Code 48 - Battery voltage low - with new battery!

[Stupink]

im not confident enough in that answer for you to spend your money, but you shouldnt need 2,500rpm to make it charge, so once its loaded up like that how much did you need to rev to get it back charging? ie above your standing voltage?

[Leigh]

D'oh, brain fade again, I was revving it from the engine bay (no one around at the time to rev it or watch the multimeter for me), so I couldn't see the rev counter, at a guess around 2000-2500.

I'll do the load test again tommorow and use a brick or something if there's no one around

[Stupink]

get some longer wires for your multimeter just nice big fat ones.

[Leigh]

LOL, did think of standing it up, but the wires are too short to even reach that far.! Have to get some longer flyleads, hehe

[Leigh]

This little lovely fault has reared it's head again after 2 weeks of having the car back and no ECU light.....
Drove to Oulton Park yesterday morning for a days marshalling, 50 mins or so no problem. Car sat parked up all day, almost immediately I left the circuit the ECU light came on, same sort of pattern.
Driving at a steady pace = no light
Accelerating , especially in higher gears = ECU light, yet the car felt 'OK' and got me home no problem at all.

Read the fault codes out this afternoon and had Low Batt Voltage, Lamba Sensor Mixuture rich (which I expected as it did the 'almost-cutting-out' a week ago and I saw the sooty tail pipes telltale signs again).

But this time I've got another one for the collection..
145 Incorrect immobiliser signal received Faulty unit or break in wiring

arrrrrrrghhh

Not had any problems with the key starting the car yet..

Never had time today to check the earth strap to/from the alternator, I so hope all these annoying recent faults are related to each other and one fix will kill them all!!

[Leigh]

I had a bit of a (possible..) lightbulb moment today.
Since the ECU light started coming on again not long after leaving Oulton Park on saturday, and each morning when I drive to work I seem to get maybe 2 or 3 mins driving before it starts lighting up again..

Do you think it could be something as simple as the drive belt needs replacing? It hasn't been done for many years Just checked back through my maintenance log and it was May 2004..) and I noticed a few weeks ago that it's looking like it's starting to crack slightly. I was wondering if, after a few mins of running and the belt heating up, it's getting slacker and not turning the alternator pulley 100%. Seems to be getting worse, as initially it only happened when revving in higher gears, but now it seems to do it under less load, even sat idle occasionally (once the car has been run for a while that is..)

I had a quick look in the Haynes for the change procedure and it sounds like a bit of a bugger, any shortcuts ? Mines a 1996 so I'm assuming it's the single belt, tho it's got a Bosch alternator and the Haynes says later models had the Delco-Remy..

[Leigh]

OK, sorry this is a bit of an old one, but I've done some more 'tests' recently and was after some thoughts..

I changed the main earth strap from the battery to the engine block a few months ago for one in good condition (no dodgy electrical tape on this one!). I left it disconnected for a few hours to clear the fault codes etc, and for about 2 weeks afterwards I didn't have one single instance of the ECU light appearing. I don't do a high amount of miles a week so it will be taking the car at least 1 or 2 weeks to relearn it's behaviour after the battery was off.
There's me thinking "great, earth strap has fixed the problem", only for 'ping' , engine light comes on again . Read the codes out and it's the same , 48 - Battery low voltage.

It's been like that for a few months now, and I really want to get it sorted as the motorsport season is underway again and I'll have semi regular trips to Oulton Park etc.

I've timed it and it seems that around 3 mins after starting the engine is when the ECU light will first come on, this seems to be regardless of engine load as I've timed it both on the run to / from work, timed it sat idle on the driveway, and sat in car park at work in neutral with revs held at 2000, all the same.

Does 3 mins sound about the time it would take for the engine to start using it's sensors (doesn't it run closed loop or something until things warm up?)

I'm noticing more and more now that it's affecting the performance and fuel consumption...
With the trip comp on instant consumption, if I sit at the same speed the consumption is steady, but the slightest (and I mean really, just *breathe*..) on the accelerator brings the ECU light on, and the fuel consumption plummets.
Avergage consumption is about 19.5 right now, where it used to be around 24-25.(most of my runs are A & B roads to work and back )

Sorry this is kinda like a jigsaw puzzle without any reference image ..
Other symptoms I've noticed :
i) Along with the fuel consumption, the exhaust has the sooty appearance again similar to previous occurences (for the 2 weeks when I had no ECU light it was clean, I deliberately cleaned it up after changing the earth strap so I could see if it was resolved),

ii) The car hesistates on accelerating, most noticeably from a standstill.
The best way I can describe is it it's almost like I imagine turbo lag is (never having driven a turbo..) . Theres a definate pause for maybe 1/2 a second the the car picks up and goes, whereas it used to be instant (one thing I always liked about the 8V was that it was good for pulling away quickly even if it didn't have the top end grunt of it's bigger sisters).

At first I wondered if the fuel pump was possibly on it's way out, but now I'm wondering if the Air flow meter might be the culprit. I took the plastic lid of it while the engine was running and the pointer'vane was moving freely, and I can affect the engine if I manually nudge the pointer, is there any way to test it aside from swapping out with another one.

I have noticed also sometimes that the fuel pump fuse can be a bit warm when I remove it (I normally take it out when it's parked up for any length of time). Other times it can be cool, doesn't seem to depend much on journey length, but then I've never checked it consciously before having these problems so it could just be normal.

Air filter appears clean and is less than a year old.

Any way to determine if the sooty exhaust etc is a) overfuelling or b) under burning ?
I'm thinking if it airflow meter is giving bad readings and the engine is chucking more fuel in thinking it needs it that might be causing the bad performance and slow response, plus causing the fuel pump more work than usual?

I haven't done anything alternator wise yet aside from the previous voltage readings last year.
I'm going to disconnect the battery again this weekend for a few hours to clear the learnt values and see if the engine light stays off again for any length of time.

phew..sorry for the essay, just really want to get it running well again!

[Leigh]

I'm in Liverpool mate, about 5 mins from Aintree racecourse.

I'll see if clearing the ECU this weekend reproduces the short stint of 'no ECU' light and post back after the weekend.

[Leigh]

Minor update:
took the battery off for a couple of hours today to clear the codes and ECU, went for a 10 mile or so run , 1/2 motorway at 70, half A & B roads, so plenty of different driving,
Not a single flash of the ECU light, which is pretty much what happened (or didn't..!) last time it was cleared. I'll be watching with baited breath now for it's first reappearance..

[Robs-se]

worn bushes on the alternator only making the slightest of contacts but enough to keep you going with the engine increasing its fuel/air intake to compensate the poor running hence the sooty appearance, just a thought

[Leigh]

I did wonder about the alternator in general when I started doing the tests last year, but testing with the voltmeter seemed to indicate it's OK.
I think the slight hesitation might be a bit of a red herring as I've not got a 100% tight fit between the front pipe and mid section, need to sort that.

It's really odd that clearing the learnt values seems to have stopped it happening again, at least so far. I've made a note of the mileage when I reset it and the date, so I can keep tabs on when it reappears. You'd think that whatever is causing this weird alleged low voltage error (below 8 volts according to one list of fault codes I found), would happen regardless. It's as if once it's re-learnt my driving something is wrong, but with a blank slate starting from defaults it's OK. Maybe it's just trying to tell me it doesn't like my driving style!