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Put in rebuilt engine 2 items...
#1
I have a 94 2 door sidekick with the 8 valve engine and 3 speed auto.  I just put in a rebuilt engine and two things are acting strange:

1. The RPM gauge is acting funny on the dash. It does not work in forward drive.  It works in Park and reverse.  This is very strange to me.  Anyone have any ideas why the dash would show rpm's accurately in park and reverse but not drive? 

2. My throttle cable (not the kickdown cable) has a second wire with a small metal ball on the end.  I could not figure out where this second piece was supposed to go?  Anyone know what this is for? None of the pictures of the able online show this second piece.

Also a huge thanks for the site.  Was super useful when pulling and replacing the engine.
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#2
(06-06-2019, 03:15 PM)hyrific Wrote: I have a 94 2 door sidekick with the 8 valve engine and 3 speed auto.  I just put in a rebuilt engine and two things are acting strange:

1. The RPM gauge is acting funny on the dash.  It does not work in forward drive.  It works in Park and reverse.  This is very strange to me.  Anyone have any ideas why the dash would show rpm's accurately in park and reverse but not drive?  (even car moving fast?) reads low, dead, or? wanders? the needle.?

2. My throttle cable (not the kickdown cable) has a second wire with a small metal ball on the end.  I could not figure out where this second piece was supposed to go?  Anyone know what this is for?  None of the pictures of the able online show this second piece.

Also a huge thanks for the site.  Was super useful when pulling and replacing the engine.
this car can have the cruise control option and 3 cables at the TB throttle valve.  id need  photo yours to really be accurate.  1,2, and 3 cables are normal 1 = 5speed very common.
the Tachometer is really a analog gauge, that only measures primary ignition coil pulses.(brown wire) for RPM  so has no idea (logic) of how shifter is sitting
but , when you shift from park to Rev, or drive, the engine goes under huge load and is due to the TC clutch stalled on output side, and 3L30 transmission oil pump load.

this will cause the RPM to fall greatly in drive (gear) (and RPM is heard, felt or seen at engine belts) at the engine, if the Idle controls are dead. (ISC =ECU) RPM will fall fast.

first off?
key on , CEL lamp must glow does it?
the go out running.
then with the diagnostic paper jump clip inserted into the next to main battery DCL the CELL then flashes out code 12  (for ok)

good luck to you!

PS some tachos, this old do fail, the Capacitors inside it dry out and make it read wrong, or dead.
if the ECU goes into limphome mode, idle controls are suspended. and will fail ISC regulation checks. (mostly worse on automatic transmissions )
another test for ISC actions, is in park, hot engine 800rpm is normal hot. and you turn on head lamps and heater fan full speed at same time, this load, added should not cause RPM drop,.(if have rear frost that even add more load) (alternator loads)
http://www.fixkick.com
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#3
So strange. My CEL does come on and turn off after start. The RPM is not effected by turning on the heater and it doesn't do the same thing in Reverse making that even stranger.

I think the second cable must be unused but could be used by a cruise control or something.
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#4
(06-08-2019, 05:23 AM)hyrific Wrote: So strange.  My CEL does come on and turn off after start.  

The RPM is not effected by turning on the heater and it doesn't do the same thing in Reverse making that even stranger.  

I think the second cable must be unused but could be used by a cruise control or something.

the car with 3 speed has 2 cables,  1 is throttle and other is the 3speed kick down cable.   the 3rd cable is always the optional cruise control .
I can see after 24 years the cruise motor drive burned out and last guy parked it to curb. sure. and sure left part of cable there?

bad tacho I'd say.
or bad wiring to it.
the tach has 3 wires,  ground, 12vdc power and the brown tacho input wire called spark primary pulses, from the spark coin and the noise supressor.
many of these tachs, now are dead or 1/2 dead,  it can not bad bad brown wire signals or the engine dies. and if tacho brown wire goes dead he ECU sees that and cuts fuel to avoid a fire.
all cars do that, modern EFI,  no spark cut fuel in 1/100th of second flat. (to prevent as seen on TV crash and burn.,  )

the engine is ok, the sparks ok the car drives ok and idles ok at 800 hot, but the tach lies. so the tacho  is no good. (or the wires to it, can fail (rust happens)
why the shifter affects this no clue by me.  (actual rpm is ok at all times)  if the engine actually slows down below 800 hot (750 ,min) then that is a problem,

if other gauges all read right the tacho has full power, both wires, 12v and ground. so the caps in the tacho dried out just like he ECU love to do.
http://www.fixkick.com
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#5
. The RPM gauge is acting funny on the dash = zero rpm"

the wiring does not seem right to the tachometer.
the tach does not wire to the 3speed PRNDL switch on right side of box ,
the PRNDL does tell the ECu that more aggressive idle controls are needed for in R or D OR L.
The tacho, simple reports the spark rate (converted to RPM) Tacho is pure SPARK RATE (frequency) the spark hit rate is scaled to RPM.

i made this long ago.  on 91, see the cruise  here, find that box and unplug it, if present it could cause vary bad things, that I will never understand. (never had one)

the tachmoter is like 1 meter, 2 transistors., 4 caps and that is it , it has integrator that converts pulses to needle volts that is right the meter is voltmeter for the tacho.




[Image: tacho.jpg]
http://www.fixkick.com
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#6
Ok I pulled the cluster and I found that one of the ground traces had shorted and burned. The tach was getting ground intermittently through the throttle cable. I removed the burned trace and put a wire from two of the ground screws to act like the trace. Tach is now solid. Bizarre that it grounded out. Don't know why that happened.
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