Misfire all cylinder 2004 GTO
08-02-2015, 06:35 PM
#1
Misfire all cylinder 2004 GTO I have a 2004 GTO which is misfiring on all cylinders. All the coils, maf, O2s, and their related wiring checked out good. The car burns rich and you can smell the gas. The plugs were wet and gas fouled. The car will not idle and must be kept at 1000 RPM or higher to prevent stalling.
The cam and crankshaft sensors have also checked out ok, but I am suspicious of the CKS. A vacuum test indicates low but steady vacuum (10.5") which suggests intake vacuum leak or late valve timing. I was cruising in 6th at 65 when out of nowhere the motor started to missing badly and I limped home.
There are no codes. None. Any help you can give me with this one would be appreciated. Red.
The cam and crankshaft sensors have also checked out ok, but I am suspicious of the CKS. A vacuum test indicates low but steady vacuum (10.5") which suggests intake vacuum leak or late valve timing. I was cruising in 6th at 65 when out of nowhere the motor started to missing badly and I limped home.
There are no codes. None. Any help you can give me with this one would be appreciated. Red.
08-06-2015, 11:11 PM
#6
I found 5 dead cylinders. Meaning the injectors were not working. I find it hard to believe 5 would go out at once. I am therefore testing the wires and the PCM for failures. Will keep you posted. If anyone has a clue as to what may cause 5 injectors to fail at once, please post.
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08-07-2015, 12:43 PM
#9
I appreciate the suggestions. First, the vacuum gauge shows a lower but steadier reading than normal. Meaning it should show about 22 inches,
but instead indicates about 17 and steady . This suggests late ignition timing.
If the spring were broken, cracked, or the valve stuck, the vacuum needle would fluctuate when that cylinder fires. Are you saying that the motor goes into a safe mode by deactivating cylinders when a spring breaks?? Cylinders 6, 8, 3, 5, and 7 are dead as far as the injectors are concerned. You pull the wires and it makes no difference. I am going to borrow noids lights from a friend and check the circuit.
Also, assuming you are correct, that the motor went into safe mode, what would cause it. I will check for a cracked or broken spring, but the needle is dead steady. Also, I found one bad coil. Would this cause the motor to go into safe mode? Your impute is appreciated.
but instead indicates about 17 and steady . This suggests late ignition timing.
If the spring were broken, cracked, or the valve stuck, the vacuum needle would fluctuate when that cylinder fires. Are you saying that the motor goes into a safe mode by deactivating cylinders when a spring breaks?? Cylinders 6, 8, 3, 5, and 7 are dead as far as the injectors are concerned. You pull the wires and it makes no difference. I am going to borrow noids lights from a friend and check the circuit.
Also, assuming you are correct, that the motor went into safe mode, what would cause it. I will check for a cracked or broken spring, but the needle is dead steady. Also, I found one bad coil. Would this cause the motor to go into safe mode? Your impute is appreciated.
08-08-2015, 09:52 PM
#11
TECH Senior Member
You said your plugs were wet fouled...
your injectors may be leaking...
or your harness has short causing the injectors to stay open...
or your PCM has a fault (injector driver has short which is keeping injectors open);
if any of these are the case, then pulling their harness plug will appear to not make much difference since injector will keep spraying.
your injectors may be leaking...
or your harness has short causing the injectors to stay open...
or your PCM has a fault (injector driver has short which is keeping injectors open);
if any of these are the case, then pulling their harness plug will appear to not make much difference since injector will keep spraying.
08-08-2015, 09:57 PM
#12
TECH Senior Member
The PCM does not have this level of engine protection.
08-09-2015, 10:55 AM
#13
Right now I know that the #6 coil is bad. I replaced the coil with one known to be good and it fired. The computer also finally registered a code. It is a 356 code or circuit problem # 6 cylinder (351 for instance means #1). All of these problems are beginning to center on the #6 cylinder.
Meanwhile I do not have a great deal of time for this. So I work on it whenever time permits. Tomorrow, I am borrowing a set of noids lights and a coil tester from a friend. I will let you know the results.
The car came with a set of MSD coils. These coils are known to have problems. Although the primary circuit OHMS in each coil was slightly out of spec, each coil should have worked. There must be something wrong with the secondary circuit. That is why I am borrowing a coil tester. I have seen a number of strange occurrences with cars over the years, but not where 5 out of eight coils stop working. Stay tuned and thanks for the posts.
Meanwhile I do not have a great deal of time for this. So I work on it whenever time permits. Tomorrow, I am borrowing a set of noids lights and a coil tester from a friend. I will let you know the results.
The car came with a set of MSD coils. These coils are known to have problems. Although the primary circuit OHMS in each coil was slightly out of spec, each coil should have worked. There must be something wrong with the secondary circuit. That is why I am borrowing a coil tester. I have seen a number of strange occurrences with cars over the years, but not where 5 out of eight coils stop working. Stay tuned and thanks for the posts.
08-26-2015, 07:16 PM
#14
I do not have a lot of spare time. So, I work on the car when I can. Since last posting, all injector harness plugs light up the noids light, meaning the wires and and drivers are good. The motor registered a 200 code or injector circuit malfunction. The code is now gone but the dead cylinders remain.
Also, the injectors were replaced with a known good set. The ECM was also replaced with a known good set and and still the cylinders fire intermittently. There are no codes except for 102 (MAF) which was also replaced with a known good one. The coil and injector harnesses were carefully checked. The injectors are out of control but nothing appears to be wrong. There are no O2 codes. Besides, the injectors are dumping insane amounts of gas into the cylinders, much more than you would expect from a rich O2. Also, both banks are effected, which means both O2s must have gone bad together for this to be the problem.
The motor makes blue smoke on start up because of the flooded cylinders. Do you think a timing chain jumped or a reluctor wheel?? I have wrenched on cars for years, and never had a more stubborn problem.
Also, the injectors were replaced with a known good set. The ECM was also replaced with a known good set and and still the cylinders fire intermittently. There are no codes except for 102 (MAF) which was also replaced with a known good one. The coil and injector harnesses were carefully checked. The injectors are out of control but nothing appears to be wrong. There are no O2 codes. Besides, the injectors are dumping insane amounts of gas into the cylinders, much more than you would expect from a rich O2. Also, both banks are effected, which means both O2s must have gone bad together for this to be the problem.
The motor makes blue smoke on start up because of the flooded cylinders. Do you think a timing chain jumped or a reluctor wheel?? I have wrenched on cars for years, and never had a more stubborn problem.
Last edited by rednari2; 08-26-2015 at 07:59 PM.
08-26-2015, 07:24 PM
#15
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I do not have a lot of spare time. So, I work on the car when I can. Since last posting, all injector harness plugs light up the noids light, meaning the wires and and drivers are good. The motor registered a 200 code or injector circuit malfunction. The code is now gone but the dead cylinders remain.
Also, the injectors were replaced with a known good set. The ECM was also replaced with a known good and and still the cylinders fire intermittently. There are no codes except for 102 (MAF) which was also replaced with a known good one. The coil and injector harnesses were carefully checked. The injectors are out of control but nothing appears to be wrong. There are no O2 codes. Besides, the injectors are dumping insane amounts of gas into the cylinder, much more than you would expect from a rich O2. Also, both banks are effected, which means both O2s must have gone bad together for this to be the problem.
The motor makes blue smoke on start up because of the flooded cylinders. Do you think a timing chain jumped or a reluctor wheel?? I have wrenched on cars for years, and never had a more stubborn problem.
Also, the injectors were replaced with a known good set. The ECM was also replaced with a known good and and still the cylinders fire intermittently. There are no codes except for 102 (MAF) which was also replaced with a known good one. The coil and injector harnesses were carefully checked. The injectors are out of control but nothing appears to be wrong. There are no O2 codes. Besides, the injectors are dumping insane amounts of gas into the cylinder, much more than you would expect from a rich O2. Also, both banks are effected, which means both O2s must have gone bad together for this to be the problem.
The motor makes blue smoke on start up because of the flooded cylinders. Do you think a timing chain jumped or a reluctor wheel?? I have wrenched on cars for years, and never had a more stubborn problem.
08-27-2015, 02:33 PM
#17
Well you hit it on the head. Number 7 Exh. rocker arm pounded its way through the retainer. The valve is stuck. It only moves when tapped with a hammer. The spring is off of it. The retainer center is pounded out. The right bank looks good.
I am an old school SBC guy. I never would have believed a stuck valve in one cylinder would take out 4 other cylinders. Didn't someone suggest that there isn't a safe mode on these cars?? If not, it apparently acted as one. Thats why I spent so much time going through the ignition and injection.
I was hoping to change the retainer and spring with the head on, but I have a stuck or bent valve. It appears as thought the OE rocker trunnion is very loose and that may be the reason for the retainer pounding. But, it may have loosed after getting pounded from the valve sticking. Who knows. The spring is good.
The car had a set of Crane duals and titanium retainers, with a 580-585, 224-228, 114 cam. Apparently a prior owner installed them when he upgraded to 243 heads. Titanium is supposed to be as strong as steel, but I'm not sure. I could only find fragments of what may have been the keeper.
Anything I should look for after taking off the head other than piston damage? I was hoping to change just the bad valve and retainer. The springs and the rest of the retainers appear to be good. I am also going to do the rocker arm trunnion upgrade. Anyone have any parts for thisi??
I am an old school SBC guy. I never would have believed a stuck valve in one cylinder would take out 4 other cylinders. Didn't someone suggest that there isn't a safe mode on these cars?? If not, it apparently acted as one. Thats why I spent so much time going through the ignition and injection.
I was hoping to change the retainer and spring with the head on, but I have a stuck or bent valve. It appears as thought the OE rocker trunnion is very loose and that may be the reason for the retainer pounding. But, it may have loosed after getting pounded from the valve sticking. Who knows. The spring is good.
The car had a set of Crane duals and titanium retainers, with a 580-585, 224-228, 114 cam. Apparently a prior owner installed them when he upgraded to 243 heads. Titanium is supposed to be as strong as steel, but I'm not sure. I could only find fragments of what may have been the keeper.
Anything I should look for after taking off the head other than piston damage? I was hoping to change just the bad valve and retainer. The springs and the rest of the retainers appear to be good. I am also going to do the rocker arm trunnion upgrade. Anyone have any parts for thisi??
08-27-2015, 03:33 PM
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Well you hit it on the head. Number 7 Exh. rocker arm pounded its way through the retainer. The valve is stuck. It only moves when tapped with a hammer. The spring is off of it. The retainer center is pounded out. The right bank looks good.
I am an old school SBC guy. I never would have believed a stuck valve in one cylinder would take out 4 other cylinders. Didn't someone suggest that there isn't a safe mode on these cars?? If not, it apparently acted as one. Thats why I spent so much time going through the ignition and injection.
I was hoping to change the retainer and spring with the head on, but I have a stuck or bent valve. It appears as thought the OE rocker trunnion is very loose and that may be the reason for the retainer pounding. But, it may have loosed after getting pounded from the valve sticking. Who knows. The spring is good.
The car had a set of Crane duals and titanium retainers, with a 580-585, 224-228, 114 cam. Apparently a prior owner installed them when he upgraded to 243 heads. Titanium is supposed to be as strong as steel, but I'm not sure. I could only find fragments of what may have been the keeper.
Anything I should look for after taking off the head other than piston damage? I was hoping to change just the bad valve and retainer. The springs and the rest of the retainers appear to be good. I am also going to do the rocker arm trunnion upgrade. Anyone have any parts for thisi??
I am an old school SBC guy. I never would have believed a stuck valve in one cylinder would take out 4 other cylinders. Didn't someone suggest that there isn't a safe mode on these cars?? If not, it apparently acted as one. Thats why I spent so much time going through the ignition and injection.
I was hoping to change the retainer and spring with the head on, but I have a stuck or bent valve. It appears as thought the OE rocker trunnion is very loose and that may be the reason for the retainer pounding. But, it may have loosed after getting pounded from the valve sticking. Who knows. The spring is good.
The car had a set of Crane duals and titanium retainers, with a 580-585, 224-228, 114 cam. Apparently a prior owner installed them when he upgraded to 243 heads. Titanium is supposed to be as strong as steel, but I'm not sure. I could only find fragments of what may have been the keeper.
Anything I should look for after taking off the head other than piston damage? I was hoping to change just the bad valve and retainer. The springs and the rest of the retainers appear to be good. I am also going to do the rocker arm trunnion upgrade. Anyone have any parts for thisi??
08-27-2015, 08:39 PM
#19
Thats interesting. I did not know that a slight hesitation would it to miss. What thickness of head gasket should I use? Also, I do not want to use OE torque to yield bolts. So, what is the head torque sequence and amount for standard bolts for these motors.