4AGE Engine falls flat - logs(attached). Stumped.

[suberimakuri]

Hi everyone,

I'm a bit stumped.

Engine:
Toyota 4AGE, MS3X v1.5.1, cop, turbo (internal gate disconnected but makes couple psi).

Previously:
In October had this car out at a track day running the engine in and all was gravy. No problems. Pull through full throttle to ~7000rpm by end of day.
MSQ and MSL included.

Now:
In December, took to a drag day and I could almost always do a decent burnout at staging.
Then when launch, after about 20% throttle the engine just falls flat, as if there's a fuel cut, or lots of timing retard, or similar.
Out of about 12 runs, only 1 run ran good and I don't know why. The good run did a 16.2 or something. Bad runs were as bad as 23 or 30s because I just hobbled it over the line.
Attached log of good run and a bad run, have compared in MegaLogViewer but can't spot anything.
In bad run you can see me hold the throttle and occasionally try more throttle (up to 50%) but the engine doesn't respond.
The log does show very rich on accel at this time and hitting 9s... however the accel enrich was pulled back to way less than October track day amounts and didn't make any effect during the December track day. Even the good run shows it going richer on accel then what it did in October, however 10's rather than 9's hence it moved.
Tried checking over settings in TunerStudio.... tried changing different settings including loading last msq from October track day without any change.
Spark plugs looked okay, but it's a long way at good running condition from end of track to pits.

Changes between track days:

• Wired in: oil pressure, oil temp, fuel pressure, speedo, all confirmed working correctly in TunerStudio.
  **By 'wired in' I mean that I put a DIY harness pre-pinned wire back into the DB37 plug for input and then tee'd VREF & sensor ground as required. So both DB37's been apart.**
  Wired in: CANH&CANL&VREF&Ground for TinyIOx board and terminated into a plug that's unconnected as TinyIOx not yet mounted in a suitable box /etc.
  Wired in boost solenoid, however fuse not in so no power going to solenoid.
  Changed relay power feeds for coils/pump/etc to run off a post by relays instead of back to kill switch. Large wire used.
  ECU and coil grounds disconnected and reconnected.

Thoughts:
I don't believe accel enrichment or VE table an issue as went way leaner throughout the day without any effect, I just haven't included a dozen logs and msqs.
I thought maybe ignition power was faulty or had bad joint, but have just had harness out and can't find anything.
Thought maybe bad ground for coils, but it looks and feels fine (not loose).
The tune is not marvelous as it's a fresh build and vehicle is not street legal so I can only adjust on the days, run hefty ego and take care, October track day logs are good, just December since all the changes looks bad.

Any help would be much appreciated. Thank you.

[Matt Cramer]

All I'm really seeing is the engine running rich. Are the sensor readings OK?

[suberimakuri]

Thanks for having a look Matt. I agree, looking rich is the only standout on the logs.

I don't know why it looks rich.
In the October logs we can see that it is no where near as rich at steady state or on accel for the same or lower VE and TPSAE. It's reasonable.
During the December track day I took out ~50% fuel from VE and TPSAE but it never made any difference to logs or performance.

I see one potentially major change I did was from SD to %Baro for December track day.
Although again it wouldn't explain why the engine didn't run like October when I loaded October tune (SD).
Granted the dual fuel and ignition tables makes things more complicated than normal. It's itb-turbo.

Based on what was changed between October and December (wiring), I still think maybe coils not getting enough juice or not grounding or something which would show as rich due to not firing.
Or the motor is magically running a lot more fuel efficient since I shut it down in October?!?!?!
Will keep hunting.

[Matt Cramer]

Any chance the fuel pressure has changed?

[suberimakuri]

In December I wired in the fuel pressure sensor which was already in the rail in October.
It read consistently in December and when pulled vacuum ref line at the track the pressure changed as expected.
This shows in the logs.

The fuel pump power feed was also moved after October. Whilst I don't think it was getting limited current I guess it's possible.

We're going to do a test drive and pull all the fuel again and see what happens.
I've changed the rumbly locker for a tight LSD and have split coil fuel vvt etc powers over two relays so can test the lot.

Could the extra 5v draw from Speedo, oil and fuel pressure sensors be related?
Next drive I'll unplug these to test as well.

Thanks again.

[Matt Cramer]

If the VREF dips significantly below 5 volts, this can skew many of your external sensor readings.

[suberimakuri]

Thanks Matt.

I always wondered about feedback circuits for different things like OEM do.
I guess you need to reference it to something and that means building a second 5v regulator (dropping from batt 12v) that isn't under load.
Isn't the nitrous-in or another input (pt4?) 12v capable? Could I feed VREF into that and always datalog it?

I'll put a multimeter across VREF to ground whilst I ponder this.

[MegaMicra]

PT4 is 0-5v. You may damage it putting 12v into it.

Sent from my WAS-LX1A using Tapatalk

[suberimakuri]

Thanks MegaMicra, I would look it up before doing anything.
Multimeter will do.