I noticed this a while back but under acceleration, my tach needle starts to bounce. Doesn't matter what gear as long as I'm above 3k RPMs. Oil has just been changed and level is perfect. Whenever this happens I never notice a difference in engine noise, engine SOUNDS constant even though the RPMs are jumping back and forth. Here is video but you can barely see it because I used my cell phone and it was dark.

 

check the rpm sensor on top of the tranny, disconnect it and clean it out. i had the same problem in my 5th gen, i cleaned the sensor and it works just fine now

 

this just happend to me today!!!!!!!!!!!!!!!! i was about to post this up right now but im getting EXACTLY what you are describing...i better clean that sensor if thats it!

 

new to preludes.

but had a similar problem in my b16 crx.

It was the wire going to the heat sensor under the distributor.

Its a single wire.

It was loose. Clamped it down, never had problem sense.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vteclude07 &raquo;</TD></TR><TR><TD CLASS="quote">check the rpm sensor on top of the tranny, disconnect it and clean it out. i had the same problem in my 5th gen, i cleaned the sensor and it works just fine now</TD></TR></TABLE>

OK i could be wrong, but I have never seen any RPM sensor on a trany before? At least not a Honda one, on a 5 speed I see a reverse sensor and a speed sensor.
The RPM output that you see on your tach comes from ECU which reads the pulses from the igniter output.

When I've encountered the bouncing tach problem its usually been a bad igniter or bad grounding to the motor.

Hope that helps

Edit: after watching the video again, its your speedo thats the problem not the tach

clean your speed sensor

 

Well I'm going to check that wire on the dizzy the other guy suggested. Also I have a ground kit I have yet to install so that should help.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by no1knows908 &raquo;</TD></TR><TR><TD CLASS="quote">Well I'm going to check that wire on the dizzy the other guy suggested. Also I have a ground kit I have yet to install so that should help.</TD></TR></TABLE>

Umm no one here suggested a wire on your dizzy.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RaysBoomBoomLude &raquo;</TD></TR><TR><TD CLASS="quote">
It was the wire going to the heat sensor under the distributor.
</TD></TR></TABLE>

Under the dizzy maybe his ground wire was loose, in any case its NOT your TACH, your speedometer is the problem. Tach = RPMs, speedometer = MPH.
The problem is with your speed sensor on the back of your trany.

/sigh

 

My bad I meant the ground wire. Anyway I don't get what you mean by it being my speedometer and not the tachometer. The tach is jumping not the speedometer. Do you mean that the VSS is sending the ECU a faulty signal which causes it to bounce?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by no1knows908 &raquo;</TD></TR><TR><TD CLASS="quote">My bad I meant the ground wire. Anyway I don't get what you mean by it being my speedometer and not the tachometer. The tach is jumping not the speedometer. Do you mean that the VSS is sending the ECU a faulty signal which causes it to bounce?</TD></TR></TABLE>

yeah your right, its just a crappy video..

check the ground, if not, your igniter is on its way out

 

Is the igniter part of the distributer? I'm guessing just buy whole new one?

 

yah mine did the same after i installed a new clutch....the sensor on top of the tranny wasnt clip in all the way i believe its the speed sensor

 

so after driving my car today i notice the tach jumping after 3k rpms...and on like 3rd,4th and 5th gears...this time i did notice a change in speeds of the engine..as the needle jumped...the engine felt as i had let go of the gas for one bit...im going to check grounds..if not then for sure is the ignitor??

 

ok, i had to bring this thread back because this sympton has gotten worse....i searched the crap out of this forum and pages of pages suggest that its the igniter. so i went ahead and changed...it did not work...so i bought a BRAND NEW not remanufactured dizzy(the complete thing) and well it did not work...i remember cleaning out the connections from the dizzy to the ecu...the connection of the MAP sensor and the main ground from the body to the engine thats to the right of the engine...when i did clean the connections...the issue got worse...so after replace the dizzy and the problem still exist...could it be my MAP..my tach still jumps everywhere but now when i step on the gas...at times the car seems to bog down...the rpms go to zero and go back up with the back of seconds...at idle i also hear a bit of poping sound coming out of the exhaust...something it was not doing...what do you guys have in mind it is? i already spend alot of money on the dizzy i dont want to keep on wasting money...i was to get to the bottom line of this. thanks for any help

 

This might not be the case to your problem, but it worth a thought. I got that bog and felt almost like ignition is going to cutoff with needle jumping up and down, but mine only happens when turning or drove fast on the curves and sometimes over the bumps. At one point I noticed it only happens when i'm low on the gas about a quarter of a tank and below. So I took out the fuel pump, I found the strainer was broken off the pump. I replaced the fuel strainer and never had that problem since. Good luck!

 

thats ounds zkylude...i have a full tank of gas now and it even happens when i accelerate at a stop...the car sometimes does not to be moving and i just rev and feel the bog....=/ glad you fixed YOUr issue

 

i will paypal money to anyone willing to send the right direction...sounds like i am desperate...which i AM!

 

Hit any puddles lately?

Yea i figured out mine is oil related. It only happens when my oil is about a quart low. Damn I really need to fix that leak...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Edul59 &raquo;</TD></TR><TR><TD CLASS="quote">i will paypal money to anyone willing to send the right direction...sounds like i am desperate...which i AM! </TD></TR></TABLE>

i suck at reading, does the car drive normal and the tach just bounces? or is it breaking up as well?

 

it drives normally...the tach just bounces under WOT or load and above 3k rpms

 

Looking at the schematic for '93 lude:

The RPM signal is generated by the igniter (ignition control module or ICM) and goes to:

1) Main gauge assembly in your dash (your tachometer).
2) Cruise control unit.
3) Transmission control module (TCM) if automatic.
4) Test tachometer connector, which is in the engine compartment and on top of the right, front suspenion tower. The connector is 2-pin and white.

Maybe you can run a test-tach from the test connector to the interior of your car. If the test-tach doesn't glitch, then probably your dash unit is failing or has a loose connector.

 

I replaced my distributor lately and now I'm getting a similar thing happening where tacho will jump around up in the high revs.

I dont understand why.