I have a 93 VIN p (non zr1) OBDI and it was giving an occasional miss for a couple of days, just like the fuel pump was going, (have had it happen several times) and then the third day it just died and has not made a pop since. The miss might just be a fraction of a second cutting out upon acceleration or just a fraction of a second cutting out as it was running. The length of time of the cutout varies but was in the millisecond range. I took a shortcut and replaced the fuel pump (never looked for a trouble code) I was so **** sure it was the pump and with the new pump nothing. I even saw some fuel pressure (when key comes on I think I read it only turns pump on for two seconds) so by the time I got out there I think the pressure was down – I did not actually measure. Anyway just to be safe I manually squirted gas behind throttle plates to see if it would even pop, nothing so I went looking for an electrical failure. I pulled the trouble codes and there was a DTC_36 which is the high resolution signal from the distributor back to the ECM. Now the shop manual says it will still run with a 36, just not nice. Well mine is dead as a doornail. I cleared the codes and tried again and nothing (trying to start it) plus no new diagnostic codes were set. I have not followed the shop manuals diagnosis as of yet. There is supposed to be an intermediate connector between the IC (ignition module behind the coil) and the ECM you can disconnect to read the 5v reference from the ECM and then the low and high res signals going back. Anyone know where this is on the motor – the connector? My problem is there is only me, no one to turn the key so I can check spark etc. Anyone know of a way one person can check for the high voltage secondary output while in the car? Now the shop manual does tell you how to check the coil with an ohmmeter to see if it is open or shorted. I understand the distributor is a big problem on these cars – anyone know what usually shows up with the distributor? Basically it is two separate parts – the spark distribution from the secondary of the coil and a completely separate part is the low high resolution signals back to the ECM which allow it to figure out the rotation of the camshaft. Anyone know which side of the distributor usually causes the most trouble? Is there a rotor in there like a conventional distributor? Can the photo detectors get dirty or oil on them and appear not to work? The reason I say that is this was not a hard electrical failure – it was causing problems for a few days and then failed. Solid state components generally do not fail in that manner. I would have expected it to have given me a DTC-16 and 36, since the 16 says loss of the low resolution signal without which the car will not run. The intermittent failure pattern makes me think it was more like the coil. I have seen coils (conventional ones) fail over a period of time – days – related to temperature. And if you look at this coil – it is pretty much a conventional coil – nothing fancy and no solid state devices in it. Does anyone know if the coil is receiving the IC signal from the ECM which basically controls the dwell – can they assume the distributor and low res signals are working correctly? The shop manual really lacks any theory of operation and the schematics really make it hard to distinguish what is and input and what are outputs from various modules, plus their troubleshooting seems to look for open or shorted wires more than crappy signals. With a little more information it would be much easier to troubleshoot.

Any help or shortcuts or suggestions would be appreciated. Thanks…..jim

Oh if it is the distributor - it looks like the least expensive alternative is the Accel sold by summit and places like that. Do there work ok? Any other suggestions?

 

Wholly cow,man you like to write.

Have a 93 and opti's are pretty good. You stated the you got a 36 and did not diagnose this code, why?

If the car cannot detect the code, it will not set the code. Meaning the car has to start before the ECM will see that part of the opti.
Get a remote starter and you can crank the car and test.

Never assume the wiring is good, lots of people have had wiring problems, also search over in Tech/perf section. There are hundreds of threads on diagnosing no start problems.

 

I never realized it had even set a trouble code. It never caught it the days before and when it died it did it within a few seconds in traffic and I never saw the display light up. After I found the DTC-36 code I investigated it. Like I said, code 36 is a loss of his res signal. According to shop manual the car should start with a 36, which it won't. All I can diagnose is ensuring the 5v reference is there to the dist and the high res signal comes back. Now you suggest using a remote starter switch but are you sure that the start position and on position of the ignition switch are the same? IF the clutch is not depressed will the ECU detect that and inhibit something electrical? For example in the start position the fuel pump pumps, in the on position it will for 2 seconds and stop if the car is not running. I guess what I am saying is am I guaranteed the ignition circuits work the same in the on position as they would work in the start position? Remote starters work fine for old time cars with out an ECM. The reason I wrote the thread is because the DTC-36 explanation in the manual and the symptoms my car has do not match and I was asking anyone if they had encountered this. If you look at the shop manual for DTC-36 there is not much you can do. Basically all they do is check for the ref volt and high resolution signal. I also asked if anyone knew the location of the intermediate connector since that is where you must break the circuit open since I can’t make the measurements without opening that connector. Again as I have said – with a DTC-36 the car should start and run, mine won’t so it is more than a DTC-36. I suspect you have never worked on one of these or you would be familiar with the process. The DTC is a best guess the ECM can make at what it sees as a problem, they are pretty dumb, the software can't go into much detail because it can't diagnose the problem, it flags the first thing it sees and that is its best guess. From what I have learned the resolution side of the distributor is pretty reliable and the cap and rotor are the weak points. I am going to pull it all apart and check the wiring since I have seen a lot of complaints of bad connectors and bad wires etc. It is just once you start pulling stuff apart you potentially can disrupt the problem such as an intermittent and you are chasing in a circle. I have also found other sites with an abundance of info on diagnosing the entire system. I just am not in any hurry to drop $200 on a distributor or more money on parts that are not required due to guessing or incomplete diagnosis. Look at the gas I am saving by riding my cycle every day!

 

Imagine this - local Chevy dealer quoted $711 for a new distributor, Napa $245 for a rebuilt with 1 yr warranty, advance auto $149 rebuilt with a lifetime warranty. There are cheap ones on eBay for less but I can just imagine some Chinese flimsy junk arriving in the mail. I heard Chevy was over $400 for a distributor but in the threads people have said you can get a new distributor with labor for$700 to $1k from Chevy. Guess the cost of gas makes the distributor more expensive - or is it the cost of food, maybe the housing crisis? I have to question the sanity of the GM engineers who decided to abondon HEI for Optispark and go from a $100 distributor to a flimsy troubleprone $700 part. I don't see any reason why that distributor could not be run off the back of the cam line the old one.

 

I would like you to find me a distributor that is even close to the opti in accuracy and a unit that lasts 100k miles is flimsy?????

It is so mucg better than HEI, the 2 problems are the location and the early opti's are not vented. There have quality control issues w/GM aftermarket opti's, but the principle is sound.
If you dont like the opti, be glad to take the car from you.
For someone who knows nothing about the opti and how it works, you criticise it a lot. Before you say thingss you know nothing about, do your homework.

 

mosture got in it get ready to spend money

 

do not buy the opti from advance been down that road the car ran for about 20 minutes and did not run again. i bought a msd on here. for the 93 i think you will have to repin the plug. but at least you will only do the job once

 

93 was not a good year,I have one.I replaced the stock one,also went thru two msd's.The last one been on the car for six months.They are 550.00.They are also advance adjustable.These speed density car are too not easy,to correct problems.94 thru 96 are a lot better