Engine Misfire
Posted: 10/07/21 15:49
Hi there, can anybody help?
I bought a Mk3 in October 2020 with 6 months MOT. It ran fine for the first 6 or 7 weeks and quickly became my daily driver.
The car then developed what appeared to be a misfire, so I put some Redex in the tank and filled it up with fresh fuel, but still no improvement.
The following weekend I replaced the plugs but this made no difference.
I then checked the coils and they all seemed fine.
At this point, I thought a good blast down the nearest bypass might help to clear any kind of blockage, but the car quickly got worse and before long, I was doing 20mph with my foot to the floor. Managed to nurse it home.
Over the next few weeks did some reading up, and asked on the MR2 Facebook page if anyone had any ideas of what the problem could be.
Someone suggested I replace the 02 sensors, so I did this next. Still no joy.
Next a mate came around with his code reader and it showed ‘P0303 Cylinder 3 Misfire detected’ so next, I tackled the injectors. I took them out and blasted them with carb cleaner whilst hooked up to 12 volts, and put brand new seals at either end of each injector, put them back into the engine but the issue is still there.
(I gave it a good revving and there appeared to be white smoke coming from the exhaust - don't know if this is important or not?)
I’m aware that the issue could be the Pre-cat disintegrating, but if it is, the car’s probably a write-off anyway, so I want to make sure I’ve done everything else that I can (that doesn’t cost the earth!) before I tackle taking off the exhaust system.
Has anyone got any ideas of what else I can try?
I bought a Mk3 in October 2020 with 6 months MOT. It ran fine for the first 6 or 7 weeks and quickly became my daily driver.
The car then developed what appeared to be a misfire, so I put some Redex in the tank and filled it up with fresh fuel, but still no improvement.
The following weekend I replaced the plugs but this made no difference.
I then checked the coils and they all seemed fine.
At this point, I thought a good blast down the nearest bypass might help to clear any kind of blockage, but the car quickly got worse and before long, I was doing 20mph with my foot to the floor. Managed to nurse it home.
Over the next few weeks did some reading up, and asked on the MR2 Facebook page if anyone had any ideas of what the problem could be.
Someone suggested I replace the 02 sensors, so I did this next. Still no joy.
Next a mate came around with his code reader and it showed ‘P0303 Cylinder 3 Misfire detected’ so next, I tackled the injectors. I took them out and blasted them with carb cleaner whilst hooked up to 12 volts, and put brand new seals at either end of each injector, put them back into the engine but the issue is still there.
(I gave it a good revving and there appeared to be white smoke coming from the exhaust - don't know if this is important or not?)
I’m aware that the issue could be the Pre-cat disintegrating, but if it is, the car’s probably a write-off anyway, so I want to make sure I’ve done everything else that I can (that doesn’t cost the earth!) before I tackle taking off the exhaust system.
Has anyone got any ideas of what else I can try?