Rover MPI intake manifold: air temp sensor problem
Turbo Mini Forums

Hi,
Just to let you know.
I've used a Rover manifold on my 998 and after many attempts I gave up to use the original air temperature sensor. The manifold warms a lot and the sensor sends a too hot measure, so the engine goes lean (if the management does not use lambda measures). This is especially annoying after a hot restart, the engine is very hot, the sensor as well (sends 70C temperature), so the idle is erratic.
There is no way to correct that with the engine temperature because once the car starts moving the manifold cools down (faster then the engine), so the measure goes down as well. Until you stop in the traffic.
I've put the sensor near the air filter.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

Apparently this is a common problem.

The Rover sensor usually sits in an insulating bung to help, but obviously does not work well enough.

The only problem with putting the sensor upstream of the throttle is that it will not correct properly at part throttle.

At part throttle the air is cooled due to expansion after the butterfly, hence the density calcs will be incorrect.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

It's cooled by expansion but heated again by the manifold and by residual gases during intake opening.
If you put the sensor in the port it's warmed, if it's in the plenum the air stream may pass aside.

There is no perfect solution. Given the poor overall engine efficiency it's not worth to tune A/R perfectly. However the Rover installation is really bad, I'm just unable to make it work correctly.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

I had the same problem with heat soak using the rover sensor and bung and needed a quick solution at the time, so I fitted it in the silicon hose of my intercooler pipes. Just drill a 1/4" hole about 2" in from the end of the hose, then push and twist the sensor in, position the 'bung' (aka nut) on the inside of hose, and twist the sensor pulling the 'nut' upto the inside of the hose.

It sealled perfectly, and that was around 4 years ago. Did the same to Jimsters with no issues when we did his 16v as well.

TurboDave: your solution is the best because it measures the temp elevation after compressor and all the hot plumbing. I was just hesitating to drill expensive hoses.

Edited by alpa on 30th Apr, 2008.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

It'll be fine


http://www.efiminis.olicentral.com/index.php?topic=34.60

Edited by matty on 1st May, 2008.

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1/4mile in 13.2sec @ 111 terminal on 15psi

Do you not have a heat soak factor setting on the ECU?

The current ECU I am using has this. you adjust it to give you the best result, where it ignores silly daft temperature readings caused by heat soak.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

On 1st May, 2008 matty said:
It'll be fine


http://www.efiminis.olicentral.com/index.php?topic=34.60

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm