Heres the deal. Recently rebuilt 355, 9.5to1, ported TPI, ZZ4 cam, stock prom. I've been getting a pinging type noise from the engine from 2500 to 4500 rpm under heavy acceleration. Also performance is noticibly poor in this range. I'm running 8 degree advanced, 93 octange gas, shouldn't be a problem there. I also have a constant code 42 which doesn't set the ses light. Once the ticking starts i get code 43 and ses light. It is not the knock sensor or ESC module, as i have tested them. When i hook the car up to the laptop, when the car is warmed up the ecm is reading around 243 degree coolant, new CTS. Obviously this isn't right, the gage (yes, i know they aren't accurate) reads around 190, and my secondary fan switch (new and known to be good) doesn't turn the fan on when the ecm thinks its 243 degrees. Also, before i had my cooling system issues worked out, it got up to 220 and the secondary fan came on when the gage read 220. So it is working properly. Also when i hear the pinging i get no spark counts, yet it still throws a code 43. Anyone agree with me that my problem is ECM related?
Thanks guys
John

 

Could be the ECM.

You might also try changing both temp sensors (theres one for the gauge and one for the ECM). That they aren't matching up is a bad thing, and could be as simple as the sensors themselves.

To put your mind at ease, find someone with the same ECM as you and swap them out. Takes about 5 minutes to do and may save you $100 in the end of it isn't the ECM.

The temp sensors are reasonably priced, too.

The temp won't explain your code 42 and code 43, though. That these pop up during pre-ignition makes sense, though.

 

Actually i just solved my problem today. It was the ECM, I went to the yard and picked one up out of an S-10. I didn't think they would be the same but it was a 165 ECM also, so i assume they are the same, right? Car runs awsome now, this is the first time i've had it running correctly since the rebuild. I think it has a 13.9 in it, the way it sits. But of course the tracks closed last weekend.
Thanks everyone for all the help in the last month or so
John

 

coolness. there you go.

165's are famous for going out. I'm on my 3rd in my car, and no one I know with a 165 has the original.

 

Count me in too. I'm running a remanufactured 165; the EST timing control circuit died on the original.

3 years+ on the new one: I'm keeping my fingers crossed.

Jake