Tuning Turbo Safety Question

[Schmieder]

I understand punching a turbo w/o tuning is dangerous to the engine.

I need to understand the danger a little better. I feel if I know what is up, I can take steps to ensure detonation/ect doesn't happen.

Tell me if I am correct, please......

The danger is this, if the STFT/LTFT are widely off, then the engine will pull the fuel when it enters PE during WOT. So if the engine was running -20 LTFT per a specific cell just before WOT, then the engine would essentially go +20 when it enters WOT, causing a dangerous condition.

So when I tune, I dissable PE and data log the fuels trims as I drive around trying to hit all cells. After a good bit of driving, I save the data log and adjust the VE tables accordingly. Once, the VE tables are accurate, I then enable the MAF and tune the MAF curve. The details of tuning I have.

Once the STFT/LTFT are tuned below +/- 5, it then becomes safe to enable PE?

Any advise of what dangers are involved would be greatly appreciated. I DO NOT want to destroy my engine and throw away all my hard work, pride and future fun driving.

Thanks

[robertisaar]

So if the engine was running -20 LTFT per a specific cell just before WOT, then the engine would essentially go +20 when it enters WOT, causing a dangerous condition.

that doesn't make a whole let of sense... in OBD1, if the engine was running rich before it hit PE, it would command the PE AFR and remove any kind of long-term correction. if the engine was running lean before PE, it would command PE AFR + whatever long-term correction was present.

i imagine OBD2 would work the same or similar.

[Schmieder]

that doesn't make a whole let of sense... in OBD1, if the engine was running rich before it hit PE, it would command the PE AFR and remove any kind of long-term correction. if the engine was running lean before PE, it would command PE AFR + whatever long-term correction was present.

i imagine OBD2 would work the same or similar.

See why I am confused a bit....lol

What I think I meant to say is, the LTFT/STFT are not expressed in WOT/PE. So if there is -15 fuel trim from the AFR to maintain 14.7 and the car enters PE, it should lock in and cause an unwanted lean condition.....I think.

I just need advise and information. I want to know specifics of the dangers of driving an untuned turbo. I'm not looking for excuses to drive it WOT untuned, I already decided I won't do that. I just like to know specifics so I have better control of the situation while tuning.

[IsaacHayes]

You are OBDII right? You need to do a VE tune first, with MAF disabled, but if it's a stock motor, I'm not sure that will change a whole lot. You tune for boost in OBDII with the MAF from what I know. So I'd be looking at the MAF values vs fuel adding fuel where it is lean etc.

[Schmieder]

You are OBDII right? You need to do a VE tune first, with MAF disabled, but if it's a stock motor, I'm not sure that will change a whole lot. You tune for boost in OBDII with the MAF from what I know. So I'd be looking at the MAF values vs fuel adding fuel where it is lean etc.

Yes, OBDII.

The VE tuning I have a tutorial and I can follow the instructions as I have read it. Isn't too hard.

Now, tuning for boost with the MAF is new to me and I haven't a clue about that. I have read about tuning the MAF itself AFTER tuning the VE tables, but tuning for boost is ???

I tried looking for a help file in regards to turbo tuning from a n/a engine pcm, but no luck.

I need help, lol.

I figured the VE tables would be referenced at WOT and I need to adjust the VE into +100 ranges as needed and understood from WB readings when under boost. As the boost is basically increasing the VE of the engine and possibly beyond 100% if the psig is high enough? Of course, after the basic tune VE/MAF.