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I'm running an unmodified Turbonator stage IV cal in a 87 T2 LM and seems to run fine for the most part but the CEL comes on at basically anything over 10 psi. Base timing is 12 degrees, I only run 93 octane, A/F is fine, and I don't hear any audible knock. I going to data log the knock voltage tonight. Am I missing anything that could cause a false or real ignition knock?
You should also be data logging the knock voltage threshold.
I will do that! Added to my gauges.
My car was same way, make a det can and tune the knock voltage table with it. Just listen for knock and tune the table for it.
two piece intake ?
do you have the support bar under the neck to head if so ?
I've read that support bar has more to do with reducing echo from the manifold re knock sensor than supporting the intake
Now that is something interesting I hadn't thought of.Quote:
Originally Posted by Dr. Johny Dodge
Interesting. But no, it's a one piece.
Here's a video of a quick pull. It wouldn't let me go over 10 psi and the cel flashed once in second gear. https://youtu.be/PULG2bBj8XA
Highest knock voltage I saw was .59V, on a 0-5V scale, it's pretty much nothing.
Yeah I just don't understand why the cel would come on. There are no codes stored like if something else is causing it.
Here's a video of the cel coming on.
https://youtu.be/KAghwTrzxj8
And here's the log of that run.
https://youtu.be/-lkkxC31dNQ
I thought I was having a similar issue. I never heard knock, the car ran awesome, made good power, A/F was good, even was running water/meth injection (which I believe kept the car together). Years later I *finally* popped the head gasket bad enough that I had a miss. Pulled the head...I suppose I *was* having knock! LOL The gasket was blown all over the place, pistons showed signs of very light pitting and the rod bearings were pretty beat.
I know this doesn't help solve your issue, but the take-away should be you probably are having knock, just really light knock. It may be that it just needs a slightly less aggressive timing ramp.
Don't trust that CEL light, always look at the voltage.
Here is the RPM vs knock voltage table. Anything below the blue line is considered "noise" and not knock.
http://www.thelostartof.net/tryingbe...yslerknock.jpg
You should also be logging RET to see if the ECU is actually sensing knock and pulling timing.
+1 on the Detonation can to hear what is really happening. Mounting a Bosch Wideband Knock sensor on the Intake manifold and putting the output through an audio amplifier and listening while driving will tell you for sure what is really happening. It is REALLY apparent when knock starts when listening.Quote:
Originally Posted by cbw1994
Then you can start narrowing down under what conditions the knock is occurring correct the conditions that cause the knock, or tune the knock sensor table in the cal to only pull timing when knock is actually occurring.