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        General >> Problems >> Stalling and electrical problems
        
(Message started by: femtoman on Jan 8^th, 2007, 5:45pm)

Title: Stalling and electrical problems
Post by femtoman on Jan 8^th, 2007, 5:45pm

Hi to everyone and can I just say congrats on the fantastic website. I'm very new to all this so you'll have to bear with me. I should also say that I'm not a mechanic but I'm ggod mates with one who has been helping me out with this.

I have a '97 scorpio 2L petrol with the 8 valve engine(200k mls) and air con (not climate cntrl). The miles are high but i know the car was well serviced by the previous owner. I have a problem with the battery discharging itself overnight. We performed the test with the ammeter and discovered that there was a drain of 3.5 Amps coming off the battery when the car was off. Removing the 30Amp fuse for the cooling fan caused the drain to return to normal. We noticed that re inserting the fuse caused the magnetic clutch for the AC to engage, i.e. with everything off the compressor clutch is engaged....this is what was causing the battery to drain. With the car running and the AC knocked off the compressor clutch is engaged and condensation forms on the pipe. i.e the AC compressor clutch is permanently engaged even when the car is off. We checked both fuse boxes for water ingress but they both seemed fine. The battery cover has been on the car since I've had it (about 6 months). I thought that for now I'd just disconnect the plug to the compressor and do without the AC. Has anyone come across something like this before?

Around the same time as the battery discharging problem I had started to experience a stalling problem. With the engine ticking over the revs would drop to nearly stalling, then pick up again, drop again and so on, until eventually the engine would just stall. Because both problems occured at the same time I thought they might be related. I don't have access to a diagnostic service and am reluctant to go to a ford garage because of the cost.

We worked through the idle problem page on this site. We changed the plugs and leads, cleaned MAF, cleaned butterfly valve, swapped IACV with one from another scorpio, checked for leaks on air inlet and vacuum systems and couldn't find any. None of this solved the stalling problem. One thing I have noticed is that i don't hear the hissing noise when i open the petrol cap, so maybe there is a problem with the EVAP system. Is there another way to check this?

I have since discovered that there was a crack in the exhaust manifold which the previous owner had welded. Perhaps the crack is re-emerging..could this be a possible cause for the stalling?

We're still not sure whether we have two separate problems or if they are connected in some way. Any ideas or advice would be much appreciated.

Oh yeah, other strange electrical things were happening after reconnecting the battery. On one occasion the central locking just started locking and unlocking itself continuously. I had to disconnect the battery and i waited a few minutes and then reconnected and it was back to normal.

Sorry about the length of the thread but I wanted to include everything.

Thanks in advance,

John.

Title: Re: Stalling and electrical problems
Post by TiberiuS on Jan 8^th, 2007, 6:21pm

Hi John, welcome aboard mate :).

From problems other members have described, a siezing AC compressor can drag down the idle revs and even make the car stall, I'm presuming the compressor being engaged all the time is causing this rather than the compressor itself siezing. As for the clutch being engaged all the time I'm no expert on the system but I'm presuming the fact that you can hear it engage means it's working properly and the fault lies elsewhere in the circuit. The wiring diagrams are here (http://www.carsoft.ru/avtorepair/sierra_el.html), the clutch is fed from the WOT relay, make of it what you can ;).

Regards, Bruce.

Title: Re: Stalling and electrical problems
Post by femtoman on Jan 10^th, 2007, 10:44am

Thanks Bruce,
We're going to work thru those circuit diagrams..........someone has suggested that it might be a diode in the circuit which is casuing the fault........I'll let you know how we get on,

John.

Title: Re: Stalling and electrical problems
Post by TiberiuS on Jan 10^th, 2007, 5:44pm

John, backward facing diodes like in the clutch circuit are normally put there to stop surges and spikes when the component is energised (like you often have a backward facing diode placed across relay coils). But anything's possible, it sounds like you have a good idea where the fault lies.

Good luck ;)

Regards, Bruce.

Title: Re: Stalling and electrical problems
Post by femtoman on Jan 12^th, 2007, 1:09pm

Problem solved...............
Found that the leads coming of the Lambda probe were frayed and damaged. replaced these and everything is ok again.

Thanks for the advice...much appreciated

John.