loss of boost when hot.

[xantiaman]

i have just come back from holiday and been in some nasty long traffic jams, up to an hour at a time with a mixture of crawling and stopped, after fixing my fans as posted previously everything was fine except that  after finally  getting underway after sitting in our first jam for an hour i only had 0.3 to 0.5 bar boost instead of 1 bar i normally have.the car drove fine except for the lack of full boost for the 100 miles of our journy  untill i stopped for petrol after which i had full boost again.any ideas??? could it be some sort of sensor cutting out but re-setting itself after the ignition was turned off and then on again. just curious really.

[pauldazzle]

Sound like the ECU is going into limp mode. You need to get a diagnostic done as there are many things that can cause limp. Recycling the ignition usually pulls it out of limp.

[xantiaman]

I thought of that myself but as i said the car was pulling fine for the 100 miles home,, easily doing 100 mph  on the m4 for  25 odd miles but i will say the speed did have to be built up a bit as there was no turbo push so to speak,,the turbo did work as i could feel it kick in it was just not as punchy as normal and ran out of puff at 0.5 bar.