Jays92Camaro

I know this post is long, but if I want good answers you need the info.

I've got a 92 RS 305 that used to be a TBI and was converted to a TPI before I got it (very popular upgrade). This all started over failed emissions,but I fear it's more serious. It would knock under load, in trying to diagnose the failed emissions, I stumbled on a bad EGR valve, the entire intake stream was coated with black carbon and I thought I found the cause for the knocking. I cleaned everything and reassembled. I had difficulties timing it...in that I couldn't get the idle down to the specs 600rpm, I could only get down to 720.

Now here's the first question.
It's an L03 (TBI) block and, I assume, heads so swapping to a TPI made me think it should be set up as an LB9 (TPI)...LB9's have 6*'s BTDC timing at 600rpm while the L03 has 0* at 600rpm. Have I assumed correctly or is this the cause of my knocking under load and should it be set to 0*? I have no trouble codes the EMC is correct for the TPI swap and it's a MAF 9th injector so I've been using 88 setup specs for everything else. Timing is the same. The knocking is not apparent on startup, but becomes so after it warms up. I'm stumped and looking for guidance. in advance for any advice...you guys have been right on so far.

Jays92Camaro

OK was it something I said. Not one response. Please don't tell me I stumped the wizards.

jstrdn90rs

If it failed emissions I would guess it failed on NOx/CO levels??...from the sounds of it ...no codes..that would rule out the knock sensor circuit.I would lean towards the rich condition and say you have too much carbon deposits on top of the pistons and it needs to be cleaned..it basically increased the compression ratio and the knocking is coming from the low octane gas?..try running some fuel additive or injector cleaner for a few and see if it help.

Jays92Camaro

Thanks for the reply. It failed emission across the board primarily due to a stuck EGR valve but you're right, I need to clean the heads and pistons. I'll give it a shot of SEAFOAM and see what happens.

So, on the timing front, you think leaving it at an initial 6* BTDC is ok?

Because the ECM controls the timing advance, I have no idea how to capture that reading or if it would even be necessary.