Technical Powerloss at operational temp / after hot restart?

[BlackWooZ]

So long story short.
I have owned this car (1.2 8v) for about 3 years now and this point it became annoying with this issue.

Basically everytime i restart the car at operational temperature the power just simply drops, barely accelerates, struggles, cant pass damned 50cc scooter which becomes embarrassing at some point like it lost 10-20hp instantly.

At cold starts it just runs like a dream, pulls without any problems or anything until you turn it off and on again... there we go again :bang:



What i have done to the car so far last few months:
- New fuel pump
- New alternator
- New battery
- New spark plugs,ht leads, coils
- New both O2 sensors
- New belts
- Cleaned throttlebody (and also fitted an intake, why not)
and other basic miscellaneous as liquid's and such...


I never had check engine light up, it doesn't overheat neither, everything is simply in function but yet it ''looks like'' its some kind of heat related issue (possibly)?


Could someone please enlight me up, i would be thankful!

 

[Brendan W]

Disconnect the temperature sensor for a hot restart and see if it makes any difference. I would expect this to put the temp warning light on, increase the idle speed and put the radiator fan on.

 

[BlackWooZ]

Disconnect the temperature sensor for a hot restart and see if it makes any difference. I would expect this to put the temp warning light on, increase the idle speed and put the radiator fan on.

I have gave it a try today, disconnected the temp sensor and gone for a drive.
It was even worse when disconnected, and then i have connected it back and give it another run!


It was running smooth, no stuttering and even rough idle was fixed,
but the powerloss is still simply there, can't pull the same as on cold mode.


Guess i gotta live with it then.


Thanks for the help buddy!

 

[Brendan W]

Have you got a temp gauge on the dash and if so what is it doing after the car has warmed up?
The ecu relies on the temperature sensor for information about the required fuelling. If it's telling lies the car will struggle. It's supposed to tell the ecu to back off on the fuel when the car warms up. For what they cost I would replace it.
You could pull a plug and see.

 

[BlackWooZ]

Yeah i do have temp gauage, well it stays in middle where its supposed to be when its warmed up.
It doesn't do anything weird, it works completely normal if you were referring to that though.

 

[judderbar]

Yeah i do have temp gauage, well it stays in middle where its supposed to be when its warmed up.
It doesn't do anything weird, it works completely normal if you were referring to that though.

So it runs fine when hot until you switch it off? Seems like a fixable problem. Just have to troubleshoot it.


What happens when you plug the sensor back in with the engine running?

 

[BlackWooZ]

So it runs fine when hot until you switch it off? Seems like a fixable problem. Just have to troubleshoot it.

From first/cold start reaching hot runs fine, after you turn it off and on
(while hot) back again it simply loses power.
But since i have tested it today with unplugging and plugging back in with test drives in between it fixed rough idling vibrations and stuttering while driving.



Still doesn't have that full acceleration/torque pull power as when its cold, it barely accelerates especially on uphills, so yeah...

What happens when you plug the sensor back in with the engine running?

Fan turns off, gauge works again, throw's check engine light (which goes away after 5mins), doesn't have any difference in sound of engine when i unplugged/plugged it back in.


I have no idea how temp sensor could just kill power of the car by that much?
It should work even better when hot, but it's totally opposite haha

 

[Ziggy122]

Temperature sensor can cause weird running issues

As it has a great affect on the fueling
If the sensor pegs out cold even tho engine is warm
Way to much fuel in the cylinders will cause poor performance....

One thing id suggest - a compression check
Espically hot as when hot it could have a lack of compression causing power loss
Cold the compressions ""okay"" and drives okay till it warms up

Ziggy