tach only working part-time?

[malloynx]

well for like 4 months i've had no tach and about a month ago it just started working. now it only works some of the time. seems like the colder it gets outside the better the tach will work. i checked all my wiring and all seems to be good.

could i have a faulty igniter???

 

[IJ.]

When I installed my MSD CDI's I had to have the Tach reworked and the shop that did it was saying they're VERY fussy about voltage in so if you have any drop to the dash from say a dud/dirty ground that may cause it.

If it were a faulty ignitor I'd expect to hear/feel the car stumble at some point while driving.

 

[malloynx]

i think the voltage thing seems right.. i have other electrical issues and sometimes my wideband won't work either.

what can cause a voltage drop. what are the things i need to address.

 

[IJ.]

Start with the basics and unbolt the grounds and give em a clean with some fine sandpaper the refit em.

The Tach thing is annoying that's what mine was doing with the MSD's it would work when it felt like it and at other time play dead.

It's now plugged into the Wolf ECU but still had to have the V adjusted due to Toyota's electronics being so fussy.

Where are you getting the power for the wideband's heater circuit?

 

[malloynx]

thanks IJ i'm getting the power from the cig. lighter. i have it tapped into it.. is that a good spot??

also on my wideband i'm only reading around 11volts or so.

here is the stranger thing,, the car runs top-notch. nothing wrong with the vehicle driving and she boost fine.

should i measure the resistance of my grounds???

 

[IJ.]

Not sure what the config is on your wideband but I know the heater circuit in mine draws a LOT of current so I wouldn't think the Cig Lighter wiring could cope so maybe that's it!

If it's dragging mucho power it would cause a voltage drop in the dash and the Tach will have fits.

 

[malloynx]

wel here is the thing, i bought the car as a rolling chassis and the tach never worked. recently it just starting work off and on. where is a good.

also my wideband has a cig. plug so i just plug it in.. i forgot about that..

 

[IJ.]

How many wires go to the 02 sensor?

 

[malloynx]

i really dunno.. 3 or 4.. my whole system is plug and play. no cutting or splicing.

 

[IJ.]

Ok sounds like it's a heated 02 if it's 3>4 wire!

Sort of surprised it has a cig plug though!

Can you get a heavier power source from one of the bigger relays and try that?

I'm off to work on mine so I'll check back in at lunchtime.

 

[IJ.]

Any news?

 

[malloynx]

same thing. i really don't know where to begin. i just want my tach to work

 

[IJ.]

What did you try?

 

[malloynx]

nothing yet electrical is my downfall. i have a nice blue point multi-meter but i really don't nkow how to use it.

can you give me a starting point IJ

 

[IJ.]

ROFLMAO no probs! (Thought you tried something that made no difference)

I'd try another power source for the WB and see if that makes any difference.

Even to the point of carefully hooking up wires direct to the battery.

A quick test might be try it with the WB unplugged and see if anything changes.

Next I'd start checking all the grounds under the dash give em a snad and sand the place they mount as over time they will react from the different metals in contact.

Pity ShawnDude isn't here!
(he's really good at trouble shooting the Mk3 electricals)

 

[malloynx]

hmm
i was unaware of grounds under the dash??
all the grounds under the hood seem fine and i even added 4gauge wires last month.

i'm not really concerned about the WB, it's my tach that i want to work. i just drove to the autoparts store and the tach worked. i don't get it.. it will work some times but not all the time..

 

[IJ.]

Next time it's working try turning the headlights on and see if it dips.

Yep there's a bunch of ring terminals under there.

 

[malloynx]

would i have to remove my dash to have access to all them??

 

[IJ.]

Not really sure they're usually white wires with a black trace grab a flashlight and have look and see if you can spot them.
(knowing Toyota they built the car around them)

I know there are a couple on the passenger side behind the glovebox.
(keeping in mind my car's RHD so may be a little different)