Power loss whfn getting warm/hot

Hi guys,
i am trying to buy a Clio with a 2.0 F7R engine of a megane. The car is really lovely, but owner says, it has problem after running a while - it starts to loose power and only runs at max. 80 km/h.
The engine was overhauled last year and ECU was corrected to work with newer equipment.
The owner thinks, that it might be a problem with a faulty temperature sensor or fuel pressure regulator.
I don't want to buy a scrap car :-(

A new radiator with a SPAL ventilator is fitted, also a MOCAL oil cooler.
As of the owner, its not a problem of overheating. Maybe thats limp mode...

Did someone had same problems here earlier or do know reason for sich thing???

Thank you very much!

Christian

What ecu does it have? What connects to the spark plugs, HT leads or coil pack?

As far as I know, the megane F7R's don't have a limp mode :???: Have you compression tested it?

Temperature sensors only usually affect the idle running but try unplugging the temp sensor & see if it makes a difference

As far as i know, it works still with Clio 16v ECU, also ignition and engine wiring is from Clio (which is from 92, the engine is 98). ECU is modified to work together with newer engine.

The car runs normal, with power after start. But if you go more km, then it starts to go only 80 km/h. But it doesn't overheat.

The owner says, he can then hear noises from fuel pump, maybe pressure regulator doesn't open up right, when hot????

The ecu wont have had anything done to it by the sound of things, if the ignition & wiring is all from a 92 car, the head will have been machined to accept the distributor and it will be using the standard clio flywheel.

The obvious points will be checking the coolant sensor on the thermostat and the lambda sensor, unplug them to see if it makes any difference. The fuel pressure regulator could be a cause of the problem, all I can suggest is try swapping it for a known working 1 just to rule it out

I noticed from your other post that you've got a sports cat, I had a similar loss of power when I had a sports cat on mine & the cat had actually collapsed & partially blocked up the exhaust but was only noticeable when it was warmed up

In the moment it is the original cat in the car, but maybe ithas this problem too...

Yesterday i went to get the car from previous owner. I was a bit worried about the problem, but after i pumped 102 octane fuel it it, it has no failures/problems on 370km way home. Of course it was night and not that warm (around day we had 30° C), i have to wait for more drives to see what happens.