question for anyone.......
been doing loads of tests on the circuits this morning via the ford manual

test for engine coolant temp sensor operating voltage-+pin no 29.-vepin no1.ign on should be between 0.3 and 3 volts

im getting 4.5 volts

have plugged in another p8 ecu and am getting 2.8 volts,but cant run it on my p8 as its for 8 injectors.

to all you clever people-does this mean i have an ecu fault???

thank you
jay

 

measure the resistance of the sensor itself

 

we have measured the resistance at the ecu on pins 29 and 11 and gives indifferent readings.ive used 3 different sensors and the wiring has been checked for continuity and is ok,so no breaks in the loom

 

cool

 

but does that mean the ecu is at fault then?ive tried virtually everything now

 

so with the coolant at ambient( say 20 dgc) , the resistance across pins 11 and 29 of the ecu multiplug (with the ecu disconnceted) should be around 3750 ohms, run the car up to temp(80 dgc) , disconnect teh ecu again and measure across the multiplug pins 11 and 29 again and the resistance should drop to about 380 ohms.


this will prove whether its a wiring/sensor problem, one thing to note, if you have pushed the multimeter probes inteh bottom of teh multiplug and opened up teh spingy connectors too far , they they will not make a good contact on teh ecu pins, this will give a falsely high resistance (ie the ecu thinks its cold) and so will over fuel acordingly...


hth, dave.

 

also, to add, just to try,, you can interchange it for a L8 ecu, its wired up teh same and will at least run the engine to eliminate a faulty ecu..

 

the car will not start......it is flooding badly still which is why we are trying to test everything.
if i am getting the wrong voltage at the ecu can that cause it to do what it is doing.
when checking the resistance it seems to be one set of figures or another as if to show a wire problem,but we have checked for continuity on both and they are ok.can the different voltage cause the resistance to be wrong.im not an auto spark and my head is starting to hurt now

 

What do you mean by "indifferent readings" ? Are they within spec or not ?

Just because you've got continuity, it doesn't mean the wiring isn't damaged resulting in a high resistance.

 

when i say indifferent sometimes it was 2.21k with ign off but went off the scale with ign on.

another time it was 1.8k then with ign on 1.3k

but either way it still floods

do the figures make any sense?

 

give up-----going to collins monday

 

ah, there is the thing, u cant test the resistane of teh ect circuit with teh ecu inplace as you will see the input impedance of the ecu itself in the circuit aswell, thats why u must have the ecu disconnected to measure out the resistance, if u unplug the ect and measure across the ecu multiplug, you should see open circuit (ie infinate resistance) now short out the two pins in the ect plug and measure at the ecu plug again, the resistance should have dropped to less than 1 ohm, while u r measuring this, performa 'waggle test'. ie grab all the loom and waggit all about, move the wires around the location where they sit normally and see if the short circuit opens . the probelm with old car looms is that the copper work hardens with age and heat, when u unplug it and move it it may make contact again, but when its all back in its original location the break in teh wire may now be apparent.

dont forget electrical problems on cars are not usually complicated, just hard to locate, and 99.9% of car electrical probs are down to bad or corroded connections. which leads nicely onto the next bit...

have u had teh 2 multiplugs removed yet from behind the headlight near the ignitiopn coil (they join the engine loom to the car loom) and these notorios for fcukin up , they could not reallyt be in a worse place, right under neather the bonnet vent, rain= drips in = water in connections and over the years teh connections rot away and cause all sorts of wierd things. many people (me includd) have chopped these wires out one at a time and soldered them together so that a good eledtrical connection ismade. doing this does afect how u work on teh car as there are literally only a couple of retaining bolts thathold the whole loom to the engine anyway and the whole thing ca be moved out of teh way if u need to work on the head etc..

have faith... u will find it and it will be something simple

 

i will have a look at the multi plugs on mon
thanks for your help