factory tach....way off?

[fiveoho]

mr wizard...must have been b4 my time

 

[Adam95GT]

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.

YERP! my probe seemed to be dead on but i got a deal on a new automeeter 3 3/4 tach the perfect tach IMO for $20.... i slapped that on and sure enough... i was off by about 600 rpms.... when i thouhg i was shifting her at 7k i was shifting at a little under 6400 sure enough wit the tach i dropped like 2 10's im thinking about getting one for my mustang last time i went to the track though second gear it would like stop.... then jump... then stop... and jump... only when i really shift the crap out of it....


but when i was in my friends probe he was shifting at 4k and i was like WTF...... he was like yea its off by 3k rpms.... i LOLed at that one....

 

[gcomfx.com]

Mr. Wizard rocked..... I got many a Science Fair projects off of his shows.

Yeah the compression was hurting me. I really didn't notice it THAT bad (different dynos show different power anyway) But I was down to 115 average in the cylinders a couple of years ago. LOL Little sucker held in there. I just kept spraying it.

My tach may have been a rare one indeed. But I've had my car on a Mustang Dyno, Dynojet, and even a Snap-on driveability dyno. Took it to a HS auto tech teacher's place. He asked if he could really open the car up on a pull and see if his manual was accurate at what it would top out at. It did. HAHA I think it was 200hp max.

If you go back and look at the 2004 charts I posted. You'll see a flat spot before it climbs again in the upper rpms. That problem haunted me for a couple of years. Had MANY mechanics scratching their head. Turned out to be the dizzy was flaking out. It finally went completely nuts at the track. I could hear the timing start jumping around as it would detonate, then stop, then detonate, then stop at random rpms. Crazy..... New Dizzy and it stopped.

 

[Synned]

Well, I don't know if this is a problem with my tach but I'm assuming.
Under really high RPMs, my tach jumps like by 100rpm or sticks in the same spot.
Its much more noticable like at the top of 3rd or OD.

 

[gcomfx.com]

Could be why mine was low... it was sticking or dragging. It's very "free spirited now"

 

[fiveoho]

free spirited .

 

[Labora]

I bet ford would prefer them slow so people don't hit redline as often. D:

 

[HISSIN50]

Mr Wizard applies to many of you (like the guy whom knows so much about him. ) before it would me.

I'm full of useless BS that means nothing (if anyone needs to know the critical temp for a TFI, what temp a fox starts pulling timing or other uselessness like that, I can pull it off the top of my head). I'm not good for much more than that however.

Also, I heard a rumor that when Daggar kindly provided me with my avatar, it had previously been Grady's but Grady ditched it for more of a sleeper-look.

 

[fiveoho]

21,000 posts might have something to do with all the knowledge

 

[gcomfx.com]

21,000 posts might have something to do with all the knowledge

In hissin' case yeah... I have 23,682 posts on my forum. Not as wise as he is.

 

[fiveoho]

In hissin' case yeah... I have 23,682 posts on my forum. Not as wise as he is.

he def is a smart one...but dont sell yourself short

 

[fiveoho]

dumb question-

does the shift light read by the tach or does it read by actual engine rpm

 

[gcomfx.com]

You mean adding a shift light only to the car? If so it reads by the engine signal before the stock tach or directly from the engine. Either way works on it's own. Just make sure you get one you can adjust or change pills in. Your shift points will change as your mods change. The reason I went with an aftermarket Tach w/shiftlight. Plus I got a good deal on it. LOL

 

[fiveoho]

You mean adding a shift light only to the car? If so it reads by the engine signal before the stock tach or directly from the engine. Either way works on it's own. Just make sure you get one you can adjust or change pills in. Your shift points will change as your mods change. The reason I went with an aftermarket Tach w/shiftlight. Plus I got a good deal on it. LOL

cool. summit has a $36 adjustable light. requires no pills. should be ok i guess. so i can set my light at say 5500 and even if my tach says 5000 or 6000, the engine rpm is really 5500.

so in short, just pay attention to the light...not the tach. ( no aftermarket tach...im cheap )

 

[fiveoho]

well wait a sec.....how do i KNOW its 5500 when i set the light? i cant go by the stock tach.....

 

[gcomfx.com]

LOL - I think you are use to the light on tachs. With just the light you either change a pill out or turn a knob w/ numbers on it.

 

[fiveoho]

LOL - I think you are use to the light on tachs. With just the light you either change a pill out or turn a knob w/ numbers on it.

i know i probably sound like a idiot....but just on a shift light with a dial.....how do u -know- u are turning 5500 ( or whatever ) when u set it to that with the factory tach? because if the factory tach is off.....


?



...i'll get it eventually

 

[final5-0]

You are not an idiot

You just missed the info above

After market tachs or shift lights
get their data from the ignition

Now on a shift light ....
you only have a concern about
a specific rpm
and
You specify that rpm with .....
pills, dip switches, etc

Grady

 

[fiveoho]

You are not an idiot

You just missed the info above

After market tachs or shift lights
get their data from the ignition

Now on a shift light ....
you only have a concern about
a specific rpm
and
You specify that rpm with .....
pills, dip switches, etc

Grady

so if the shift light has a dial...you just set the dial to the rpm desired.

do not sync it with the factory tach....

 

[final5-0]

so if the shift light has a dial...you just set the dial to the rpm desired.

do not sync it with the factory tach....

I could not say if it has a dial or not
but
They offer a way of selecting different rpm values

I can say

It ain't got anything to do with the oem tach

It is a separate device apart form the oem tach.

It gets a signal from the ignition ... not the tach
so
You could display both the hosed oem tach values
and
The accurate values from an after market tach or lite

Hows that I didn't even know I knew that much

Grady