Pinging after LT install?

[misl302]

Hey all,
I recently went from 1-5/8" shorty headers and O/R h-pipe to BBK 1-3/4" long tubes and catted x-pipe. I've since noticed some engine detonation/pinging under load in 5th gear. The car is quieter now with the cats so there is a slight possibility that I just wasn't hearing this ping with the O/R h-pipe. The LT's do move the O2 sensors sveral inches further downstream than the shortys. Any chance the LT's are the culprit? Could I now be running leaner than before? Does running lean cause pinging?

Thanks.

 

[2002BLGT]

Hey all,
I recently went from 1-5/8" shorty headers and O/R h-pipe to BBK 1-3/4" long tubes and catted x-pipe. I've since noticed some engine detonation/pinging under load in 5th gear. The car is quieter now with the cats so there is a slight possibility that I just wasn't hearing this ping with the O/R h-pipe. The LT's do move the O2 sensors sveral inches further downstream than the shortys. Any chance the LT's are the culprit? Could I now be running leaner than before? Does running lean cause pinging?

Thanks.

whats your timing at ?

 

[Paul Perreca]

are you sure its a ping? could it be an exhaust leak?

 

[jackchan]

humm. one way for sure to know, check timing first then look for exhaust leak. IF you fix both those you could have it fixed!
good luck
Jack

 

[misl302]

I'm pretty sure it's not an exhaust leak. I had a leak with my old shortys due to a broken gasket. After the LT's and new gasket - no leak. I recently lowered timing to about 16° btdc (aluminum heads, compression ratio probably lower than stock, 93 octane gas). I do wonder if my timing pointer is slightly off. I seem to remember that when reinstalling after h/c/i swap, that the pointer mounting location seemed a bit "vague". Probably within 2° accuracy though. Fuel pressure is around 42 psi. I'll play with fuel pressure next.

Just seems odd this pinging did not occur before the LT's.