Problems After Engine Rebuild

[Jeffersonwillis]

So I just did an M50b30 build. The engine ran great during the initial break in period, but after the first oil change I am having an issue.
The car no longer runs well. It idles rough, engine shakes, has seriously lost power. I double checked the timing as that seemed like the most logical step to me. Timing is right where it should be.
I decided to get the test codes for the car. It first had a 1281 code for DME memory. Swapped the ECU and tuning chip, still had the code. Swapped back to my 413 with W.A.R. Chip, and the code changed to 1271 which is for the ignition coils. Tested the coils, all tested within .1 ohm of .7 ohms. Just to double check I used a spark checker kit and each plug is getting spark. Changed the plugs just to be sure, the problem persists. The ignition wiring checks out too.

What is my next logical step? I am thinking after some research that perhaps my ICV or the hose between it and the intake mani may be faulty. I happen to have a spare, but given the steps required to swap it, I turn to those who will know more than I.

[bmwdirtracer]

Smoke test the intake system with a pro smoke machine. Put a fuel pressure gauge on it, clip the gauge to the windshield, and drive it. Do a leak down test. Do a compression test. Unplug the MAF then start it and see if it runs better

Is the oil filler cap on correctly? What spark plugs are you using?

Does the engine run badly at only low rpm or high rpm? Is there a "dead miss"? (In other words, is one cylinder dead? You can unplug each coil as the engine's running, to verify this.) When you unplugged all the injectors, did you very carefully remove each clip with a bent pick, or did you just prybar the injector wiring rail off? (I have to ask, you know)

Have the injectors been to RC Engineering or Marren, or ever been professionally serviced?

Why did you rebuild the engine, and what parts were changed? And how exactly did you achieve an M50B30?

[Jeffersonwillis]

Compression test came back all around 155. It does run a little better with the MAF unplugged, but only a little. Oil filler is on all the way; I am using BKR6EKs (I am aware some have had them not run properly, I have never had this issue).

Engine runs poorly at all RPM, performance drop is noticeable when each coil is unplugged. I did remove each injector clip (though not the most careful I've ever been; nothing broke).

Injectors have not been serviced

Engine needed a head gasket and some other gaskets here and there. Had an M54 crank, rods and pistons all laying around in decent shape so I figured "why not?" Has S50 Cams as well.

Will need to do smoke test (no one near me actually has a machine, I am in the middle of nowhere), leak down, and fuel pressure gauge.

[328 Power 04]

When everything else is checked:

What injectors and MAF are you using?

What injectors and MAF is the tune written for?

Does the tune account for the extra displacement?

[Jeffersonwillis]

Injectors are the greens from the M50 with the M50 3" MAF, the tune is currently mapped for this. I wasn't going to change any of them until further down the road with an AFR gauge and a dyno found (seriously when I say the middle of nowhere, I need to drive an hour and a half for a dyno I can rent).

Tune SHOULD account for the extra displacement as it is a base S50 tune and this has been done before with success (according to Miller team), however I see no differences between it and the performance m50 base tune. What areas should be different?

[MarcoZandrini]

The key is that the engine started running badly after the oil change. Check your work, system something is wrong.