2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

new rx7.. ? about tach output wire.

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Old 03-21-09 | 05:41 PM
  #26  
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From: reading,pa
Originally Posted by SonicRaT
Sounds like a short to me. Follow the yellow/blue back (remove that electrical tape if that's what I saw in the picture) and try to locate where the short is at.





yes it has electric tape if ur talking about the one in my picture coming off the white plug.....

ok i'll try to connutiy test it.
Old 03-21-09 | 05:42 PM
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That's the one, that 4 wire plug with the yellow/blue that has electrical tape on the yellow/blue is your tach's signal, I'd take that tape off and have a peak at whats going on under there.
Old 03-21-09 | 05:44 PM
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From: reading,pa
Originally Posted by SonicRaT
That's the one, that 4 wire plug with the yellow/blue that has electrical tape on the yellow/blue is your tach's signal, I'd take that tape off and have a peak at whats going on under there.
ok well i gone done took the tape off already and the wire under the tape is like half-way almost broken and ready to fall apart if I give it 1 strong pull. .... should i cut,re-strip, and try soldering it back together?
Old 03-21-09 | 05:47 PM
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Yes. Use some heatshrink tubing if you've got it to seal it up when you're all done.
Old 03-24-09 | 06:44 PM
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hey guys I got my stock tach working now... all i did was wrap electric tape on bottom of coils, and on top of the brackets, now my tach works so werid..... but now I have noticed my rx7 will not rev pass like almost 4,200rpm. problem related to trail coils or something else thats easy to fix?
Old 03-24-09 | 07:02 PM
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So, you wrapped tape around the coils (effectively insulating them from the car body, that they need to function correctly) instead of fixing the problem???
Old 03-24-09 | 08:02 PM
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Originally Posted by Icemark
So, you wrapped tape around the coils (effectively insulating them from the car body, that they need to function correctly) instead of fixing the problem???
no the tape is not wrap around them... the tape is only sitting on top of the bracket and on the under side of the coil! because everytime my coil would touch the metal bracket tach wouldn't work... so cover metal up with tape and bolted trails back down and now it work for the tach.

so whats the problem with the 4,000 - 4,200 rpm rev limiter feeling and not going any higher?

is this related to my problem or different?
Old 03-24-09 | 09:47 PM
  #33  
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Okay, the coils need to be mounted to function correctly. They can not be insulated by tape. This is part of your problem.

So get rid of the tape and find out where the short is. If there is a broken or damaged wire that needs the be fixed... not band aided with a hunk of tape.

Did you fix the broken wire that was talked about earlier this thread?
Old 03-24-09 | 11:06 PM
  #34  
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From: reading,pa
Originally Posted by Icemark
Okay, the coils need to be mounted to function correctly. They can not be insulated by tape. This is part of your problem.

So get rid of the tape and find out where the short is. If there is a broken or damaged wire that needs the be fixed... not band aided with a hunk of tape.

Did you fix the broken wire that was talked about earlier this thread?
ok i'll try loosing the tape but if i do that my tach wont work again. lol...

no i didn't fix the broken wire yet... cuz the yellow/blue wire coming off white 4 pin plug its gonna be hard to re-cut and re-strip it cuz there's like no room.

but i'll try i was just hopeing it wouldn't have to come down to that..
Old 03-25-09 | 11:28 AM
  #35  
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Okay, the Yellow/blue is the tach output wire. This is the summed signal from both coils and it feeds everything in the car that needs an engine speed signal (like the tach on the dash, the Engine Computer, the cruise control, the power steering computer, the ABS computer, etc).

So if you are shorting that wire (which it sounds like you are) then you are:

#1 causing all those things above to get an incorrect signal so the car is never going to run correctly.

#2 possibly destroying the coils ignitors, meaning that you sooner or later will need to spend money on replacement ones

#3 and wasting gas because the car won't run correctly.

So fix the car right instead of trying to band aid out the problem
Old 03-25-09 | 04:26 PM
  #36  
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The ignitor is probably getting its ground thru one of the two inboard studs that holds it on. The outboard stud/mount is isolated so it can't be that one.

As said, if the coil assy is isolated from the chassis, then the coil/ignitor won't/CAN'T work.

As for the short wire/damage.......just extract the wire/terminal out of the plug, then solder it to the part of the wire it's broken off from. Shrink tubing is called for.
Old 04-01-09 | 02:21 AM
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From: reading,pa
Originally Posted by HAILERS
The ignitor is probably getting its ground thru one of the two inboard studs that holds it on. The outboard stud/mount is isolated so it can't be that one.

As said, if the coil assy is isolated from the chassis, then the coil/ignitor won't/CAN'T work.

As for the short wire/damage.......just extract the wire/terminal out of the plug, then solder it to the part of the wire it's broken off from. Shrink tubing is called for.
well yeah my outter stud is isolated by a rubber o-ring type looking thing... but my two inner studs are don't have those things for some reason.... is that why my problem is that my tach is not working? should i go and buy rubber o-rings that'll fit the studs?
Old 04-01-09 | 10:08 AM
  #38  
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From: Rohnert Park CA
Originally Posted by FCmidnight Blue 88
well yeah my outter stud is isolated by a rubber o-ring type looking thing... but my two inner studs are don't have those things for some reason.... is that why my problem is that my tach is not working? should i go and buy rubber o-rings that'll fit the studs?
They are not isolated, because they are not supposed to be. They are supposed to be used, to ground the assembly.

So using tape, rubber studs, or O rings is just about the last thing you want to do.
Old 04-01-09 | 11:41 AM
  #39  
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Repeat of the above post.

The internals of the ignitor assy need to be grounded to the chassis. If you look at the attached jpg, I pointed to the symbol for the chassis ground for the internals of the ignitor. The pitchfork symbol.



Earlier I mentioned the outboard mount being isolated. I did that so you'd know that that mount can't give a ground to the ignitor. The inboard two mounts are not isolated and they are the ones that give a chassis gnd to the internals of the ignitor. Gotta have at least one of those studs making contact with the body of the coil/ignitor assy for it to work.

I'm clueless why your ignitor isn't working when the assy is grounded. Try another coil assy. Cheap from the wrecking yard. Twenty bucks and rarely fail if ever.

The Blue/Yellow can not ever be allowed to touch ground or the thing won't work.
Attached Thumbnails new rx7.. ? about tach output wire.-chassisground.jpg  

Last edited by Icemark; 04-01-09 at 12:23 PM. Reason: Added blown up picture for easier comprehension
Old 04-01-09 | 12:25 PM
  #40  
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Originally Posted by HAILERS
The Blue/Yellow can not ever be allowed to touch ground or the thing won't work.
Which what I am suspecting has happened.
Old 04-09-09 | 08:23 PM
  #41  
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From: reading,pa
hey guys its been a long time since upate on my problem... here goes... I repaired the broken wire and tach still doesn't work, so then i checked for spark while engine was running. I pulled the trail spark wires and there was no spark at all so that means its time for a new trail coil right????

i also pulled my plugs on the lead coils and those had spark.

so it needs a new trail coil correct guys?
Old 04-10-09 | 02:01 AM
  #42  
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are you guys still out there with me?
Old 04-10-09 | 04:53 PM
  #43  
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I guess i lost u guys.
Old 04-10-09 | 05:29 PM
  #44  
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test your wires going to the coil. to see if there is power to the coil. i would more likey bet it is the coil though but better off testing for power to it before getting a new one and being pissed that it doesn't work
Old 04-10-09 | 07:48 PM
  #45  
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From: reading,pa
how to i test the trail coil if it it's getting power?
Old 04-11-09 | 11:40 AM
  #46  
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volt meter you can pick one up at an auto parts store or radioshack then test using the plug prongs
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