weak spark????????

[baja1]

'97 with blown head gasket, installed '02 using everything that was off the perfectly running '97. zero spark. replaced the ICM now all plugs have spark but weak, I believe too weak to run. coil packs meter fine (I now have six to chose from all within specs) new NGK's almost new NGK wire set.......the voltage at the coil plugs with key on is 11.75, timing is correct and i've double checked all the grounds, good compression on all cylinders.
weak spark, any ideas?.....thank you!

 

[TheDurk]

'97 with blown head gasket, installed '02 using everything that was off the perfectly running '97. zero spark. replaced the ICM now all plugs have spark but weak, I believe too weak to run. coil packs meter fine (I now have six to chose from all within specs) new NGK's almost new NGK wire set.......the voltage at the coil plugs with key on is 11.75, timing is correct and i've double checked all the grounds, good compression on all cylinders.
weak spark, any ideas?.....thank you!

11.75 is about 25% charge. See chart below. You're in the red!

Charge it up and then see what happens.Or is voltage at the battery with key off a lot higher? Do this((from the FSM):

3. (Maintenance-Free Battery)
CHECK BATTERY VOLTAGE
Measure the battery voltage between the negative (-) and positive
(+) terminals of the battery.
Standard voltage: At 20°C (68°F): 12.7 - 12.9 V
HINT:

Before measuring the voltage, turn the ignition switch
OFF and turn off the electrical systems (headlight, blower
motor, rear defogger etc.) for 60 secondsto remove the
surface charge.

When measuring the voltage, however, turn the ignition
switch OFF and turn off the electrical systems.
If the voltage is less than the specification, charge the battery.

 

[baja1]

11.75 is about 25% charge. See chart below. You're in the red!

Charge it up and then see what happens.Or is voltage at the battery with key off a lot higher? Do this((from the FSM):

you are correct, my battery was not fully charged when I took that reading. excited to think my problem could have been as simple as a low battery I installed a fresh battery and was seeing 12.20 at the plugs, hooked everything back up checked the timing one last time and cranked it over....ZERO SPARK AGAIN! :help:

 

[TheDurk]

you are correct, my battery was not fully charged when I took that reading. excited to think my problem could have been as simple as a low battery I installed a fresh battery and was seeing 12.20 at the plugs, hooked everything back up checked the timing one last time and cranked it over....ZERO SPARK AGAIN! :help:

Now that you have a good battery charge, follow the FSM:

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/ig5vzfe/ignsy/ovi.pdf

I'd pretend I was starting from zero, don't assume anything is good.

 

[catrains]

'97 with blown head gasket, installed '02 using everything that was off the perfectly running '97. zero spark. replaced the ICM now all plugs have spark but weak, I believe too weak to run. coil packs meter fine (I now have six to chose from all within specs) new NGK's almost new NGK wire set.......the voltage at the coil plugs with key on is 11.75, timing is correct and i've double checked all the grounds, good compression on all cylinders.
weak spark, any ideas?.....thank you!

no spark could be the crank sensor. the PCM/computer needs to know where the crankshaft is to then create the proper coils to ground out and then make a high voltage for that plug cylinder at the correct time/position.

could be you disturbed the wiring to/for the sensor.

 

[JayRolla]

No spark can be crank sensor like stated. I believe some vehicles wont spark also when timing belt is broke or stripped because cam is not spinning. Is the timing belt in good working order?

 

[baja1]

No spark can be crank sensor like stated. I believe some vehicles wont spark also when timing belt is broke or stripped because cam is not spinning. Is the timing belt in good working order?

brand new timing belt. i've swapped crank sensor's but haven't actually bench tested, will do!

 

[Nickydj88]

Hey did you get to the bottom of the problem?
I have the same problem atm

 

[Ibrad]

This post is coming up on being 8 years old!!!!! Start a new post or let the forum know some history on your rig.