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#1
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*LS1 Experts needed inside!*
See last post for latest update/problem.
Ok listed below is a thread from the External section and since I now believe it to be a internal problem I will post up all the relevant posts from the other thread.
I am really clueless why this problem is so bad.
Basically all I did was swap intakes, take the car on the road, miss a 3-4 shift @5500+ RPMs and now I have a completely dead cylinder. You should find all the necessary info in the posts below.
Sorry for the novel and all help is greatly appreciated!
Post # 1
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.
Post # 2
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?
Post # 3
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.
Post # 4
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?
Ok listed below is a thread from the External section and since I now believe it to be a internal problem I will post up all the relevant posts from the other thread.
I am really clueless why this problem is so bad.
Basically all I did was swap intakes, take the car on the road, miss a 3-4 shift @5500+ RPMs and now I have a completely dead cylinder. You should find all the necessary info in the posts below.
Sorry for the novel and all help is greatly appreciated!
Post # 1
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.
Post # 2
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?
Post # 3
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.
Post # 4
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?
Last edited by TARV; 11-26-2007 at 02:05 PM.
#2
I'm no expert ... but you sound like one of those manual driver horror stories you hear about...
you didn't happen to do a I went into 2nd gear from the top of 3rd kind of mis-shift???
It's possible to mechanically overrev, have a piston kiss a valve and be the end of it. If you have bent pushrods, then there's a high chance you did that and you've got no choice but to pull the heads...
you didn't happen to do a I went into 2nd gear from the top of 3rd kind of mis-shift???
It's possible to mechanically overrev, have a piston kiss a valve and be the end of it. If you have bent pushrods, then there's a high chance you did that and you've got no choice but to pull the heads...
#4
a smoked ring wouldn't read that low unless there was a huge ******* hole in the thing...there may be a hole in the piston but you DEFINATLY would have noticed that...i'm going to go with a bent valve, it explains the loss of compression but you may also consider checking your oil for flakes and fuel as these would indicate a more of a piston/ring problem
#6
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Where did the intake come from? I put an intake on my car that I pulled off of a wreck and a piece of plastic that was hiding inside of it lodged one of my valves open. I pulled the head to see where the miss was coming from and found a large chunk of plastic sitting on top of the piston. The valve did hit the piston but luckily didn't bend. So I just buttoned everything back up and it ran like a champ.
You need to pull your head and see what's going on. Hope you find something simple like I did. Good luck.
You need to pull your head and see what's going on. Hope you find something simple like I did. Good luck.
#7
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I got the intake from a friend of mine. Yes, I am really starting to think that I am at the least going to need new heads. I was offered a set of 98 heads for free, but why replace stock for stock when I will still have to pay $800 for the labor anyway? I was told that it would be fine to drive around easy until I was able to pull the heads adn really find out what the probelm is. I really wish it was something as simple as a piece of plastic like Jimmy says, but I used an air compresser on the intake before I installed it and blew air through all of the runners.
Damn this'll ruin a Friday!
Damn this'll ruin a Friday!
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#8
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IT IS NOT O.K. TO RUN THE CAR!!!! If you bent that valve, the valve is weak. The valve face can brake off, lodge itself in the head and punch a hole in the piston causing everything else to be junk. Don't start it, don't turn it over, just pull the head.
#11
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Well the car will be parked and only driven to get me home and then to swap the heads. I have a guy willing to give me a stock set of 98 heads as long as I give him the bad one. Great guy! I just hopet that the write up on LS1howto is suficient enought to get the job done.
Has anyone done a head swap themselves without pulling the motor? If so how long did it take you to do it right? I was thinking it will take it all weekend.
Let me know!
Has anyone done a head swap themselves without pulling the motor? If so how long did it take you to do it right? I was thinking it will take it all weekend.
Let me know!
#12
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OK, I put another set of heads on the car. Turns out the problm was indeed a bent intake valve. It looked like it got in a fight with a hammer. Piston had a slight half moon shaped gouge in it but not too severe. I upgraded the bolts to ARP's. The swap took about 2 days to complete. 4 hours to get the heads off and 4 to get everything back on and about 8 to clean everything the way I wanted it.
However, I am still throwing a P0300 random misfire code. Is this a spark plug or bad O2 sensor? The car doesn't like low RPM's in the higher gears and seems to buck and surge randomly while driving.
Advice needed again
However, I am still throwing a P0300 random misfire code. Is this a spark plug or bad O2 sensor? The car doesn't like low RPM's in the higher gears and seems to buck and surge randomly while driving.
Advice needed again