I don't honestly think they can be Oscar. When they go, they go and there is not much that can be done with them short of replacement. a quick blast of solvent like carb cleaner may be worth a try but i don't hold out a lot of hope.
Often the problem is external to them, a perished pipe or an air leak upsetting what it is trying to read. If it is bulkhead mounted, the pipe going to it is often the caused, either because it is split, perished or blocked.
Thanks Jim. But suppose the vacumm hoses are OK but there is some crud inside the sensor. Can it be cleaned using the carb cleaner? Can the sensor withstand this?
Oscar Lopez
'94 ZX 2.0 8v petrol (restoration to its former glory on its way after being neglected by stupid Ex)
The MAP sensor is fed with ground & +5V from the ECU on 2 terminals. The third terminal (usually the mid pin) returns a voltage proportional with the vacuum : 0.5V - 4.5V.
Switch on the ignition (dont start engine) and have a go with your voltmeter using the vacuum hose as a mouth suction straw.
If you are going to try and clean it with carb cleaner, DONT spary it into the MAP sensor - you'll kill it. It can only withstand either immersion or pouring of the carb cleaner into the hole. As such, it may dissolve a little bit of crud but it might only keep it going for a bit (if at all). Start budgeting for a new one...