MyE28.com

Video of behavior: http://ogrestrength.com/nostart.mov

Datalogs and msqs:
http://ogrestrength.com/StartFailure.zip

1989 BMW 325i w/ M30B35 engine from 1991 535i, HX40 turbo setup
MS2 v3.57 board
Wasted spark with DIY autotune coils + Glen's Garage breakout board
MS 3.0.3.r
Tune reset to an MSQ that was known to work last year. So, my crank settings and everything should be fine.
72lb/hr Low-Z injectors
New starter, getting ~300rpm cranking. Pulling down to about 90kpa vacuum
No idle control, just a cracked throttle plate (tried the gas during cranking)
Battery trickle charged back to 12.5v+ before starting

Car was working fine until about January, when the flywheel bolts vibrated loose. Once that was sorted, the car randomly seemed to run on 4 cylinders - it would start, but ran horribly. So, I dug into the wiring, and re-did a BUNCH of the grounds - I thought it was probably a weak spark issue. I pulled the ground wire from the GG wasted spark board by hand, so I thought that was the culprit. I screwed some other grounds up in the process, but I believe everything to be alright now.

FUEL:I can hear the fuel pump prime pulse when the key is turned. I have a gauge fore of the fuel rail and it's reading 45 psi. I'm not SURE if the injectors are firing, but the (switched ground) wiring seems OK, and I checked that I had 12v at every injector with the key in running position. Should I test the injectors somehow to make sure that they're firing? Could the Low-Z be causing issues? Do I just pull the darn fuel rail and spray fuel into a bucket?

SPARK: I pulled a wire from each coil pack to ensure I was getting switched ground, I am. I didn't have a good connection to the tower (just barely touched) so I had a weak orangy spark. I tested one coil pack with a proper spark wire and got white-blue spark. The spark plugs ran a little rich in tuning the turbo, but I'd think they should be ok enough to start the car considering until I messed with the wiring it could at least run itself on a few cylinders with a bad spark ground.

COMPRESSION: I'm pulling some vacuum during cranking (down to 90kpa) - I'm not sure how else to test this. The behavior didn't start after any hard running; the car's been sitting except for intermittent attempts to start it for more or less 5 months. Should I be seeing more vacuum?

Timing/Pickup: I'm kind of leaning this way. My tooth log shows 1-4 sync loss events in some of the cranking logs, would this be considered normal? Is this enough to prevent starting? I'm getting a decent rpm signal, it seems, but my tooth logger does show a "2nd longer tooth" that the literature I've read suggests a "compression effect" - I wasn't able to get the trigger logger to save to csv in tunerstudio, but my signal looked very much like this: http://www.msextra.com/doc/ms2extra/Gen ... _crank.png

I did redo the wires for the VR sensor pickup, could that have caused this issue?

I feel like I'm incredibly close to having this thing running again, I just could use some help to figure out...whatever this is.

Ryan

If you're getting fuel you will smell it from the exhaust and the plugs will be wet.

Sprayed starting fluid into the intake manifold via the throttle plate - no change in symptoms. This is making me lean towards timing, though I think I'll pull the easiest plug to make sure it's getting wet with fuel and all that. I'll smell down the tailpipe a little better for fuel, still not 100% convinced it's fueled, but if the starting fluid didn't help, that makes me think its not for lack of fuel. It didn't even fire/hiccup at all with the starting fluid.

I'll post tooth logs tonight, looking at them again I think that has to be the culprit - significant noise.

Tooth logs (composite and tooth, and a another log just for kicks.

http://ogrestrength.com/toothlogs.zip

Current plan:

check injector firing
rewire VR sensor
check grounds

My "Output stage ground" Motronic pin 24 is not hooked up, but I don't think this is the issue.

I don't know much about this.. you can tell by my posts, I suck at MS.. but for what it is work when mine was full rich it still started and somewhat ran- my eyes would water from the fuel smell, so I would say you would know if it WASNT going to start due to a significant amount of fuel on startup.

what was your vacuum when it was running well before? could your map signal vacuum line have cracked?

I just had a similar issue (among others, but for what its worth) I had a leaking MAP signal line so it was around 60kpa AND my coil 12v was loose. add those together and it sucked.

happen to have an O-Scope handy and pull the VR sensor off and wave a wrench infront of it?

I would think something in the VR signal is fuzzy or its misaligned - either way it will manifest in no start, while still providing mis-timed spark and a wet plug. Even when you fix it you may need to diagnose a no start due to plugs at that point.

As I mentioned- im sure I didn't tell you anything you didn't already know- just thinking out loud!

9

I'll check my MAP vacuum line, I was seeing cruising vacuum down to 30kpa and idling 40kpa or so.

I did check my 12v at the coil and it was true to batt.

VR signal does look a little fuzzy, but it's keeping sync...My tooth logs aren't fantastic but it does seem to have rpm signal. Before I added a 10k ohm resistor when I originally set the car up I was getting REAL VR issues, RPM spikes and massive sync loss and it felt a lot different than this.

I forgot to mention that I re-wired my triggering signal to the ignition board during the car's downtime - I'm thinking I probably swapped them and have 2/6 cylinders timed properly on ignition now.

I'll check my MAP vacuum line, I was seeing cruising vacuum down to 30kpa and idling 40kpa or so.

I did check my 12v at the coil and it was true to batt.

VR signal does look a little fuzzy, but it's keeping sync...My tooth logs aren't fantastic but it does seem to have rpm signal. Before I added a 10k ohm resistor when I originally set the car up I was getting REAL VR issues, RPM spikes and massive sync loss and it felt a lot different than this.

I forgot to mention that I re-wired my triggering signal to the ignition board during the car's downtime - I'm thinking I probably swapped them and have 2/6 cylinders timed properly on ignition now.

I had a similar problem 2 years ago, I checked all the things you have tried. I turned back to the Spark plugs even though they were quite new, these had run rich while tuning. I bought new spark plugs and she fired straight away.
I hope this will help.

Appreciate it, man! If the measures I have planned fail, I'll definitely pull the plugs

Yep, looks like you nailed it.

I checked again, I really had no sync loss.

Traced everything, and I'm pretty sure it was the spark plugs - pulled them from the engine and I got no spark in the gap in the ones I pulled. Reference spark plugs I'd been using to test spark are strong, blue spark.

So, yea, switching from BPR8ES to BPR7ES. I figure I have meth/h2O injection to keep my tune plenty safe at around 20 psi, and even at those cylinder pressures, BPR7ES should be fine.

Great! Enjoy that engine again.