Overheating and rough running

[Spiike]

Hi all,

Having a problem with my 4.0, car had been great until sometime last week. Starts and runs great cold but once the temp gets over about 90 it starts running fairly rough, shunting etc, almost feels like fuel starvation, the temp gauge will sit just below 100 whereas before it would sit around 80. Another thing I've noticed is the revs jumping up and down at idle, anywhere between 900-2000rpm, this usually stops after 20 secs or so and rests at 900. After a hard run a few days ago I got back to the house and the car cut out, started it up, revs jumped to 2500 then over about 7-8 seconds dropped down the rev range to zero again.

Any help or suggestions would be greatly appreciated!

Thanks in advance

[Steve_D]

It's all guesswork until you have some figures.
So, you need RoverGauge. This will tell you what all the sensors are doing.
Look in the classifieds it is not expensive.
Then when you have the figures someone can point out any issues.

It may be something really silly and you will spot it for yourself...like you check it from cold and the water temp is reading something really strange and nothing like the fuel temp (from cold they should both be about the same).

Steve

[blitzracing]

It dose not make a lot of sense on the surface- but...

Look for an air leak around the plenum. This would make the idle unstable, and possibly make the engine run hot if its running lean. Also check the ignition timing has not shifted- unlikely but retarded timing can cause the temperature to rise.

[Spiike]

Thanks for the replies! Only other real info I have is that it does seem to run smoother at higher revs, which does sound timing related, do you happen to know what degree it should be at?

Thanks!

[Zeb74]

Test the voltage on your Air Flow Meter, I had the same symptoms in the past with a defective one.
https://www.actproducts.co.uk/2011/lucas-14cux-fue...

[Spiike]

Everything I could see seemed to be normal, on RoverGauge the temp was going into the red sometimes and getting up to about 218F at it's highest. I have a log, not sure if possible to share that or not.