RomRaider

So I've been running well on a conservative map while I learn a bit more about tuning (I have a vf48, sti up pipe, sti tmic, gs ebcs, perrin inlet, perrin divorced downpipe, 3" exhaust), but all the sudden I started having issues the other day. After driving for about a half hour, I get sudden power loss with backfiring. It seems to be going rich (into the low 11s), though that might be a safety measure and not the cause. Everything seems to be fine when I let off the gas, so just under load. I'm wiring my wideband back up and will be logging later to start trying to diagnose this issue, but wanted to know what parameters I should start looking at so I'm not just logging a whole slew of things.

start by grabbing the LTV info and comparing to the last one you have when everything was good. By the sounds of it I'd also be checking if any of your hoses have escaped and you've developed a bit of a boost leak.

As for what to log I would probably start with:
Engine Speed
Engine Load
Feedback knock
Fine Learned Knock
Final Fuel Base
Gear
Ignition Total Timing
Injector Duty
Manifold Relative Pressure
Target Boost
Primary Wastegate Duty
Mass Airflow Volts
Throttle Opening Angle (or accelerator pedal angle)
Wideband
AF Sensor #1
AF Correction
AF Learning
IAM
Intake VVT Angle
Requested Torque

Should give you a rough idea where to look and dig deeper based on what you find but start with the LTV info and checking things over under the bonnet.

Thanks! I'll report back with any findings.

Here were a couple quick logs I was able to get before having to go back to work in case anyone can get to them before I get home. Might not be enough data, but the issue was present when shifting into second gear on the middle log. I watched my AFR drop to mid 10s on my wideband (unfortunately not logged due to my laptop usb apparently not being able to output enough amps for the phidgets adapter?), but the stock wideband is logged.

Side note: I had to cut a couple parameters from logging because with all the suggested ones checked, the logger kept trying to connect and wouldn't read anything until I dropped a couple. Is that a limitation of my laptop or RR?

hard to say without seeing the logs, do you have fast polling turned on and are you using 1 or 2 byte values where they are available?

Whoops, forgot to upload the logs.

take a look at those knock figures, -11.75 fine learned, -3.87 feedback and an IAM of 0.125. I fear its time to stop driving, lift the hood and get stuck in to find whats busted.

Oh I definitely haven't been driving it besides to log. Any idea where to start troubleshooting? It happened out of nowhere, not after changing parts or anything.

Sorry, pretty inexperienced with all this.

If your not sure then it might be quicker to go to a mechanic, first job would be check compression and leakdown / take a look at the plugs, check for boost and vac leaks and anything rattling around d in the engine bay that the edu could be picking up as severe knock

Oh gotcha, so those corrections are dumping fuel because it either is, or thinks it is knocking? I had my avcs solenoids stuck a bit ago when the banjo filters came apart. Hopefully the cam timing didn't screw something up internally. I'll poke around. Hopefully it's an easy fix. Thanks!

Seems to have been a bad map. Went back to stock and am going to start over. Logs on the stock map look a lot better from what I can see (still on the free trial of MegaLog Viewer HD).

better but still not great, you've -3 feedback knock and -1.3 fine learned as well that will be worth investigating. How does your wideband compare to target AFR on a pull?

Also looking at your a/f correction#1 i get the feeling you might have a boost/vac leak or something else wrong that also needs looking at.

I'll check those two points out tomorrow. It's an open midpipe right now and the neighbors probably want to sleep. Haha. I used to be able to log afr with my wideband through my phidgets interface, but for some reason my computer doesn't like more than 8 or so basic parameters before it runs out of buffer (displays something like "problem with init, waiting for 61 more bytes") and won't read params until I deselect a few. I'm assuming it's an issue with rr, not my laptop, since my old laptop was waaaay worse and still worked (this one is 8th gen i5 and 8gb ram). I definitely didn't expect the stock map to run well given my mods, but since it seemed to clean up a bit I'm hoping it's a tuning issue and not mechanical?

do you have fast polling enabled and are you using up to date car/ecu/logger defs? That's usually the issues i see when people have logging problems.

as for mechanical vs tuning issue - if you don't do any mechanical checks then you'll find out eventually which it is. If its actually a mechanical issue then ignoring it can cost more in the long run.

I just reinstalled everything on this laptop a month ago with the latest defs, so it should be good but I'll see if there are newer ones. I enabled fast polling as well.

I definitely will be going over the mechanical side of things as well, just keeping my fingers crossed it's nothing internal.