Jochen

Hi,
i have a view questions which i couldnt answer to myself by just using the search function:
I have the following Mods done on my 97 C5 LS1: K&N FIPK gen. II, High Flow MAF, High Flow Air coupler, B&B Triflow cat backs, R/T Cats, R/T x-Pipe. I dynoed the car and got 362 (DIN) HP. That was 6 HP less than the previous Dyno (DIN 368,5 HP)which i did without the R/T x-pipe and cats.
So acctually i lost 6,5 HP from the R/T cats and x-pipes (i guess car is running too lean under wot). I bought HPTuners to reprogramm Fuel trim to recover the lost ponies.
The question is, how to approach this now. I logged a view runs and found the ltft beeing OK logging MAFless (cells between -4 and 0, just a little spot is positive which i will recalibrate). However, when i plug in the MAF Sensor, the ltfts are all between +13 and +20. There is no knock retard at all during any driving condition, even i have the Hypertech PPIII installed.

So what is the best way to find best fuel trim for this condition, MAF tuning or PE settings ?

I really hope you guys can help me with this problem.

Take care,

Jochen

white2001s10

iTrader: (4)

What problem?

oange ss

iTrader: (50)

put stock MAF back on

horist

^^^ what he said ....

You can try scaling the MAF tables as well to bring the LTFTs back down to 0, but I would stay w/the stock MAF ...

What kind of high flow MAF do you have? SLP 85mm? LS6 85mm? GMS?

Jochen

The problem is, how to recover the lost HP. Thats the question.
Aint there a way to calibrate this MAF Sensor for best fueling ?

Thanks,

Jochen

Jochen

The MAF is a Stock Unit, without screen and polished from Westcoastcorvette. They advertised as well "recalibrated" . . .

horist

ok, there's a MAF table under airflow (don't have HPT installed on this box but can check tonight) , if you're happy w/your VE tune then you'll want to scale the MAF to bring the LTFTs back inline

Keep in mind also ... even w/corrections for weather, a dyno may not yield the same value today as it did 2 weeks ago ... depends on how the weather is still

Jochen

Thanks, i understand.
So you think as long as i plan to keep the MAF installed it is a good idea to calibrate the VE table while the MAF sensor is installed like i did it with the MAF sensor unplugged. After that calibrate the MAF/Airflow table to get fuel trim right . . .

I appreciate your fast help !


Jochen

white2001s10

iTrader: (4)

that's exactly what I was thinking, that there may be no lost power other than tired plugs, springs, or just different DA (air).

If you want to change your fueling for a power tune, then you'll need some test equipment like a wideband O2, and an accelerometer so you can do multiple power tests.

First you want to get an idea what your AFR looks like by doing a few full baseline runs with a WBO2.

When you get to that point let us know and post the results.