VE Tuning Disaster, Help Please

[gr8vet]

Hey guys,

To start, this is a 1999 Vet, LS1, Manual. Friend added the STS kit, running 5 PSI, added 36# injectors. No other mods.

I took the original stock tune, changed the injectors to 36#, left the VE table alone except for the 105 line which was raised. Adjusted the PE to be a little richer. Did not change the MAF table. Adjusted spark table down for safety.

I basically took the % changes from my 02 vette (Stock tune vs. sts starter tune) with similar setup and applied as a starting point.

Now:

I tried to do the VE tuning via cpig's write up, doing the STFT method, and after some street driving and then within 4 to 5 pulses on the throttle, engine went into limp mode. Tried again at higher speed, same thing. Finally gave up and reloaded the starter tune (i.e nothing disabled). Did not know what else to do here?

With the original starter tune I did the car actually feels/runs good. Have not allowed him to go into boost thus far. But, I am concerned with some knock retard showing up at low RPM's as shown on scan, the LTFT appear all over the place, and I just don't feel good about where this thing is and of course getting frustrated. The attached scan also shows the final tune I tried with some simple driving around and on the interstate, maybe 20 miles or so. The STFT scan shows data from setting up cpig's STFT VE tuning method when engine went into limp mode.

I would appreciate any look see and let me know if you see something stupid I have done or not done. Damn, I feel like I am making this so much harder than need be.

Thanks in advance, I owe you one

[WS6FirebirdTA00]

Why are you trying to VE tune a boosted car? Or are you only doing part throttle low load stuff?

[gr8vet]

Yes, just trying to make sure he is ok to cruise around. Low load stuff only at this point.

Thanks

tt

[gr8vet]

Sleeping on this, on cpig's write up, it mentions that you can just jump to the STFT method. As I understand this, is this after doing some LTFT scans and updates, or can you skip the LTFT. I just loaded tune, cut off LTFT, disabled PE, disabled MAF, cleared old LTFT and went right into the STFT method, starting the throttle pulsing? Then wound up in limp mode. Correct???

[gr8vet]

Why are you trying to VE tune a boosted car? Or are you only doing part throttle low load stuff?

Thanks for the reply, but, now I am really confused. I thought the ultimate goal on a boosted car would be to go to SD, which fails the MAF to the VE tables? Did I miss something somewhere?

Thanks

tt

[gr8vet]

Another question, when just crusiing around, looking and logging LTFT's, and not having the MAF disabled, is this data valid to paste back into the VE table? I know the MAF can interfere, but, this may allow me to get closer on the VE table????

thanks

tt

I figure if I keep talking to myself I'll figure this stuff out.

[WS6FirebirdTA00]

Maybe I am confused. Do you still have a 1 bar MAP sensor? If so, you can only tune in vacuum when doing the VE.

No you can not change the VE with the MAF enabled.

[gr8vet]

Alright, you da man!

Yes, this car has 1BAR MAP. No wonder all this stuff is going nuts on me, Yes I am a loser, yes I was trying to adjust VE while MAF was on last week. But, when I did try to do some VE tuning, with MAF disabled yesterday, car ran not so good. When took new data, pasted into VE table, dang thing would hardly run at all.

I am assuming if tune is so far out on VE, that the STFT method may be a little aggressive to start with. i.e. car went into limp mode.

Big question, and I have seen your post on doing a updated tuning guide, (God Love You), out of all the posts, books, guides, etc. I have read, and read, what is the correct approach to tuning. Start with MAF, Move to VE, Spark? I think I am chasing my tail on this one.

Thank you for your help!
tt

[WS6FirebirdTA00]

Yeah, that is a good idea.

Ideally, IMO, I would run a base timing table, dial in the fueling, and then tweak as needed. Always start with the VE as it will influence the MAF under 4k RPM.