My 95 S50US (in an E30 M3) was running fine until the last session at Mid-Ohio. It starts and dies. If I run it at higher RPM it 'seems' OK. (but I haven't driven it much since unloading it off the trailer.
I pulled the intake manifold off and cleaned the idle control valve and trimmed a kinked section of vacuum hose from the fuel pressure regulator.
I replaced:
fuel pressure regulator
TPS (it gave me weird readings)
Plugs
No change. Idles rough - dies.
I cleaned the MAF with the CRC sensor cleaner. I blew it dry and let it sit for a few days.
I checked all clamps on vacuum hoses and they are tight. Upon refiring it -very loud BANG! A lot of smoke. It backfired and smoked like crazy UNDER the intake. I pulled the air filter off and smoke was pouring from the intake. (I thought it was an electrical short under the intake initially)
WHAT!!??
I'll pull the intake back off - but any ideas?
Bad MAF? Cracked hose I overlooked? (the one from the intake to the idle control?).
Help
Thanks
Chris
Last edited by cw635; 09-14-2020 at 08:49 PM. Reason: found a huge hole
Ahhh - easy to miss if you don't spread the old hose open. Check this out! I hope (and really believe) this is the root cause!
But why the huge misfire? That still concerns me. I'll pull it out in the driveway when I fire (no pun intended) it back up.......just in case
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