I recently put a ProCharger D1SC unit on my 89 Formula 350. I have the two core intercooler running 9psi boost. Other mods include a ZZ4 cam and valve springs, Edelbrock double roller timing chain, Edelbrock TES headers, Flowmaster cat back system, 160 thermostat, 2400 stall and built 700R4 tranny, with a 3.73 posi rear end. I'm using Diacom to log what my ECM is seeing. I keep getting knock counts, and lots of them! Its pulling my timing back up to 16.5 degrees. I run nothing but 93 octane gas, but today I ran the tank almost dry and filled up with 100 octane. Just went out and logged some WOT romps, and I'll be damned if it still isn't registering knock. The peak being at 4000 rpms. I replaced the knock sensor with a LT1/LT4 sensor, and replaced the ESC with a GM #16038331. Nothing is helping. Anyone have any suggestions? The base timing is at 8 degrees. I tried it at 6 degrees, the car turned into a slug. It seems to run quickest at 10 degrees. At 6 degrees advance it gets about 13.5 degrees of knock retard, compared to at 10 degrees advance it gets 16 degrees retard. I'm running the stock ECM and chip. Oxygen sensor voltage is between 860 and 950 mv at WOT.

 

Sounds like your leaning out. Your 02 sensor may be out of wack, with readings that high it says your running rich, which you want at WOT, but if the sensor is bad you may be actually running lean. It's a cheap check anyway, they're less than $30 at autozone. Are you using an AFPR?
What's the diacom saying your air temp is? If you intake charge is really hot that may be your problem as well. The intercooler should be helping that, but if the supercharger or intercooler is having an issue that could be it as well.
If that's not it you may have more serious problems like excessive blow by, or oil getting into the chamber.

 

Air intake temp. is at 84 degrees. The oxygen sensor is new and so is the air temp. sensor. Fuel pressure gauge shows 75 psi. during boost. The motor has 30,000 miles on it. I'm not consuming any oil. No contamination of the oil either. I had logged some runs last summer also. At that time the only mods were a Hypertech ThermoMaster chip, 160 thermostat, Flowmaster, and 3.73 gears. I was running race fuel that day at the track too, and was getting up to 12 degrees of knock retard. It was like 110 degrees out that day, and I had an air intake temp of 122 degrees. The coolant temp. was around 220 degrees. This leads me to believe that my knock readings are false. I have never heard audible knock from the car.

 

what are your BLM's? how about injector size? it could be you are running out of injector and leaning badly. knock or detonation starts long before you will hear it. if your fuel system as a whole checks out, you can "tune" the knock sensor by varing how "snug" you torque it into the block. cheers Bob

edit: also you may want to check out a WB O2 to really know whats going on. www.diy-wb.com has a cheap do it yourself WB for around $200 in parts and general opinion of it is that it rocks...

 

BLM is hovering around 150, with it at 129 WOT. I'm using 22 lb. injectors. 47 psi. fuel pressure not under boost, 75 psi. while under boost. What really gets me is that last years Diacom logs are showing knock retard also, and that was with a pretty much stock setup.

 

A BLM of 150 is seriously lean. Also 22 pounders are way too small to supply your engine under boost no matter what pressure. I would look into getting 30 pound injectors at least, with a larger injector (35-42lbs) being better.

 

BLM has a range of 0 thru 255, with 128 being neither rich nor lean. 150 shouldn't be way too lean. Oxygen sensor is showing rich condition at WOT, ranging from 860 to 950 mv. I was told by ATI that I wouldn't need to upgrade injectors until 12 psi. boost or more. Last years runs were showing BLM of 143.

 

Do you think that it could possibly be caused by my plugs being too hot? Someone else responded to another question I posted regarding using platinum plugs with a supercharger. He said the platinum plugs retain too much heat and can cause preignition. I am using Bosch Platinum Plus 4 plugs right now. Anyone think that changing plugs to regular old plugs and going one notch colder would help?

 

Are you still running the thermomaster chip? If so, try the stock chip. That chip adds more timing at WOT and should not be used in boosted applications.

 

No ThermoMaster chip. I made sure to put the stock chip back in when I did the supercharger.

 

Checking the plugs couldn't hurt, if it doesn't help your only out 10 bucks or less, and if it does problem solved for that little.

 

boxeat,

i'm still a newbie at this myself but 150 is definately WAY too lean.

BLM only has a range of about 108-150. any higher or lower and it sets an O2 error code/check engine light. there is no way you will EVER see a BLM of 0 or 255 or anything even close to that.

the reason it's at 128 WOT is because the computer no longer reads the O2 sensor under power enrichment. you could be so lean that you're melting pistons and it would still show 128.

at the very least you do need some bigger injectors like the other poster stated.