No start condition after chip swap (and back to stock chip)

[username]

I just swapped my OEM chip for the Turner/Conforti one, following the instructions and being very careful. Upon putting everything together, the car stumbled for maybe a second when I tried to start it, and died. Subsequent attempts to start give me no "stumble" at all, just the sad mechanical cranking sound of a engine that's not firing at all.

The instructions for the chip have a troubleshooting section, with all the popular failure modes that can happen (wrong chip for DME, chip in backwards or pins misaligned, you messed with other engine stuff at the same time, etc). I checked everything and didn't mess with anything else on the car which could have caused the condition. Even grounded myself during the operation to avoid static electricity. And removed/resocked the chip and reconnected everything. Wiring harness to ECU connectors are nice and shiny.

So this where it gets interesting - I put the stock chip back in (oriented correctly, pins line up, etc) and still the same problem. So maybe it's not the Turner chip... Perhaps the DME or wiring harness got damaged during the swap? Or maybe something else on the car just decided to die at this inopportune time? (Not likely but...)

Does anyone have any bright ideas? Any leads on what to specifically look at before starting down the general diagnostic tree (does it have spark, fuel pressure, injectors firing, etc...)?

Thanks...

Aaron

[username]

I put the old girl on the trailer and took her to BimmerHaus. It dawned on me after writing this up that I don't have the time to do diagnostic work right now. Plus Bimmerhaus is a fun place to visit.

I'll make a follow up post on what the problem is, so that others may benefit...

[username]

I picked her up the next morning. The plugs were fouled with gas, which they cleaned up, and there were some codes (misfiring?) which they cleared. No smoking gun at this point.

Man our car responded well to the chip. Way more torque in the lower and middle parts of the powerband where it's most useful. I haven't noticed much change at the top end, maybe the bottleneck there is more breathing than mixture and ignition timing.

[milehigh96caliti]

I love Mark at Bimmerhaus. I leave him my 330ci vert to fix and he lets me have another vert for a loaner since I work nights and sleep during the day...the dude is really cool.

[tiFreak]

I'm guessing the chip must let in a bit more gas than stock, glad you got it figured out