Land Rover Repair: Not Starting, throttle position sensor, mass air flow

Question
The day before the starting problems i took the vehicle through the mud and water. Could a sensor be dirty and need cleaning?
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Followup To

Question -
1995 disco 3.9 Disco started running rough and took a while to crank. now it will not turn over at all. Seems like something was was slowly dying and just finally gave out. Replaced cap, rotor, plugs, and plug wires. Currently at mechanic who says it has spark,fuel,and vaccum. mechanic states it has to be something electrical.          Please tell me some electrical components it could be. Box under passenger seat not showing and trouble.

Answer -
Hi Andrew,

could be timing related, the alternator, the coil, the spark modulator, mass air flow (MAF) sensor or other such ignition related sensors (TPS, VSS, O2, TS).

Rough running engine before final 'cough' points more to one of the above components instead of an electrical fault.  It may also be within the engine management system (EMS) and the ECU.

Your best bet is to have an experienced LR technician diagnose this on a 'testbook'.  If you start swapping out parts it could cost you even more that the difficult trip to the dealer service department.

For example, the spark modulator (found on the distributor) can cost about $800.  The MAF is about $1200... and so on.  

Have it diagnosed by a LR service department and at least find out what is causing the trouble.  Make sure they do a complete analysis of ONLY the starting and rough running problem.  Sometimes they insist you repair that left rear shock or the old ...  stay clear of additional work and focus only on what's immediately wrong.  I've seen service departments to load up the bill instead of correcting a $500 faulty throttle position sensor.

Best of luck,

JohnMc

Answer
Hi Andrew...

how much mud and water?  Must have been 'loads' of fun!

wow...if you got water high enough, you could have affected the SAM (spark amplifier module).  This little #$$%## is very sensitive to water and I've seen many Disco's affected this way after the engine was cleaned with high pressure and even garden hoses.  You have to wrap those electrics in plastic to prevent them from being exposed to water.

I think most local garages can test if the SAM is working.

Best of luck,

JohnMc

NB: oh, yes... YES, water can affect the sensors if splashed high enough.  MUD...well it could clog the rad and cause overheating but that's about it.