EJ20G Swap - No Spark on 3rd Cylinder

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BoostAddict
First Gear
Posts: 136
Joined: Thu Apr 08, 2004 3:52 am
Location: Toronto, Canada

EJ20G Swap - No Spark on 3rd Cylinder

Post by BoostAddict »

Hey,


I'm the guy with the WR-blue '91 Legacy Turbo who was asking you all the questions about transplanting and wiring up an EJ20G last winter.

I haven't posted on the board in a while, but I'm still trying to complete the EJ20G swap in my '91 Legacy Turbo:
http://bbs.legacycentral.org/viewtopic. ... swap+write

I've got the engine in, all the wiring modified to run with the SVX (6-channel) ignitor on 4-channels from a stock Ver.1 JDM WRX ECU. The car starts up, but there's no spark on the 3rd cylinder coil-on-plug.

We're eliminated the fact that the coil might be bad and we've traced the problem to the ECU not sending a "correct" signal to the 3rd ignition channel. The SVX ignitor is fine too. The problem is that the JDM WRX ECU isn't sending out spark on the 3rd ignition channel. We've even measured the voltage on this wire right by the ECU harness and it's not getting the same voltage as channels #1, #2 and #4. Most of the time the voltage is 0 and sometimes is "blips" to 0.5v. The other 3 ignition channels are getting a nice and smooth 1.5v.

When we pulled the coil plugs off the engine, #1, #2 and #4 had spark, but #3 doesn't.

The car's now at a car electronics specialists' shop and he says that there aren't any problems with the ECU or wiring. I've even tried running the car with a spare Ver.1 WRX ECU, but the same thing's happening. No spark on the 3rd ignition channel.

Does anyone have any idea what could be causing the ECU to send out the ignition signal to only 3 of the 4 channels? How does a Ver.1 JDM WRX ECU know when to send out a signal to a specific ignition channel? Is it solely based on the signal it receives from the cam sensor?

How does a cam sensor get its information about the position of the cam? Does the right-top cam sprocket have a magnet on it, whose position the cam sensor picks up? Is it possible that my cam sprocket is damaged and be causing this?

...Does this sound like a timing issue to anyone? I just wanna double check before I pull off the timing and re-install everything again.


Any help would be greatly appreciated :)

Thanks in advance,
PC.
'91 WR Blue Legacy SS (EJ20G, Mods) - SOLD!
[url]http://bbs.legacycentral.org/viewtopic.php?t=40572[/url]

Gravity Bureau Inc.
[url]http://www.GravityBureau.com[/url]
cjc
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Joined: Sat Apr 08, 2006 6:15 pm
Location: so cal desert

Post by cjc »

two things to look at cam sprocket and crank sprocket. either one is damaged will cause problem like stated
93 turbo legacy
97 legacy gt wagon (rip)
2000 legacy l (rip)
1990 legacy wagon
BoostAddict
First Gear
Posts: 136
Joined: Thu Apr 08, 2004 3:52 am
Location: Toronto, Canada

Post by BoostAddict »

Hey,

Thanks for your reply. The missing spark turned out to be a faulty +positive wire running to the coil on cylinder #3. 5minute fix :)

I'm currently getting all the wiring re-done professionally at Planet Motorsport (http://www.planetmotorsport.com/). These guys always do swaps professionally and guarantee their work!

After it's all done, tuned and running 100%, it'll be up for sale. It'll be a fun car :)


PC
'91 WR Blue Legacy SS (EJ20G, Mods) - SOLD!
[url]http://bbs.legacycentral.org/viewtopic.php?t=40572[/url]

Gravity Bureau Inc.
[url]http://www.GravityBureau.com[/url]
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