1990 Eclipse GSX Tach Problem!

[slammed608]

Ive got a 1990 Eclipse GSX, and my tach seems to die when i get on it hard or even when i normally drive it, it works up untill about 4000 then will sort of jump up and down a little then fall, ive got a video ill post of it but what do you think? I looked around and saw noise filter but it seemed everytime it was that the tach didnt work at all sooo im a little lost on this one. https://www.youtube.com/watch?v=2QwWnkY2l18

 

[black97spyder]

My '90 that I bought yesterday does the exact same thing, im going to remove the tach filter tomorrow and use a 3-4" long jumper wire with male spade terminals on each end, that is then plugged into where the tach filter would plug in, to see if that fixes it... things like this seem to be a pretty common problem with the '90 tach due to the bad design they had to fix.

 

[jbeaton9292]

My '90 that I bought yesterday does the exact same thing, im going to remove the tach filter tomorrow and use a 3-4" long jumper wire with male spade terminals on each end, that is then plugged into where the tach filter would plug in, to see if that fixes it... things like this seem to be a pretty common problem with the '90 tach due to the bad design they had to fix.

This is exactly what to do i had a 90 laser and did exactly as you say yours are doing and the jumper wire worked just make sure you have a tight connection on the wire to the spades i soldered mine on you can get from any rc hobby shop traxxas plug connectors and use the spade connectors thats what i used fit 100%

 

[Steve93Talon]

Are you running a '91-94 ECU?

 

[David9er]

My '90 that I bought yesterday does the exact same thing, im going to remove the tach filter tomorrow and use a 3-4" long jumper wire with male spade terminals on each end, that is then plugged into where the tach filter would plug in, to see if that fixes it... things like this seem to be a pretty common problem with the '90 tach due to the bad design they had to fix.

One of the previous owners of my 90 talon attempted this fix but it was unsuccessful. I solved the problem by installing an aftermarket tach and wiring it to ECU pin 21. This did get me thinking though.....
Is it possible to splice a wire from pin 21 to which ever pin feeds the stock tach to get it to work?

 

[Phantom DSM]

One of the previous owners of my 90 talon attempted this fix but it was unsuccessful. I solved the problem by installing an aftermarket tach and wiring it to ECU pin 21. This did get me thinking though.....
Is it possible to splice a wire from pin 21 to which ever pin feeds the stock tach to get it to work?

This is a common issue on the 90 dsm and usually is an issue with the noise filter, this was eliminated on later 1g cars.
There is a write up on fixing this without using a noise filter, ill post link below
http://www.dsmtuners.com/forums/articles-electrical-wiring/414636-how-fix-1990-dsm-tach.html

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[David9er]

One of the previous owners of my 90 talon attempted this fix but it was unsuccessful

It doesn't always work

Is it possible to splice a wire from pin 21 to which ever pin feeds the stock tach to get it to work?

Basically my question is: can you bypass the noise filter circuit all together and use the signal from pin 21 to feed the stock dash tach as an alternate fix? Unless the stock tach uses a different type of electrical signal from what is supplied by pin 21 I don't see why this couldn't be done.

 

[slammed608]

My '90 that I bought yesterday does the exact same thing, im going to remove the tach filter tomorrow and use a 3-4" long jumper wire with male spade terminals on each end, that is then plugged into where the tach filter would plug in, to see if that fixes it... things like this seem to be a pretty common problem with the '90 tach due to the bad design they had to fix.

I have tried the tach noise filter bypass like youre saying but it didnt work, i mean it helped it out a little but still did the same thing just not as quickly

 

[dsm_mike1990]

m car was doing this till it died completely. turned out to be power transistor. witch is on same bracket as coil

 

[19Eclipse90]

m car was doing this till it died completely. turned out to be power transistor. witch is on same bracket as coil

May want to clarify this. The power transistor and coil are certainly not on the same bracket.

It doesn't always work

Basically my question is: can you bypass the noise filter circuit all together and use the signal from pin 21 to feed the stock dash tach as an alternate fix? Unless the stock tach uses a different type of electrical signal from what is supplied by pin 21 I don't see why this couldn't be done.

It was discussed as a possibility in this thread, around post #19: http://www.dsmtuners.com/forums/newbie-forum/410779-90-model-dead-tach.html. Nothing ever came of it as the OP there fixed his by finding and plugging in a noise filter and trying the alternate method already posted above.