Need help: ST-205 severe rpm hunting, no clue

[Riiken TSh]

TST205X was running majestic with only street tuned map, but shenanigans happend and became jackstand project for 3yrs, now start up again starting is really smooth no issue at all. But after startup, car has very unhealthy rpm hunting symptom, and I could feel she refuses go beyond 2500rpm and when stepping throttle feels lack of power. 

Here's current map & log 1503 pclx & llgx; you could see some very strange hunting waving after startup and TPS let off. I tried step a lil gas and felt lack of power almost like she won't go beyond 2500rpm, and didn't push further for safety. After let off it's quite dramatic hunting and shaking

Background: same map as before only engine fan and TPS recalibrate, last time yrs ago she was running absolute majestic. Did replace many with used parts( examined healthy per manual ), everything changed includes: ISCV, coil & igniter, changed distro cap insitu. Changed wideband sensor generic LSU4.2. Repaired leaking in/ex manifolds, AC delete, very intensive luricant & rear radiator coolant replumbing - those plumbing doing very well so far idling test

Have really no clue, checked all ECU wiring loom, grounding proper; diagonised parts and borescoped engine condition just like she was. She should run like before but not... Really scratching my head, any input would be appreciated

Now not sure ignition base timing, timing light won't light not picking up spark wires, could be ignition light faulty or weak spark, already ordered new timing light will see. And didn't comp test yet but could do, though I don't believe any comp issue her last running was when all 4 cyls reading 184-186 very consistant healthy

Thanks,

 

1503tps cal, iscv lower authority, still very bad.pclx 1503_still hunting.llgx

[atlex]

I had a brief look. I'd start with the following steps (but test in order.. don't just apply them all at once!)

drop the integral gain to a minimal value (from 0.50 to 0.01)

map lockout to 60kpa (currently 50kpa)

lockout above target a few 100 rpm higher, like 700rpm

 

also the fueling as it nears 50kpa at when idling is super lean - you're seeing 18:1 afr when it shouldn't really even go over 16:1 afr.

as air is let in by the cycling overreacting idle valve (see integral gain?) it's going into cells that don't seem to be right, that may be affecting the way the idle fails to settle properly.

[Riiken TSh]

5 hours ago, atlex said:

I had a brief look. I'd start with the following steps (but test in order.. don't just apply them all at once!)

drop the integral gain to a minimal value (from 0.50 to 0.01)

map lockout to 60kpa (currently 50kpa)

lockout above target a few 100 rpm higher, like 700rpm

 

also the fueling as it nears 50kpa at when idling is super lean - you're seeing 18:1 afr when it shouldn't really even go over 16:1 afr.

as air is let in by the cycling overreacting idle valve (see integral gain?) it's going into cells that don't seem to be right, that may be affecting the way the idle fails to settle properly.

Thanks for advises will try out today; at first i thought lean only after let off, but as your pointing out does seems going dangerous lean even on TPS when ~2000rpm. Dunno why... I don't think hardware fuel/intake have much change, fuel table was perfect. But maybe increase master fuel just test behavior. Also waiting for my new timing light to test base timing. Hopes the engine could turn out well without much shenanigans...

[Adamw]

Mostly just looks too lean to me, when it started oscillating at the beginning of the log the idle valve was still in decay mode so air flow would have be relatively stable.  The 18 deg jump in ign advance between 1000 & 1500RPM is probably contributing also.  

Confirm base timing, make idle region richer, smooth out Ign table.  

[koracing]

What mods or additional sensors have you added to your car/engine?  I may have a modelled base map I've made for a mostly stock setup you could try also.

[Riiken TSh]

Update: resolved

(1) I was eliminated the reason if vacuum leak, since I THINK I tightened down every hosing and car seems keeping vaccum...

But I actually forgot go connect carbon canister and fuel tank hardline... silly me. Now the car's running rich, which is to be expected since my DIY header was wrecked in a sus incident, I changed back to stock log which should flow worse. 

 

(2) Now I know the lean and weak power was due to another reason, and I did replaced ISCV, now I'm sure hunting idle is purely ISCV issue maybe. Lowered integral to 0.4, 0.35 did me great but I'm scared to set too low, now trying idle position base table, lower bias has no positive effect, so I increased lil now she idled better, still slight hunting now easy to die when low speed turning / braking etc. 

Will try idle base table again. But now she's already OK if I careful and lightfoot with clutch. EDIT: now checked new logs I believe I shouldn't mess with ISCV much further, should instead change fuel map to match worse flow of stock log manifold?

 

(3?) I was confused timing light 'bad', why a reliable xenon flasher could go bad and falsher lamp tested working. Bought new timing light and she's 3deg retard comp to before. But silly me it might be I mistaken the induction clamp direction polarity... rofl

 

These're current first step neighborhood test... Rear rad behaves great yay! Now using G4X+XS expansion I could set DIY fan & pump control darn easy. 

https://drive.google.com/file/d/1CCY_lYAvZP66GN8Ckzv9H9xtPMQDNPgY/view?usp=sharing

https://drive.google.com/file/d/1rxN2fRQvDmFbn3DGj0Y18aAHZ6ZmH1Vu/view?usp=sharing

 

 

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