I'm looking to install Kooks stainless steel headers instead of just replacing exhaust gaskets on on the stock exhaust manifolds. Will a tune be required afterwards?

Also, I've read that on a kooks install we lose the oil level sensor? Or is that just on specific models?

 

I was looking at this thread:

https://www.camaroz28.com/forums/exh...review-865570/

 

Generally on 93-95 cars no tune is needed, on 96 and later a ‘tune’ is needed to turn off the rear O2 sensors so it doesn’t trip the check engine light (93-95 cars don’t have rear O2 sensors).

 

In my experience the car will run a bit leaner after the header install. If you're on a stock tune to begin with then I would say that's a good thing.
I had already (DIY) tuned my car before getting headers/exhaust, tweaking it after the install was worth another tenth in the 1/4 mile.

 

That's good news. I would guess the FTs would adjust.

 

Cruising trims will adjust, power enrichment is a different animal. I'm a bit rusty on how PE works (with stored BLM values) in a stock tune but it is typically so rich that a small percentage variation isn't going to matter.

 

In theory, the headers improve volumetric efficiency. Higher VE means higher mass air flow. The MAF sensor picks up the added mass air, and the PCM makes its normal calculation to add the extra fuel to match the extra air mass. No involvement of the LTFT's, no leaning out in closed loop, and no leaning out in PE mode. Since a failure of the MAF sensor causes the PCM to default to speed-density, tweaking the VE table might be in order.

In a 93, with its speed-density setup, the VE table would have to be adjusted in the tune, so that the speed-density calculation of mass air flow reflects the changes in VE.

In reality, in mass air, there may be some minor changes due to relocation of the O2 sensors, improved scavenging during cam overlap, etc. Probably not enough to require a tune. BUT.... a tune on a totally stock engine can yield a 10-15 HP improvement in peak HP. This is accomplished by leaning out the stock tune’s overly rich target A/F ratio (~11.7:1) in PE mode, to something in the range of 12.8-13.2:1. Why not do that now?

 

MAF mode will involve the BLM (a.k.a. LTFT) values, at least in 94-95 cars.
I had to look it up (memory hole) but it appears that the pcm will add additional fuel to PE mode if BLMs are above 128 (i.e. lean condition)

 

My point was NOT that the BLM (LTFT) is not used in PE mode. My point was that adding headers should be picked up by the MAF sensor, and there would be no impact on the BLM's in the first place. Hence adding headers does not require a differentiation between closed loop or PE.

 

And I was saying that this is not accurate according to what I saw on my car/tune. It ran between 3-5% leaner across the board.

 

That's why I prefaced my first post with the words "in theory". And then expanded it with the words "in practice".