07 jku 3.8 I had a p0303 so I checked for spark on 3 and nothing.. I changed the plugs wires and coil pack and still no spark on 3. I understand that 3 and 6 fire as a pair but I have spark on 6. Why ? I've searched for hours and can't find anything similar. I know I don't have spark at 3 . If it were wiring or computer wouldn't it be both 3 and 6 ?
No spark from new coil #3 but fine on #6
- Thread starter Jdad
- Start date
Check your wire connection on the harness on the coil, could have a pin that's dirty and not making good contact. Are you sure that no3 wire is good, maybe swap it with another wire that you know is good.
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I checked connections and the pins are OK. I eliminated the plug wire by using a piece of hose and a spark plug directly from the coil. All posts provide spark except number 3. If 3 and 6 fire at the same time and 3 doesn't provide any spark why does 6 fire ? If 3 was burnt wouldn't 6 also not fire? It's a new coil pack that worked for about an hour then stopped firing 3 again. I replaced the pack plug and wire cause I had a p0303 prior. It went away for an hour now 3 doesn't fire again. Checked for voltage and signal at coil connection and all is good. Should I return pack and try another ?
I bought the jeep used about 4 years ago. It ran without a hitch til this nonsense. I don't think the coil that was in there was stock so I got one from napa . It's an eichlen branded coil. From what I've researched it doesn't make sense as to why 3 isn't providing spark and 6 is. It's the same coil with 2 terminals. The wire that feeds them is also the same. If 1 gets hot the other should to. If 1 goes out the other should as well. What am I missing here. I'm getting constant voltage and pulse signal at the connector for all. Do u know if the pcm shuts down that cylinder cause it sensed a misfire ? If so once reset should it at least spark ?
Was no 3 not firing on the old coil and when you installed the new coil then no 3 still isn't firing? If that's the case then it can't be the coil.
How are you checking the no 3 cylinder to know it isn't getting a spark? Are you sure the sparkplug is good?
How are you checking the no 3 cylinder to know it isn't getting a spark? Are you sure the sparkplug is good?
Yes no spark from 3 on old coil so I replaced it. It was fine for about an hour then same thing happened. Cel started blinking and threw same code p0303 so I checked for spark again and nothing. I used the same plug and checked every post for spark and all were good except 3. I checked for constant voltage at the clip and get a steady 10.8 volts. I understand it should be between 10 and 12 volts so it should be ok. Right ? I used a piece of hose to connect plug directly to coil to eliminate a bad wire but they are brand new as well. I also get a pulse signal from the other 3 wires at the clip. If u have a different method to check for spark I'm all ears. It's my kids jeep and he's busting my balls here. Lol what other tests can I do ?
Then that's telling me that there is a problem with no 3 plug and or wire. If it was me i'd swap no 3 plug and wire with another plug and wire from a cylinder that the wire will reach. Then if no 3 starts firing and the cylinder that now has the no3 wire and plug isn't then you know the problem.
I eliminated the wire and plug by putting a known good plug directly on the coil and no spark only at 3 same plug fires on all other coil posts
I put a new on . Also took the other 5 new wires and hooked them up to #3 coil post and grounded the plug. No spark with any wire on #3. All others have spark with same wire and same plug
Where did you get the info that no3 and no6 were to fire at the same time? I didn't know that any plug fired at the same time another one did.
I just went out and looked at my coil and they do both fire at the same time. I'll have to say I learned something new today, never saw anything like that before.
I just went out and looked at my coil and they do both fire at the same time. I'll have to say I learned something new today, never saw anything like that before.
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It's called wasted spark ignition or something. Paired cylinders fire at the same time. Now do u see why it's confusing ? All my research leads to 2 paired cylinders not firing not just 1. So in theory from research is if 1 fires the other should to and if 1 doesn't fire neither should the other 1. Makes sense to me. What doesn't make sense is why my 6 fires and 3 doesn't. If it were wiring there 1 wire that send a signal to those 2 so both would not fire. It makes sense that it is the coil but 2 coils doing the same thing ? Coincidence maybe ? My luck could be but doubtful. This is bs now. I've done tested just about everything and nothing is adding up. Hard to believe nobody has had this issue. Any chance u have a wiring diagram for an 07 ? That's another thing that seems to be confidential on the web
2007 - Google Drive
drive.google.com
I went and ;looked at my Jk and there is 4 wires going to the coil, so 2 have to fire at the same time like you say.
A p0303 is pin1 on the coil plug. I don't have a manual for an 07, but it's from an 08.
I'm not sure if this helps but here's the wiring for the coil pack/connectors.
You're right though, it doesn't make much sense.
The only thing that does make sense, but would be very ironic, is if you had a bad component you replaced with a new component which was bad for the exact same problem out of the box.
I have seen that happen though, and not just for automotive stuff.
Did you check spark at the coil pack itself instead of at the end of the plug/wire?
Vman thanks for the diagrams. Your a God... in my previous posts I mentioned that the new coil worked for an hour or so then #3 went out again. Also I connected a plug directly to the coil terminal and no power..I used a piece of hose and grounded the plug. Checked on all other terminals with the same plug and they all fire. Tomorrow I'm going to trace some grounds and check thise and try to get another coil when the store opens hopefully Sunday. I'll post what happens. If I can't find anything off to the shop it goes unfortunately. Thanks again and merry Christmas to all
Anyone know what voltage the coil input wire should be getting ? I read somewhere 10 to 12 and I have 10.8 but then I saw 11.45 and up.
Manual uses a 12v test light to check that, not a dvm, for testing. Didn't see a voltage range.
Did you check the PCM side connecter C2? The pin is #7 from PCM to pin #1 on the coil connector.