*HELP* Cylinder missfire from???
11-03-2007, 09:10 PM
#1
Staging Lane
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*HELP* Cylinder missfire from??? I did the LS6 intake swap last weekend and installed the new coolant lines but reused the LS1 intake gaskets. Now I am throwing a P0304 code and my car is not even firing on the 4th cylinder. I changed the spark plugs and wires out for new ones. TR55's went in.
That didn't help it.
I swapped coil packs from cylinder # 4 to # 2 and the missfire stayed in cylinder # 4.
I want to say that it's a vacuum leak but everyone that I've talked to seems to think that it is more of an electrical/spark problem than vauucm.
The car wants to shake really bad around 1400 rpm and there is a definite power decrease. I have searched everywhere on the forum to see if someone else has had a similar problem. No luck.
Any ideas would be greatly appreciated.
That didn't help it.
I swapped coil packs from cylinder # 4 to # 2 and the missfire stayed in cylinder # 4.
I want to say that it's a vacuum leak but everyone that I've talked to seems to think that it is more of an electrical/spark problem than vauucm.
The car wants to shake really bad around 1400 rpm and there is a definite power decrease. I have searched everywhere on the forum to see if someone else has had a similar problem. No luck.
Any ideas would be greatly appreciated.
11-04-2007, 11:47 AM
#2
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I'm giving you a bump on this one. I'd really like to know also. With all the technical advice on this site somebody on here has to have some kind of input on this.
11-04-2007, 10:11 PM
#4
if you switch coil packs and it remained at #4 then it could be a wiring issue on the coil packs for the #4 coil. You have eliminated the coil pack as being the issue so going backwards, the next question is... The wires that feed the coil. are they getting juice to supply the coil?
11-05-2007, 08:01 AM
#6
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The injector is plugged into the harness. I haven't put a volt meter on the coil pack yet or the wires.
I've tried spraying starter fluid around the intake to see if there was a leak and the engine didn't act any differently but I can't get under the intake all that well with the spray.
I'm really starting to wonder if I didn't break a pushrod?
I've tried spraying starter fluid around the intake to see if there was a leak and the engine didn't act any differently but I can't get under the intake all that well with the spray.
I'm really starting to wonder if I didn't break a pushrod?
11-05-2007, 08:56 AM
#7
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Is it possible you damaged one of the intake gaskets since you said you used the old ones? I dont know much on this motor but I change a lot of intake gaskets on 3100s, 3400s, and the 3.8s and usually when there bad they miss. Its a thought I guess. If everything worked fine before I cant see how you now have a bad coil pack or bad plugs and wires when you switched a intake. Unless like they said you left a injector wire off but you already cleared that up. Good luck
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11-05-2007, 09:37 AM
#8
TECH Resident
Could be an injector issue. Perhaps wire in the plug is damages, perhaps some dirt in the top of the injector, perhaps coil packs.
I would swap a few more parts around like moving the injector to another cylinder.
Good luck.
I would swap a few more parts around like moving the injector to another cylinder.
Good luck.
11-05-2007, 02:36 PM
#9
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Check For Injector Pulse On Cyl No 4 With A Test Light Attatched To Your Negative Terminal Backprobe Your Conncector The Test Light Should Pulse On Both Sides Of Terminal With The Car Running If It Doesnt You Have A Shorted Injector Or Bad Harness....also Put Spark Tester On Coil To See If Getting Spark....start With Your Basics All You Did Was Change An Intake Go Over What You Did...
11-05-2007, 02:38 PM
#10
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Also Use Long Screw Driver Or A Stethascope And Try To Listen For Injector Pulse And Make Sure The Injector Is Opening And Closing If You Dont Know What This Sounds Like Listen To A Different Injector For A Refrace
11-05-2007, 05:42 PM
#11
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I tried the injector pulse test and yes it is still pulsing. I am really starting to think that I did not seat the intake correctly and that I need to take it off and put it back on.
Unless you guys have some other ideas I'll let you know how that works out.
Unless you guys have some other ideas I'll let you know how that works out.
11-09-2007, 08:45 AM
#12
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Ok, I don't have a vacuum leak on the intake. I swapped out the injector and the problem stayed there. I put in new pushrods (the old ones on cylinder 4 were slightly bent, you couldn't tell until you rolled them) and the problem stayed.
We did a compression check on the cylinder and the highest it got was 5. Yes I typed the # 5.
So I am thinking bent valve? Or a cracked piston or ring? Anyone have these problems before?
I still need answers. ANyone got a clue or advice?
We did a compression check on the cylinder and the highest it got was 5. Yes I typed the # 5.
So I am thinking bent valve? Or a cracked piston or ring? Anyone have these problems before?
I still need answers. ANyone got a clue or advice?
11-09-2007, 12:06 PM
#13
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I had a similar problem on mine. I bought a new coil pack still go the code. Did some examining and found out that the wire had backed out slightly from the harness. Put it back in good as new.
11-09-2007, 12:23 PM
#14
If you did a compression check and that cylinder is that bad, then there is some kind of mechanical problem. My theory, while doing the intake swap, something fell into the #4 intake port. I would put the valve cover to check to make sure the intake valve is closing completely, but if you're only seeing 5psi from the #4 cylinder, that would tell you that the cylinder is dead.