so yesterday i scanned my 93 Z with a friend of mines snap i in off brick lol , and we got two code one for the high resolution circuit low and one for my right bank O2 sensor then i looked at the live data and noticed my pcm thought my coolant was 81 deg. F when my car was warmed up already .

so i put in a new pcm temp sensor, right bank o2 and deleted my a/c and did an oil change ,

so to get to my point i have been having this missing / sputter at any rpm above 3k when my temps reach 190 in the city but she runs about 170 if ur not hard on it then it does not miss till then temps reach 190 the it misses all the time past 3k anything under that its fine . but if its cold it wont miss at all

is my opti on its way out

 

You should check the voltage to see what spark you are getting. My car had similar problem and it turned out to be the coil once it heated up my car started to miss never threw a code for it either but ended up changing that and no problems

 

i do have a tester to check spark voltage and current to test it will that work, do u think it could be a icm? or my opti harness , i really need to figure out what this is my head and cam and intake are coming in this next week and i dont wanna have this issue after my H/C/I swap

 

I would start testing everything from the opti to the plugs themselves when is the last time it was tuned up meaning plug and wires. If all checks out keep going till you find it could be that o2 sensor too. Just trouble shoot until you find the problem. I think your best bet is if your doing a cam job when you take the opti out and check it for problems like cracked cap and so fourth. Also do you do you have a scanner that can show you real time data cause if you do try to get it to heat up again and see what cylinder isn't firing.

 

inoticed when it starts to miss both my tachs drop bout 2 hundred rpm's, it had new plugs wires and cap rotor about 5k ago ,so it could be a few things , i noticed my icm gets hot real quick when u first start it up , but that could be normal , is it normal?

 

Yeah that's normal. Where did you route your wires otvc or in the stock looms. But you should check all the boots and make sure they aren't any loose connections also if you routed them in the stock place they might have burned wire. Also what brand opti did you get is it a gm or cheapy

 

mine are in the stock looms , i checked all boots and wires for elec leakage and wear all looked great. this is really driving me bonkers , i really really dont wanna have to replace my opti , i did get a code for high resolution circuit low , so i need to check my opti harness to see if it is dirty and has chitty connection, did anyone run down that guy on the impala forum that had a fam member that worked for gm and could get the optical sensors for like 60 each?

 

yeah it is a pain in the *** but if it is that you don't want to be chasing ghosts either and if you got a code for a high resolution circuit low. Now thats not going to tell you that your opti is bad. But if your having a miss and you have a code on your ignition system the last thing you want to do is start replacing everything and if the opti is bad spend like twice as much for it with all of the replacement parts. Have you checked the spark on all the plugs when it was heated up also you should do some research on the lt1 tech section there are ways you can test if the opti is bad idk them off the top of my head but try there

 

Ar you getting a DTC 36 (faulty High Resolution Pulse OR Extra Low Resolution Pulses) ? there are two outputs from the opti - 8 Low res pulses per camshaft resolution used to tell the PCM when to send the signal to the ICM to fire the coil, and it's used for engine speed (tac) in the PCM. High res signal is 360 pulses per cam rev and is used for checking the low res pulse. If you get 40 low pulses without a high pulse the 36 is set, usually means an opti or opti harness failure. How old is your opti, has it ever been wet ? When you do the cam pull the opti apart and check for corrosion or oil inside the rear section (optical sensor wheel and pickup). Heard rumors about replacing the low voltage optical sensor in the opti but never saw one, some of the slotted wheels are welded on and would be a bitch to replace. My wheel was rusted and I had oil on there so I replaced the whole opti when doing the CAM just for insurance (car had 72K miles). Alkso the ICM's in these cars are notorious for failing when hot, and testing when cold in a parts store usually works, If you get a new opti or ICM look for a delco or delfi OEM part, watch out for cheap e-bay deals.