LT1/LT4 Tech 1993-1997

Codes 16 & 32 Any relation?

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  #1  
Old 10-20-2015, 03:34 PM
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Default Codes 16 & 32 Any relation?

Driving home the other night I got an ses light. I did notice a definite miss. Got home and pulled the codes which were 16 and 32.


I've drove it a few times since with no problems and no ses. Just wondering if there is any relation between these codes.
 
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Old 10-21-2015, 12:50 PM
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should not be. one is the opti other is egr. check connections at the harness for the opti. one end is on the passenger side of the intake manifold, about half way. egr could need cleaning. try and clear codes and see if they come back.
 
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Old 10-22-2015, 04:14 AM
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I didn't think they were, just checking. but...........


Driving home from work the car started missing again. This went on about 8/10 mi. but never popped an ses light. The first time it missed for a good while before I ever got the ses light.


I started testing using the fsm when I did get the code 16 and it said to clear the code and run the engine 15 seconds to see if the code returned. It did not.


I did test the harness at the ignition test port and also at the plug that goes to the opti and got 5.02v on the "A" terminal at both places.


This whole opti thing is new to me but if it was bad wouldn't it miss all the time or just quit all together? I don't understand it running fine then missing then running fine then missing again. Could something else cause the code 16 or is that strictly opti?
 
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Old 10-22-2015, 08:33 PM
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Almost every one of the several Opti's I have repaired have been intermittent, meaning the fault would come and go. Usually it was worse at elevated temperature but not always.
 
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Old 10-23-2015, 04:42 AM
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Well this just blows!


GrayDoug; I see that you mentioned "repaired" is that a possibility or did you mean replaced?
 
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Old 10-23-2015, 06:44 AM
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It's usually possible depending on the fault and model of Opti. The OEM one is more difficult than aftermarket because of proprietary design. Some parts are not available.
 
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Old 10-23-2015, 04:05 PM
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My opti is a Delphi unit. I believe the model is CZ20003. The thing that sucks is it has less than 1000mi. on it


I'm assuming that by "fault" you mean what is wrong with the actual unit and not the code 16 I pulled? Would you mind explaining how to diagnose a fault in the opti?


I have searched pages and pages for this info without any luck on this subject. I have also searched for parts for the opti to no avail except finding caps and rotors.
 
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Old 10-23-2015, 04:41 PM
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Originally Posted by simplez
My opti is a Delphi unit. I believe the model is CZ20003. The thing that sucks is it has less than 1000mi. on it

Why was it replaced only 1000 miles ago? What were the symptoms? It is possible that the defect isn't in the distributor but in the wiring outside.

I'm assuming that by "fault" you mean what is wrong with the actual unit and not the code 16 I pulled? Would you mind explaining how to diagnose a fault in the opti?

First define the failure indication. In this case it is a code 16. Code 16 is set when the pcm sees too few, if any, low-resolution pulses compared to a number of high-resolution pulses being produced. Both signals are output, but only the low-res pulses are necessary to run the engine. If both signals go dead, there is no code set because there are no alternate pulses with which to compare. Code 36 works the same way, too few hi-res pulses for a number of low-res pulses. There are four wires to the distributor, ground, 12v power, hi-res and low res outputs. If any signal output is present, the ground and power must be ok. That leaves just the signal output wire path. Connection defects are the most common ones, either internal or external to the distributor. Obviously it is better and easier to check the external connections before the internal ones. I would even go as far to bypass all wiring from the distributor to the PCM before assuming the distributor has failed. After that you just follow the path inside the distributor to see what connections may be loose. That path varies a lot depending on the design (OEM or aftermarket). The OEM Opti's have 2 circuit boards, as do some of the aftermarket ones. One handles the interface to the PCM and the other contains the optical sensors. Some aftermarket Optis, have just one circuit board. I have found that the connections at the first circuit board are frequently poor quality and intermittent, even the OEM ones. Resoldering those 4 connections fixes over half of them. Sometimes you will have to cut off a cover to get to those connections. So far, I have found the optic emitters (IR LED's) are the second most likely failure, especially at elevated temperature. Troubleshooting the Opti requires a test bed to spin the shaft while monitoring points in the circuit with some instruments (meter, scope, etc). Sometimes that test bed has to be inside a heating or cooling chamber to fully test, if the distributor shows no failure at room temperature.

I have searched pages and pages for this info without any luck on this subject. I have also searched for parts for the opti to no avail except finding caps and rotors.

You will not find any. The parts must be identified somehow and replaced with generic electronics ones available. Some are marked and can be found easily. Some are disguised and cannot be sufficiently identified by circuit function. The OEM units are very difficult in that regard. Sometimes you have to guess.
.....
 

Last edited by GaryDoug; 10-23-2015 at 04:45 PM.
  #9  
Old 10-23-2015, 08:30 PM
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Why was it replaced only 1000 miles ago? What were the symptoms? It is possible that the defect isn't in the distributor but in the wiring outside.

No way around this long story, sigh.


I bought this car from a divorcée who's ex from what I'm told was no mechanic. I was told that they had put two opti's on and couldn't get the car to fire. Radiator, fans and water pump were removed and the engine would not even turn over.


The security light was on and after the removal of the aftermarket security system I found that the p/o had added a second resistor just in front of the one installed to defeat the vats system by the aftermarket security system installer. Removed the second resistor and the car now turned over, still didn't fire but I felt I was making progress.


I then pulled the opti that was on it and replaced it with the Delphi unit that is on there now. Still no fire so I checked and replaced the icm and coil. Actually the icm a couple of times as the parts store kept saying they were testing bad. After the third one I just figured they weren't testing them right and moved on.


I checked and rechecked the fuses and wiring. While putting the ignition fuse back in by hand (I had been removing and replacing with needle nose pliers) I noticed that the fuse just kinda fell back into place so I did the best I could to tighten the connection up and waala it fired right up.


After putting the car back together and realizing the water pump was bad I replaced that, oh yeah the plugs to the fans had been cut off, for what purpose I have no idea, so I replaced them.


I waded thru a host of overheating issues and finally got to drive the car more than a few miles with no problems.


Got in it to go to town one day and fired it up and it died after about five seconds. Done that a couple of times so I checked to make sure the ignition fuse was still tight and wiggled the wires under the fuse box. Did the same thing again so I left it and went to town in the truck.


When I got back home the darn thing cranked and ran until I shut it off several times. I drove it around the house and it definitely had a miss. I let it set a few days. Trying to figure this out I cranked it again and the miss is gone. I drove it about 12mi. or so to my brothers with no issues. Car sat about four hours then on the way home it starts missing again and just before I got home the ses light came on. Pulled the codes and had 16 and 32 which lead me to this post.


The fsm said to clear the codes and see if the code came back after 15 seconds, it did not. I drove it to work, again about 12mi. with no issues then about 3mi into the trip home it starts missing again. Made it home and had no ses light.


All the test I've done to the opti harness, the icm, the coil, they all come out good. I drove it around the house today a couple miles for the first time after parking it with a miss and the miss is gone again.


Sorry for the long story, just hoping someone will see something I haven't. I guess I will take the suggestion to replace the opti harness to see if that will help.


Wish me luck. I need it.
 
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Old 10-24-2015, 10:15 AM
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just to take it out of the equasion i would consider a new opti wire harness. common fail point with this code. Wiring Harness Cable for Chevy 95 97 LT1 Optispark Distributor LT1 07 CB | eBay
 


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