So yesterday I had a little dyno time with datamaster and a wideband running, Found a couple of issues and had a thought before i start screwing with things. my wot afr was between 12.5 to 13.0 except between 3100rpm and 4500rpm, it spiked to 11:1 or less then came back up, about the same time it detected spark knock was when it went fat. so my question is, is this obd1 pcm smart enough to add fuel and retard timing in and event of spark knock? in the wot area of the main and extended spark tables its set to 36, but on datamaster we have seen 40 and i heard this is normal? I didnt think about this till i got home last night otherwise i would of pulled 2 and did another pull, also when we tried to pull fuel out from the maf table in that area the spike got worse. any thoughts or am i on to something.

 

If it's misfiring or detonating, and pulling timing, then you can get unburned fuel. Don't read too much into it. What you need to do is to get it to not misfire or knock if it's real and to not retard the timing.

 

Today I had more time on the Dyno and got my issues resolved, the rich spike on my AFR was due to the knock retard, We pulled timing down to 34 degrees and turned off knock retard in P.E. and its gone. earlier this week I had time to drive the car and log it to test if my knock retard was false or not, after pulling timing down to 30 it still showed spark knock and was pulling 7 degrees out, the way I look at it, I never had a knock sensor on any of my old carb junk so off it goes, at least in P.E. mode anyway.

 

Your "old carb junk" may not have been as high compression or as agressively timed as the car you are working on, but I can sympathize with your problems with false knock since just about everyone who has eve worked on these has had that problem at one time or another. It will save your engine, though, if it is detonation prone, or if you are tuned to the edge and get bad gas. When my setup is working right, I get a little blip of retard when it shifts gears and that's about it.

 

Timing retard is probably noise from the 1.6RR. You can get a LT4 knock module, it cleared my timing retard issue. Like stated above, if you get a batch of bad fuel that knock sensor will keep it from pinging and blowing the motor.