The car misfires when its hot.

 

Some times it just wont go over 4000-5000rpm and its almost on hot days when the engine is hot too. Also when driving home on the motorway, the accelerator just stopped working while acclerating from 80mph. The car started to slow down. I had to let off the accelerator for a sec and then apply it again before it started to respond.

 

My thoughts are

 

A) PTU over heating. Its roughly the same symptoms I had when my PTU failed. IM thinking with the hot days and the fact my engine has been running quite a bit hotter lately that its over heating.

 

B) The fuel is evoporating before getting into the cylinders because it so hot.

 

C) Fuel pump is not working well and not pumping enough fuel.

 

Personally I think C is unlikely as on cooler days there is not problem.

Any you lot got any ideas?

would a problem with the intercoolers cause this problem?

any particular (coolant) temperature when the problems start to occur ? or is it random ?

 

Do you have a new or old model PTU ? (the new ones are pretty heat resistant)

 

option B sounds unlikely, but it could have something to do with the fuel (rail) temperature.

The ECU takes (safety) measures as soon as the fueltemps get out of hand and it might be what you are experiencing.

 

and ofcourse, the standard question: got any errorcodes ? :D

any particular (coolant) temperature when the problems start to occur ? or is it random ?

 

Do you have a new or old model PTU ? (the new ones are pretty heat resistant)

 

option B sounds unlikely, but it could have something to do with the fuel (rail) temperature.

The ECU takes (safety) measures as soon as the fueltemps get out of hand and it might be what you are experiencing.

 

and ofcourse, the standard question: got any errorcodes ? :D

 

 

It is a series I PTU and still in the standard place. There are no Error codes but I will check tomorrow. This is not the first time I have experienced this and there have been no error codes afterwards.

This was happeneing when the water temperature was reading just 100ºC, which is hot but not over heating. The temperature problem is going to get sorted out soon with a nice new Radiator.

>> It is a series I PTU and still in the standard place.

 

ok, then this is the first suspect.

 

Also check the CAS, as it can get extremely hot as well and can cause the same similar strange behavior as a dodgy PTU

I will move the PTU then.

 

Where is the best place to put it? Near the where the induction is?

yes.

 

under the nosepanel is the best location, but involves a bit of work the get the harness in that direction:

http://aus300zx.neuralmotion.com.au/tech/moveptu/movingptu_option3.htm