Opti Problem?

[Jodirte]

You sure the scanner doesn't just report ignition advance as a negative number? Some do. Confuses people. Typical advance at idle will be around 18°-22° in a stock tune. No idea what the tuner might have done to tame the big cam.

Or is the scanner actually reporting knock retard? Generally, the max retard the PCM can set is 15°. Tuner can change that, but generally they lower it.

The only codes for knock are for failure of the sensor (P0332) or the knock module (P0325). If a failure code sets, he PCM defaults to an (almost) full time ignition retard based on throttle, RPM and MAP. You might see knock retard at idle.

As difficult as it seems to be to mis-index the Opti, you would be amazed to see how many times it gets screwed up. Did they replace the Opti seal in the timing cover?

Tuner was Mo Bailey, from what I understand he is good. This car did sit for a quite awhile though so I really don't know what all it might require. I saw the posts on timing advance regarding how scanners read - vs +. and we have used hi dollar setups from the shop down to my cheap OBD2 Wifi setup with OBD2 fusion (mine reads "-" as retard and advance as a regular number) however the car definitely runs like a car with a big cam too much timing taken out. I agree with you on the opti, it is the most simple mechanical thing that could change timing, and I see post after post with them installed wrong. Anyway I'm pulling it again tomorrow to see. All seals were replaced.My goal was to get the opti changed and see if I could contact Mo Bailey again and just be sure everything looked good on tune. Anyway try to make some progress tomorrow. Thanks Injuneer.

[Jodirte]

Worked on it a bit to today with mechanic and have a little better understanding. Tested grounds, ICM, used the optispark troubleshooting chart on the website here to kind of eliminate things. Which brings me to a question Step 4 on verifying pulse on pin B for the ICM.... I test this for voltage and it had between 1-4 volts and also with the scope it had a square wave that was very consistent. It then says A: If no pulse go to step 5 or b: if pulse is present ICM faulted, replace and return to step 4. Is this correct? I was under the assumption that we do want a pulse??
So from there I also learned a bit more on the timing so hopefully this will help with any suggestions. There scanner reads CPK timing I believe at -14, the actual Spark timing is 38 at idle. The odd thing is while watching it run for about a minute every once in awhile the CPK will jump from -14 to 50... this happen maybe for less than a second and it doesn't ramp up or down just instant. The Spark timing does not change during this. I ran it 3 times for about a minute or so and you see it happen several times over each run? My AFR also stayed around 11-13 for a few runs and then the third time stayed between 8-9... No codes besides P0336, Opti has signal on both low and hi-res. The car definitely is running way rough, won't idle for long and giving it gas it sputters and sometimes backfires through pipes. The plugs actually looked OK, granted it has been run long or driven in this condition.

[SSlowBoat]

Worked on it a bit to today with mechanic and have a little better understanding. Tested grounds, ICM, used the optispark troubleshooting chart on the website here to kind of eliminate things. Which brings me to a question Step 4 on verifying pulse on pin B for the ICM.... I test this for voltage and it had between 1-4 volts and also with the scope it had a square wave that was very consistent. It then says A: If no pulse go to step 5 or b: if pulse is present ICM faulted, replace and return to step 4. Is this correct? I was under the assumption that we do want a pulse??
So from there I also learned a bit more on the timing so hopefully this will help with any suggestions. There scanner reads CPK timing I believe at -14, the actual Spark timing is 38 at idle. The odd thing is while watching it run for about a minute every once in awhile the CPK will jump from -14 to 50... this happen maybe for less than a second and it doesn't ramp up or down just instant. The Spark timing does not change during this. I ran it 3 times for about a minute or so and you see it happen several times over each run? My AFR also stayed around 11-13 for a few runs and then the third time stayed between 8-9... No codes besides P0336, Opti has signal on both low and hi-res. The car definitely is running way rough, won't idle for long and giving it gas it sputters and sometimes backfires through pipes. The plugs actually looked OK, granted it has been run long or driven in this condition.

if you are getting a pulse at the icm connector that means the opti is signaling the computer and the computer is signaling the icm

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[Jodirte]

if you are getting a pulse at the icm connector that means the opti is signaling the computer and the computer is signaling the icm

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Yes so I am guessing that -"B.) if pulse is present, ICM is faulted. Replace and return to step 4".... Is not correct on the trouble shooting chart?? Lol, I am just trying to figure out if I am misreading it or nobody ever used it?

[SSlowBoat]

if pulse is read at icm harness plug, but vehicle wont run, icm is bad, replace and move on.

Yes so I am guessing that -"B.) if pulse is present, ICM is faulted. Replace and return to step 4".... Is not correct on the trouble shooting chart?? Lol, I am just trying to figure out if I am misreading it or nobody ever used it?

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[Jodirte]

Uh yes it runs. Therefore the timing numbers, AFR, stuff included in the quote you used... This chart was very helpful however it seems that info is incorrect? Was just trying to be sure I am not misreading it as I am not familiar at all with the ignition systems on these cars at all and I am relying on this data to fix it.

[SSlowBoat]

Uh yes it runs. Therefore the timing numbers, AFR, stuff included in the quote you used... This chart was very helpful however it seems that info is incorrect? Was just trying to be sure I am not misreading it as I am not familiar at all with the ignition systems on these cars at all and I am relying on this data to fix it.

if the car runs it's not the icm.


pcm is bad, or knock module is bad, or they somehow made the ckp reluctor move or something in my opinion.

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[Injuneer]

Opti Fault Logic Chart:

What it’s saying is that the PCM IS sending the pulse (confirms PCM is receiving and responding to Opti cam position signals) to the ICM, so the problem may be the ICM. But it sounds like that chart covers the case when the engine isn’t running. That's not your problem. I don’t recall what chart is on this site. I have my own set of GM manuals.


CKP “Timing”:

The CKP reading is neither “ignition advance” nor retard. It is called “CKP:LoResolutionAngle”. This is the offset of the cam position sensor pulses from the CKP sensor signals. It's telling you the crank signal is offset from the leading edge of the Opti cam position sensor low resolution pulse. Should be close to “0”. You are getting P0336 because -14° is outside the range of -10° to +7° I posted in post #4.


”Actual” Spark Timing:

The scanner tells you how much ignition advance the PCM is calling for. The PCM has only one reference for ignition timing - the pulses from the Opti. The PCM assumes the Opti is correctly indexed. There is no feedback to tell the PCM what the actual advance is (although the excessive offset of the CKP from the cam position sensor may be pointing to a misalignment). That’s why the timing doesn’t change - the scanner shows the advance value the PCM is picking off a table with RPM on one axis and MAP on the other (plus offsets based on other sensor inputs). 38° at idle seems like a lot, but check w/ Moe.


An Aside:

And just to clarify - my previous post comments were in no way questioning the quality of the tune. I was only trying to point out that the values I was quoting for timing at idle and max knock retard are the stock settings, and they may have been changed by the tuner.


CKP Jump:

The occasional spike in the the CKP (offset) reading may be the result of a high voltage induced spike in either the CKP signal or the Opti signal. The fact that only the CKP reading changes may suggest the interference is on the CKP circuit. A spike in the Opti signal may be high voltage interference from an external source, or a spike generated by the Opti itself. Maybe 6 months back I found this happening with MSD units made over the past couple months. But this series of spikes was so severe that the PCM would record the engine RPM being as high as 7,000 RPM (which was false) for a single frame of data, and in response the PCM would start to open up the IAC motor counts (which it normally does as RPM increases), driving the idle RPM into surges to as high as 2,500 RPM. After providing data logs to MSD they finally agreed there was a problem with their units, and they appear to have changed both the cap and the optical module. Which leads me to believe (but not confirmed) that the high voltage interference was actually coming from somewhere internal to the MSD Opti, maybe the cap.

[Jodirte]

Opti Fault Logic Chart:

What it’s saying is that the PCM IS sending the pulse (confirms PCM is receiving and responding to Opti cam position signals) to the ICM, so the problem may be the ICM. But it sounds like that chart covers the case when the engine isn’t running. That's not your problem. I don’t recall what chart is on this site. I have my own set of GM manuals.


CKP “Timing”:

The CKP reading is neither “ignition advance” nor retard. It is called “CKP:LoResolutionAngle”. This is the offset of the cam position sensor pulses from the CKP sensor signals. It's telling you the crank signal is offset from the leading edge of the Opti cam position sensor low resolution pulse. Should be close to “0”. You are getting P0336 because -14° is outside the range of -10° to +7° I posted in post #4.


”Actual” Spark Timing:

The scanner tells you how much ignition advance the PCM is calling for. The PCM has only one reference for ignition timing - the pulses from the Opti. The PCM assumes the Opti is correctly indexed. There is no feedback to tell the PCM what the actual advance is (although the excessive offset of the CKP from the cam position sensor may be pointing to a misalignment). That’s why the timing doesn’t change - the scanner shows the advance value the PCM is picking off a table with RPM on one axis and MAP on the other (plus offsets based on other sensor inputs). 38° at idle seems like a lot, but check w/ Moe.


An Aside:

And just to clarify - my previous post comments were in no way questioning the quality of the tune. I was only trying to point out that the values I was quoting for timing at idle and max knock retard are the stock settings, and they may have been changed by the tuner.


CKP Jump:

The occasional spike in the the CKP (offset) reading may be the result of a high voltage induced spike in either the CKP signal or the Opti signal. The fact that only the CKP reading changes may suggest the interference is on the CKP circuit. A spike in the Opti signal may be high voltage interference from an external source, or a spike generated by the Opti itself. Maybe 6 months back I found this happening with MSD units made over the past couple months. But this series of spikes was so severe that the PCM would record the engine RPM being as high as 7,000 RPM (which was false) for a single frame of data, and in response the PCM would start to open up the IAC motor counts (which it normally does as RPM increases), driving the idle RPM into surges to as high as 2,500 RPM. After providing data logs to MSD they finally agreed there was a problem with their units, and they appear to have changed both the cap and the optical module. Which leads me to believe (but not confirmed) that the high voltage interference was actually coming from somewhere internal to the MSD Opti, maybe the cap.

Going to change ICM, just because-can't hurt. CPK timing was out of spec immediately after replacing the original Dynaspark and my mechanic said this. I personally was confused on this and the difference between actual spark timing so wanted apologize for the miscommunication there. An Aside! You have been more than helpful. I was only stating Moe Bailey did the original tune-I do not know him but across the forums he seems to be very good at what he does so my assumption is the tune was solid, unfortunately I don't have any data on what was actually done. My game plan was simply to take it in put a new optispark and then have Moe recheck the tune.. Lol. Now 2 optis in and probably at least $1k in my car won't even idle. Anyway man I truly hope I did not sound offensive in any of my posts. I am grateful for the info and everything you have recommended .

[Injuneer]

Moe is a regular and well respected here. I just wanted to be sure everyone understood my comments. No problem.