factory tach....way off?
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WhiteDevil
New Member
I have heard many stories about how far off our tacs can be. But i have never noticed it being off. I verify it with my autometer shift light which lights up the moment my Tac hits 6,000rpm. And with my Tweecer data logs showing me shifting at like 6,100 or so but hey im sure it revs for a second while i react to the shift light. All in all i would say its right on.
i will just use the factory one if it is that close. i was just going to do similar to what u are doing and throw a summit shift light on there for $36. think that will work?
-im assuming you can adjust a shift light in 100rpm increments, not 1000. the summit light requires no pills
thanks
WhiteDevil
New Member
gcomfx.com
Founding Member
Many of them get old and tired. Mine was fine until 4 years ago, then it slowly started losing accuracy. Now the thing is crazy.... it'll spin around and get stuck under the peg for no reason. 
I should have unhooked it when I put the Autometer in. Might put that on my to-do list. 
I should have unhooked it when I put the Autometer in. Might put that on my to-do list. 
That's the issue - they are not super reliable across the board (it's hit or miss if the tach in a given car will be right-on). If you have a friend with a known accurate tach, hook it up and use it for a day and see if the stocker stays in concert with the the aftermarket gauge. Remember that tachs tend to be off by percentages.
Good luck.
Good luck.
gcomfx.com
Founding Member
lol. expensive way to find out if my tach is off
i would like to dyno tho. by the way, care to list your mods and how much power you put down?
Mine reads about 300 too high
I've seen all kinds of reports in the range of 200 to 800 off
btw ... they have been on the high side
Wonder ifFord did it that way on purpose?
Grady
so if its reading higher than its actually turning....thats a good thing
all the ones you seen that were off read higher?
gcomfx.com
Founding Member
lol. expensive way to find out if my tach is off
i would like to dyno tho. by the way, care to list your mods and how much power you put down?
Not expensive if you are planning to dyno the car anyway. It's a free bonus.
94 Mustang GT AODE, 3,000 Street Edge Converter, TransGo shift kit, 3.73s, Cobra Intake, 75mm pro-m M/A, 24lbers, 65mm TB, MagnaFlow mufflers, O/R h-pipe, performance chip, Eibach drag springs, 255lph fuel pump, Mac pullies
ET's from 2006:
14.07 @ 96.86
12.79 @ 107.14 - 125 shot of Zex
2005 Dynojet- http://www.100mphclub.com/community/album_pic.php?pic_id=185
Had a heck of a time with the dyno and the stall. If you'll note the runs, we ran it 11 times! Club dyno days come in handy.
2004 Mustang Dyno N/A stock stall - http://www.100mphclub.com/community/album_pic.php?pic_id=180
2004 Mustang Dyno 125 shot and stock stall - http://www.100mphclub.com/community/album_pic.php?pic_id=181
Example of what happens when the car downshifts. LOL
http://www.100mphclub.com/community/album_pic.php?pic_id=182
My engine was noticeably loosing compression (worn rings) in 2005. They are REALLY worn now. Car still starts and drives good. Just a dog at WOT.
Edit: Oh and my stock tach read LOW....
so if its reading higher than its actually turning....thats a good thing
all the ones you seen that were off read higher?
I guess from Ford's point of view ...............
What the customer don't know ..........
can only be beneficial to them
When I wanna go to the limit .......
I just usually shift at 6500 ... or there abouts
It being off don't cause me any lack of sleep at night
cause
I know what is what
Now ... My wife sets her SUV clock 10 mins fast
that way
According to her ... she won't be late
I'd never be able to forget about it being wrong
anyway
Yeah all the peeps I've seen on these boards said .......
theirs was too high somewhere in that range
Grady
gcomfx.com
Founding Member
Actually I edited my post. ET's are from 2006. My car club has a yearly "Fastest List" You have to run your time THAT year. Some guys have gone slower, but that's the way it goes.
I really think the only thing that kept my times fairly consistent were the spring, shocks, and converter upgrades. My engine kept losing power, and I kept adding other mods to keep it hanging in there.
I'm finally working on the engine now.
Actually I edited my post. ET's are from 2006. My car club has a yearly "Fastest List" You have to run your time THAT year. Some guys have gone slower, but that's the way it goes.
I really think the only thing that kept my times fairly consistent were the spring, shocks, and converter upgrades. My engine kept losing power, and I kept adding other mods to keep it hanging in there.
I'm finally working on the engine now.
that loss of compression was hurting you wasnt it
I think the norm is like some of us noted (reading high), and it may be that Paul's situation is a little bit unnormal (just for a general consensus).
All stock tachs that I've seen (mine included) read higher than true RPM's. I also think that they do it on purpose - the motorcycle guys have been doing it for years and years (with the speedo's too). Though I think it's done intentionally, if you're going to error high or low, reading too high is the way to go.
Note that I have NOT been to a dyno to make use of their tools, as Paul has. I only can compare a diagnostic tach to my stocker, as they sit next to eachother. And on the 94, I can see RPM while viewing PIDs.
All stock tachs that I've seen (mine included) read higher than true RPM's. I also think that they do it on purpose - the motorcycle guys have been doing it for years and years (with the speedo's too). Though I think it's done intentionally, if you're going to error high or low, reading too high is the way to go.
Note that I have NOT been to a dyno to make use of their tools, as Paul has.
I only can compare a diagnostic tach to my stocker, as they sit next to eachother. And on the 94, I can see RPM while viewing PIDs.hissin' is like a knowledge base
Yes he is :Word:
Thats whats makes his Avatar so appropriate
He is Mr. Wizard
Now ... For all you ... Young Folk
That is me paying J T a compliment
I had to say that
cause
ya'll wern't around to see Mr. Wizard
He was plenty smart
Grady
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