Tach on crack... any ideas?

Christ · #1 08-28-2006, 02:30 PM

Lol.. did the MPFI swap, put in a new igniter in the HF dizzy we used, PM6 ECU, and the tach hasn't worked right since... was wondering if anyone had any ideas on why?

What to check, etc. haven't really messed with it yet, so any info is appreciated. and it worked fine when the old engine was in it.

SiZ · #2 08-28-2006, 08:54 PM

Maybe you should explain what you mean. Mine used to jump at highway speeds every once in a while, then my coil shat out on me on my birthday, 5 minutes away from Honda.

Christ · #3 08-28-2006, 09:33 PM

Umm.. sorry about that, was in a hurry, had to replace some rolled main bearings quick...

It's just way off.. only jumps occaisionally, but we're shifting at better than 8k rpm.. and it's a D15B2/D16A6 combo... with a PM6.. it SHOULD cut off at 7200RPM I believe.. but yeah, when it's at 8k+, it sounds like about 4 maybe 4500... and on the stock LX trans, we should be doing like 30-35 in first @ 8k... not even close.. maybe 20 so far.

The igniter we used came from the old DPFI dizzy that was originally in the car, and the tach runs off the ignitor via the blue wire on the two pin clip... We're getting no readings from the coil as far as hooking up a ohm meter or anything... nothing on either test. The car will start and run fine though, every single time... just sometimes after it warms up, it rolls over for a lil longer to start.

FrodoGT · #4 08-28-2006, 10:21 PM

Mine will jump at around 4k rpms.. and usually will stabilize by 5500.

Christ · #5 08-28-2006, 10:29 PM

This thing is just all sorts of wrong, except at idle... engine idles around 1k... after that, it's all fucked up.. bounces sometimes, smooth sometimes.. but always wrong.

BTW frodo, nice 'rex.. i have a 1988 HF for sale for the right price.. I dun wanna get rid of it, but its' got alot of rear damage.. typical rusted rear wheel wells, and smacked rear drivers side.. both bumper frames need replaced.. no engine in it, the engine is sitting in the rear of the car... lol

Know anyone that's interested, have them email me, or msg me on AIM

if I keep it, it's gonna end up being on a 5 year plan lol

CRXperiment · #6 08-28-2006, 11:54 PM

Quote:

Originally Posted by Dr0pZ0n3

The igniter we used came from the old DPFI dizzy that was originally in the car, and the tach runs off the ignitor via the blue wire on the two pin clip... We're getting no readings from the coil as far as hooking up a ohm meter or anything... nothing on either test. The car will start and run fine though, every single time... just sometimes after it warms up, it rolls over for a lil longer to start.

I'm not sure about the DPFI/ MPFI dizzy interchangeability. Your problem may lie in the fact that you used a DX ignitor unit. DX ignitors are different from HF/Si ones. I know this for a fact since Honda has put recalls on the ignitor units of all dpfi 88-91 civic/crxs, where the mpfi's dont have any recalls...

Christ · #7 08-29-2006, 12:54 AM

Meh.. it works.. it runs the car.. and it was doing the same shit with the HF igniter in there too, whenever it would actually start, I mean. It's prolly gonna get changed out anyway to handle 100kv ignition (dual coil) I guess we're gonna do a complete rebuild of it... dual external coil, stronger pickups and reluctor, and I guess a better igniter too, not sure yet.

It's possible that it's the igniter, I guess, but it doesn't make any sense at all... since the igniter is still starting the car, and the only signal the tach gets is from the igniter... All the wires were in the same place, mounts the same, etc...

>
>Edit - Part Numbers provided by www.rockauto.com
> 1988 Honda Civic LX - 1.5 Liter (D15B2) - Ignition - Module / Igniter - Honda Part # 06302PT2000
> 1988 Honda Civic/CRX Si - 1.6 Liter (D16A6) - Ignition - Module / Igniter - Honda Part # 06302PT2000
>
> Sorry... Same part number = same part... if there was a recall on one, which I"ve never heard of... there was a recall on both.

turtlecrxsi · #8 08-29-2006, 07:35 AM

Sounds more like your actual gauge is messed up. You really don't need an external coil either. Trust me. I had a dual coil set up and it didn't make a difference.

Christ · #9 08-29-2006, 01:16 PM

Eventually, the car is gonna be all motor street/race... prolly close to 13:1 compression or so... 100kv ignition is a good option for it b/c of the internal atmospheric pressure.. I know the motor isn't built for the kind of pressure we're gonna put it through.. but it's gonna be a slow project.. start off fixing the things that aren't right, improving them instead of wasting money on stock parts, not to mention that heat is a major reason for coils not working to their full potential, as with any electrical device, so external coil will allow for cooling of the coil, adding to it's potential. I've done my research on this option.. but thanks for the input.

The block (if not this one, the other one we have in the shop) is gonna be align-bored for fitment of a 1.6liter D series crankshaft.. maybe even a B.. have to get the measurements first to find out what we can do w/o risking the block.

As for the gauge, it worked fine 4 months ago when the car came off the road, but we're hooking up a aftermarket tach out of the guy's truck for the hell of it anyway.. I was just wondering if anyone knew what it was, or maybe had the same problem..

turtlecrxsi · #10 08-29-2006, 01:22 PM

I had a built d-series motor running over 11:1 compression and I had an ignition. I thought it was great until my engine detonated and the engine caught on fire. Stock ignition is good up to 400hp.

These tach needles get weird after sitting for long periods of time. I've heard plenty of stories of how the tach is going beyond redline but is only at 4,000 rpms. Or the other way around where the tach is at 6,500 rpms and you're bouncing off the rev limiter. Hell, I thought my ecu was chipped for the longest time because I'd take it up to 8,500 rpms without hitting any limiter. But now I know the tach is just off.

Christ · #11 08-29-2006, 01:59 PM

@ Turtle..

Ever heard of anyone rebuilding/repairing the stock Tachs?

I'd like to keep it in there, at least until we get to tearing the dash apart, so it can be sold.. but I'm excellent at wiring and fixing small circuits, so if you have any info about fixing them, plz post

turtlecrxsi · #12 08-30-2006, 07:25 AM

There was one dude in Estonia? that posted on here who took apart a bunch of tachs and put them back together. He said it was pretty easy. Mine has those paper white face gauges done by the previous owner and I just figured if I took it apart it would never go back right so I left it alone. I wish it was stock but it's tolerable in the day time. But I don't really drive the crx anymore so it doesn't bother me... LOL... That car was giving me high blood pressure...

viper-blue · #13 09-01-2006, 01:46 AM

A really knowledgeable guy at honda told me when you mix and match various sensors and sending units from different cars the gauges don't read the signal properly. For instance my gauges are made by denzo and are not totally compatible with hf, and some dx model sending units and sensors. Could be a bad tach, or the parts aren't compatible with one another

hondacivic99sivtec · #14 09-01-2006, 03:33 AM

just a thought don't know nothing 'bout d series but what about the vss?

FrodoGT · #15 09-01-2006, 04:42 PM

VSS only controls the speedo. In our vehicles it is cable driven and has no electronics related to the actual meauring device, however it does send a signal to the ECU. And when swapped it is used as one of the conditions that must be met before vtec will activate. I believe 25 mph. ECU also controls speed limiter from that signal.

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