PCM codes? Test this first

mikeeman_ford · 08-05-2018, 04:49 PM

Hi All,

Just to let u know what nightmare i have been through with my 5L.

I have been recieving an error code P0340 (cam sensor) Since purchasing the car 8 months ago.In searching the internet i found out about alternator diodes, crank sensor stuffing around with the signal, u name it.
I have replaced
Alternator
Alternator Plug
Battery
Cam Sensor
Cam Syncro - That was stuffed
Crank sensor - as per a mechanics advice.
Coil packs -They were 18year old original ones anyway.

Anyway - Upshot is, i replaced these items in the hope it would resolve these codes and also, given the age of the car, i figured, they were due to be swapped anyway. After all these swaps, same code, same running rich.

The next step was the PCM to be faulty.

Then an EFI guy in Tasmania told me to check for voltage drop on the earth side.... i wish i did this from the start, i was losing 0.3v from battery to engine, and 0.4v from engine to chassis. Swapped out the straps and sure enough the car is running like a dream.

So, if you are getting error codes on your car, just double check the earth side for voltage drops first, would have saves me a **** load of time.

Cheers

Vortex-98 · 08-05-2018, 07:20 PM

How were you losing 0.3v from battery to engine

mikeeman_ford · 09-05-2018, 08:26 AM

There was resistance in the old earth strap. So when you put the DMM on negative battery to engine earth mount (or the block) the Meter showed 0.3v. Electricity will always follow the path of least resistance, so it found resistance in the earth strap, the volts that couldnt flow through the strap then go via the multimeter. In testing i found some epic youtube videos on testing voltage drop, and voltage drop explained

speedzter · 09-05-2018, 01:19 PM

Interseting. I have the Cam sensor error, so I replaced the sensor with no change in the code.
Car runs fine, so I haven't looked any further, but I will take a look what you mentioned.
Where was it running rich ? Idle, cruise ?

mikeeman_ford · 09-05-2018, 04:06 PM

My car was running rich the whole time Speedzter. what was the most noticable thing for me was when i in second gear trying to rev it out, it would hesitate around the 2000rpm, then it would clear its throat and off it would go. basically, if put the DMM to measure voltage and get more than 0.1v they say replace the earth.
so 2 places i was told to check and replaced was
1. Battery negative to engine block (i had 0.3v) so i swapped the earth strap.
It didnt help, then i read about the one from the block to the chassis so the
2. Engine block to chassis (that got me 0.4v)

Its hard to explain typing, check out a video on voltage drop test. If your earth cant handle 14.4 (or 12.6 turned off) it will show up on the DMM.

Hope this helps, i wish i did this at the start. would have saved me a **** load of money. Especially as the cars are getting older and the earths are getting brittle

speedzter · 09-05-2018, 10:37 PM

I measured about 0.13v drop from the battery to the engine block.
Where is the engine block to chassis earth located ? Couldn't seem to find it.

mikeeman_ford · 11-05-2018, 02:14 PM

Sorry for the late response. Mine (5L) was from the bolt that holds the oil distick to the engine mount bolt. If yours is the 6, it might be somehwere else. you can just touch anywhere on the engine block, to somewhere on the frame to see voltage, you dont need to test it at the cable