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-   -   fc stales issue with tach not working (https://www.rx7club.com/new-member-rx-7-technical-256/fc-stales-issue-tach-not-working-1010664/)

rx7240 09-05-12 11:30 AM

fc stales issue with tach not working
 
ok, i have searched but found some pretty confusing "answers"
ISSUE= 88 fc n/a stales at random times usually ok after warn up but idle is way low about 400 -500 rpms noever above 600 rpms ever
SECOND ISSUE = tach randomly works as well as the trailing coils spark sometimes works then dont if i turn the car off and on usually floods but after clearing the fuel out of the rotors it will start and work fine this issue is completely random i can drift all day then get home take it off the trailer then tach and coils wont work turn it off and on an no issue.
car does smoke (oil) when sitting and cold after warm up it doesnt smoke
and randomly floods out when starting

satch 09-05-12 11:56 AM

You probably have no BAC or if it is still on the engine then it doesn't work properly. Its role is to keep the idle above 750 rpm especially when load is placed on the engine.

The coil/igniter must be firmly bolted to the fender making good clean contact for this is how the unit receives its ground. Are you using the lack of a working tach to deduce that the trailing is not working at times or have you physically checked to prove that the trailing is incognito at times (not working).

DankDoobie 09-05-12 02:01 PM

FC bouncing idle on cold start
 
Whats up guys new to the forum and just bought a 87 n/a rx7... Not sure where to post this but.... The car runs perfectly fine once its warm but on a cold start the rpms bounce in between 1000 and 1500 and dies out if i dont give it some gas. Im hoping someone here can point me in the right direction to get this fixed.


I have a video of it, just cant figure out how to upload

rx7240 09-05-12 02:53 PM

i indefinably have leading spark at all times...shocked the hell out of me getting the two confused
thinking that the leading was closer to the fire wall, i maybe wrong on which is what but the coil pack near the fire wall is not firing when the tach stops working which i have thought was the trailing coil set which feeds the top plugs spark,
when the tach is working i have spark on all four however when in line waiting to go onto the track idle is low
I have no idea what the bac is but going to research now lol
and car was used on a farm for point a to b and has been driven off road mostly i got mud everywhere i have had it for a few months now and still cleaning things off most things are loose i will check the connection on the coil and ground im thinking it is atleast covered in dirt.
what does bac stand for something air controll

rx7240 09-05-12 03:08 PM


Originally Posted by DankDoobie (Post 11211440)
Whats up guys new to the forum and just bought a 87 n/a rx7... Not sure where to post this but.... The car runs perfectly fine once its warm but on a cold start the rpms bounce in between 1000 and 1500 and dies out if i dont give it some gas. Im hoping someone here can point me in the right direction to get this fixed.


I have a video of it, just cant figure out how to upload

DankDoobie,
i would start with vac lines and maf i had the same issue i had a couple cracked vac lines and a dirty maf

satch 09-05-12 04:24 PM

Bypass Air Control.

DankDoobie 09-05-12 06:00 PM


Originally Posted by rx7240 (Post 11211517)
DankDoobie,
i would start with vac lines and maf i had the same issue i had a couple cracked vac lines and a dirty maf


Awesome, I will see what I can find out. Very much appreciated

hioctane-dtc 09-05-12 06:10 PM


Originally Posted by DankDoobie (Post 11211440)
Whats up guys new to the forum and just bought a 87 n/a rx7... Not sure where to post this but.... The car runs perfectly fine once its warm but on a cold start the rpms bounce in between 1000 and 1500 and dies out if i dont give it some gas. Im hoping someone here can point me in the right direction to get this fixed.


I have a video of it, just cant figure out how to upload

It may also be the TPS out of wack and the throttle cable being too tight, I had similar issues before until my mechanic got it all fixed up.

rx7240 09-06-12 09:37 AM

ok , so i think i got something figured out, last night was drift practice and noticed that only when flooded and i pull the fuse to kill the spark and put it in does this happen i figure i confuse the ecu or something even tested this sure enough if i pull the fuse and crank it to un flood it then throw the fuse back in no trailing coils thinking im just going to run a switch to my fuel pump should solve the flooding issue idle is still low i think im going to pull the bac and clean it
thanks for the help!!!

rx7240 09-06-12 11:00 AM

i know that fc's flood thats just what they do ...but why? im going to route a switch to switch off pump when needed any other suggestions

DankDoobie 09-06-12 12:12 PM


Originally Posted by rx7240 (Post 11211517)
DankDoobie,
i would start with vac lines and maf i had the same issue i had a couple cracked vac lines and a dirty maf

Would any of those issues throw a check engine light? on my previous cars it would, but there is no light on in the fc

DankDoobie 09-06-12 01:18 PM

Maf sensor is drying off so cant test that yet

I found two vac lines plugged off under the intake. And then coming from the bottom of the charcoal box is a open line that goes to nothing, is that supposed to be like that?.... Everything else seems to be in place.

Thanks in advance

rx7240 09-07-12 11:06 AM

...Probably not i would search for vac line routing there is some good stuff on here about location and what not

DankDoobie 09-07-12 01:10 PM


Originally Posted by rx7240 (Post 11213553)
...Probably not i would search for vac line routing there is some good stuff on here about location and what not

Thanks for the info


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