Evo 9 tuning STFT goes rich during warmup at 83C CLT

Hello,

So I've been reflash tuning Evo Ecus for a while now, facing a weird issue with my own car where the STFT would randomly go full rich at around 83C Coolant temp (Possibly 50C oil temp) during warmup from cold start then would normalize after driving for 5 minutes or once oil temp is at operating temperature around 82C degrees. After the initial warm up issue, regardless of coolant temperature STFT will stay stable at +/- 5% variance at which the car is dialed in at even if coolant temp drops to 83C after long highway cruise. Oil Temperature is a separate gauge not connected to the ECU and has no way of influencing fueling, and there are no warmup compensation tables in my rom that would influence this behavior (All warmup enrichment is 0'ed out after 50C Coolant Temp).

Car is an Evo 6 with an Evo 9 swap including ecu. Relevant mods are:

2.3 Stroker 4G63

HKS 274/278 Cams

FP Red turbo

FIC 1200 Injectors

DW420 Fuel Pump

Speed density & Flex Fuel using Tephra V7 Rom using AEM 5 Bar Map Sensor and GM IAT Sensor installed at upper intercooler pipe

Aquamist WMI

I've attached logs and screenshot of the problem area from the log.

I've tried changing Map sensor, Coolant temp sensor, different rom, different injectors with appropriate scaling values inserted in the rom but to no resolution. Any advice to this will be highly appreciated.

O2 Feedback Trim in the log is STFT.

That could be due to closed loop coolant temperature threshold settings. Usually it's 20C. Try to change it up to 40C and check if anything changes...

I've set it to 43C but to no avail. Same scenario.

Can you send me your tune file at georg1970@bk.ru ?

Just sent, thanks.

Ok, I'll check it out. But to be honest STFT isn't something i would worry about at all as long as LTFT are within +-5 percent.

So LTFT is turned off in my rom, car runs off only short term trims.

How does it affect your actual afr vs target afr? What consequences make you worry about STFL going high just temporary?

So when stft hits -25, actual afr on the wideband reads 10 gasoline afr and car becomes a little difficult to drive at that moment, sometimes it recovers back to target stoich afr of 14.7 and stft just stays at -14 to -17 for a while and goes back to normal, some days it'll stay pegged at 10 afr and -25 stft for a long time.

I'm inclined to believe the problem is mechanical and not tuning related. Just can't figure out what mechanical issue causes this since when the car is dead cold 30C-80C CLT stft and afr would be on target.

Try to log at what MAF frequency your actual afr is too rich. Then go to MAF smoothing table and reduce the number in corresponding cell proportionally. For instance your target afr is 14 and actual afr is 10 at 75Hz. In MAF smoothing table in the cell corresponding to 75Hz reduce the value 25 percent and check what's happening. If actual afr is still too high reduce that number some more.

For your information - I came across some Evo 9 ROMs that didn't work properly at idle as afr mixture was too rich regardless of any changes and noone could fix it, even gurus couldn't. That's the reality of open source tuning system

Okay thats a good idea I'll try this.

Also will try going from 8859 to 8858 rom and see if that helps. Although I've tuned dozens of Evo 9s on 8859 rom with no such issues.

I just realised that you have 2.3 stroker. How did you compensate in the tune file for additional displacement? Usually if MAF size and engine size aren't properly described in tune file the actual load will not be corresponding with the load being logged and that can lead to all sorts of issues since two different types of load are used (and neither one of them is logged properly) for fuel and ignition timing values to be chosen.

Injector scaling scaled down by 20% than what it would be for a 2.0. I'm also running speed density and not maf. Once car is fully warm no fueling issue is present btw.

Ok. When car is fully warmed up it has no issues - it makes sense as all warm up fuel tables are disabled...

Around 85C CLT or 75C oil temp fueling comes back on target. Warmup tables disabled from 50C onwards. From 30C (dead cold engine) upto 82C CLT stft is within +/- 5%, then suddenly car will go rich and stft will go -25% and wideband will read rich. Recovers once car hits 85 issh CLT and 75C oil temp and will stay on AFR target even if coolant temperature drops back to 83C.

Is the engine from Evo 9? If that's the case did you check warm up tables for mivec? Can you log it along with TPS?

Yes Evo 9 Mivec Engine. I've attached screenshot of all warmup related tables, and the log including TPS. Jump to line 998 in the log that's where the issue starts to happen.

I'm not at home now. Once I'll get there I'll check everything you sent me.

OK it was a wiring issue on the map sensor wiring. Now fixed after rewiring that.