chris mac

i've got a 99 SS that i bought used with a Powerdyne blower upgraded injectors and Mac midlengths already on it. that's all the performance mods that i know of on the car. since i've had it it's been detonating really bad (it's audible) above 5000. my buddy lent me his predator and it's showing 3.?? - 4.??* KR from 4300 on up. i've ran some 101 mixed with 91 and am still gettin it. the mix was roughly 94. i've put in a new Walbro 255, different MAF, different coil packs, new tr6's, and different wires. when i say different, i borrowed those parts from friends. i've also checked the pushrods and replaced 4 that were slightly bent. i've got an A/F gauge that shows both banks running equally in the slightly rich zone with neither changing at all up to 6000. also the temp seems to stay in the 185-200 range according to the Predator. my buddy logged it with his HP tuners and the injector duty cycle was about 50% all the way up, the O2s looked good, and we (i'm far from educated about tuning) couldn't see too much out of the ordinary except the KR and the subsequent timing drop from 18-19* down to 14-15*.
i'm pretty well stumped!!! could the blower be pushing out too much heat? or could i have some serious carbon buildup? that's all that i'm coming up with... anyone got any ideas? the frustration is really starting to set in and i'm wanting to drive this thing less and less, and that sucks!!!
any input would be greatly appreciated!

thanks

mac

chris mac

anyone got any ideas?

Mazzenger

iTrader: (5)

I say you pull the heads and blend the bowls??
Start that this weekend.

Slowhawk

iTrader: (12)

Sounds like it's running lean up top. Probly a tuning problem.

SmaknaSS

iTrader: (1)

I would run straight 101 unleaded race gas temporarly just to see if it goes away(a few WOT blasts). you could also try using a breather on your PCV system for like 20 miles and see if it clears up the KR. these cars really like to drink oil though the PCV system.

Tordne

If you look at the logs does the knock appear to be real or false? I am a big fan of disabling Burst Knock Retard. I found it tends to introduce more logged knock for me.

chris mac

Slowhawk... i'm pretty sure that it's not leaning out. my A/F ratio gauge shows slightly rich and neither bank falters from the other, but i know that they're not totally reliable. i'm also getting a periodic "rich" SES for both banks.
SmaknaSS... i ran some 101 last weekend and it did cure the "audible" knock and the Predator only showed 2.??* KR as opposed to the 3.87 that it was showing... but it just wouldn't go under that!!! i probably went WOT 10 or so times and it just didn't get any better than 2.??*. i have also been dabbling with different PCV setups and nothing's working...
Tordne... how can u differentiate false from actually knock?
i'm still stumped. maybe new knock sensors?

Tordne

Not 100%, but... Say you get 3* of KR in your log. If you look at the retard being decayed out (timing being reintroduced) you may notice the following.

1) Real knock: Tends to look like a saw tooth. As the timing is being reintroduced you will get more KR repeatedly.

2) False knock: It may appear like the timing is reintroduced with no further occurance of KR. This will look like a gradual slope from the point of knock back to 0 retard.

Hope that makes sense?

SmaknaSS

iTrader: (1)

Man thats just weird. Since you did have audible pinging and you did use race gas I'm not shure if It's real knock of false Knock.some times using too much antiseize and appying it too close to the end of the spark plugs could cause this kind of issue but that ussauly goes away after some miles of driving. I would also check the exhaust system for anything banging and maybe replace the Knock sensors or at least inspect the wiring on the knock sensors, check for rust and water around the knock sensors too.Make shure the knock sensor is tight. maybe a bad injector? or loose injector wiring? good luck.