I've ordered a new MAP sensor, but while I'm waiting for it to arrive I've gotta do a few long drives. When I was testing the sensor yesterday, I tried unplugging the vacuum hose at the engine end and then driving. Apart from a rough idle, the car purrs along beautifully with it disconnected! I'm tempted to drive like this until I can fit the new MAP sensor - do you think it would do any harm to the engine or give me terrible fuel economy or other bad things?

Hi,
A vacum leak would give a weak fuel air mixture on a carburetter car, but not sure what would happen on a fuel injection car, the map sensor controls the spark advance on this type of engine, so the timing would be out as the ecu would stick to a pre-set spark timing and this could lead to overheated spark plugs which would cause the engine to loose power and stop untill the plugs cool down a bit.......I think its a case of not a good idea....

Thanks
Paul T

If you plug up the pipe to stop the air leak, then all you will loose is the advance of the spark. Gentle acceleration will be possible, flooring the throttle will cause a huge flat spot.

Cheers

D

If you unplug the map sensor it causes the ecu to use the tps input only so it will drop mileage and power response a bit