You get credit for a triple. I started taking it apart last night, I should know for sure soon. Thanks for the suggestion about the cam timing. Probably a rookie mistake on my part, this was my first rebuild on an engine that had 2 cam chains.
Help! Engine misfire 2000 Mustang 4.6
- Thread starter 1984Convert
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I just finished putting the engine back together. The passenger side cam was mis-timed by 180 degrees. It is running great now! I might have given up and had to take it to the dealer if it wasn't for all of you that took time to help me diagnose the problem. With my son starting college - I really couldnt afford that. Thanks to all of you, with a special thanks to wmburns for going through the symtoms step by step. I've learned a lot about the mod motor on this rebuild and hope I can help some of you in the future.
Jim
Jim
I had some time to drive the car around since the last post. It's running pretty good, but there's a couple of minor things now. It seems like it has a slight miss, but not all the time - maybe it's just the fuel mixture. The check engine light came on. I pulled 2 codes out, the first - P0133 O2 sensor CKT Slow Response (Bank 1 Sensor 1), the second P0153 O2 Sensor CKT Slow Response (Bank 2 Sensor 1). The car has 87,000 miles on it. Is this just a matter of replacing the O2 sensors, or is it something to do with the MAF? Is Sensor 1 the sensor closest to the engine? I did clean the MAF with MAF cleaner spray when I had the engine out. The engine is stock except for the BBK longtube headers and BBk catted H pipe.
wmburns
SN Certified Technician
Check for air leaks. Long tube headers?
First, glad to hear the engine is running. This was a real head scratcher.
Let’s assume that all of the codes were cleared from the original problem.
Note, long tube headers can cause slow O2 response depending upon where the O2 bung has been installed. Maybe someone else can chime in if this is a possible source of the problem and recommendations.
DTC P0133 and P0153 uses pinpoint test map H20. This mainly deals with air/fuel control. Since you are getting codes for bank 1 and 2, we should focus on those things common to both sides.
Note, following good engine rebuilding practices/recommendations, critical sensors should be replaced. While I am not sure the O2 sensors are causing this problem, it is still a good idea to start out with known good O2 sensors. Many people believe O2 sensors are good for 100k miles. Other people believe they are good until the PCM throws a code. My personal believe is that after 100k miles, they may work but will respond slower. This hurts fuel mileage. Further, after a catastrophic engine failure, coolant may contaminate the O2 sensors. For this reason, I would replace the O2 sensors when doing an engine rebuild/replacement.
Of course, this could be a combination of old O2 sensors and long tube headers.
On to the Pinpoint tests. Test H23 states to look for any sources of unmetered air. Vacuum leaks. PVC system is tight. Exhaust tight? Vacuum hoses to the inside passenger compartment? All hoses connected to the throttle body. Is the oil dipstick tight and sealed? Even the smallest air leak can cause drivability issues.
Let’s stop there for the time being. If we go further down the pinpoint test map, we start looking for sources of coolant in the exhaust. Seams unlikely on a new rebuild. That is unless some coolant got in the exhaust previously.
Do you have any white smoke in the exhaust? Have you run the engine long enough to thoroughly heat up and burn off anything in the exhaust? After my Son’s truck dropped a valve, it took several hours of running to burn off all of the oil/water mix in the exhaust (I did replace the O2 sensors).
Let us know.
First, glad to hear the engine is running. This was a real head scratcher.
Let’s assume that all of the codes were cleared from the original problem.
Note, long tube headers can cause slow O2 response depending upon where the O2 bung has been installed. Maybe someone else can chime in if this is a possible source of the problem and recommendations.
DTC P0133 and P0153 uses pinpoint test map H20. This mainly deals with air/fuel control. Since you are getting codes for bank 1 and 2, we should focus on those things common to both sides.
Note, following good engine rebuilding practices/recommendations, critical sensors should be replaced. While I am not sure the O2 sensors are causing this problem, it is still a good idea to start out with known good O2 sensors. Many people believe O2 sensors are good for 100k miles. Other people believe they are good until the PCM throws a code. My personal believe is that after 100k miles, they may work but will respond slower. This hurts fuel mileage. Further, after a catastrophic engine failure, coolant may contaminate the O2 sensors. For this reason, I would replace the O2 sensors when doing an engine rebuild/replacement.
Of course, this could be a combination of old O2 sensors and long tube headers.
On to the Pinpoint tests. Test H23 states to look for any sources of unmetered air. Vacuum leaks. PVC system is tight. Exhaust tight? Vacuum hoses to the inside passenger compartment? All hoses connected to the throttle body. Is the oil dipstick tight and sealed? Even the smallest air leak can cause drivability issues.
Let’s stop there for the time being. If we go further down the pinpoint test map, we start looking for sources of coolant in the exhaust. Seams unlikely on a new rebuild. That is unless some coolant got in the exhaust previously.
Do you have any white smoke in the exhaust? Have you run the engine long enough to thoroughly heat up and burn off anything in the exhaust? After my Son’s truck dropped a valve, it took several hours of running to burn off all of the oil/water mix in the exhaust (I did replace the O2 sensors).
Let us know.
After reading the codes, I erased them. They haven't come back yet although I did get one new code P0136 O2 sensor circuit Malfunction (bank 1 Sensor 2). I know the back sensors aren't as critical as the fronts, and are not used to set the fuel mixture. I'll run it a little more and see what happens. I'll probably end up replacing all 4 sensors.
I don't think we had any antifreeze go through the exhaust, but before pulling the engine for rebuilding we took it to a high pressure car wash to clean it. This of course got a few spark plugs wet which caused some missing on the 4 block drive home. The missing put some raw gas through the converters which got them red hot. I wouldn't be suprised if the heat damaged the O2 sensors some.
All in all it was a good project. We bought a 2000 Mustang GT for my son that wasn't running right. We paid $3500 for it which gave us room for engine repairs. It is a rust free Florida car.The owner didn't know what was wrong other than it was making strange noises. It turned out that the noise was the blown out threads on the #3 sparkplug. It sounded like an exhaust leak. Fixed that with the Timesert kit (great kit) and then noticed a rod knock. I decided to pull the engine and give it a complete rebuild. I'm glad I did. The timing chain guides on these mod motors isn't the best. The one guide on the non-tension side is all plastic. The one on the passenger side was all broken up. The small pieces of plastic were down in the oil pan. The oil pump pickup screen was packed tight with them, which most likely caused the rod bearing to fail. Luckily my neighbor across the street owns an engine parts store, he was able to get the crank kit, gaskets rings... for us at a decent price.
My son is thrilled with the 2000, his previous car was a rough 1990 Mustang LX in that we bought for $600. This one is much nicer. I learned a lot about the mod motor that will come in handy if I ever do any mods on my 2007.
I don't think we had any antifreeze go through the exhaust, but before pulling the engine for rebuilding we took it to a high pressure car wash to clean it. This of course got a few spark plugs wet which caused some missing on the 4 block drive home. The missing put some raw gas through the converters which got them red hot. I wouldn't be suprised if the heat damaged the O2 sensors some.
All in all it was a good project. We bought a 2000 Mustang GT for my son that wasn't running right. We paid $3500 for it which gave us room for engine repairs. It is a rust free Florida car.The owner didn't know what was wrong other than it was making strange noises. It turned out that the noise was the blown out threads on the #3 sparkplug. It sounded like an exhaust leak. Fixed that with the Timesert kit (great kit) and then noticed a rod knock. I decided to pull the engine and give it a complete rebuild. I'm glad I did. The timing chain guides on these mod motors isn't the best. The one guide on the non-tension side is all plastic. The one on the passenger side was all broken up. The small pieces of plastic were down in the oil pan. The oil pump pickup screen was packed tight with them, which most likely caused the rod bearing to fail. Luckily my neighbor across the street owns an engine parts store, he was able to get the crank kit, gaskets rings... for us at a decent price.
My son is thrilled with the 2000, his previous car was a rough 1990 Mustang LX in that we bought for $600. This one is much nicer. I learned a lot about the mod motor that will come in handy if I ever do any mods on my 2007.
patman0911
Founding Member
Congratulations on getting the engine going again - that was a strange one. Sounds like a great project for you and your kid.
Slight sidetrack while you're figuring out your O2 sensor issues:
I wonder if there are any coil-pack engines running around with a 180 out-of-phase cam? With the waste-spark ignition, it might actually run OK. I imagine vibration would be worse since the firing order wouldn't be balanced correctly and idle quality and low-RPM economy & performance might suffer some since the injector firing would be out of time with the valve events on that side. Should have a nice galloping syncopated exhaust lope
EDIT: Upon further reflection, the the power strokes would still happen at the right times, just on the wrong cylinders with respect to engine balance so I don't think the idle would be syncopated after all but it should have more vibration. I think.
Slight sidetrack while you're figuring out your O2 sensor issues:
I wonder if there are any coil-pack engines running around with a 180 out-of-phase cam? With the waste-spark ignition, it might actually run OK. I imagine vibration would be worse since the firing order wouldn't be balanced correctly and idle quality and low-RPM economy & performance might suffer some since the injector firing would be out of time with the valve events on that side. Should have a nice galloping syncopated exhaust lope
EDIT: Upon further reflection, the the power strokes would still happen at the right times, just on the wrong cylinders with respect to engine balance so I don't think the idle would be syncopated after all but it should have more vibration. I think.
wmburns
SN Certified Technician
syncopated. Now that's a $5 word.
Interesting question. However, the intake valve will still be CLOSED when the fuel injector fires. So the only fuel getting into the cylinder is the non-atomized fuel on the valve itself.
Further, the intake valve is opening on the EXHAUST stoke. This will pressurize the intake manifold. Pushing any air/fuel mixture deeper into the manifold.
The excess air/fuel charge is most likely drawn into a working cylinder on the next power stroke resulting in a rich mixture.
At the end of the day, I think it runs the same way.
Interesting question. However, the intake valve will still be CLOSED when the fuel injector fires. So the only fuel getting into the cylinder is the non-atomized fuel on the valve itself.
Further, the intake valve is opening on the EXHAUST stoke. This will pressurize the intake manifold. Pushing any air/fuel mixture deeper into the manifold.
The excess air/fuel charge is most likely drawn into a working cylinder on the next power stroke resulting in a rich mixture.
At the end of the day, I think it runs the same way.
The engine actually ran pretty smooth with only bank 2 running. It didn't have much power though. There was a occasional popping sound in the intake manifold probably when the injector was open and it sparked.
How do I get a picture next to my name at the beginning of a post, like others do?
- Nevermind I figured it out. It's called an Avatar on the settings page.
How do I get a picture next to my name at the beginning of a post, like others do?
- Nevermind I figured it out. It's called an Avatar on the settings page.
patman0911
Founding Member
syncopated. Now that's a $5 word.
Interesting question. However, the intake valve will still be CLOSED when the fuel injector fires. So the only fuel getting into the cylinder is the non-atomized fuel on the valve itself.
It is kinda interesting isn't it?
The fuel injector firing at the wrong time wouldn't ideal but in this case (with waste spark ignition) I don't think it would keep the motor from running. It should only be an issue at idle and low RPMs. Early multiport injection systems were batch-fire and they managed OK and I'm just about positive I've come across something somewhere mentioning that some sequential injection systems switch over to batch-fire above a certain RPM because the timing becomes irrelevant as the firing events become so close together and the injector is open for so long anyway and the air is moving so fast that it just doesn't matter anymore.
I don't think that would be the case though. The intake valve would be opening at what used to be the power stroke and would suck the air/fuel mixture (however poorly mixed) on in like normal. Since the cams turn 1/2 the speed of the crank, the valve timing events still happen in the same place and order relative to the piston, it's only mis-timed with respect to the other cam and what the computer thinks is the correct timing. Imagine the cam timing is correct and the engine is at TDC and we're at the beginning of the intake/end of the exhaust strokes, now flip the cam 180 degrees and now it's at the beginning of the power/end of the compression strokes and as far as the cam is concerned, everything is fine as the piston is right there at TDC right where it expects it.
The reason 1984Convert's engine didn't run right is because the spark plugs fired at the end of his new exhaust stroke instead of the end of the compression stroke and the air/fuel mixture was just pushed out the exhaust mostly unburnt or uselessly burning in the exhaust manifold and sounds like it was backfiring up in the intake occasionally too. With the waste-spark system, there would still be a spark event at the right time and we'd get a normal combustion cycle.
Thinking it through a little more, cylinders 1 & 6 would fire together at the same time, as would 3 & 5, 7 & 4 and 2 & 8. So would it act sort of like a giant 4-cylinder engine? Hmmm...
(another thought I had is you could easily do some manual cylinder deactivation on the 4.6l - just pop out some cam followers and yank their injector plugs and you've got a 2.3L 4-cylinder, although with a lot of extra rotating mass - not as seamless as the OEM systems though when you want to switch from economy to power
)Might be a fun experiment next time someone's got time to screw around with nonsense like intentionally putting a cam in 180 degrees
Testing the driveability of mis-timed injectors would be easy enough to test though if you had enough slack in the injector harness or some extenders so you could just move some of connectors around to the wrong cylinders.
It's remarkable how few cylinders a V-8 can operate on.
wmburns
SN Certified Technician
This was an interesting post. Suggest editing the title to something like “cold headers, CAM 180 degrees out of phase”. May make it easier for someone else to find.
Also suggest opening a new thread for any addtional problems. This one is getting kind of long and off topic.
At the risk of hijacking a good post, (and beating a dead horse), I still think a Coil pack motor runs nearly the same (or worse) as a COP motor when timed 180 degrees out of phase.
Patman0911 brings up some interesting points. BUT….. In the 4 cycle engine, what is the next thing after power? Exhaust! For the 180 degree engine, where is the exhaust going to go? Intake manifold!
If there were a power stroke, the expanding hot gases are going to blow right past the fuel sprayed over the intake valve.
Where is the fuel/air charge going to come from? Our newly re-designed engine is going to open the exhaust valves on the intake stroke. The exhaust side is at a higher pressure (in relationship to inside the cylinder), it is reasonable to expect exhaust gas to flow in during the new intake stroke. Exhaust gases are inert (from the combustion stand point). Nothing for the off cycle coil pack to ignite.
The only source of a fuel/air charge is any intake back wash from the messed up exhaust stroke. Without a pressure differential to drive it, I have real doubts any will flow.
Consider also, if any gas does make it into cylinder, doesn’t gasoline have a Lower Explosive Limit (LEL) of 1.4% by volume? This means that it is possible to be so lean that explosion is no longer possible. If my math is correct, that works out to an air/fuel ratio of 71.5.
Granulations if you made it this far. Will close before I put everyone to sleep. On 2nd thought, this post will self destruct in 60 seconds………
Also suggest opening a new thread for any addtional problems. This one is getting kind of long and off topic.
At the risk of hijacking a good post, (and beating a dead horse), I still think a Coil pack motor runs nearly the same (or worse) as a COP motor when timed 180 degrees out of phase.
Patman0911 brings up some interesting points. BUT….. In the 4 cycle engine, what is the next thing after power? Exhaust! For the 180 degree engine, where is the exhaust going to go? Intake manifold!
If there were a power stroke, the expanding hot gases are going to blow right past the fuel sprayed over the intake valve.
Where is the fuel/air charge going to come from? Our newly re-designed engine is going to open the exhaust valves on the intake stroke. The exhaust side is at a higher pressure (in relationship to inside the cylinder), it is reasonable to expect exhaust gas to flow in during the new intake stroke. Exhaust gases are inert (from the combustion stand point). Nothing for the off cycle coil pack to ignite.
The only source of a fuel/air charge is any intake back wash from the messed up exhaust stroke. Without a pressure differential to drive it, I have real doubts any will flow.
Consider also, if any gas does make it into cylinder, doesn’t gasoline have a Lower Explosive Limit (LEL) of 1.4% by volume? This means that it is possible to be so lean that explosion is no longer possible. If my math is correct, that works out to an air/fuel ratio of 71.5.
Granulations if you made it this far. Will close before I put everyone to sleep. On 2nd thought, this post will self destruct in 60 seconds………
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