Misfire & no power (and then fine again!)

[jonnie5]

Over the last 18 months my Cerb has never let me down, in that it has always started and got me to where I wanted to go etc. Yes I've had niggles and failures but most of the spend has been voluntary.

Yesterday, my car wouldn't start - flat(ish) battery. I have been away on holiday but it was driven for about an hour 5 days earlier with no problems. Anyway a jump start last night solved that, had a spirited drive for 3/4 hour and tucked her away for the night.

This morning, the car started fine so off I set to work. The car behaved perfectly as usual, lots of popping and banging etc etc but just one bang when I didn't expect it i.e. a misfire. Shortly after, sat in a queue at a junction I stall the car - very unusual, but basically when I pressed the accelerator there were no revs. Car restarted fine, but when I went to pull out of the junction, had absolutely no power - very dangerous as I was turning right and almost couldn't cross the road. Tried to get as much revs as possible, but felt like it was only firing on 4 cylinders. Popping and banging whilst trying to accelerate, apologising to the car I pulled out in front of , I slowly got to about 30mph. There was a bit of smoke and crap coming out of the exhaust as it was misfiring away as I tried to accelerate. This went on for about 30 seconds.

Then, suddenly, all was fine and the car was back to normal. Stopped at some lights, the car pulled way fine and behaved as normal, but at the next roundabout the same thing happened again, but for a much shorter length of time.

So, any ideas please? Do I brave a journey home or will I potentially do damage. Is it likely to be just a throttle pot or lambda sensor? Or could it be that it will never happen again and I'll be doubting it for the next couple of weeks?

Lots of detail above, but hopefully some of it will help in the diagnosis! For information I had an engine rebuild about 4000 miles ago.

Thanks
Jon

[christmc]

You need to speak to Joos,,mate he will be able to help

[SXS]

This is what I would do before calling a specialist...

Take the top service panel off...
Take the air pipes off...
check each wire-plug for each injector...
make sure tight fit, might help to remove
and blow some wd40 in there (check the wiring)
leave pipes off....
and start car, get the other half to pump the pedal
a little and listen to the noise....
and look in the trumps, if there is a missfire, you will notice it.... (dont get too close, might get sucked in )

If there is still a problem...

Then, using a multimeter, you can check each throttle pot... find the faulty one if any... and order a new one and fix her up...

If you cant get anywhere from here...
Drive her in, to a specialist...

Goodluck, hope its a simple one...

[kojak69]

May not be the same problem as I had, as it corrected itself, but did MIL light come on? Did rev counter stop working? May be big fuse loose/gone.

I'd check it anyway. Doesn't take long.

[jonnie5]

kojak69 said:

May not be the same problem as I had, as it corrected itself, but did MIL light come on? Did rev counter stop working? May be big fuse loose/gone. I'd check it anyway. Doesn't take long.

Hmmm - the big fuse did cross my mind.. I didn't notice the MiL light on nor the rev counter not working. But saying that, the rev counter does go completely bonkers sometimes when making progress. Could that be a symptom?

Can I presume that by driving it, I will not be doing any damage if it's any of these things.

cheers
Jon

[rjben]

Are you sure your battery is charging? Sounds like clasic 'big fuse' to me.

[jonnie5]

rjben said:

Are you sure your battery is charging? Sounds like clasic 'big fuse' to me.

Pretty sure in that it was completely flat last night, took it for a 3/4 hour drive and it started this morning - so it must be charging at least a minimal amount.

Are you saying that the misfiring & lack of power are also classic 'big fuse' symptoms?

Thanks again.
Jon

[kojak69]

jonnie5 said:

rjben said: Are you sure your battery is charging? Sounds like clasic 'big fuse' to me. Pretty sure in that it was completely flat last night, took it for a 3/4 hour drive and it started this morning - so it must be charging at least a minimal amount. Are you saying that the misfiring & lack of power are also classic 'big fuse' symptoms? Thanks again. Jon

This was my problem 6 weeks ago.

www.pistonheads.com/gassing/topic.asp?f=6&h=&t=112506

This was my problem 6 weeks ago.

[jonnie5]

hmmm , thanks. I'll take a look at lunchtime and firstly try and fnd the fuse and then see if it looks damaged ...

cheers
Jon

[kojak69]

Hi Jon.

As I said, it might not be your problem, but if you take off the inner bonnet, it'll take you all of 10 seconds to check.

Good luck.

[rjben]

jonnie5 said:

rjben said: Are you sure your battery is charging? Sounds like clasic 'big fuse' to me. Pretty sure in that it was completely flat last night, took it for a 3/4 hour drive and it started this morning - so it must be charging at least a minimal amount. Are you saying that the misfiring & lack of power are also classic 'big fuse' symptoms? Thanks again. Jon

Sorry, I'm no expert on this but recently my car was reluctent to start and when running I experienced worsening misfire until total failure. It turned out to be the big fuse. I hadn't noticed that the baterry light was on - have you noticed if yours is?

[njw 77]

jonnie5 said:

But saying that, the rev counter does go completely bonkers sometimes when making progress. Could that be a symptom? Jon

Under load my rev counter seems to stick at about 6-6250 then bounces around a bit, but the car is still pulling strong (havent been brave enough to get the shift warning buzzer going). Is this quite normal? Well, normal for Cerbs anyway. Or is this the onset of a Big Fuse problem?

Nick

[jonnie5]

rjben said:

Sorry, I'm no expert on this but recently my car was reluctent to start and when running I experienced worsening misfire until total failure. It turned out to be the big fuse. I hadn't noticed that the baterry light was on - have you noticed if yours is?

Haven't noticed, but at the time I was more concerned with getting out of the way of oncoming cars etc. - I'll take a look at lunchtime. I have no tools at work so getting the inner bonnet off is not going to happen until tonight.

Thanks for your help guys, I'll let you know what I find.

cheers
Jon

[jonnie5]

Ok, just borrowed some tools and had a look at the big fuse - it looks fine, but as previous threads have indicated it may be a hairline crack or under the screw head so I'm going to change that anyway. I can't source one locally, does anyone know who would be the best bet to contact for a next day delivery?

If the problem doesn't re-occur then I'm happy, if it doesn't I'll be looking at your suggestions SXS!

Cheers
Jon

[kojak69]

I got one from a local auto electrician - 60p.

[jonnie5]

kojak69 said:

I got one from a local auto electrician - 60p.

I've tried the two local auto factors without success, along with garage around the corner that works on old Astons, I'll try the auto-electrician route now.. Thanks.

[J_S_G]

jonnie5 said:

Ok, just borrowed some tools and had a look at the big fuse - it looks fine, but as previous threads have indicated it may be a hairline crack or under the screw head so I'm going to change that anyway. I can't source one locally, does anyone know who would be the best bet to contact for a next day delivery?

I'd just screw down the two wires on the same terminal, bypassing the fuse for a bit whilst I waited for a new one.

[jonnie5]

J_S_G said:

jonnie5 said: Ok, just borrowed some tools and had a look at the big fuse - it looks fine, but as previous threads have indicated it may be a hairline crack or under the screw head so I'm going to change that anyway. I can't source one locally, does anyone know who would be the best bet to contact for a next day delivery? I'd just screw down the two wires on the same terminal, bypassing the fuse for a bit whilst I waited for a new one.

Nice one, that may happen... Warren at Top Cats has just come up trumps and is sending me one in the post today!

Cheers
Jon

[J_S_G]

jonnie5 said:

J_S_G said: I'd just screw down the two wires on the same terminal, bypassing the fuse for a bit whilst I waited for a new one. Nice one, that may happen... Warren at Top Cats has just come up trumps and is sending me one in the post today!

I had to do that for a couple of days once... fuses are there for a reason, mind...

[jonnie5]

A quick update...

I haven't changed the fuse yet, but have driven about 120 miles in the last 24 hours without missing a beat. Even passed her MOT today, so who knows what the problem was.

Cheers
Jon