Technical Misfire P0300 P0301 P0302 After Engine Replacement. Any suggestions?

[AmixTJET]

Hello everyone.

As some people know i melted my 2nd piston on my 198A4000 TJET engine. Long story short, i decided to go with engine replacement since the rebuild was expensive and i was skeptical if it would work.

So, new engine in from Mito (199A8000 , same as Abarth GP) . It starts smooth, with no issues , no misfires or strange sounds. After taking it to a spin to test if everything is ok i came across to a strange problem. When trying to accelerate above 3500 RPM the engine starts to misfire and CEL flashing.

I stopped, turned off the engine and then started again. No misfires again. Tried to accelerate and same thing. Misfire and CEL flashing.

It gives me P0300 P0301 and P0302 . Tried new spark plugs, coils , injectors with no chance.

I did a lot of research and came across to couple of threads talking about bad cat converters causing misfire with same DTC.

I also remember before swapping the new engine , the old one with the melted piston worked a lot and it was stinking gasoline which probably went into the cat and damaging it.

Anyone knows if a clogged/bad cat converter could cause this ? Is there anything i can try to see if the cat is performing as it should?

If i remove slightly the cat from the turbo so the gas could escape would that work?

 

[bugsymike]

Hello everyone.

As some people know i melted my 2nd piston on my 198A4000 TJET engine. Long story short, i decided to go with engine replacement since the rebuild was expensive and i was skeptical if it would work.

So, new engine in from Mito (199A8000 , same as Abarth GP) . It starts smooth, with no issues , no misfires or strange sounds. After taking it to a spin to test if everything is ok i came across to a strange problem. When trying to accelerate above 3500 RPM the engine starts to misfire and CEL flashing.

I stopped, turned off the engine and then started again. No misfires again. Tried to accelerate and same thing. Misfire and CEL flashing.

It gives me P0300 P0301 and P0302 . Tried new spark plugs, coils , injectors with no chance.

I did a lot of research and came across to couple of threads talking about bad cat converters causing misfire with same DTC.

I also remember before swapping the new engine , the old one with the melted piston worked a lot and it was stinking gasoline which probably went into the cat and damaging it.

Anyone knows if a clogged/bad cat converter could cause this ? Is there anything i can try to see if the cat is performing as it should?

If i remove slightly the cat from the turbo so the gas could escape would that work?

The cat is probably damaged , especially if any melted piston remains got into it.
The removing "slightly" of the the cat as you mentioned may help with one error code but will likely bring up a load more.
Re melted pistons, many years ago I had a customer with a rare Tickford 2.8 Turbo charged Ford Capri that had had many melted piston issues and various garages had worked on it. The problem was it was designed to work on high Octane 5* petrol which was no longer available, I was able to rebuild the engine using as special set of German Mahle Pistons which reduced the compression (cranking compression from original 180psi down to 150 psi) but then when on full turbo boost flat out is was able to get it's full performance without "pinking"/ detonation and so didn't melt any more pistons, so customer was well pleased.
On much newer vehicles such as yours that are designed to run on the lower grade fuels available now, they use "knock" sensors connected to the ECU and other devices to adjust timing to prevent "pinking " detonation etc. by controlling the timing advance, it may be an idea to check if that side is working correctly as you could end up with the same problem on the replacement engine.

 

[AmixTJET]

The cat is probably damaged , especially if any melted piston remains got into it.
The removing "slightly" of the the cat as you mentioned may help with one error code but will likely bring up a load more.
Re melted pistons, many years ago I had a customer with a rare Tickford 2.8 Turbo charged Ford Capri that had had many melted piston issues and various garages had worked on it. The problem was it was designed to work on high Octane 5* petrol which was no longer available, I was able to rebuild the engine using as special set of German Mahle Pistons which reduced the compression (cranking compression from original 180psi down to 150 psi) but then when on full turbo boost flat out is was able to get it's full performance without "pinking"/ detonation and so didn't melt any more pistons, so customer was well pleased.
On much newer vehicles such as yours that are designed to run on the lower grade fuels available now, they use "knock" sensors connected to the ECU and other devices to adjust timing to prevent "pinking " detonation etc. by controlling the timing advance, it may be an idea to check if that side is working correctly as you could end up with the same problem on the replacement engine.

Bringing another error codes won't be a problem. I want to see if the misfire will stop. I will give it a try tomorrow. Let's hope it's the cat and not ECM or something.

 

[AmixTJET]

Update 02/06/2023

Car went to an Auto Electrician/Tune Shop 4 days ago and found out that the ECU was the problem of misfires. Bought 2nd hand ECU and re-programmed it. All good for now.