Electrickery - Current

[paulW]

I seem to have an electrical gremlin with this shed of an S1.

Initially failed its emmissions test, but other odd things have happened....like cutting out when you put the full beam on.
(Although this was sorted by leaving the battery on charge overnight)

The issue I have at the moment, is while trying to diagnose the emissions, I've connected up my wideband sensor, but it can't get enough current.
(Apparently it needs a 3 amp draw)
Now I can maintain this, whilst revvving the engine, but as soon as I let it drop to idle, I no longer have the current.

It has a nice stable 12.7V supply though.

Any ideas?

I have 3 alternators here, including a brand new one, so that is my next though...although not sure how you are suppose to tighten the belt.
(yes I have read Robin's warnings about disconnecting the negative terminal while tinkering with the alternator)

So anyone able to explain why I can get volts and not amps? battery? alternator? wiring?

I've checked the grounds, and get same voltage at engine block as I do at the battery terminal....but haven't a clue how I can measure a 3 amp load.

Any help much apprecaited.

[Stu160]

Hi Paul

I would check the earth first, even run a cable direct from the engine to the neg battery , just to rule bad earth out. Could still be a duff battery, may take a charge, but will not output load?, not sure, but cheep to rule out.

I am sure i recognise that number, who did you buy the car from ?

Stu

[paulW]

Hey Stu,

Who did I buy the car from? You and Ali

Yup, someone has already run a thin blue wire from the battery to engine block, and not showing any voltage drop between the two.

[Stu160]

Thought that, just couldnt remember.

Are you running it on the emerald?, it cut out with me a few times, and Simon, the previous owner , with that , and we never could find out whey, i sent the ecu back several times, still never fixed it. I think i run the earth myself.
I would look at the battery first then, if its running at 12.7 volts on idle, then I would guess the alt. is Ok.

Stu

[robin]

On idle the alternator is less able to provide current - the more revs the more the alternator can produce, up to some limit of course.

Ordinarily your battery makes up the difference.

The ECU requires a certain minimum voltage before it can run the engine.

If you increase current draw in engine bay and battery provides the difference in current then any resistance in the +ve leads and earth path will reduce the voltage in the engine bay thus (possibly) leading to the point where the engine cuts out.

Before you change anything at all I suggest you start the engine and once at warm idle measure the following three voltages:

1. battery directly at the battery terminals.
2. right hand stud on the back of the starter and the engine block (right hand assumes you're standing pax side leaning into engine bay looking at rear of starter).
3. engine block and -ve battery terminal (you'll need to use a jump lead from the battery -ve terminal as an extension lead so you can get your voltmeter probes to stretch).

Now use the tip of a tie wrap or similar to wedge between the throttle stop and quadrant so as to hold the throttle open a tad - you're looking for 1,500-2,000 RPM.

Repeat the three measurements above.

With the engine still at approx 2,000RPM turn on the full beam lights and blower on full speed and measure the battery voltage again.

In this condition also measure the voltage between the battery -ve terminal and the chassis (you need to find something in the services bay that's bolted solidly to the chassis to measure this).

Also measure the voltage between the engine block and the chassis.

Post your findings ...

Don't start changing alternators just yet ...

Cheers,
Robin

[paulW]

Ended up swapping the engine out as I couldn't get the the bottom of the oil into water leak. Replaced the head gasket, etc, but suffered a major overheat in France and ended up pushing it onto the train at the channel tunnel. so just running a standard engine on a standard ecu now.

Emerald was working ok after I got the software updated, but don't have a map for the standard engine.
Would like to put the 633 cams in at some point.

Definitely something a miss with the electrics, be it dodgy battery, alternator or wiring.

Random fluctuations in stack temp reading, cutting out on full beam, occasional rough idle, wide band not warming up, etc.
All fine when giving it some beans though, so would think wiring is most likely issue.



Thanks Robin,

Will get all those measurements done this afternoon and post results.

[paulW]

Engine Off

1. Battery Terminals 13.36V
2. Starter and Egnine Block 13.36V
3. Engine block and -ve battery 0.01mV

Warm Idle

1. 14.12V
2. 14.12V
3. 3.5mV

3,000 rpm (couldn't get a steady 2,000 rpm)
1. 14.1V
2. 14.12V
3. 4.1mV

4. Battery -ve and Chassis 0mV
5. Battery -ve and Engine Block 3.7mV (doh!! was supposed to be engine block to chassis)

[robin]

OK, so all that tells me that there is nothing wrong with your earth wiring.

The last measurement is low enough that the block->chassis measurement is irrelevant.

So your fault is that when you attach your wideband lambda sensor the wideband doesn't work, or the engine stops?

Can you describe where in the wiring you are attaching the wideband?

BTW, if you're using standard ECU and standard engine and you're failing emissions, if emissions are high then almost certainly the lambda sensor in the manifold is bust. If the emissions are too low then you have an air leak into the manifold/downpipe. Once in a blue moon it might also be the ECU coolant sensor, but normally that also results in other issues and the fan runs all the time.

Cheers,
Robin

P.S. Or you have that hooky cat fitted

[paulW]

Emissions failed, high CO.

Knew I had a leak in the exhaust manifold gasket, so fixed that.

After that, lots of soot coming out of exhaust, so decided to swap out the narrowband with the wideband....destroying the narrowband in the process.

Since that I've had a rough idle....with no lambda sensor in the exhaust. (it is bunged up.)


But currently trying to get the wideband working.
On the battery alone it won't quite heat up, with some revs it heats up, but fails after about 20s.

Just replaced the battery terminal connectors as they were totally cuffed, could pull them off without even loosening them.

So might not even be an O2 issue, matrix in the cat seems nice and clean though.

[paulW]

I did find a switched live near the ecu, blue connector - green and purple wire. so was taking the +ve from there.

Now I've got it connected directly to the battery with a jump lead, as a temporary measure, until I find a good reliable switched live.

[paulW]

So any idea on best place to buy a new narrowband sensor?

[r10crw]

On your battery neg terminal you will see one thicker wire which goes to the chassis and as above seems good however you should also see some smaller ones, what condition are these? On tuts car these were badly corroded and replacing the terminals helped with his lights issues (although still not right but nothing ever was with that car) since I believe its these wires that earth most of the dash instruments? Have not got manuals to hand but certainly rings a bell.
This does not explain the emissions of course but is a starting point.
Craig.

[robin]

With it jumped to the battery, does it work?

[paulW]

Nope, it is supposed to heat up in 20-30 seconds, but not even warmed up after 5 mins.

However, it was heating up much quicker using jump leads as oppose to the thin wire I was using previously.

Two ideas, the +ve wire to LC-1 might be damaged
Also I seem to remember some issue with the system ground wire and the heater ground wire.
Something about not been able to cut the heater ground wire as it's resistance is used to calibrate the heater.
The heater ground wire hasn't been cut, but the system ground wire may have been.

Looking at price of narrowband sensors, wide band sensors seem cheaper!
(especially as I have 2 already)

So be good to see if we can get it working.

I've got a 12v mains supply, but only good for 1.2A, so no use for testing.

[hiscot]

LC1 is known for problems it has to be installed right with good earth grounding , on mine I had a controller fail and with all the bother of the free air callibration I went to plx instead
there was also a faulty batch of controllers at one time ( see above i got a new one foc from dta )