEL on, and if i killed the engine it would start again no problem, but after about a minute or so, the rpm hop came back and the CEL went out, so i turned off the engine and tried to start it again, and then it flooded and would not fire at all. smells like raw fuel when cranking and the plugs get soaked in fuel.

EDIT: found my issue. faulty coolant temp sensor.

know engine mods: m52 manifold and s52 exhuast

things ive already done: cleaned maf, cleaned icv, new fuel pump, new fuel pressure regulator, new o2 sensor (not related to cold starts but wasnt in the car when i got it), new plugs, and other various little things.

anyone have an idea what would cause the rpm hopping? it goes away once the car warms up. i suspected it to be the cold start valve/injector but there isnt one on the m52 manifold, so im lost there. the person who swapped the car cut some corners and im stuck cleaning up the mess, but this is my first bmw, and im pretty lost. the car seems to start and run strong consistently if the rpm hopping issue isnt there, but i cant find the source of it

[DesertBMW]

M52 intake manifold on M50 engine never heard of anybody doing this sense M50 manifold flows more, and S52 exhaust manifold is same as M52. Who ever did that swap made a mess, you need to find someone who can get all that in straight order.

[th3gentlegiant]

yeah thats what baffles me too. ive been in close contact with the guy i bought the car from, and hes pretty knowledgeable with bmw. at this point im not worried about which manifold flows better i just need the car running reliably again. and you have no idea how much of a mess this swap really is. there are some points where its well done, but the wiring was a total botch job.