All cylinders showed the same compression levels? What psi was it coming in at?
Really NEED HELP , misfire p0303 2018 MUSTANG ECOBOOST
Iam very new to mustang side,
My car has misfire and throwing codes p0303 and p0300, only at the start.
Car starts at 1100-1200 rpm, later comes down, but once it reach between 900-1000, car shakes vigorously and misfires and throws codes. But later it smooths out after it heats up and comes around 850 rpm.
Changed spark plug and coils, cleaned and tested injectors, fixed catch can, did compression test, checked with new ECM and electricals. Found nothing.
The problem exists only during cold start. No misfires, while running and after it heats up.
Coolant level not dropping, but has minor leak from the timing gear side.
My car has misfire and throwing codes p0303 and p0300, only at the start.
Car starts at 1100-1200 rpm, later comes down, but once it reach between 900-1000, car shakes vigorously and misfires and throws codes. But later it smooths out after it heats up and comes around 850 rpm.
Changed spark plug and coils, cleaned and tested injectors, fixed catch can, did compression test, checked with new ECM and electricals. Found nothing.
The problem exists only during cold start. No misfires, while running and after it heats up.
Coolant level not dropping, but has minor leak from the timing gear side.
1 - 15 of 15 Posts
Just throwing this out there. But has the LPFS been replaced?
Hi,All cylinders showed the same compression levels? What psi was it coming in at?
Garage performed two times, one in the evening and one in the morning as my issue was with misfire during the first start or starting after a long time. If I drive around and stop and start the car when its heated, nothing is there. Its so smooth.
I need to check the holding pressure with them.
Ps: they informed that its a problem with the ECM, but why only during start?
Hi,
Garage performed two times, one in the evening and one in the morning as my issue was with misfire during the first start or starting after a long time. If I drive around and stop and start the car when its heated, nothing is there. Its so smooth.
I need to check the holding pressure with them.
Ps: they informed that its a problem with the ECM, but why only during start?
Yes they informed only 4 or 5 psi difference is there.
No brother. They checkes the cam shaft sensor, purge valve, did evap tests, checked the LFPS and all with another 2018 mustang also. Checked all wiring, currents, also mine checked on another 2018 ecoboost. Said all working fine.Just throwing this out there. But has the LPFS been replaced?
And i enquired any chance to be a problem with LPFS, THEN they said if due to that, rough idle and misfire will come thorough out. Not only on the start
While checking the purge system, you say they check the purge valve. Did they also check the cannister? The biggest problem with the EB evap system is when you try to keep filling the gas tank after the pump handle clicks off to squeeze in every drop you can fit. This result in eventual purge valve failure and in some cases the cannister gets saturated with fuel and also causes problems. I believe there is another solenoid associated with the cannister also.
Yes brother. They checked that also as they said may be cos that might be stuck open.While checking the purge system, you say they check the purge valve. Did they also check the cannister? The biggest problem with the EB evap system is when you try to keep filling the gas tank after the pump handle clicks off to squeeze in every drop you can fit. This result in eventual purge valve failure and in some cases the cannister gets saturated with fuel and also causes problems. I believe there is another solenoid associated with the cannister also.
Which was also found normal. 😞
Is this the stock tune? Or does it have a modified tune?
Stock tune..
Only cat deleted, adapter fixed to avoid check engine light.
Only cat deleted, adapter fixed to avoid check engine light.
Deleting the cat, increases flow by removing that restrictrion. This will throw off the PCM as the wastegate tables will be off. Also, the O2 adapter is a MacGyver fix with regards to the CEL, but does not address the resulting changes in the emissions thresholds, and again the PCM OEM tune will not be optimal. Every sensor that is "read" (dynamic data) by the PCM are input variables that are used in conjunction with various stored lookup tables (static data) and plugged into it's ongoing calculations and resulting actions. Do anything to change the OEM equipment that changes operational characteristics, and the PCM will attempt to compensate. Get too far out of the bounds of what it can compensate for and start to get undesirable behaviors. This is why changing the downpipe, especially to a cat delete, is usually not done unless a custom tune is in the immediate future.
I had this issue even before the cat delete. The engine was throwing p0300 and p0303 code wah before cat delete. Then i started to het p0420 code and when chekced found the cat to be clogged. Thats y i deleted the cat so that nothing happens to the turbo.Deleting the cat, increases flow by removing that restrictrion. This will throw off the PCM as the wastegate tables will be off. Also, the O2 adapter is a MacGyver fix with regards to the CEL, but does not address the resulting changes in the emissions thresholds, and again the PCM OEM tune will not be optimal. Every sensor that is "read" (dynamic data) by the PCM are input variables that are used in conjunction with various stored lookup tables (static data) and plugged into it's ongoing calculations and resulting actions. Do anything to change the OEM equipment that changes operational characteristics, and the PCM will attempt to compensate. Get too far out of the bounds of what it can compensate for and start to get undesirable behaviors. This is why changing the downpipe, especially to a cat delete, is usually not done unless a custom tune is in the immediate future.
Swung the pendulum the other way instead of landing on the middle ground. Went from clogged and flow restricted, to wide open and above normal flow. Neither side of that equation is optimal, even if it isn't the primary problem, its still a problem.
Interesting topic, and I think you're on the right track.Swung the pendulum the other way instead of landing on the middle ground. Went from clogged and flow restricted, to wide open and above normal flow. Neither side of that equation is optimal, even if it isn't the primary problem, its still a problem.
A while back, we had a thread going, where we discussed if the factory ECU has the ability to modify itself in case of a change in the drivetrain, and if so, how long would it take!??
I'm also wondering, what caused the catalytic converter blockage...?
This sounds like the classic symptoms of impending head gasket failure. The next test to do would be a cooling system pressure test, with the spark plugs removed. Make sure the engine is cold when performing this test. If the pressure drops, start looking inside the cylinder (s) for traces of coolant. You'd want to look at #3 cylinder first, of course. If you find coolant, you know what the next step is. If the car does need a head gasket, the Brian Crower head gasket is the one to use, along with the ARP head stud kit.Iam very new to mustang side,
My car has misfire and throwing codes p0303 and p0300, only at the start.
Car starts at 1100-1200 rpm, later comes down, but once it reach between 900-1000, car shakes vigorously and misfires and throws codes. But later it smooths out after it heats up and comes around 850 rpm.
Changed spark plug and coils, cleaned and tested injectors, fixed catch can, did compression test, checked with new ECM and electricals. Found nothing.
The problem exists only during cold start. No misfires, while running and after it heats up.
Coolant level not dropping, but has minor leak from the timing gear side.
1 - 15 of 15 Posts
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