One Tach reading lower at WOT

[BigGib]

So I just got my tachs rebuilt by Faria and I'm still having an issue with the port tach reading a few hundred RPMs lower than the starboard. Computer shows both engines turning the same at full throttle. Just curious what else this could be?

Thanks!

[cmattj]

Hey Gib,

Do you have manual throttle or DTS? If DTS the synchronization is reading the engine tach output from the engine then displaying to the tachs on your dash.

It could be a resistance in wiring to the tach so my diagnosis would be simple.
Now did you put the same tach back in the same left / right position??

Swap the tachs ( I loce Twins ) then if the problem remains in that side we need to find we’re the drop in value is on the wiring.

[akorcovelos]

Have you confirmed RPM beyond the computer, with a diagnostic tach that reads off the #1 plug wire? Or swap the ECUs and see if the other tach starts reading low?

[Big Block Power]

I would Make a notch in the left/port throttle so we are on the same page. so it can go further down. See problem solved. Hey thanks for taking my advise ahead of time.

[BigGib]

Took it out and ran it today, looks like it is off by about 300 RPM throughout the whole range. You can hear and feel when they are synced up and it's off just a little.

It has manual throttles, no DTS. I did put them back in the same side so I could try swapping first. Haven't tried anything other past verifying on the computer.

[BigGib]

I would Make a notch in the left/port throttle so we are on the same page. so it can go further down. See problem solved. Hey thanks for taking my advise ahead of time.

Can I notch both to get even more throttle on both sides?

[Big Block Power]

I would Make a notch in the left/port throttle so we are on the same page. so it can go further down. See problem solved. Hey thanks for taking my advise ahead of time.

Can I notch both to get even more throttle on both sides?

I like your thinking. It's like adding more current to a led. It gets brighter right till?

[NautiGirl]

I would Make a notch in the left/port throttle so we are on the same page. so it can go further down. See problem solved. Hey thanks for taking my advise ahead of time.

Can I notch both to get even more throttle on both sides?

Yes, you would effectively be making the knobs go to 11.

Spinal_Tap_-_Up_to_Eleven.jpg

[BigGib]

I would Make a notch in the left/port throttle so we are on the same page. so it can go further down. See problem solved. Hey thanks for taking my advise ahead of time.

Can I notch both to get even more throttle on both sides?

Yes, you would effectively be making the knobs go to 11.

Spinal_Tap_-_Up_to_Eleven.jpg

Ha, sounds like a cheap upgrade to me! If only it were that easy

[Big Block Power]

Can I notch both to get even more throttle on both sides?

Yes, you would effectively be making the knobs go to 11.

Spinal_Tap_-_Up_to_Eleven.jpg

Ha, sounds like a cheap upgrade to me! If only it were that easy

Did you switch tachs yet. That's sounds like the easiest place to start.

[BigGib]

Yes, you would effectively be making the knobs go to 11.

Spinal_Tap_-_Up_to_Eleven.jpg

Ha, sounds like a cheap upgrade to me! If only it were that easy

Did you switch tachs yet. That's sounds like the easiest place to start.

Not yet, been too busy using them

[Big Block Power]

Ha, sounds like a cheap upgrade to me! If only it were that easy

Did you switch tachs yet. That's sounds like the easiest place to start.

Not yet, been too busy using them

That's even better. I'll give that to you!!