Misfiring and cutting out (intermittent)
Discussion
Hello, first post from me, after much interest in the forum generally.
I’ve had a 93 4.0l Chimaera for nearly a year and it suffers from occasional misfire and occasionally cuts out while going along. Despite servicing and a few bits replaced, this is still there. Essentially, once I’ve been driving for a few miles it hesitates, misfires and occasionally cuts out. Once on the hard shoulder it restarts and normally all is well for another few miles. Occasionally, it restarts and then cuts out again immediately after, but normally after a minute it is back working again. Otherwise it seems to run ok and recently passed its MOT.
I got some rather strange looks on the M4 this morning, as I overtook a van about 4 times in 15 minutes, but had to stop on the hard shoulder every few miles (which just starts to get a little embarrassing). Sometimes it can be fine for miles with no issue.
In case it helps, the car is standard and original, expect I’ve now replaced the coil, ignition amplifier and it has recently been serviced.
Have read a number of threads on here with interest, but no-one seems to have exactly the same problem as me, so hoping someone might have a suggestion, before I give it to a specialist? I’m a bit reluctant to do that immediately, as its an intermittent problem, so I would expect it to be expensive (in time for them just driving the car) to work out what might be wrong...
Thanks
Pete
I’ve had a 93 4.0l Chimaera for nearly a year and it suffers from occasional misfire and occasionally cuts out while going along. Despite servicing and a few bits replaced, this is still there. Essentially, once I’ve been driving for a few miles it hesitates, misfires and occasionally cuts out. Once on the hard shoulder it restarts and normally all is well for another few miles. Occasionally, it restarts and then cuts out again immediately after, but normally after a minute it is back working again. Otherwise it seems to run ok and recently passed its MOT.
I got some rather strange looks on the M4 this morning, as I overtook a van about 4 times in 15 minutes, but had to stop on the hard shoulder every few miles (which just starts to get a little embarrassing). Sometimes it can be fine for miles with no issue.
In case it helps, the car is standard and original, expect I’ve now replaced the coil, ignition amplifier and it has recently been serviced.
Have read a number of threads on here with interest, but no-one seems to have exactly the same problem as me, so hoping someone might have a suggestion, before I give it to a specialist? I’m a bit reluctant to do that immediately, as its an intermittent problem, so I would expect it to be expensive (in time for them just driving the car) to work out what might be wrong...
Thanks
Pete
You need to watch the rev counter closely as the engine dies- If it drops rapidly to zero when the engine is still turning as speed its an ignition or ignition supply related fault as the tacho has lost it trigger pulse. Otherwise if its ECU related then something is doing something really nasty like loosing the 12v supply to the injectors or possibly the pump- 2 relays involved here. Dont forget the vagueries of the TVR immobiliser for causing intermittent engine cut outs.
blitzracing said:
You need to watch the rev counter closely as the engine dies- If it drops rapidly to zero when the engine is still turning as speed its an ignition or ignition supply related fault as the tacho has lost it trigger pulse. Otherwise if its ECU related then something is doing something really nasty like loosing the 12v supply to the injectors or possibly the pump- 2 relays involved here. Dont forget the vagueries of the TVR immobiliser for causing intermittent engine cut outs.
Mine keeps doing the same thing cutting out randomly but the the rev counter does not drop to 0 it keeps reading the engine speed as it slows down to a stop. Does that mean it is not an ignition system fault?MPoxon said:
Mine keeps doing the same thing cutting out randomly but the the rev counter does not drop to 0 it keeps reading the engine speed as it slows down to a stop. Does that mean it is not an ignition system fault?
Read my comments on this post.http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Definitely worth checking the rotor arm. I had probs with my MG last summer, intermitent cutting out especially when hot. Changed several ignition components - including a new rotor - and guess what? The new one was a dud too only I wasn't expecting that so went on looking for other problems.
Following a suggestion I switched to a red rotor and it's good as new again. Could have chased a ghost of a fault for the sake of a £5 part.
Moral of the story - not all new stock parts are faultless.
Following a suggestion I switched to a red rotor and it's good as new again. Could have chased a ghost of a fault for the sake of a £5 part.
Moral of the story - not all new stock parts are faultless.
MPoxon said:
Mine keeps doing the same thing cutting out randomly but the the rev counter does not drop to 0 it keeps reading the engine speed as it slows down to a stop. Does that mean it is not an ignition system fault?
It means the Tacho is still getting its firing pulses from the ignition amp and coil primary circuit, plus the coil has its ignation feed, so those bits are OK. It wont cover failure in the HT side of things. Mind you a complete engine failure would be a very bad HT fault- they are normally just misfires as things break down. Id be looking else where in this case.blitzracing said:
You need to watch the rev counter closely as the engine dies- If it drops rapidly to zero when the engine is still turning as speed its an ignition or ignition supply related fault as the tacho has lost it trigger pulse. Otherwise if its ECU related then something is doing something really nasty like loosing the 12v supply to the injectors or possibly the pump- 2 relays involved here. Dont forget the vagueries of the TVR immobiliser for causing intermittent engine cut outs.
I second that. It was my META imobiliser. Had it bridged no more problems.MPoxon said:
Cheers for the advice gents.
I have replaced the relays and cleaned the contacts on the inside of the dizzy. I have checked the ECU for fault codes - none present. I will give it another run and see if the issue is still there. It only happens every 30 miles or so which is annoying.
Poss ignition amp failing when hot?I have replaced the relays and cleaned the contacts on the inside of the dizzy. I have checked the ECU for fault codes - none present. I will give it another run and see if the issue is still there. It only happens every 30 miles or so which is annoying.
Ignore me now seen your post above - on my phone that's my excuse and I'm sticking to it!
Edited by Barkychoc on Tuesday 23 April 19:04
Thanks all for the various suggestions. For my car, I'll replace the rotor arm, and the fuel relays and see if that fixes it. If not, I presume I'm looking at the immobiliser as most likely culprit. Is there a way for me to test whether the immobiliser is the cause? I'm not sure whether they can be removed, or whether the wiring makes that difficult (from a theft point of view, one would hope the latter)? Does anyone know what can be diagnosed on the immobiliser, or whether better to leave to an alarm expert - thought I had read before that the alarm specialist had left the country, but maybe I misunderstood.
cheers
cheers
MPoxon said:
This Guy got mentioned recently in another alarm thread:http://www.abacuscaralarms.co.uk/alarms/remote_con...
Perhaps he could help now Carl has left to be a cheese eating surrender monkey
This probably doesn't help.....but I had a similar sort of thing on a Mercedes a couple of years ago. Accelerated to overtake someone, and the engine would die at the most embarrassing moment possible, usually when I was half way past, and hang me out to dry.
In my case it was a problem with the fuel rail valves (twas an oil burner), and the effect was to put the ECU into limp wrist mode. Hence I coasted to a halt in silence, and then having turned the ignition off and on again, the system was reset and the car started normally and ran until I tried another overtake....with the same result.
In my case it was a problem with the fuel rail valves (twas an oil burner), and the effect was to put the ECU into limp wrist mode. Hence I coasted to a halt in silence, and then having turned the ignition off and on again, the system was reset and the car started normally and ran until I tried another overtake....with the same result.
Afternoon all, seeking a bit more help so going to try resurrecting this thread. Car is still misfiring intermittently. I've now replaced hte rotor arm as suggested, as well as both the metal cased relays. Str8Six also did some work on loose wiring around these relays a few weeks ago, and yet still the problems remain.
The rev counter doesn't die ahead of the engine cutting out, and given the intermittent nature, I susect this is still electrical in cause.
Does anyone have any more ideas? For example, are there things I could check when the car is actually misfiring (at the side of the road) that might help narrow down the options.
I haven't ruled out the immobiliser, despite being a 1993 car, it has a later Meta alarm and immobiliser fitted, but given the car doesn't always cut out but just misfire, assume its still better to look elsewhere?
Any other thoughts, experiences or ideas?
Many thanks
The rev counter doesn't die ahead of the engine cutting out, and given the intermittent nature, I susect this is still electrical in cause.
Does anyone have any more ideas? For example, are there things I could check when the car is actually misfiring (at the side of the road) that might help narrow down the options.
I haven't ruled out the immobiliser, despite being a 1993 car, it has a later Meta alarm and immobiliser fitted, but given the car doesn't always cut out but just misfire, assume its still better to look elsewhere?
Any other thoughts, experiences or ideas?
Many thanks
I'm no expert, but I would check all the electrical components; coil, ignition amp, leads, dizzy cap. Disconnect, clean and re-connect all the electrical connections. Ensure all the plugs are good too and properly threaded. Have you checked for any air leaks as this may cause cutting out etc? Is fuel getting continuously to the system?
Where are you based? I'm in the South East (Deal), so if you're close enough, you can pop round and we'll try swapping a few components from my car to see if we can eliminate the problem.
Where are you based? I'm in the South East (Deal), so if you're close enough, you can pop round and we'll try swapping a few components from my car to see if we can eliminate the problem.
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