Running problems @ Castle Combe today

[trig]

Just got home from Castle Combe track-day, great day except for a few running issues Going onto the motorway I gave it some beans and then fuel cut + engine light came on, did my track session trying not to hit over boost again same thing happened this meant I had to slow down which put me in harms way on very busy session with a wet track, so I was glad when it finished


On the way home I noticed what looked like my petrol was disappearing fast and the car running ruff so I pulled off the motorway and looked under the car for leaks, , there was none....I then turned off my side lights and Hey Presto the fuel gauge climbed up to almost full again?

So it seems my battery is not holding charge? , would this be the cause of the fuel cut engine light as I had lights on when on track?

A similar thing happened last w/end wile travelling down the M5 with lights on I tried to overtake a lorry and car started throwing a fit an then engine light on
stopped for fuel and the car would not start after spoiling it with optimax petrol lucky its an easy car to bump by yourself....when I got home turned the engine off then on the off then on..no problem??

[Dave Eds]

paper clip test will show up a fault code Steve!

[trig]

paper clip test will show up a fault code Steve!

Good idea Dave , I've never used the paper clip test before but will give it a go tomorrow

[GeoffSmith]

Fire up ElanScan to read the code and maybe try to replicate the problem - why else would you have an interface?

[trig]

Fire up ElanScan to read the code and maybe try to replicate the problem - why else would you have an interface?

Elan scan!! , I'm still working out how to get a paper clip into a u shape

[trig]

Just finished the paper clip test and no fault codes displayed..

did a quick battery test and there seems to be a problem , I hoping it is just the battery and not the Alternator

My previous battery reads : Engine off = 12.46v , Eng on = 14.36v , Eng on with lights on = 14.23

Now my battery reads : Engine off = 12.17 , Eng on = 11.84 , Eng on lights on = 10.84 and falling


But would my battery problem cause the over boost fuel cut then engine light I did have lights on every time this happened

[MPx]

Not sure what your telling us there Steve. If the "previous battery" line is a historical record, then I think this data points at the alternator. The "previous battery" line looks tickety boo. The next line shows that the alternator isn't putting out enough to charge the battery or run the car and the battery is doing everything. But if its the alternator I'd expect the red [not] charging warning light to come on.

But if the "previous battery" line is current (ie you swapped it back in, did the test then swapped it out again for the "now battery") then the alternator is OK (cos it was on the previous battery so the "now battery" must be fubarred. If this is the case then it will probably have a collapsed cell or two and is draining more out of the alternator than it can supply trying to keep alive. I would guess that the significant voltage changes could easily result in the engine check light coming on, but I cant see how it would be linked to the overboost problem. HTH Mike

[trig]

Both reads are the same battery , the previous read is a few months old

Would a battery or alternator cause over-boost symptoms? every time its happened I have had the lights on
the first sign of this problem it felt like running problems at full revs but when it happened this Saturday I spotted the boost gauge hit the 1bar before fuel cut, I can see no issues with hoses

I will hopefully fit a new battery soon then see if the running problems disappears

[Dave Eds]

Have you wiggled your wastegate?


Get your battery tested!

[bobbrown]

If the voltage is low then it is possible the ECU is getting false readings, as the normal line voltage with the engine running is nominally 13.8V (13.5 to 14.4V is OK). If when you switch your lights on any sensor that would normally see 13.8v but now only has a supply at 10.8 the its output is not going to be correct and could lead to all sorts of strange behaviour.
I would be inclined to suspect the alternator, but an easy check would be to try another battery first and see if the readings are the same.
With regards to the alternator warning light they do not alway show a fault when the rectifier pack is faulty as it may not be the phase that operates the light that is at fault.

[lotusgirlmarie]

I agree with bob on this. Fluctuating voltage can throw false readings from the sensors.

[GeoffSmith]

Where are you measuring Steve? An earthing/supply lead problem could also give erroneous readings/coughs and splutters which would be made worse by increasing the load (putting the lights on). Make sure you measure directly across the battery as well as in the engine bay.

Most of the sensors run off e.g. 5V regulated supplies so there should be plenty of margin, however if earth is not 0V it could f**k things up. The ignition/fuel pump/injectors may also suffer if the volts are low.

ElanScan would tell you what voltage is at the ECU and also the sensor readings!

[trig]

Thanks for all the replies

Geoff all readings taken from battery using multi-meter

I've now fitted a brand new battery and all is not good my reads with new batt prior to start up a healthy 12.58v
Engine running = 12.09
Engine running lights on = 11.79
Took the car for a run to see if I could induce fuel-cut and the car was perfect on full throttle in 3rd, 4th, 5th gear...with the lights off , my reads after the run with engine on = 12.15 and eng off = 12.38

So it seems I have an alternator problem the alternator is new, only done 1000 mls but was a aftermarket Unipoint alternator as it was a lot cheaper than a recon ,
For a while after re-fitting the replacement engine with new alt I had the battery light on constantly which is why I have a record of the battery readings because I feared there was a problem But the battery light eventually went away or so I thought! I now believe the battery light no longer works ,, if I turn ignition on there is no battery light, didn't notice this till now

[Dave Eds]

So was your battery confirmed as being fooked? If it's not a least you have a spare.

I have an alternator from the last group buy if it helps, although I guess Pinkster does too, and he is a bit closer to you!

[inkitin]

Beat me to it Dave!

Still here goes.

Alan (soss29 on ebay) was back selling his "new" M100 alternators on ebay a week or two ago (£155 plus £10 P&P if I remember correctly). He hasn't got a listing up at the moment but neither had he when I needed mine, so I contacted him by telephone and managed to buy one directly from him. Fast delivery as well.

His phone number was 07738 609804 or I suppose you could contact him through ebay.

The one he sold me was fitted in January 2009 and it's still going strong (Famous last words again!!).

[trig]

So was your battery confirmed as being fooked? If it's not a least you have a spare.

I have an alternator from the last group buy if it helps, although I guess Pinkster does too, and he is a bit closer to you!

Dave I think the old batt would be OK if charged up and yes could be a spare now
I'm convinced the alternator is playing up but it cant be shot its brand new!! , I will check connections again and at a push remove it to get it checked out, that will be fun
If all else fails it will be a new jobby, thanks for the heads up on were to look and contact number


Funny thing is my old one was working fine before I removed my old engine but had a large crack so I thought I would fit a new one for piece of mind

[dapinky]

although I guess Pinkster does too, and he is a bit closer to you!

Sorry, used mine

but i still have the old one (seized up) if you want to use it as a core for a rebuild to keep yours on the road for now....

[trig]

although I guess Pinkster does too, and he is a bit closer to you!

Sorry, used mine

but i still have the old one (seized up) if you want to use it as a core for a rebuild to keep yours on the road for now....

thanks Dave, I will keep that in mind , I should hopefully be able to sort out my brand new unit....I wish I could remember my training when I was an auto-electrical apprentice and we would strip and recon alternators and starters, I'm sure it will come back to me