Hi guys, my 3.6l engine is dead and Im thinking about 4.2! I want to know are these two engines (PT and ABH) and wirings the same??? I know that ECU are different, but I dont know about wires! If anyone could help me I would be thankful

or maybe there is some other 4.2 engine that fits well???

Wires partially different, depending on your exact year of production. More facts, more details, more answers.

My 3.6 died.
1990 PT engined. UK car.

I have fitted a 4.2 (1992 ABH engined, UK car), and initially used the injectors and rail from the ABH. I have since gone back to the original fuel rail and injectors.
The engine fired up with no major issues. I do have a few minor problems which will be looked into when I get a chance to have it serviced.

In addition.
I used the original Hydraulic pump, and Air con pump, to avoid losing fluid or gas. For expediency.
Both starters worked fine, so one is my spare.
I left the knock sensors installed on the ABH as they came from the donor car.
The original PT wiring loom connected up to all the same locations on the ABH.

I pretty much managed to do the whole thing single handed, using mainly a trolley jack to get it apart.

If they aren't already done. Use the opportunity to check and replace brake lines while the engine is out.

Anything else I can add, or provide insight into, PM me.

Mark

Small update

The few small issues turned out to be faulty temp sensors on the donor engine.
So I would advise checking the sensors work before installing and running.
Especially the oil temp sensor as it is a pain to remove once installed.

Take a look at the rear crank seal too. It's very easy to replace.
If the engine hasn't been run in a while, I would consider changing the cambelt. For several reasons-
It is relatively easy to replace, even without the special audi tools. The main difficulty being locking the crank. I'll post a link to some details for making a crank locking tool. Watch this space.

Check around the replacement engine for signs of oil leaks. I've seen several reports of leaks at the rear of the cylinder heads. Much better to find it at an early point.
Same for the oil filter and cooler manifold.

I wanted to do a full rebuild of my engine before I installed mine. This will happen over the next winter. The cylinder head gaskets of the 4.2 are cheaper than the 3.6.

i have 3,6 car with 4,2 engine
a have change -
engine wiring
ECU engine
ECU automatic transmision
throtte switch
throttle (is different )
clock (tachometer is different)
make a relay for lambda heating
some pins of plug 14 and 15

Small update.

First MOT of my car with a 4.2ABH running with PT ECU, electrics, and fuel rail. ABT chip.

Emissions passed
120ppm on hc
0.78on CO2 for emissions

I've not done a dyno run yet- not enough time. But performance wise it's great.

It really is as straightforward as has been suggested

Wow!
That's kinda shocking!
I know that even S8 injectors are below 180 cc, so even 3.6 injectors can flow adequate. I'm waiting for a street and dyno test. I hope you won't have your pistons melted due to high temp of under lean fuel mixture...
Nevertheless, it's a nice try!

Not sure i understand you completely.

You are shocked that the engine fit straight in?
Shocked that it fires up?
Shocked that it get's sufficient fuel?
Or shocked because a charged battery is fun sometimes....

It works