Help with turbo tune please.

[Cubicylndr16]

This is my first experience with (a) tuning and (b) turbos so I can desperately use your help please. Please advise on anything in addition to my issues below that may be off. I have attached my current tune and most recent log. This log doesn't show any WOT boost pulls because I have been focusing on low end around town driving. The car drives excellent at WOT under boost.

My current focus is on:

1) Hanging idle at random times. No consistent pattern other than snapping the throttle usually brings it back down. I can not find any vacuum leaks.

2) I have a hesitation when snapping the throttle. For example, when I "heel-toe" shift, I snap the throttle to keep rpm’s up. When I do this my TPS goes up but the engine stays flat and rpm’s do not increase. It seems to take a generous amount of throttle to get a response. The problem seems to relate to quick throttle changes as throttle response between 0%-10% is sluggish.

3) Is B0107 & B0108 set correctly?

4) My map kPa with the engine off is 95. Given my altitude I should be at 100. I notice the scale and offset in the tune does not match the GM setting for the ZR1 map I use. Is this an issue? I've tried using linear 312.50 offset -11.25 but the engine performed poorly.

5) I think my LC-2 wide band may be reading inconsistent. I have it hooked up to my V2 via a serial cable I made.

18879

18880

408ci LQ4
9.2:1
317 heads, stock valve size
Cam is 232/238 .612/.615 116+4 114icl
Twin PT 6776, .70/.81ar ball bearing
46mm PT gates (7.5 lb springs)
Dual 44mm bov's
E-Boost 2 with dual solenoids
Ls6 intake
ZR1 3 bar map
Bosch O2 Sensors (front only)
No MAF
Stock ls1 throttle body
A1000 fuel pump and pump controller
-10 feed, -8 return,
FIC 1000 injectors
Tko 600 manual trans
26.9" wheel height
3.08 gear
2 speed fan - no a/c
180* T stat
99-02 pin outs
Pump gas, no meth spray
Lc-2 wideband

[joecar]

1) May need to do some idle tuning (I'll find a link to various idle threads), may need to correct VE table first.

2) This is a sign that VE table is not correct.

3) B0108 should probably be set to 0% throttle.

4) you have to get the correct scaler/offset for your MAP sensor... did you tune with the incorrect scaler/offset...?

5) Your LC-2 shows semi-open loop is working nicely (any cell in B3647 that is stoichiometric); other swings I see point to VE not being correct.

[joecar]

Questions/comments:

Is your FPR manifold referenced...?

What does rail pressure measure (temporarily remove reference hose during measurement)...?

Did you populate as many injector tables as you could from all the data that came with injectors...?

Did you tune in OL with B3647 cells set to stoich (it performs semi-open loop STFT trimming ahead of you, aka SOL)...?

You have a cable throttle (not DBW), right...?

Are you planning on running SD/VE-only or MAF-only or VE+MAF...?

Are you planning on running OL or CL/LTFT/STFT...?

Are you getting a MAF DTC (either of P0101, P0102, P0103)...?

You have CL enabled (via B4205) but LTFT disabled (B3801), and your log shows STFT's pegging.

Spark tables (HO, LO, BIG, BP/N) look wrong (too much timing for boost in some places, and something wrong at low rpm)...

[Cubicylndr16]

Thank you. I have been tuning with the MAP numbers currently in the tune. Those came as a suggestion from another person. The correct numbers for my MAP are linear 312.50 offset -11.25 but the engine performed poorly using those number so I'm stumped.

Any suggestions on which way to go with the VE table?

[joecar]

With KOEO (key on engine off), SAE.MAP should show barometric pressure, 100 kPa (where you're located?);

with a vacuum hand pump (e.g. Sunpro) when you apply 15 inHg vacuum, SAE.MAP should show about 50 kPa;

edit the scaler/offset to get SAE.MAP to match those values.


You want MAP to be correct... you'll have to adjust VE table (you'll have to do this anyway since you corrected it with SOL trimming ahead of your WB).

[joecar]

B3601 is 14.63 and the LC-2 stoich is 14.7, they don't match (sure they are only 0.5% apart)...

log GM.EQIVRATIO and EXT.WO2LAM1 and use CALC.WO2BEN from the Calc.VET thread (post #1)

i.e. avoid using AFR, and work with Lambda and EQR (defined as 1/Lambda) instead.

[joecar]

For VE table, we can try to recover using you current VE...

or might have to start with stock 2002 F-car VE and increase it 10% and see how we go from there...

[joecar]

VE being incorrect means that spark table lookup is also incorrect.

[joecar]

Also things to note:

when you go boosted, you will be exceeding MAF limit 512 g/s so you will have to scale VE/MAF/IFR and shift any tables that reference cylinder airmass down.