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Old 03-07-2013, 03:46 AM
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Default Maf sensor short circuit + CO volts

While testing the new maf I have just mounted, one of my crocodile clips and pins I was using to check voltages fell out and shorted on another, now the landy won't start.. any ideas.. Its 10.43 in Denmark and I have to get my kids at 14:00 so kinda need the car to be running if possible. I hope te ECU isn't fried. Any quick replies are much appreciated. With the Maf connector on or off it won't start.. I've checked al the fuses and they all seem ok unless there are some hidden ones somewhere I don't know about. Help!!!

Jason
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Last edited by Scotauto; 03-07-2013 at 05:31 AM.
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Old 03-07-2013, 04:26 AM
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There are fuses in the engine compartment and under the dash, be sure you checked the ones up front.
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Old 03-07-2013, 04:44 AM
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Thanks for your quick reply. I had checked the fuses but started methodically and did it again and sure enough fuse blown.. It's running now :-) my kids will be happy...
I've just checked the CO volts and they appear to have the same volts as the battery. Any thoughts there... Factory set should be 1.8v I believe
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Old 03-07-2013, 07:40 AM
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One lead of MAF is fed by fuse F7, so that would be battery volts. Other leads from ECU.
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Old 03-07-2013, 08:27 AM
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I get a reading of around 0.2mV with no flow (engine of) and basically no change when engine running/revving. Isn't one of them a ground wire? does that also come from the ECU? Is my ECU dead?
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Old 03-07-2013, 08:56 AM
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I've got the co trim to read 1.8v now so it's only the air flow which doesn't seem to change.. (MAF is new) I'll check the wiring to the ECU but if anyone has other ideas let me know. My Co from the exhaust is still way too high!!! and I'm going for my test soon..
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Old 03-07-2013, 10:20 AM
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Early LUCAS ECU info attached, has expected readings for many things.

Connector should be:

2 - red/black (ground via ECU pin 25)
3 - Blue/green (0.3 to 0.6 reference from ECU pin 35)
5 - Brown/orange (+ battery when truck on)
6 - Blue/red (MAF signal to ECU pin 22) [typical 1.3 to 1.5 volts at idle, sets code 12 if less than 0.122 volts at idle or more than 4.96 volts.]

Do you need to adjust your base idle? Assumes with a 3.9 you have an older Lucas system. The 4.0 with the GEMS system does not have a base idle adjust. One way to tell the difference is look of the MAF sensor.
Attached Files
File Type: pdf 1314CU_14CUX_Systems info.pdf (577.0 KB, 18 views)
File Type: pdf LR_Fuel_InjectionSystems.pdf (413.4 KB, 12 views)
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Cooling System Problems: http://landroverforums.com/forum/gen...verview-51034/

Last edited by Savannah Buzz; 03-07-2013 at 10:25 AM.
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Old 03-07-2013, 10:28 AM
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thanks for these. Are these with the rave documents? I couldnĘt find them.. I'll first be able to check things properly next week... wiring etc. I'm suspecting ECU unfortunately
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Old 03-07-2013, 10:33 AM
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P.S. I can't get codes per OBD2 in Europe this standard is first from 1999 so I need a land rover computer system to check I think if I want codes like code 12 Its a 3.9 engine. Base idle you mean tickover right? It ticks over quite fine at around 600rpm.
CO emissions don't really change whether at tick over or 2500RPM (still over 10.0 CO)
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Old 03-07-2013, 10:43 AM
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Typical MAF output voltage at idle is between 1.3 and 1.5 VDC. A diagnostic trouble code (12)
is produced if MAF voltage is:
• less than 122 mV with RPM in excess of crank speed.
• greater than 4.96 V with RPM less than 976 for more than 160 milliseconds.


Does this mean that if the crank sensor is not working it would give a problem also?
How can I test that?
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Old 03-07-2013, 10:43 AM
 
 
 
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15, 1997, 1998, 39, circuit, discovery, ecu, failure, internal, land, problems, rover, sensor, short, v8


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