If I had my 94z dyno tuned with a 4.17 in puley and then changed to a 4.25 to reduce boost. Will I now be running a little rich under less boost? Do I need a retune?
Stock engine, headers, 3" cat back. 42# injectors. D1SC w/ twin i/c's.

 

A little rich on a stock engine is usually a good thing.

 

yea no kidding! Given the size difference in the pullies it wouldnt decrease boost too much, but when it comes to having FI on the stock cast pistons, its usually best to play on the rich side. Ive got mine at 12:1 right now to be safe.

 

The tuner set mine a/f to 10.5, and that was with the smaller pulley.
Any downside to too rich? Its during fuel inrichment mode only, isnt it? System s/b closed loop when your foots not in it.

 

The A/F ratio you have sounds really rich...How much boost are you running? Do you see any type of bog at lower rpms? If your running quite a bit of boost, im sure that it leans out in boost. I see 7 psi right now, and my tuner had mine set at 10.5 which bogged like crazy throughout the revband. For the most part, its best to play on the rich side with FI to keep cyl temps down and avoid detonation (especially on cast pistons).

 

Interesting you should ask, I do have a stumble, bog, off idle...
too rich?

 

Possibly. Do you have any datamaster logs?

 

running around 7 boost.

 

I would retune. The thing to keep in mind is if you lean it out a little to remove the bogging, it essentially can lean it out too much at righ rpm, which may lead to detonation. The only way to do it is to get on a dyno, get a wideband on it and watch you a/f ratio throughout the revband.

 

I dont have any logs.
I probably paid too much for original tune, and car has never run right. I'm hesitant to go back, but hate to pay someone else too. Even if i I bought a wideband, I quess I have have to buy some software to lean out. tough choices.

 

Kredz28, how long have you had a D1sc on stock pistons @ 7 #'s??