Hi all,

I've been reading here a lot but only recently joined.

2004 LS430, was showing a P0306 engine code. I noticed the wires had come loose from the injector. I rewired the injector but when listening to the injector you can hear it is not clicking at all. I tested the injector for resistance and it was fine, so I though perhaps it physically failed internally.

I thought it was a bad injector, so I took it to a mechanic who insisted that it was the computer as he wasn't seeing "signal/pulse" from the ECM. He said they traced the wiring back to the computer and it was all good so it had to be the computer.

I pulled the computer and sent it off to be examined and fixed but just got the call that they found nothing wrong with it.

What am I missing? Is there a switch, relay, fuse, fuseable link or something like that which is between the ECM and the injector? Is there something else which controls the pulse to the injector which I am missing?

I really like the car a lot and hope to get back to enjoying it soon.

Thanks for any input.

Edited to add:
I have replaced/tried the following:
MAF sensor
Spark plugs
Had ECM sent off to be tested (no issues found)
Battery
Swapped coils

 

Are you 100% sure you rewired it correctly and with electrical connectivity? I ask because I had a similar situation with 1 wire pulling out of the COP when changing my plugs. I thought I rewired the COP properly and with good electrical connectivity. My solution/fix lasted a couple minutes, lol. As others had suggested, using a new connector with solder+heatshrink is really the best way to do the COP.

Could you swap locations of your suspected bad injector with a good injector? See what results if you move a good injector to that cylinder, or what happens to the "bad" when you move it to a good cylinder.

You will need a OBD2 scan tool or disconnect the battery to clear the code once you make the repair.

Keep us informed and good luck!

 

Thanks for the reply. I fixed it myself (the injector wiring) and when still not getting any click, I figured maybe my crimp job wasn't good enough or the injector was broken. I was getting battery voltage but don't have a noid light to test for pulse. The mechanic I took it to rewired it and soldered it properly, so it SHOULD be good to go but he indicated it was not receiving pulse. He checked the wiring harness too but with the computer testing good, the issue seems to be in the wiring harness I'd think. I don't see that he cut the wiring closer to the computer to make sure the signal was leaving the computer and getting to the wire.

I'm trying to think of oddball things which it may be, relays etc. If a vacuum hose or EGR were leaking, I wouldn't just have an issue on one cylinder I'd think?

I have a scan tool which has been helpful. I swapped the coils between cylinders and changed all the plugs but it didn't fix it.

I had the shop do the work on the injector as I was wary of pulling off the fuel rail myself. I may have to learn how to do this since the shop couldn't fix it. I appreciate any tips on this as I haven't done it before.

Thanks for replying. I like this car a lot but this has me and my mechanic stumped.

 

When the wires were loose from the injector, I can see a definite likelihood of them shorting out something, but I'm not sure what as I've checked all the fuses (this car has a ton) and I had the computer tested by SIA Electronics and they saw no issues with it.

 

LS430inDE. I'm reading your old thread. Seems like we had kind of a parallel headache!

My car was running fine but leaking oil from the valve cover gaskets. So I thought, well that's an easy fix. Apparently that's when I yanked the wires from the injector.

My sympathies go out to you.

 

So, I'm a little confused with what was all done but it sounds like this wasn't an issue until the coil pack was unplugged in order to get to the valve cover gaskets. Putting it all back together is when you saw the issue.

P0306 I believe is a misfire on #6 cylinder so you know it's either the coil pack plug/wiring/plug itself. From the posts it sounds like you swapped the coil packs with another cylinder and still #6 is throwing the code? Just to eliminate things have you tried swapping the actual spark plug with a good cylinder? If that still doesn't work then you can narrow it down to the wring harness or clip. On my son's GS300 I was going round and round with a coil packs (they have one coil pack for two cylinders) and after replacing the coil packs and plugs I found that the clip just didn't clip on well enough to the coil pack. It was close and seemed like it fit but I just never heard that "click" sound of it locking in place. His GS already had aftermarket coil pack clips on it when we bought it. I had to get another set of coil pack clips and even with brand new ones a couple of them didn't click on properly. I had to go through and find both new and used clips that would click on securely to get it to work.

I've also had to replace a coil pack clip on my LS as well when I pulled a wire during a spark plug change. I ended up cutting off the OEM clip and soldering on an aftermarket one and it worked just fine. I'm wondering if there is a wire in your factory clip that might not be obviously pulled out but still isn't making a good enough connection inside the clip. I know this is something you probably don't want to do but if you are truly running out of ideas you might consider removing the OEM clip and replace it with an aftermarket one. If you do, wire/solder one wire at a time. There are 4 wires per plug and each cylinder's plug is wired differently so make sure to take a picture of the wire on the specific plug so you can look back for reference.

 

Forgive me for that, rereading my posts, they were a bit rambling.
Answering your questions:

• I have swapped coil packs around and have changed spark plugs with new ones. I'll double check the coil pack connection and the clip.
• I've been very focused on the fuel injector as I can hear it is not clicking. If the cylinder isn't making spark, does the ECM know not to send it fuel? Have to admit I have not checked for spark but will do so.

Thanks!

 

Plugged the computer back into the car. Producing the same issue as before P0306.

I confirmed the #6 cylinder has spark. I used a noid light on a good injector plug to confirm it worked then tried it on the #6 injector plug, no light/no flashing light.

So I'm down to testing the ground wire which goes back to the computer.

Figuring it either has to be the ground wire or the computer itself (though the electronics shop that tested the computer said it was fine).

I'm still accepting advice and input!

 

This may be helpful...

 

Update:

Hey folks,

I appreciate all of the good help I received here.

Turns out it was the computer.

Lexus dealer replaced for not much more than I could have done it for myself.

Back on the road and enjoying the car!

 

How much was it?