ignitor question for experts, please help

[kmn5]

Question for eletrical gurus.
I have a 1994 lexus sc300 (stock 2jz-ge motor)
and it's eating up ignitors
I'm on my 5th one.
they would last anywhere from a few weeks to 6 months, and then just die.
The car would crank and get fuel (can smell it)
but it would never turn over; no spark. At least until I swap in another ignitor. Anyidea why they are going bad?

someone suggested a bad connection at the altenator, but I'm not so sure.
I've even tried changing the ecu and coil, but the problme still keeps coming back.
Right now I'm thinkning of wiring up new wires from the ecu to the ignitor.

looking at the diagram at http://www.autoshop101.com/forms/h39.pdf
figure 3-03

the signal goes from the ECU to the ignitor then the coil then the distributor.

I have a few posts asking this on supraforums in the NA section (2jz-ge motors) but so far everyone is stumped


any ideas?
thanks
Ken

[TcmaBoy]

Good luck finding the problem. I have been helping a guy try to chase down a similar problem with an older 4 Runner for a year now and haven't solved it yet.

[Pineapple]

Look for overheat, overload (current, voltage), short, bad ground, water. Try aftermarket ignition box. This will isolate the ignitor from the coil and probably prevent overloading.

[Hemi3TC]

Make sure you never leave the ignition ON without having the engine running. That
is one thing that destroys ignitors.


h3tc

[toyotaspeed90]

Originally Posted by Pineapple

Look for overheat, overload (current, voltage), short, bad ground, water. Try aftermarket ignition box. This will isolate the ignitor from the coil and probably prevent overloading.

actually having an aftermarket coil (or bad coil) that doesn't match the correct resistant ratings can cause the ignitors to go out..... this was a big problem i had when i went from a 4afe to 4age but still using the 4afe wiring.... i swapped in an msd coil during the motorswap and it fried ignitors (completely at random). threw in an mr2 coil and one hasn't gone since

also... when replacing.... put computer heatsink compound where ever the ignitor attaches to the distributor (or wherever it attaches to in that car)

[Pineapple]

MSD recommand a 0.8ohm resistor in series to the coil to limit current on stock point fire ignition system.

[Doctor J]

Try to troubleshoot TACH. wire from igniter.This wire goes to tachometer and a/c amplifier. If a/c condensate drain tube is plugged, the condensed water floods the a/c amplifier causing shorts.
Long, long time ago, on my 79 Supra the igniter was destroyed, after BIG specialist had bypassed thecurrent limiting 1kOhm resistor in the line from tach . terminal.

[Vicoor]

The part of the diagrams that you need to look at is on page 4 http://www.autoshop101.com/forms/h39.pdf.

Here you can see the power transistor in the igniter and how it provides a cicuit to ground for the current that flows through the primary windings of the igition coil. Anything in the circuit that would cause too much current (too low of circuit resistance) would overload the power transistor and cause premature failure.

Are you using factory parts? I've found that aftermarket ignitors and coils can be a source of problems.

Let me know if you are still chasing this and if you would like me to check on some specs and more specific tests for this circuit.

By the way the info in that link is just what they taught us in Toyota technical training

Victor

[philbert]

hey guys it sounds like to me that it could be an earth or a power supply fault i would try securing the earth to the igniter toyotas utilise the body of the igniter for the earth so check that also chech that your fusalbe links are all ok do not try to rewire the igniter due to the sheilded cables that the computer sends the signals to the igniter for dwell timing