R3VLimited Forums - 24V Engine Swaps

Question about emissions equipment

dice2012 — Fri, 08 May 2026 15:10:56 GMT

Hey guys. I'm installing a swap exhaust with a cat on it. I'm wondering how harmful deleting the SAP and secondary O2 systems would be for the cat long term. I am tempted to buy the SAP pump off an e36 partout near me, or rockauto, as I have most of the other parts for the system. I'd also have to figure out wiring up new secondary O2 plugs, as the guy I got the engine from just cut the wires instead of unplugging when pulling the engine.

If it's nbd for the health of the cats, I'll just do what everyone else does and flash them out of the ECU. My main concern is the cats clogging and having to pay for a new, or replacing the mid pipe.

Crank no start with M54 swap

clarinetnerd — Sun, 03 May 2026 01:13:27 GMT

Like the title says. M54b30 from an automatic e39. Chassis is '91 325i. DME is MS43.

Turning the key to on gets the fuel pump going, I can hear that clear enough.
Spraying brake clean (the flammable kind) down the intake doesn't help, so it isn't getting spark.
After cranking for a while (probably 10+ seconds) I can't smell any fuel, so I don't think the injectors are running either.
No fuel and no spark tells me it's probably EWS.
Using MS4x Flasher, I wrote MS430069 (with MS4x wiki's immobilizer bypass patch) onto the DME. Crank, no start. Tried it with an unaltered version of the wiki's MS43x custom firmware, which has the immobilizer bypass patch included. Same result.
MS4x Flasher shows me a half-dozen diagnostic codes:

A little poking around online gave me definitions for most of these:

DTC 113 is motor throttle valve potentiometer. That makes sense. I swapped the throttle body for an M52 cable throttle. I realize this might also be causing problems.
DTC 11 is coolant temp sensor at the outlet. Makes sense; that sensor isn't plugged in any more.
DTC 35 is the secondary air pump. Makes sense, that got deleted.
DTC 140 and 126 are evap related.
125 is for the cooling fan.
115 is "range check for throttle position adaptation". Read above (at 113) for the throttle situation.
And DTC 69 is for the fuel pump relay, which makes little-to-no sense.

Other than the throttle situation, this is a fairly basic swap, following the guide posted on this forum. I did rebuild the VANOS while I was doing everything, but I can't imagine that would have any impact.

Let me know if you need any more information.

I'm really out of ideas and I don't know where to go from here.

M20 flywheel with 24v questions

dice2012 — Thu, 30 Apr 2026 18:09:17 GMT

I'm planning on using my M20 flywheel as I already have a new clutch for it, and a new 24v flywheel and clutch looks expensive. I have read that my options are to either get the M20 flywheel lightened down to <1mm above the ring gear, or shave the e34 oil pan. I'm looking to daily drive this E30, so I have a few questions regarding everything.
Is the lightweight M20 flywheel bad for daily driving?
IF I want to go down the route of shaving the oil pan, what part do I shave, and how much do I shave off? I can't find any pictures, and I feel it would help a lot to actually see it done. Also, is shaving the oil pan risky?

Broken part on throttle body

dice2012 — Wed, 22 Apr 2026 20:13:16 GMT

Hey everyone. I’m tearing down an S52 right now, and I discovered that the clip that holds the throttle cable on the throttle body is completely missing. Is there any way to remedy this? Would hate to have to throw this one out just because of a plastic clip. Including a pic for reference. The clip that holds the cruise control still works, maybe I could just use that for now.