Noisy tach signal.

I've seen the symptoms before:

1) faulty tach 2) bad plug wires

Jan

Reply to
Jan
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Hi Everyone,

To make a long story short, I have put a remote starter in my bug (Dual port

1600, stock ignition) which is working beautifully, but the remote starter is shutting the engine off after a random amount of running time. I have installed several different types of other remote starters, but they were all fuel injected vehicles, and they all worked fine. I noticed on my bugs tach which is a digital unit, with a bar graph,(uses LED's) that the tach reads a very high signal every so often, I assume its due to the points ignition (noise). I think the remote starter is detecting "over-rev" speed and shutting the system down.

I remember hearing that some of the early 70's chev cars had problems with noisy tach signals and they had a filter that fixed this so the tach needle wouldnt bounce around. It looked like a condenser, and it was mounted near the coil, and it was grounded. Does anybody know of any junkyard fixes such as this? I would go to the local remote starter installation place, but the last time I went there with a question, they laughed at me and wanted an insane amount of money for a simple part I needed. Ended up going to the junkyard.

Ryan.

Reply to
Ryan Lester

Now that you mention the points, I did notice a significant reduction in noise on the tach after I changed the points. Its still there though, and the points only have about 2 hours on them since they were changed. I also changed plug wires, the old ones were so bad, they were almost glowing.

Yeah, a homemade filter would work, but I lack the time to mess with it, I would rather install something that has already been tried and known to work. Thanks for the advice, I guess I'm looking in the right direction.

Ryan.

Reply to
Ryan Lester

Ryan:

Check your plug wires - voltage arcing through old or crappy wire insulation could cause the jumps on your tach....

Reply to
Patrick

Change also the condensator in the distributor. Failing condensator leads to sparking between the points and eventually ruins them.

Reply to
Olli Lammi

.....................On my '77, I've experienced this tachometer 'needle bounce' with both the Petronix module and conventional points & condenser. I finally was able to eliminate the problem with a diode in the wire from the coil to the tach. Go to RadioShack and get diode # 1N4005, catalog #

276-1104. It's less than $2 for two of them if I recall. If you solder it in place like I did, be sure that it's got the polarity mark on the end closest to the gauge I think..........before you solder it in place. Also, take care that the heat from soldering doesn't get too high and damage that little son of a gun (maybe that's why there's two of them in the package). It's a cheap fix that worked for me.
Reply to
Tim Rogers

Thats great advise Tim, I'll be sure to try this. Although, I'm not sure how a diode would do the trick, its basically an electrical one way valve. Worth a try though.

Ryan.

Reply to
Ryan Lester

I have some diodes handy here so I'll try it and report back.

How did you learned about this trick?

Reply to
Eric Desrochers

..............Let the group know how it works.

Reply to
Tim Rogers

...................You know how they say that memory is the second thing to go? Well, I read it somewhere but I have no recollection of where . . . . . it's embarrassing.

Reply to
Tim Rogers

Ryan,.................And Group.

There are many ways to get a clean signal for your remote start, that are outside the distributor..........................most of the remote start systems require a steady pulse, which is what yours needs. I have had planty of chance in the past to experiment with a few and found that the best one was the generator/alternator "charge Wire"......................this sounds weird, but there's a way to use it.

Clifford ( A Well Know Old Alarm Company- that has been purchased by another well known company DEI, maker of Viper, Python, and many other levels of alarms ) had a little module that you could wire tie to the Charge Wire of just about any car , and get a solid Clean "tach" signal for your remote start..................Now, I have no idea where to get one nowadays ( I am no longer in the installation portion of the biz ), but I think You may be able to use this type of sensor to produce the signal you need without using the Tach Signal or Ignition circuit at all.

If it were me, I'd find a shoppe somewhere that installs the same and see what I can get from the installers,.......................lots of cars have tach signals easily usable, and the kits we used to install had one in every kit, so there's bound to be someone out there that has a couple of these in their toolbox for sale,..............cheap even. ( By the way , the kits we were installing were the top of the line kit, by Clifford, and had sattellite control and all that hooplah too. You could call your car from anywhere and start it for a ten minute span, and it'd automatically shut off ,..............just to charge the battery for a spell while on a remote vacation type event................. I suppose.)

I know this whole post is likely to not matter but I thought I'd share a quick thought that is out there and many have never heard of at all.................MO INFO!!!!!

Remove "YOURPANTIES" to reply MUADIB®

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Reply to
MUADIB®

...................OK, I found it. It was in the FAQ section for VDO gauges at

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..........Here's a copy and paste:

Will VDO tachs work with points ignition or Pertronix? Answer: Yes, with diode in line on the signal lead. Instructions are as follows: Purchase a diode #1N4005 from a local electronics store such as Radio Shack or Circuit City. Cut both ends of the diode so each is approximately 3/4" long. Crimp 1/4" female spade connector on the end of the diode with the silver band. Crimp butt-splice connector on the other end of the diode. Crimp the opposite end of butt-splice connector to the wire connected to the ignition signal source. Connect 1/4" female spade connector used in #3 above to terminal #4 on the back of the tachometer. Connect a ground (-) wire to terminal #3. Connect a switched 12-volt power wire to terminal #2. Set switches for appropriate amount of cylinders.

Reply to
Tim Rogers

I've been doing tune-ups for 35 years. I've never seen a bad Bosch condensor. The only time I replace them is if they are physically damaged or if they are not Bosch. (And sometimes I wonder if the latter is silly.)

Bosch used to offer a reward for anyone who could give them a bad Bosch condensor. They no longer do that, and I take that as a sign that the new ones may not be as reliable as the old ones.

-

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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Reply to
Jim Adney

First, Radio shack no longer carry the 1N4005 diode (in Canada anyway). I went to some other electronic parts supplier and got a 1N4007 (1000 volts rating instead of 600 volts).

It stabilised the needle great but now the reading seem to be way off. At first it wouldn't got any higher than 1500 rpm (on the tach). I tried tweeking the dip switchs "cylinder selector" but had not the proper VDO spec sheet handy to find the correct seting. I'll have to look to the VDo web site since I no longer have the paper spec sheet.

By the way, I paid a whoping 20 cents CDN each diodes. At this price, I think VDO should install them de facto in their tach...

Reply to
Eric Desrochers

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