Toyspeed.org.nz Message Board

by **Hachiroku** » Sat Sep 28, 2013 6:22 pm

I realise its not a Toyota but hey, it doesn't hurt to ask :wink:

Having misfire issues with a BH9 Legacy, EJ25 SOHC. Cylinders 1, 2 and 4 are fine but there's no spark on cylinder 3. We've replaced the coil and leads to no avail. With the key in the on position, the wire for cylinder 3 going into the coil plug has power but the others don't. Any ideas?

by **crispy'86** » Sat Sep 28, 2013 9:23 pm

Does this have the single coil pack on top of the engine or separate coils per cylinder?? If it's a single coil have you tried testing spark. If it's individual coils per cylinder they all should have igniton power on one of the 3 wires. This is going off a dohc be5 legacy twin turbo. May even be the transistor as they play up at times

by **Hachiroku** » Sun Sep 29, 2013 4:11 am

Single coil pack on top of the engine. Cylinders 1, 2 an 4 give a spark but nothing from 3.

by **Crucible** » Sun Sep 29, 2013 9:16 am

Was this a new or second hand coil. They are wastespark from memory so you get spark from one coil at once then the other, spark to two cyls and then the other two. If the other 3 have spark then it sounds like you have control (ignitor and signal to ignitor ok) otherwise you wouldnt have spark on the paired cylinder for that coil.

My guess would be a bad coil? Would.be a huge coincidence though.

by **Hachiroku** » Sun Sep 29, 2013 9:56 pm

Yeah brand new genuine coil. I'd assume it would be way too much of a coincidence for the new one to have the same fault as the one we replaced.

I'm a bit confused about the power going into the coil though. The cylinder that doesn't have spark gets power with the key on, the three that have spark get no power with the key on?

by **matt dunn** » Sun Sep 29, 2013 11:51 pm

Hachiroku wrote:Yeah brand new genuine coil. I'd assume it would be way too much of a coincidence for the new one to have the same fault as the one we replaced.

I'm a bit confused about the power going into the coil though. The cylinder that doesn't have spark gets power with the key on, the three that have spark get no power with the key on?

How many wires on the coil?

From memory there are only three?

by **Hachiroku** » Mon Sep 30, 2013 12:11 am

No it's definitely a 4-pin plug coming into the coil with 4 wires.

by **jondee86** » Mon Sep 30, 2013 12:16 am

Does the coil look like this ??

And does the plug have four wires ?? If it does, then you have two
double-pole coils running in wasted spark with a built-in two-channel
igniter, and the wires will be:-

Pin 1 = 5V IGN channel 1+2
Pin 2 = 12V supply
Pin 3 = GRD
Pin 4 = 5V IGN channel 3+4

Or you could have something completely different :-P

Cheers... jondee86

by **Hachiroku** » Mon Sep 30, 2013 1:20 am

That's it! I obviously had my wires crossed (excuse the pun) in thinking that the 4 wires each related to a cylinder :oops:

So given that it's wasted spark I'm confused why 3 cylinders are getting spark, everything I've read seems to suggest that they should fail in pairs?

by **sergei** » Mon Sep 30, 2013 9:02 am

Hachiroku wrote:That's it! I obviously had my wires crossed (excuse the pun) in thinking that the 4 wires each related to a cylinder So given that it's wasted spark I'm confused why 3 cylinders are getting spark, everything I've read seems to suggest that they should fail in pairs?

unless one plug is shorted.

by **jondee86** » Mon Sep 30, 2013 10:23 am

As above ^^^. Plug fouled or bridged inside the cylinder, or tracking
over the insulator on the outside. Try a new plug in that cylinder.

Cheers... jondee86

by **Crucible** » Mon Sep 30, 2013 1:21 pm

Hang on. So you have checked for spark at no3 coil and have no spark with new coil is that correct.
Or are you just down on one cylinder still?

by **Hachiroku** » Mon Sep 30, 2013 1:25 pm

Hang on. So you have checked for spark at no3 coil and have no spark with new coil is that correct.
Or are you just down on one cylinder still?

Yeah that's right. Cylinders 1, 2 and 4 give spark at the coil. The output for 3 gives nothing.

by **Crucible** » Mon Sep 30, 2013 2:10 pm

Ok.

All you can do is check voltage at the plug and make sure the earth is good. Really need a scope or good multimeter to check the the other two signal wires. Having internal ignitors means you cant test coil negs for switching.

A scope would be king right now. Very strange why you have spark on 4 but not 3 as they share the same signal circuit.

by **Hachiroku** » Mon Sep 30, 2013 7:11 pm

We have a resolution

It turns out that the brand new genuine coil was faulty on the same cylinder as the old one straight out of the box. A quick trip to the wreckers and a second hand coil has it running sweet as. What are the chances eh? Appreciate the help.

by **Crucible** » Mon Sep 30, 2013 7:55 pm

Bingo

Might want to check No3 plug gap while your at it and ht lead resistance there Maybe a reason that coil has gone on that cyl.

by **matt dunn** » Mon Sep 30, 2013 8:01 pm

Was it an Excel branded coil that was faulty from new.??

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