This is the first time I data logged my 88 Iroc (L98). I used the DataMaster logging software. This was sitting in the driveway reving the motor in park btw.

At 2875rpm it pulls 3* of knock retard (26.7 spark advance - O2 volts are 226 - BLM - 128 ) by 3850rpm it pulls 14.2* of knock retard (28.8 spark advance - O2 volts are 773 - BLM - 128) and at 4600rpm it pulls 20.0* knock retard (29.2 spark advance - O2 volts are 879 - BLM - 122).

I'm just getting into this stuff and plan on DIY Prom tuning (PROMinator) and I do understand that your BLM's need to be as close to 128 as possible. I am currently worried about my knock retard and the fact that the O2 voltage is all over the place.

Can somebody help me out? Should I change out the O2 sensor or is there something else I can do? I saved my log so I can pull anymore specs ya'll need to help me diagnose my problem.

Edit - This is on 91 octane

 

your 02's should be all over the place. Try logging some under load and see how much retard there is.

 

I got a max of 15.6 Knock Retard when I got out on the street and gave her some gas.

3 Different times (highest 3 on knock retard in my short trip):

RPM: 2350
Speed: 19 mph
Spark Advance: 28.5
Knock Retard: 15.1
O2 volts - 932
BLM - 128
CCP DC - 100.00 (highlighted in yellow)
Fuel Trim Cell - 14 (highlighted in yellow)

-------

RPM: 4175
Speed: 28 mph
Spark Advance: 29.5
Knock Retard: 6.0
O2 Volts - 897
BLM - 128
CCP DC - 19.6


-------

Rpm: 5350
Speed: 44 mph
Spark Advance: 37.6
Knock Retard: 15.6
O2 Volts - 928
BLM - 128
CCP DC - 100.00

Does this help out any?

 

Yes, now do the same test under similar conditions with a few 104 octane boosters. If it stops pulling timing then your engine maybe actually knocking. If not then the its pulling timing for no apparent reason. Any vibrations? Loud exhaust?

 

Thanks for the response. As far as exhaust....I have a strait pipe in place of my cat and a thunderjet muffler that the previous owner had put on, I wouldn't think that would be too loud. I'll try the octane booster and see if that helps.

 

dont buy any octane boosters, might as well flush that money down the crapper....run the tank down a little bit and find some CAM2 or equivalent locally, fill up with that, couple gallons at least, and retest