Lost in a sea of tuning... (Ostrich 2.0)

[Digitalwave]

Does the tach drop out entirely when it cuts? Have you tried a different CPS (oem metal one preferably).

[McGyver]

Dumb question, but is your ECU seeing a bad condition (excessive lean/rich, loss of timing, etc.) and initiating a fuel cut as a protection? Do you have any engine protections turned on in the software?

[Tinkerer007]

Does the tach drop out entirely when it cuts? Have you tried a different CPS (oem metal one preferably).

The tach does not drop out completely. It stays around 3800 RPM. I have tried another CPS (it was used, from a parted car).

Dumb question, but is your ECU seeing a bad condition (excessive lean/rich, loss of timing, etc.) and initiating a fuel cut as a protection? Do you have any engine protections turned on in the software?

I am not familiar with the engine protection feature. I am running a tune from SSSquid that is for my engine.

If I hold the throttle all the way open, the WBO2 shows it going lean, and I get a backfire.
If I press the throttle moderately, it accelerates nicely.

[McGyver]

I am not familiar with the engine protection feature. I am running a tune from SSSquid that is for my engine.

Wait, you're using a stock ECU with a chip tune? I thought you were using a standalone?!?

If I hold the throttle all the way open, the WBO2 shows it going lean, and I get a backfire.
If I press the throttle moderately, it accelerates nicely.

Stock ECU: Are you using your stock Throttle Position Sensor? Is your TPS adjusted and functioning correctly? Does it signal WOT when the throttle is wide open?

Standalone: Are you using an e36 variable TPS? Did you calibrate the sensor?

[bmwman91]

Check the condition of the crank damper, specifically looking to see any visible cracks in the rubber. If you pry on the outside a bit, does it move a lot relative to the hub? The rubber can start to go on these, causing the outer toothed wheel to get wobbly, and then ECU loses track of crank position. It could definitely be in the process of failing and causing RPM-related problems.

[ForcedFirebird]

Dumb question, but is your ECU seeing a bad condition (excessive lean/rich, loss of timing, etc.) and initiating a fuel cut as a protection? Do you have any engine protections turned on in the software?

Ostrich 2.0 tuning is an emulator that lets you manipulate the chip file and change it on the fly. Stock ECU.

Check the condition of the crank damper, specifically looking to see any visible cracks in the rubber. If you pry on the outside a bit, does it move a lot relative to the hub? The rubber can start to go on these, causing the outer toothed wheel to get wobbly, and then ECU loses track of crank position. It could definitely be in the process of failing and causing RPM-related problems.

That makes me wonder. More than once at the shop I have come across an engine build where the assembler didn't tighten the crank bolt enough. When that happens, the reluctor is relying on the woodfruff key. That key gets damaged and the crank hub moves causing all kinds of issues.

Tinkerer007 Whet compression numbers do you have after moving the cam?

[ForcedFirebird]

Are you using your stock Throttle Position Sensor? Is your TPS adjusted and functioning correctly? Does it signal WOT when the throttle is wide open?

Standalone: Are you using an e36 variable TPS? Did you calibrate the sensor?

With Ostrich, you can see the maps that the ECU is reading in real time (just like in Tunerstudio), so it would be very clear during that data tracing if the WOT maps were not being read.

[Tinkerer007]

Thanks for the additional things to check.
I am not sure if I will get to it before I go out of town for the long weekend.

Here is a video of acceleration. The first pull is light throttle. The second pull is all the way to the floor.

https://www.youtube.com/watch?v=30UjGDLSN8Q

[bmwman91]

That makes me wonder. More than once at the shop I have come across an engine build where the assembler didn't tighten the crank bolt enough. When that happens, the reluctor is relying on the woodfruff key. That key gets damaged and the crank hub moves causing all kinds of issues.

Oof, yeah that's a recipe for a bad time. A lot of folks don't quite know how important the toothed ring on the damper is...the single most important thing for the ECU!

I suspect that my HG blew in a large part because the rubber in the damper wheel failed and let the toothed ring go partially unconstrained, leading to the ECU firing the ignition way too early. I guess if one was "lucky" and they instead had the woodruff key shear, the damper would get "stuck" a little off and just cause severely retarded ignition timing.

[bmwman91]

Thanks for the additional things to check.
I am not sure if I will get to it before I go out of town for the long weekend.

Here is a video of acceleration. The first pull is light throttle. The second pull is all the way to the floor.

https://www.youtube.com/watch?v=30UjGDLSN8Q

Hmm, well it is likely not the crank damper or CPS. If it was, it would have an issue revving all the way regardless of the throttle input. Same goes for the ignition coil.

Honestly, it may well be the dynamic compression or something like what FF was suggesting. I can't quite think of what else would lead to a cut / misfire like that.

[Victell]

I would verify correct spark plug gap. Even if it is correct, tighten it up some and see if that makes any difference.

[ForcedFirebird]

Oof, yeah that's a recipe for a bad time. A lot of folks don't quite know how important the toothed ring on the damper is...the single most important thing for the ECU!

I suspect that my HG blew in a large part because the rubber in the damper wheel failed and let the toothed ring go partially unconstrained, leading to the ECU firing the ignition way too early. I guess if one was "lucky" and they instead had the woodruff key shear, the damper would get "stuck" a little off and just cause severely retarded ignition timing.

Actually what happens is the key gets wallowed out from acel/decel and the timing becomes erratic. Of the ~.5 dozen times I've come across it, it blew one stroker motor. After dissecting it, put an angle finder on it and the reluctor could move something like ~10° advanced to -22° retarded while the crank was stationary. o.0

[bmwman91]

Wow, yeah that will certainly not do anything good for the engine!

[vWBIRDWv]

Actually what happens is the key gets wallowed out from acel/decel and the timing becomes erratic. Of the ~.5 dozen times I've come across it, it blew one stroker motor. After dissecting it, put an angle finder on it and the reluctor could move something like ~10° advanced to -22° retarded while the crank was stationary. o.0

Found this on my Stroker, Woodruf key wallowed out the inside of the crank and the timing gear..... had .05 play in each direction.car ran just fine but the dampener was so loose it sounded like it had a spun main bearing..thankfully i caught it when i did could have been disastrous ...

[Tinkerer007]

Even with the cam timing retarded 4 degrees, I still need octane boost for high loads. If I unplug O2 sensor on freeway, it runs rich, 10 - 15. With O2 it runs 14 -16. Here is a pic with compression numbers: Sent from my VS995 using Tapatalk