Nistune Forums

Hey guys,

Finally got around to starting to tune my SR20DE+T in my S12 gazelle.

The ECU is originally a SR20DE Automatic ECU, which matt installed 52F0F feature pack MT code into it.

My specs are the following:

- Internally STD S13 lowport SR20DE 9.5:1 comp
- S15 manifold w/ ATR28SS15 with std 7psi actuator on currently
- 950CC Deatschwerks drop in injectors (yellowtop)
- Nistune (obviously, 52F0F feature pack)
- STD fuel pressure reg
- At the time of testing (changing to walbro 450) stock ca20e pump lol
- 3" induction pipe with Z32 airflow meter to pod filter

So first thing, my K constant is very close to maximum, after nistune did its calculations with injector resize and AFM change. it went to around 589XX, which i had to increase to around 61XXX to start tuning properly. Is this Ok to have the kconstant so high? i am assuming it is due to the fact it is going from DE std maps to much larger injectors and AFM.

Second, it is wanting to stall out coming to a stop. Usually i would put this down to reverb through the AFM. However even if i come off boost, wait 10 seconds and then come to a stop it still stalls. It also did this to a much lesser extend (idle fell very low and would sometimes go to stall, however never did) when it was N/A without the nistune on stock map.

What you can try is injector reszie and untick the TIM/TID tickbox so it reduces K constant on resize instead of total injection multiplier

This will lower K constant and keep you within factory scales

Having TP (load) operate near factory is what you need, so lowering the K using this method will get things running better

With the stalling, need a log file to see what it is being caused by

I will check kconstant again tomorrow. I forgot i had not plumbed my PCV system properly and did today. Starts and runs much better, however still stalls coming to a stop. Shall record some logs as soon as i get time.

Heres the map so far and the logs, both logs cut out once the car stalls. this is just coming off the throttle and coming to a stop. If you keep blipping it once you are stopped. it sorts itself out. Not reverb coming off boost or anything.

Lol noticed tps 0.30v

Adjusted to 0.45 fixed stalling.

Sometimes its the simple things -.-

Ok did I need to look through the logs still or sorted? Increasing TP min can help too

Not fixed haha. TpS idle now not active and causing very hard starts. Any idea how much to add to TP min matt?

Yeah if you could go over the logs please matt. It seems to only do ut while warm. Over 70 it seems

I tried varying settings in Idle stabilization advance + retard, recovery duty, TPmin ect, also raising target idle to 950. Am starting to think it may be possibly my IACV is defective. Although very strange that it only does it once warmed up..

Firstly you should not be changing your TP scales like you have. Put the scales back to the factory values, and instead adjust K constant / TIM until the load cursor reaches the end of the scales, but your AFRs are around 14.7:1 cruise and around 11.5:1 on boost

After this you should end up with lower K constant than 62721 and might help your decel issues perhaps

Min TP depends on if its going too lean/rich around idle on decel so only needs adjustment based on your wideband readings. I cannot see AFRs in the log so not sure with this

Normally enrichment should not need adjustment (enrich - cold crank)

Knock retard limit table has some funky values (copy original ones from 52F0F)

Try disconnecting IACV and see if any difference made

If vehicle is very difficult to start then look at your 'crank enrich' table futher at the temperature ranges affected. These are very large injectors so more difficult to control (normally about 740CC would be suitable even with E85)

When holding RPMs about 1ms of injection time, but this increases to 3.67ms as the RPMs decrease (load is fairly steady but more fuel is added). Are the mixtures going too rich on decel?

Lowering TP min here might help

Timing is fine as its holding about 15 deg BDTC but perhaps too much fuel is causing engine to stall?