Scan 9495 random stall
06-09-2021, 05:06 PM
#2
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Re: Scan 9495 random stall
I can look at it, but there are 5 logs in line in front of yours. Plus it's probably the largest file I have ever seen at 44.5 minutes. May take a while.
Can you describe the circumstances under which it stalls in a bit more detail? Cold? Hot? Waiting at a light? While driving?
Appears you had DTC 16, 44, 48, 64 stored for the first half of the log, you shut it down and cleared them. Was it stalling BEFORE you cleared the codes? Or only AFTER you cleared the codes? Did you capture a stall in the second half of the log? Do you remember roughly when?
Can you describe the circumstances under which it stalls in a bit more detail? Cold? Hot? Waiting at a light? While driving?
Appears you had DTC 16, 44, 48, 64 stored for the first half of the log, you shut it down and cleared them. Was it stalling BEFORE you cleared the codes? Or only AFTER you cleared the codes? Did you capture a stall in the second half of the log? Do you remember roughly when?
06-09-2021, 06:16 PM
#3
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Join Date: Jun 2021
Posts: 14
Re: Scan 9495 random stall
Hi, thank you for the quick reply Injuneer. Sorry for the long scan, I was so excited that the homemade cable worked and that the software worked as I was using a MacBook Air with Paralles to run windows 10, I was sitting in the car looking at all the settings as this was my first scan, and I found all the instructions for the cable and software on this forum.
Here is what happened stalled once in traffic after about 10 miles and then started up after about 30 minutes and I drove a few more miles then stalled again and would not start again after a few hours (installed new battery). On the drive home 10 miles it stuttered once at about 2500 rpms but did not stall, like someone taking the wind out of you sails for a second. I installed new fuel filter and checked the fuel pressure which is at 38 at prime and while running, It goes up to 47 when the FPR vacuum is disconnected. When you bump the throttle it goes down to 36. After shutdown it goes down to 34 and to 27 after 1/2 hour.
I erased the codes in anticipation that they might comeback. In the csv file line 6132 (this is when I cleared the codes and it stalled), 7200, 7861 these are when it stalled. I am waiting on a fuel shut off to do the test procedures outlined in the service manual, I don't feel comfortable clamping the fuel lines with vice grips. The optispark is 3 years old, as is the coil, and icm, the throttle body was cleaned and the IAC cleaned. Vacuum is within specifications. The idle is super improved after cleaning the IAC but still feels a little loppy I think that is just an LT1 thing. There is 30k miles on the rebuild when new cam, heads and cylinders were bored and engine refreshed. Fuel pump has been replaced since then but years ago. There is also stock tune. The fuel pump or what I think is the fuel pump makes noise once in a while almost like someone honking at you, the noise has been intermittent like 3 times in 100 miles it happens moving or not, more so when hot. I was going to check the tank vent and also see if there is anything unusual when I put the car on a lift this weekend.
In the scan it seems like when the 'EGR duty cycles' the 'ignition voltage' goes down to 11 the car stalls and also the 'fuel injector pulse width' goes really high. I was trying to find anomalies in the scan but can't see anything obvious to me anyways I don't really know what to look for... I look forward to your insight. Thank you.
Update: I scanned my 1994 Firebird again and got DTC 16 so I think I know what direction to research my problem. I was hoping that it was not the optispark for obvious reasons. That is why I deleted the codes to begin with to see if it would resurface. I drove around my neighborhood for about 20 minutes car felt good no hesitation started right up drove fine no stalling, I did not get up on it in my neighborhood. I went back home hooked up the computer and scanned with scan 9495, as I was trying to get the program to work with my diy set up the car stalled. I did not have the scanner hooked up to see the stall but It took a few seconds of cranking to fire up, when it finally fired up I could see DTC 16. This my friend must be one of my issues... I attached the new scan file. I thank you so much for your time your website is a very valuable resource for the LT1.
Here is what happened stalled once in traffic after about 10 miles and then started up after about 30 minutes and I drove a few more miles then stalled again and would not start again after a few hours (installed new battery). On the drive home 10 miles it stuttered once at about 2500 rpms but did not stall, like someone taking the wind out of you sails for a second. I installed new fuel filter and checked the fuel pressure which is at 38 at prime and while running, It goes up to 47 when the FPR vacuum is disconnected. When you bump the throttle it goes down to 36. After shutdown it goes down to 34 and to 27 after 1/2 hour.
I erased the codes in anticipation that they might comeback. In the csv file line 6132 (this is when I cleared the codes and it stalled), 7200, 7861 these are when it stalled. I am waiting on a fuel shut off to do the test procedures outlined in the service manual, I don't feel comfortable clamping the fuel lines with vice grips. The optispark is 3 years old, as is the coil, and icm, the throttle body was cleaned and the IAC cleaned. Vacuum is within specifications. The idle is super improved after cleaning the IAC but still feels a little loppy I think that is just an LT1 thing. There is 30k miles on the rebuild when new cam, heads and cylinders were bored and engine refreshed. Fuel pump has been replaced since then but years ago. There is also stock tune. The fuel pump or what I think is the fuel pump makes noise once in a while almost like someone honking at you, the noise has been intermittent like 3 times in 100 miles it happens moving or not, more so when hot. I was going to check the tank vent and also see if there is anything unusual when I put the car on a lift this weekend.
In the scan it seems like when the 'EGR duty cycles' the 'ignition voltage' goes down to 11 the car stalls and also the 'fuel injector pulse width' goes really high. I was trying to find anomalies in the scan but can't see anything obvious to me anyways I don't really know what to look for... I look forward to your insight. Thank you.
Update: I scanned my 1994 Firebird again and got DTC 16 so I think I know what direction to research my problem. I was hoping that it was not the optispark for obvious reasons. That is why I deleted the codes to begin with to see if it would resurface. I drove around my neighborhood for about 20 minutes car felt good no hesitation started right up drove fine no stalling, I did not get up on it in my neighborhood. I went back home hooked up the computer and scanned with scan 9495, as I was trying to get the program to work with my diy set up the car stalled. I did not have the scanner hooked up to see the stall but It took a few seconds of cranking to fire up, when it finally fired up I could see DTC 16. This my friend must be one of my issues... I attached the new scan file. I thank you so much for your time your website is a very valuable resource for the LT1.
Last edited by xxvta; 06-09-2021 at 07:27 PM. Reason: Scanned again and got DTC 16
06-10-2021, 11:09 AM
#6
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Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
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Re: Scan 9495 random stall
Who tuned it for the cam? That could be the "loppy" issue. There is nothing inherent to the LT1 that causes a rough idle. What are the cam specs? The MAP readings are approaching 50 kPa at idle, so it's definitely not too close to stock.
The hardware/software setup seems to be good. It is producing a good scan rate (~7 lines per second). Too often the setups produce very low scan rata (2 lines/second or less), and that hides too much data.
Looking at the two lines of data you indicate the stall occurred, the line of data immediately preceding both of the stalls is corrupt. Did the stall corrupt the data, or did the corrupt data stall the engine? You have other repeated lines of corrupt data, and false codes being set throughout the log. It isn't unusual to see corrupt lines of data, can be caused by interference on the data line. But it would be interesting to see if the corrupt lines of data correspond directly to the various "incidents".
In general, avoid running the A/C during a log. It's just a complication. I prefer to hide the A/C related data, to make the important items more visible. I have a guide to running the logs:
https://www.camaroz28.com/forums/com...-guide-886891/
I need more time to go through the first log. Then the second log. Just got hit with a large number of requests (I do this on two other sites as well) all at once. And I'm having problems staring at the screen for an extended period of time, due to eye problems that should have been taken care of during COVID, but weren't.
The hardware/software setup seems to be good. It is producing a good scan rate (~7 lines per second). Too often the setups produce very low scan rata (2 lines/second or less), and that hides too much data.
Looking at the two lines of data you indicate the stall occurred, the line of data immediately preceding both of the stalls is corrupt. Did the stall corrupt the data, or did the corrupt data stall the engine? You have other repeated lines of corrupt data, and false codes being set throughout the log. It isn't unusual to see corrupt lines of data, can be caused by interference on the data line. But it would be interesting to see if the corrupt lines of data correspond directly to the various "incidents".
In general, avoid running the A/C during a log. It's just a complication. I prefer to hide the A/C related data, to make the important items more visible. I have a guide to running the logs:
https://www.camaroz28.com/forums/com...-guide-886891/
I need more time to go through the first log. Then the second log. Just got hit with a large number of requests (I do this on two other sites as well) all at once. And I'm having problems staring at the screen for an extended period of time, due to eye problems that should have been taken care of during COVID, but weren't.
06-10-2021, 08:17 PM
#7
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Join Date: Jun 2021
Posts: 14
Re: Scan 9495 random stall
I don't think it was ever tuned for the cam, it has been my suspicion for a long time as to why the issues with the idle. The history of this car it was my Fathers car he bought it new in 1994. My Father passed away a few years ago and I guess I never thought about asking about the tune. So I am pretty sure it is the stock tune. I looked at his papers for the engine build and it is pretty basic just says CAM, EDDLEBROCK LT1 HEADS and etc... He had it bored .30 over, and I don't know how I can see what the cam specs are without removing the cam. He has been having some issues with the stalling because he kept all the service records and most recently ( few years ago) was a distributer install...
Noted of not running the AC while scanning and I will take a look at your link at running the logs.
When I cleared the codes the first and only time the engine stalled right after.
When looking at the log afterwords I went by RPM as to when the engine stalled, but maybe I am wrong. I am a greenhorn at scans still.
Gary made a good write up about the scan cable, I used all chinese cables with tiny wires so it is good to know that you can get good data through such small wires.
I used shbox play list to diagnose the optispark and It was within specifications except the ohms were .6 at optispark harness D, I read somewhere here that that is not so bad. I also noticed some oil on the bottom of the distributer and seeing as how I was getting DTC16, I started the process of removing the optispark to see what is up. Maybe it is full of oil I don't know. I am taking my time on this procedure checking everything out under the car. I have everything off except the optispark which it got too dark out so I will save it for tomorrow. The plug wire for the optispark says delphi and it is basically just a black distributer. There is a sticker on the bottom but I couldn't read it until I get the thing off of the car. I am curious to where the oil is coming from I couldn't really see anything really obvious.
Is there optispark recommendations as to what brand or whatever? also is there a way to figure out the cam specs without removing the cam? any recommendations on tuning? I was going to research some of the free tuning software out there.
Thank you so much for your time I can't imagine all of the data that you have to go through every day I am sure that being on the screen for that long is bad bad bad for the eyes.
Noted of not running the AC while scanning and I will take a look at your link at running the logs.
When I cleared the codes the first and only time the engine stalled right after.
When looking at the log afterwords I went by RPM as to when the engine stalled, but maybe I am wrong. I am a greenhorn at scans still.
Gary made a good write up about the scan cable, I used all chinese cables with tiny wires so it is good to know that you can get good data through such small wires.
I used shbox play list to diagnose the optispark and It was within specifications except the ohms were .6 at optispark harness D, I read somewhere here that that is not so bad. I also noticed some oil on the bottom of the distributer and seeing as how I was getting DTC16, I started the process of removing the optispark to see what is up. Maybe it is full of oil I don't know. I am taking my time on this procedure checking everything out under the car. I have everything off except the optispark which it got too dark out so I will save it for tomorrow. The plug wire for the optispark says delphi and it is basically just a black distributer. There is a sticker on the bottom but I couldn't read it until I get the thing off of the car. I am curious to where the oil is coming from I couldn't really see anything really obvious.
Is there optispark recommendations as to what brand or whatever? also is there a way to figure out the cam specs without removing the cam? any recommendations on tuning? I was going to research some of the free tuning software out there.
Thank you so much for your time I can't imagine all of the data that you have to go through every day I am sure that being on the screen for that long is bad bad bad for the eyes.
06-10-2021, 10:27 PM
#8
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Location: Hell was full so they sent me to NJ
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Re: Scan 9495 random stall
The cam nose may have some info engraved on it.
There are 3 oil seals in the timing cover - water pump drive shaft, Opti driveshaft, and crankshaft. They all can leak.
The factory Opti for 93/94 was “unvented”. GM realized the high voltage spark in th cap was generating ozone, and causing serious internal corrosion. My Opti (bought the car new) started setting DTC 16 at about 50K miles. The rust particles had blinded the LED emitter/receptor that reads the slots on the rotating disc. When DTC 16 is active, the engine can't run, because there is insufficient info to time the spark and injectors. PCM shuts down the fuel and spark. to the ICM If the engine is running, it's a stored code.
The Shoebox procedure for checking the Opti harness verifies that the PCM is supplying the 12 volts required to power the optical module in the Opti, and the two 5 volt references that the output signals from the optical module ride on. Doesn’t really tell you if the Opti is working. The ICM part of the test, looking for voltage on the white wire from the PCM tellls you if the Opti is producing the required cam position pulse signals to the PCM, and the PCM is using them to send the pulse to the ICM to fire the coil. If the starter is cranking the engine and the tach needle moves up a couple hundred RPM, the Opti is Ok.
In 1995 GM added a vent system to the Opti to remove the ozone. The drive mechanism was also changed, and 93/94 unvented unit, splined shaft driven, must be used with the 94 engine. The two designs are not interchangeable without major changes - camshaft, timing set, timing cover. Current best bet for a replacement is from Petris:
https://petrisenterprises.com/
Expensive, but feedback indicates it is reliable. And both versions 93/94 and 95-97 are vented. The original factory Opti has a tarnish epoxy in the cap.
http://shbox.com/1/opti_cyl.jpg
http://shbox.com/1/opti_one.3.jpg
I can recommend a mail-order tuner. There are tuning softwares available.There's some info on tuning software here:
LT1 PCM Tuning - Tips & Tricks for DIY Tuning!
But I have a different mail-order tuner in mind.
There are 3 oil seals in the timing cover - water pump drive shaft, Opti driveshaft, and crankshaft. They all can leak.
The factory Opti for 93/94 was “unvented”. GM realized the high voltage spark in th cap was generating ozone, and causing serious internal corrosion. My Opti (bought the car new) started setting DTC 16 at about 50K miles. The rust particles had blinded the LED emitter/receptor that reads the slots on the rotating disc. When DTC 16 is active, the engine can't run, because there is insufficient info to time the spark and injectors. PCM shuts down the fuel and spark. to the ICM If the engine is running, it's a stored code.
The Shoebox procedure for checking the Opti harness verifies that the PCM is supplying the 12 volts required to power the optical module in the Opti, and the two 5 volt references that the output signals from the optical module ride on. Doesn’t really tell you if the Opti is working. The ICM part of the test, looking for voltage on the white wire from the PCM tellls you if the Opti is producing the required cam position pulse signals to the PCM, and the PCM is using them to send the pulse to the ICM to fire the coil. If the starter is cranking the engine and the tach needle moves up a couple hundred RPM, the Opti is Ok.
In 1995 GM added a vent system to the Opti to remove the ozone. The drive mechanism was also changed, and 93/94 unvented unit, splined shaft driven, must be used with the 94 engine. The two designs are not interchangeable without major changes - camshaft, timing set, timing cover. Current best bet for a replacement is from Petris:
https://petrisenterprises.com/
Expensive, but feedback indicates it is reliable. And both versions 93/94 and 95-97 are vented. The original factory Opti has a tarnish epoxy in the cap.
http://shbox.com/1/opti_cyl.jpg
http://shbox.com/1/opti_one.3.jpg
I can recommend a mail-order tuner. There are tuning softwares available.There's some info on tuning software here:
LT1 PCM Tuning - Tips & Tricks for DIY Tuning!
But I have a different mail-order tuner in mind.
06-10-2021, 10:30 PM
#9
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Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
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Re: Scan 9495 random stall
Another thing on the cam - Edelbrock sold a package of LT1 heads, camshaft, and a red “air gap” intake manifold. Cam might be from Edelbrock. The components were not very popular because Rt there were much better options available.
06-10-2021, 10:54 PM
#10
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Join Date: Jun 2021
Posts: 14
Re: Scan 9495 random stall
I don't know what was available cam wise in 2004 for a 1994 Firebird it literally just says CAMSHAFT $379 on the invoice. I know that is full blown retail for 2004 so it could be anything really. The performer LT1 heads lifters springs, probably has an eddlebrock cam too, the manifold though is still the stock intake manifold. I don't want to pull the camshaft out of the car to find out. I guess a good tuner could tune it without that information. There is a dyno tuner in my area but I don't know if they tune this old of a car I always see a lot of newer mustangs in there lot when I go by.
Do you think that the camshaft specifications or identification number is on the end of the cam that faces towards the front of the engine?
A recommendation for mail order tuner would be interesting for me to check out and research. Thank you.
https://petrisenterprises.com/ I was looking at these sound like a good option because the price for other optisparks is from $50 to $600+ and you don't know if they are garbage or not, I am sure the $50 is crap and for the amount of trouble it is to be stalled on the side of the road and not to mention installing the optispark.
Also https://www.camaroz28.com/forums/com...-guide-886891/ was amazing information thank you.
Do you think that the camshaft specifications or identification number is on the end of the cam that faces towards the front of the engine?
A recommendation for mail order tuner would be interesting for me to check out and research. Thank you.
https://petrisenterprises.com/ I was looking at these sound like a good option because the price for other optisparks is from $50 to $600+ and you don't know if they are garbage or not, I am sure the $50 is crap and for the amount of trouble it is to be stalled on the side of the road and not to mention installing the optispark.
Also https://www.camaroz28.com/forums/com...-guide-886891/ was amazing information thank you.
06-11-2021, 03:39 PM
#11
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Join Date: Jun 2021
Posts: 14
Re: Scan 9495 random stall
So now I am bound and determined to see what cam is installed hopefully there is some writing on the end facing the timing chain. I am that far anyway and am in need of replacing the gaskets in that area. I need to upgrade the bolts on my balancer puller and get something to fit in the crank hole to remove the balancer hub. I'll go to the hardware store and get something I don't want to strip anything. The optispark was clean inside with some minor corrosion on the cap and rotor, didn't look like anything that would cause a stall so it probably is what most people suspect as a problem with the optical unit. I ll keep you posted as to the progress.
06-11-2021, 05:20 PM
#12
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Re: Scan 9495 random stall
The tuner I recommend has done exactly what you need. Friend of mine picked up a 30th SS convertible (trying to relive his 9.0-second, 156 MPH 30th SS ’vert from 18 years ago - we're really old timers). Beautiful car in good shape, but had an unknown cam, lackluster performance, A4 wouldn’t shift, etc. He sent the PCM to Moe Bailey, got it back in a few days, and was amazed at how well the engine ran and the trans shifted. Moe tunes some of the quickest cars that turn out for the LTX Shootout each year.
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