Can stock Tach be improved to read accurately/precisely?
06-17-2003, 12:06 PM
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Can stock Tach be improved to read accurately/precisely? Its a question that I have been thinking about for awhile. Can the stock tach be "fixed" to read right. Or any of ther other gauges for that matter i.e. temp gauge.
From my understanding the ECM gives the signal to the stock tach and any aftermarket guages tap into this same signal. Thats when the descrepency between the stock gauge and the aftermarket gauge rears its head.
Can the stock electronics be improved to read correctly? I am posting in hopes that someone with a background in EE or electronics can shed some light.
From my understanding the ECM gives the signal to the stock tach and any aftermarket guages tap into this same signal. Thats when the descrepency between the stock gauge and the aftermarket gauge rears its head.
Can the stock electronics be improved to read correctly? I am posting in hopes that someone with a background in EE or electronics can shed some light.
06-17-2003, 02:07 PM
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Re: Can stock Tach be improved to read accurately/precisely? As stated in the post the ECM outputs the signal and the electronics in the tach handle it from there.
Can the electronics be rebuild with better components to improve its accuracy?
I am pretty sure it can be rebuilt to work better but I don't think anybody has really tried. Well at the very least I have seen no information up to now on it. There are people on this board who can do it I just hope he/she runs across this post.
Can the electronics be rebuild with better components to improve its accuracy?
I am pretty sure it can be rebuilt to work better but I don't think anybody has really tried. Well at the very least I have seen no information up to now on it. There are people on this board who can do it I just hope he/she runs across this post.
06-17-2003, 07:43 PM
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Re: Can stock Tach be improved to read accurately/precisely? find an airport near you and there should be an electronics shop there, talk to them about it they build gauge electronics for all kinds of applications... 
06-18-2003, 10:04 AM
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Re: Can stock Tach be improved to read accurately/precisely? no clues yet? I'd be real interested in this. I'm not too fond of the idea of adding an aftermarket tach when I've already got one with the instruments.
06-18-2003, 10:57 AM
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Re: Can stock Tach be improved to read accurately/precisely? Well I'm an EE with a good background, but I'm afraid I have bad news . . . the problem is not in the gages themselves, but in the PCM. It takes good data from the sensors, jacks it around a bit, then sends it to the gage controller in a digital format. The gage controller just converts it to an analog signal to drive the gages. The problem is in the firmware inside the PCM . . . what we need is a patch that could be loaded with LS1edit.
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06-18-2003, 12:02 PM
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Re: Can stock Tach be improved to read accurately/precisely?
Well I'm an EE with a good background, but I'm afraid I have bad news . . . the problem is not in the gages themselves, but in the PCM. It takes good data from the sensors, jacks it around a bit, then sends it to the gage controller in a digital format. The gage controller just converts it to an analog signal to drive the gages. The problem is in the firmware inside the PCM . . . what we need is a patch that could be loaded with LS1edit.
So u working on that patch or what?
06-20-2003, 03:50 PM
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Re: Can stock Tach be improved to read accurately/precisely?
Well I'm an EE with a good background, but I'm afraid I have bad news . . . the problem is not in the gages themselves, but in the PCM. It takes good data from the sensors, jacks it around a bit, then sends it to the gage controller in a digital format. The gage controller just converts it to an analog signal to drive the gages. The problem is in the firmware inside the PCM . . . what we need is a patch that could be loaded with LS1edit.
06-21-2003, 06:47 PM
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Re: Can stock Tach be improved to read accurately/precisely?
Well I'm an EE with a good background, but I'm afraid I have bad news . . . the problem is not in the gages themselves, but in the PCM. It takes good data from the sensors, jacks it around a bit, then sends it to the gage controller in a digital format. The gage controller just converts it to an analog signal to drive the gages. The problem is in the firmware inside the PCM . . . what we need is a patch that could be loaded with LS1edit.
06-22-2003, 02:12 AM
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Re: Can stock Tach be improved to read accurately/precisely?
find an airport near you and there should be an electronics shop there, talk to them about it they build gauge electronics for all kinds of applications...
Good luck!
06-22-2003, 02:14 AM
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Re: Can stock Tach be improved to read accurately/precisely?
2001 Service Manual. The signal that goes to the gages themselves is analog (as you say, voltage) but it comes from a controller module on the gage cluster. The Gage controller gets it's signal from the PCM in "Class 2 Data" format.
06-22-2003, 02:13 PM
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Re: Can stock Tach be improved to read accurately/precisely? Where are you getting your information Cal? It's wrong.
Most of the gauges grab their info from the class 2 VPW data bus however the tach does not. The tach has its own signal still which is perfectly fine. You can see this when you add an aftermarket tach.
The problem is the gauge itself.
I have a 99 PCM setup with a 97 cluster. If you recall the LT1's have quick responsive tach's unlike the LS1 clusters. My tach is currently off but with a tach adjuster box I hope it to still be responsive.
Also, for those of you who have tachs off at idle, you needle is off, not the signal. You need to pop the needle an dput it back on.. I've never tried this though.
Also, 99+ coolant temps are grabbed from the VPW bus as well which is why they aren't enirely accurate, however the 98 setup has its own feed from the sensor.
Most of the gauges grab their info from the class 2 VPW data bus however the tach does not. The tach has its own signal still which is perfectly fine. You can see this when you add an aftermarket tach.
The problem is the gauge itself.
I have a 99 PCM setup with a 97 cluster. If you recall the LT1's have quick responsive tach's unlike the LS1 clusters. My tach is currently off but with a tach adjuster box I hope it to still be responsive.
Also, for those of you who have tachs off at idle, you needle is off, not the signal. You need to pop the needle an dput it back on.. I've never tried this though.
Also, 99+ coolant temps are grabbed from the VPW bus as well which is why they aren't enirely accurate, however the 98 setup has its own feed from the sensor.
06-23-2003, 09:41 AM
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Re: Can stock Tach be improved to read accurately/precisely? Magnus
So your saying that the 98 temp sensor is directly hooked up to the gauge?
What parts would need to be replaced in the stock tach to improve its precision?
What makes the LT1 tach "quick responsive"?
I know theres a bit of controls engineering involved in this, unfortunately its not my specialty otherwise I would try and work something out and do a write. I also have a few sources at GM but don't want to tap it just yet.
So your saying that the 98 temp sensor is directly hooked up to the gauge?
What parts would need to be replaced in the stock tach to improve its precision?
What makes the LT1 tach "quick responsive"?
I know theres a bit of controls engineering involved in this, unfortunately its not my specialty otherwise I would try and work something out and do a write. I also have a few sources at GM but don't want to tap it just yet.
06-23-2003, 09:46 AM
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Re: Can stock Tach be improved to read accurately/precisely? the 98 temp gauge is connected to a 3 wire sensor that the 98's have.. 99+ have 2 wire connectors. You need a 98 cluster WITH a 98 sensor to achieve accurate temp sensor.. You can't rig up a 99+ cluster to work with the 98 sensor.
GM makes the LT1 tach quick responsive.. ANy more than that I couldn't tell you.
GM makes the LT1 tach quick responsive.. ANy more than that I couldn't tell you.
06-24-2003, 01:22 PM
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Re: Can stock Tach be improved to read accurately/precisely?
Where are you getting your information Cal? It's wrong.
Most of the gauges grab their info from the class 2 VPW data bus however the tach does not. The tach has its own signal still which is perfectly fine. You can see this when you add an aftermarket tach.
The problem is the gauge itself.
I have a 99 PCM setup with a 97 cluster. If you recall the LT1's have quick responsive tach's unlike the LS1 clusters. My tach is currently off but with a tach adjuster box I hope it to still be responsive.
Also, for those of you who have tachs off at idle, you needle is off, not the signal. You need to pop the needle an dput it back on.. I've never tried this though.
Also, 99+ coolant temps are grabbed from the VPW bus as well which is why they aren't enirely accurate, however the 98 setup has its own feed from the sensor.
Most of the gauges grab their info from the class 2 VPW data bus however the tach does not. The tach has its own signal still which is perfectly fine. You can see this when you add an aftermarket tach.
The problem is the gauge itself.
I have a 99 PCM setup with a 97 cluster. If you recall the LT1's have quick responsive tach's unlike the LS1 clusters. My tach is currently off but with a tach adjuster box I hope it to still be responsive.
Also, for those of you who have tachs off at idle, you needle is off, not the signal. You need to pop the needle an dput it back on.. I've never tried this though.
Also, 99+ coolant temps are grabbed from the VPW bus as well which is why they aren't enirely accurate, however the 98 setup has its own feed from the sensor.
06-24-2003, 07:53 PM
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Re: Can stock Tach be improved to read accurately/precisely? The problem with that is... the 98 guage takes a different fuel level signal than the 99+'s... 98 takes a formatted signal from the PCM where as the 99 takes it off of the class 2 bus I believe.
Switching to a 98 cluster anyway still leaves you with slow responsive tach.
PS. The service manual is wrong.. *i think* lol.. but I'm pretty sure it is wrong.
Switching to a 98 cluster anyway still leaves you with slow responsive tach.
PS. The service manual is wrong.. *i think* lol.. but I'm pretty sure it is wrong.
06-24-2003, 08:14 PM
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Re: Can stock Tach be improved to read accurately/precisely? the thing that leads me to believe the manual is wrong is, look at all the people with various types of shift lights....
the basic shift light is triggered by a certain voltage that you select, no?
for intalling the shift light you tap into the appropriate(don't remember without looking it up) wire coming off the PCM labeled tach(utilizing voltage?) thus the tach does have it's own "feed" if you will, no?
unless shift light can decode the digital signal being sent to the gauge cluster they must have a seperate feed.
the basic shift light is triggered by a certain voltage that you select, no?
for intalling the shift light you tap into the appropriate(don't remember without looking it up) wire coming off the PCM labeled tach(utilizing voltage?) thus the tach does have it's own "feed" if you will, no?
unless shift light can decode the digital signal being sent to the gauge cluster they must have a seperate feed.
06-24-2003, 11:45 PM
#19
Re: Can stock Tach be improved to read accurately/precisely?
The problem with that is... the 98 guage takes a different fuel level signal than the 99+'s... 98 takes a formatted signal from the PCM where as the 99 takes it off of the class 2 bus I believe.
Switching to a 98 cluster anyway still leaves you with slow responsive tach.
PS. The service manual is wrong.. *i think* lol.. but I'm pretty sure it is wrong.
Switching to a 98 cluster anyway still leaves you with slow responsive tach.
PS. The service manual is wrong.. *i think* lol.. but I'm pretty sure it is wrong.
06-25-2003, 01:31 AM
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Re: Can stock Tach be improved to read accurately/precisely? The temp sensor issue sounds like it may have a resolution.
Probably need to get a part number on it. I'll work on that.
QuickSSilver touched on the points that I was making. Any aftermarket tach/light taps into the same signal coming from the PCM as the OEM tach. Again I am not an EE and my background in controls engineering is very weak at best.
I figure that the electronics the stock tach has after it recieves the signal can be replaced or modified to read correctly.
So who knows how to tinker with a tach?
You know this really sucks. I just moved and I don't have access to a digital camera anymore or tools. I really want to figure this out!
Probably need to get a part number on it. I'll work on that.
QuickSSilver touched on the points that I was making. Any aftermarket tach/light taps into the same signal coming from the PCM as the OEM tach. Again I am not an EE and my background in controls engineering is very weak at best.
I figure that the electronics the stock tach has after it recieves the signal can be replaced or modified to read correctly.
So who knows how to tinker with a tach?
You know this really sucks. I just moved and I don't have access to a digital camera anymore or tools. I really want to figure this out!