94 Civic Tach Readings

[JoeyStyyles]

So I posted a few weeks ago describing a problem I had with my cluster, about how the Speedometer would read 30 Mph right as I turn the ignition on. Well I was told that it was a problem with the cluster and that a cluster with a tachometer from another year would sink up to the ECU or whatever sensors it reads off of. Well I ordered the new cluster from eBay from a compatible year and hooked it up (breaking my accessory panel along the way) and the speedometer, all the lights, my gas and temp gagues work but the Tach seems off. It tells me that at 40mph in 4th gear I am doing just under 1500 rpm. As I climb in RPMs rapidly, after 2,800-3,000 Rpm the tach starts to kick it. It seems to idle okay on cold start, showing it above 1 until the car warms up and drops to around 600-700. As I drive however, while in motion and in nuetral the RPM stays above a 500rpm idle but when I come to a complete stop the tach shows it dropping between 200-500rpm. I can hear/feel the idle roughen at the complete stop but I wouldn't think there would be enough pressure for the car to run without stalling at 200-500rpm

Here are more of the Tach - Speedo comparisons:
1st Gear - 20 Mph - 2,000-2,500 Rpm
2nd Gear - 30 Mph - Just above 2,000
3rd Gear - 45 Mph - Just above 2,500
4th Gear - 40 Mph - Just below 1,500

I own a DX with the stock D series engine in it.

This Tachometer also Red Lines at 7,200 RPM and I think my rev limiter kicks in at 5,900-6,000 but I would think that's just red tape on some plastic.

When I hooked it up, there were 3 clips hooking up to the original cluster and on the one with the tachometer there was 4 clip inserts, a blue connector that the car didn't have. Like I said everything else works and the tachometer moves so I don't know how important that last clip is or what it does.

I also don't know what a normal 94 Civics RPM acceleration looks like but judging from the Integras I've owned, I can't see that being right.

Any help would be appreciated,

Thanks
Joey

 

[JoeyStyyles]

...

Well I was driving it last night, and after about 40 miles the tachometer started to seem more accurate. In second, doing 30 I was cresting 3000 rpm, matched with the sound of the cars acceleration. I got in it this morning and the problem was back, I drove it for about 15 miles and the problem didn't self correct. I was wondering what the Tachometer reads off of (speed sensor perhaps?) and where it would normally be located.

Thanks,
Joey

 

[RonJ]

The tach gets its signal on a blue wire from the igniter unit inside the distributor. The problem could be a bad igniter unit, blue wire, or tach.