Which to trust?
12-05-2014, 04:32 PM
#1
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Which to trust?
First off, I'm not sure I'm posting in the correct forum. I din't know if I should be here or Advanced Tech or computer diagnostics. If I"m in the wrong forum just move me.
Ok, took my Z out today and I had my scan9495 connected while I was out. I have no clue whats up with my stupid temp gauge sensor. It's brand new. My scan9495 says that my temp is good. Holding with a median temp of around 200.
The red line in this chart indicates my coolant temp.
But this is what my gauge reads. (I turned the car off just to be sure)
Ok, took my Z out today and I had my scan9495 connected while I was out. I have no clue whats up with my stupid temp gauge sensor. It's brand new. My scan9495 says that my temp is good. Holding with a median temp of around 200.
The red line in this chart indicates my coolant temp.
But this is what my gauge reads. (I turned the car off just to be sure)
Last edited by brentbrowning01; 12-05-2014 at 04:34 PM.
12-05-2014, 04:51 PM
#2
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Re: Which to trust?
Looks like the gauge sensor may be shorted to ground. Low resistance indicates high temp. Time to measure the voltage on the single-wire circuit with the connector off the sensor, single pin in the connector to an engine ground. Connector off, measure the resistance of the sensor, single pin to the block ground.
Use Shoebox's instructions.
It is possible for the head temp to go very high, if the t'stat is stuck closed... but check the electrical stuff first. It shouldn't take more than 5 minutes.
Use Shoebox's instructions.
It is possible for the head temp to go very high, if the t'stat is stuck closed... but check the electrical stuff first. It shouldn't take more than 5 minutes.
12-06-2014, 12:15 AM
#4
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Re: Which to trust?
I'll do that, Injuneer. Let me be a little more clear. My gauge starts out acting normal. I can drive around for a little while and it acts normal but after about an hour it starts creeping up. I turn on the heater and make sure the fans are on when it does that and try to get somewhere I can switch off for a while just to be on the safe side. And yes, my gas gauge stays like that all the time... I've been reading up on Shoeboxs' piece on fuel gauges too.
GaryDoug, 876.19 does seem a little on the high side. I don't know what those number mean but they aren't anywhere close to the other injector numbers. So yes, please check to see if it's a glitch. Unless Shoebox has a guide on how to change injectors, I'm up the creek...
GaryDoug, 876.19 does seem a little on the high side. I don't know what those number mean but they aren't anywhere close to the other injector numbers. So yes, please check to see if it's a glitch. Unless Shoebox has a guide on how to change injectors, I'm up the creek...
12-06-2014, 05:00 PM
#5
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Re: Which to trust?
I checked the program and couldn't find anything wrong. I did see that the factory service manual states the range of valid numbers to be from 0 to 1000 msecs so I guess it is possible. Nothing like that showed in your other scans. I wouldn't worry about it, it doesn't mean replacing any injectors anyway. It's the drive duration from the pcm that it shows.
12-06-2014, 09:39 PM
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Re: Which to trust?
I checked the program and couldn't find anything wrong. I did see that the factory service manual states the range of valid numbers to be from 0 to 1000 msecs so I guess it is possible. Nothing like that showed in your other scans. I wouldn't worry about it, it doesn't mean replacing any injectors anyway. It's the drive duration from the pcm that it shows.
12-06-2014, 11:00 PM
#7
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Re: Which to trust?
There's several things in that frame that are not consistent or not heathy. Look at the MAF, knock retard, EGR at low RPM, BLM's, engine run time, fan on at 212 (reprogram)?, IAC, min IAC, etc.
With the gauge needles all out of whack, I wonder if they have been removed and reinstalled incorrectly... as to remove a dash overlay.
With the gauge needles all out of whack, I wonder if they have been removed and reinstalled incorrectly... as to remove a dash overlay.
12-07-2014, 12:03 AM
#8
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Re: Which to trust?
There's several things in that frame that are not consistent or not heathy. Look at the MAF, knock retard, EGR at low RPM, BLM's, engine run time, fan on at 212 (reprogram)?, IAC, min IAC, etc.
With the gauge needles all out of whack, I wonder if they have been removed and reinstalled incorrectly... as to remove a dash overlay.
With the gauge needles all out of whack, I wonder if they have been removed and reinstalled incorrectly... as to remove a dash overlay.
** Just researched the Shoebox website for all for those acronyms. I found all of them and looks like I can replace most. I couldn't find anything on BLM's though.
Last edited by brentbrowning01; 12-07-2014 at 02:11 AM.
12-07-2014, 09:38 AM
#9
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Re: Which to trust?
I have a 20+ page writeup on reading and interpreting the LT1 scan data. If you want, I'll e-mail you a .pdf copy.
Take MAF flow. The mass air flow is expressed in grams/second. Normal mass air flow at idle is in the range of 6 to 10 gps (grams per second). Yours is reading 495. The data indicates the throttle is closed, and that you are at 650 RPM, and the vehicle is moving 32 MPH. That MAF is a totally impossible. A stock LT1, wide open throttle, at max RPM will only flow about 240 gps. I thought the upper limit of the stock MAF table was 471 gps, and since my MAF sensor is disconnected (engine runs in speed-density, no MAF) that's the number I see on my scanner. Maybe 495 is the max value for the scaled 8-bit binary field???? In any case, your engine can't flow that much air. Is the MAF sensor disconnected? Is the the code you have?
The data indicates the engine run time is 16+ hours. Gary will have to tell us if that field is from the last start, or cumulative, but all the data I have looked at indicates it resets when the engine is started.
The knock retard is pretty much the max the PCM can make (I thought the stock limit was 15-deg), that's a serious problem, indicating the engine is detonating (spark knock) at idle, and the PCM is pulling more than 15-degrees of ignition timing to stop the knock, and prevent damage to the engine.
The stock fan temps are #1 on at 226*F an #2 at 235*F. Yours are both on, and the coolant is only 212*F.
EGR stands for "exhaust gas recirculation". There is a large black valve on the back of the intake manifold that is opened to flow exhaust gas into the intake. That flow is activated under engine operating conditions that produce high combustion chamber temperatures, which cause the formation of the pollutant "oxides of nitrogen" (NOx). The exhaust gas quenches the combustion chamber temps to reduce the formation of NOx. But in stock programming, the EGR system is not operated at idle, or above 3,500 RPM. The scanner number is the "duty cycle" of the EGR vacuum solenoid. The PCM pulses the solenoid to control the flow of exhaust gasses, and the duty cycle is the % of time that the solenoid is powered to open. Maybe there is a setup in the programming that introduces exhaust gas at any time knock retard reaches the upper limit.... it is just something I have not seen before.
IAC is the idle air control valve. That's a small valve on the bottom of the throttle body that opens and closes to allow air to bypass the throttle body, to control the idle speed. The scanner reading is the position the PCM is telling the valve to move to (there is no feedback as to the actual position), in "counts". Each count is a small increment of valve movement.
BLM's are "block learn multipliers" = long term fuel corrections. That is a correction the PCM is making to the injector pulse width (how long the injector is open) based on feedback from the O2 sensors. The number is used in the formula for calculating the amount of fuel to be delivered, and the "multiplier" is in the form BLM/128. A BLM of 128 produces a multiplier of "1", and is considered the base point for the calculation. If the O2 sensor indicates the engine is operating at the correct A/F ratio, it leaves the BLM at the default value of 128. There is a separate "BLM" for each bank (side) of the engine, and there are at least 18 BLM's for various operating conditions of the engine base on RPM and engine load. Engine load is measured by the MAP (manifold absolute pressure) sensor. Cell 16 is the idle cell, and your data tells us that is the BLM it is reporting. Your Bank 1 (left side of engine when seen from the drivers seat) BLM is 154. That indicates that the O2 sensors are reporting a serious lean condition, and the PCM has raised the BLM to 154 to add the extra fuel to correct to the desired A/F ratio (14.7 # of air : 1 # of fuel under normal driving conditions). That means the PCM is multiplying its standard fuel calculation by 154/128 = 1.203. That means the PCM is adding 20% extra fuel, to the left side of the engine, at idle, to prevent the engine from running lean. Bank 2, the right side is almost as bad.
Indicates you have one code - what is it?
Take MAF flow. The mass air flow is expressed in grams/second. Normal mass air flow at idle is in the range of 6 to 10 gps (grams per second). Yours is reading 495. The data indicates the throttle is closed, and that you are at 650 RPM, and the vehicle is moving 32 MPH. That MAF is a totally impossible. A stock LT1, wide open throttle, at max RPM will only flow about 240 gps. I thought the upper limit of the stock MAF table was 471 gps, and since my MAF sensor is disconnected (engine runs in speed-density, no MAF) that's the number I see on my scanner. Maybe 495 is the max value for the scaled 8-bit binary field???? In any case, your engine can't flow that much air. Is the MAF sensor disconnected? Is the the code you have?
The data indicates the engine run time is 16+ hours. Gary will have to tell us if that field is from the last start, or cumulative, but all the data I have looked at indicates it resets when the engine is started.
The knock retard is pretty much the max the PCM can make (I thought the stock limit was 15-deg), that's a serious problem, indicating the engine is detonating (spark knock) at idle, and the PCM is pulling more than 15-degrees of ignition timing to stop the knock, and prevent damage to the engine.
The stock fan temps are #1 on at 226*F an #2 at 235*F. Yours are both on, and the coolant is only 212*F.
EGR stands for "exhaust gas recirculation". There is a large black valve on the back of the intake manifold that is opened to flow exhaust gas into the intake. That flow is activated under engine operating conditions that produce high combustion chamber temperatures, which cause the formation of the pollutant "oxides of nitrogen" (NOx). The exhaust gas quenches the combustion chamber temps to reduce the formation of NOx. But in stock programming, the EGR system is not operated at idle, or above 3,500 RPM. The scanner number is the "duty cycle" of the EGR vacuum solenoid. The PCM pulses the solenoid to control the flow of exhaust gasses, and the duty cycle is the % of time that the solenoid is powered to open. Maybe there is a setup in the programming that introduces exhaust gas at any time knock retard reaches the upper limit.... it is just something I have not seen before.
IAC is the idle air control valve. That's a small valve on the bottom of the throttle body that opens and closes to allow air to bypass the throttle body, to control the idle speed. The scanner reading is the position the PCM is telling the valve to move to (there is no feedback as to the actual position), in "counts". Each count is a small increment of valve movement.
BLM's are "block learn multipliers" = long term fuel corrections. That is a correction the PCM is making to the injector pulse width (how long the injector is open) based on feedback from the O2 sensors. The number is used in the formula for calculating the amount of fuel to be delivered, and the "multiplier" is in the form BLM/128. A BLM of 128 produces a multiplier of "1", and is considered the base point for the calculation. If the O2 sensor indicates the engine is operating at the correct A/F ratio, it leaves the BLM at the default value of 128. There is a separate "BLM" for each bank (side) of the engine, and there are at least 18 BLM's for various operating conditions of the engine base on RPM and engine load. Engine load is measured by the MAP (manifold absolute pressure) sensor. Cell 16 is the idle cell, and your data tells us that is the BLM it is reporting. Your Bank 1 (left side of engine when seen from the drivers seat) BLM is 154. That indicates that the O2 sensors are reporting a serious lean condition, and the PCM has raised the BLM to 154 to add the extra fuel to correct to the desired A/F ratio (14.7 # of air : 1 # of fuel under normal driving conditions). That means the PCM is multiplying its standard fuel calculation by 154/128 = 1.203. That means the PCM is adding 20% extra fuel, to the left side of the engine, at idle, to prevent the engine from running lean. Bank 2, the right side is almost as bad.
Indicates you have one code - what is it?
Last edited by Injuneer; 12-07-2014 at 09:47 AM.
12-07-2014, 09:30 PM
#10
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Re: Which to trust?
Thank you for that in depth explanation, Injuneer! Yes I would like to look over and study that 20+ page writeup on reading and interpreting the LT1 scan data! I'll PM you my email.
Well, today was a good day! I replaced my 180 t'stat with a 160 and I rewired the pigtail that goes to the PCM from the sensor in the water pump. Instead of leaving the blue "Clamp" style wire connector that came with the Duralast sensor, I used a "barrel" type wire connector that I heated up with a lighter to connect the wires.Guess what! I took it for a ride and NO CODES!!! That's not saying that the BLM's and other factors aren't 100% correct but it's a great start in my eyes! I have a lot of pics of my 9495scan that I'll post. Let me know your thoughts!
The first pics are Prestart before I turned the motor over. To view the pics in order, click on each individual pic.
This batch of pics is of the scan just after initial start up running at idle.
I'll have to continue to a new reply because of the 10 pic limit. The pics will pic up with the at idle 5 pic.
Well, today was a good day! I replaced my 180 t'stat with a 160 and I rewired the pigtail that goes to the PCM from the sensor in the water pump. Instead of leaving the blue "Clamp" style wire connector that came with the Duralast sensor, I used a "barrel" type wire connector that I heated up with a lighter to connect the wires.Guess what! I took it for a ride and NO CODES!!! That's not saying that the BLM's and other factors aren't 100% correct but it's a great start in my eyes! I have a lot of pics of my 9495scan that I'll post. Let me know your thoughts!
The first pics are Prestart before I turned the motor over. To view the pics in order, click on each individual pic.
This batch of pics is of the scan just after initial start up running at idle.
I'll have to continue to a new reply because of the 10 pic limit. The pics will pic up with the at idle 5 pic.
Last edited by brentbrowning01; 12-08-2014 at 01:34 AM.
12-07-2014, 09:31 PM
#11
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Re: Which to trust?
In this pic the Red line indicates coolant temp. Blue is MAF gm/sec. Green is knock counts. Purple is intake air temp.
The last batch of pics is at the end of my trip ( after maybe 25-30 miles) car still on.
Well, there you have it. My trip info for today. Let me know your thoughts. I'm pretty happy about the no codes and my temp staying down.
Last edited by brentbrowning01; 12-08-2014 at 01:36 AM.
12-08-2014, 07:12 AM
#12
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Re: Which to trust?
Are you aware of how to run a "log"? Looking at individual frames of data in screen dumps is extremely difficult and time consuming. A .csv file of a complete data log can be viewed and manipulated in Excel, producing better results.
12-08-2014, 12:23 PM
#13
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Re: Which to trust?
Yes I can post one of those as well if you'd like to see it.
12-15-2014, 10:33 PM
#15
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Re: Which to trust?
Alright guys! I've been on a week long hiatus reading and studying Injuneers 20+ page long write up on reading and interpreting the LT1 scan data. Whew, that's a lot of info! Good info though. Though I"m not any smarter, at least I have good info.
Update on the Z28; It's been acting normal up until a few days ago. I took it out for a ride (I didn't take my computer to monitor the OBD because everything had been acting normal). Everything was going great until my Temp spiked. I pulled over and opened the bleeder valve and let about 5 minutes worth of air out of the system. That's odd because I've bled the system numerous times after my water pump install. Then, yesterday I took it out for a short ride and by the time I made it home the temp had spiked again. I opened the bleeder valve and bled another 5 minutes worth of air out of the cooling system. Drove it to work today and everything was fine... I swear this car is as temperamental as a woman......
My next project is probably going to be flushing and replacing the power steering fluid. I looked in the power steering reservoir the other day and the fluid looks like Hershey's chocolate syrup. Probably not what it's supposed to look like..
The next big project is going to have to wait until spring. Changing out the plugs and I'm debating adding headers and a few suspension upgrades.
Update on the Z28; It's been acting normal up until a few days ago. I took it out for a ride (I didn't take my computer to monitor the OBD because everything had been acting normal). Everything was going great until my Temp spiked. I pulled over and opened the bleeder valve and let about 5 minutes worth of air out of the system. That's odd because I've bled the system numerous times after my water pump install. Then, yesterday I took it out for a short ride and by the time I made it home the temp had spiked again. I opened the bleeder valve and bled another 5 minutes worth of air out of the cooling system. Drove it to work today and everything was fine... I swear this car is as temperamental as a woman......
My next project is probably going to be flushing and replacing the power steering fluid. I looked in the power steering reservoir the other day and the fluid looks like Hershey's chocolate syrup. Probably not what it's supposed to look like..
The next big project is going to have to wait until spring. Changing out the plugs and I'm debating adding headers and a few suspension upgrades.