Chimeara misfire combined with dash clicking

Chimeara misfire combined with dash clicking

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JJREED

Original Poster:

56 posts

107 months

Friday 29th April 2016
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Hello all. First TVR, purchased unseen entirely because it has a new chassis and was a bit of a bargain despite what problems I might find.
I'm very happy with the chassis - i.e. perfect, and the bodywork. Of course being a TVR it does have a couple of electrical gremlins, which a test drive wouldn't probably have spotted.
The first question I have is misfire/loss of power. Every so often it seems to just drop onto 4 cylinders, or lose power completely. It will still 'drive' but slows down and stops. A couple of key cycles and its fine again.
Tonight I noticed this happen at a T junction - the car was very low on power, HOWEVER, I realised at the same time there was a distinct clicking coming from behind the dash (at least it sounds like from behind the dash). Clicking sort of at what I'd expect firing frequency to be, and the clicking frequency rose and dropped with engine rpm's (I'm thinking injector or. I cycled the key a few times and the noise as well as the low power was there. Third or fourth key cycle, clicking gone, power back again! Definitely related. I'd say it sounded like an injector firing, but I can't hear the others firing so why would I hear this one?, possibly arcing but then why would it stop with a key cycle. Maybe a relay right up behind the dash somewhere but then why would it click at firing frequency?
The clicking absolutely must be related to the low power - too much of a coincidence. Maybe fuel starvation and the injector at the far end of the rail gets noisy? I'm clutching at straws I guess.
If it helps it seemed to do it a few days ago when I bumped over a drain cover (but this might be a big coincidence but it was at that exact moment).
Suggestions please. Kudos to the responder who gets it right first time!........

JJREED

Original Poster:

56 posts

107 months

Friday 29th April 2016
quotequote all
I should add to the above that the first time it did this I was doing 60 on the motorway and managed to 'drive' for about 1 mile before I found a place to stop, so if it is related to fuel pressure it's not total failure..... Might be more than one root cause of course.

QBee

20,903 posts

143 months

Friday 29th April 2016
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When you restart it, does it fire up enthusiastically, or a bit sluggishly?

JJREED

Original Poster:

56 posts

107 months

Friday 29th April 2016
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It fires up instantly every time (or so it seems, I've only done a couple of trips in it and it's done it on both trips)

If it's 'running fine' when I fire it back up it just pulls away fine.

If it's still 'running' bad' when I fire it back up it idles OK (but lumpy) but when I pull away it just dies (i.e. no power)

When i'm driving and it starts misbehaving, if I pull over and park up it continues to idle (but won't rev as readily / llumpy) but has no power to pul away agin.

chris212

133 posts

156 months

Friday 29th April 2016
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Check the earth points under the centre console (
Under handbrake)

QBee

20,903 posts

143 months

Friday 29th April 2016
quotequote all
Sounds a bit like the King lead from coil to distributor is a tad loose at one end.

My original thought was that your 100 amp fuse (under the car) is cracked and so the battery isn't being charged all the time, but the good starting tends to give the lie to that.

JJREED

Original Poster:

56 posts

107 months

Friday 29th April 2016
quotequote all
Okay - I'll check out the earth feeds to the chassis tomorrow morning - Are they just under the carpet or do I need to loosen the centre console?
All the ignition parts are new but I'll try a king lead anyway.
Thanks for the help so far.
I'm also thinking the two relays?

2OOM

374 posts

283 months

Saturday 30th April 2016
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My car has just been put back on the road after 18 months resting in the garage. when i used it the first leg of a trip it was fine, but after restarting it would sometimes go into limp home mode after afterwards..If I stopped the engine and restarted it was fine, but would sometimes do it again ..
I had a similar issue 5 yrs ago and I got a second hand ecu and it's been fine since .. This time I unplugged the ecu and cleaned all the contacts and bent 2 back to the same shape as all the others and it's been fine since .. My guess for my car was that the contacts weren't very good and a bit corroded ..

It's worth a try, only cost is a little time and contact cleaner ..

Belle427

8,856 posts

232 months

Saturday 30th April 2016
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The relays are the first thing you should change for peace of mind, usually found hanging around in the battery area.

s p a c e m a n

10,752 posts

147 months

Saturday 30th April 2016
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If it were me I'd pull the loom out of the passenger footwell and drive around until the car did it, then grab the relays down there and see if it was one of those clicking.

N7GTX

7,822 posts

142 months

Saturday 30th April 2016
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This ^^^^^

The fuel pump relay may be playing up and you can grab hold of it when the clicking starts to eliminate it. If it has not been renewed I would change it anyway.
The fuel pump will have been disturbed if it has had a new chassis. Do check the 2 connections are good, clean and tight.

JJREED

Original Poster:

56 posts

107 months

Saturday 30th April 2016
quotequote all
Great suggestions guys - This morning I went out and tried to locate the earth straps under the handbrake, and couldn't find them easily. So I pulled the wiring out of the footwell - Crikey what a birds nest! Original metal bodied relays are still there. I also pulled out the ECU and gave the whole lot a good shake. I drove down to the local factors to get some new relays , they don't have any in stock, so I picked up some gear oil, rotor cap and a couple of other bits and pieces. Ive since done about 30 miles over 5 journeys and it's not done it again. I have the wiring loom sitting in the footwell ready to give it a shake and see if that helps, for next time it does iit (Which I'm sure it will!)
I'm also going to replace the king lead even though it is new - Couldn't get one this morning but will do some more miles later and try somewhere else.

The spark plug extensions also look quite old - potential source of the fault?

Big beaming smile on my face though, love the noise :-))

JJREED

Original Poster:

56 posts

107 months

Saturday 30th April 2016
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Also picked up some contact cleaner and will give everything a damn good spraying.

On other thought - I disconnected the fuel pressure sensor with the engine idling and it ran just fine - I was expecting it to stall. Could this be related?

N7GTX

7,822 posts

142 months

Saturday 30th April 2016
quotequote all
JJREED said:
The spark plug extensions also look quite old - potential source of the fault?
Probably the biggest cause of misfiring on these cars. Most owners have now done away with them altogether and fitted the lead directly on to the plugs. They fit heat shrouds to protect them from the exhaust manifolds. Something like these: http://www.ebay.co.uk/itm/like/272094753460?limghl...

Someone will tell you the best and cheapest shortly, I'm sure.

QBee

20,903 posts

143 months

Saturday 30th April 2016
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The plug extenders will be suspect if you get a misfire, otherwise leave well alone. My old ones gave no issues, but my TVR guy replaced them anyway at a service.
I had six of the new ones fail inside six months, and they came from the most reputable source.
I got my socks a couple of quid cheaper, but had to wait three weeks for them to arrive, from HK, so that eBay deal looks a goodun.

JJREED

Original Poster:

56 posts

107 months

Saturday 30th April 2016
quotequote all
Another two trips and still no issues, mind you only a few miles each. Confidence builds and then you get knocked back again eh?!?

I like the look of the boots - I'm going to order a set anyway and try them out. I have a Mastercraft Ski boat with a Ford 351 that suffers from the leads degrading due to the very high temps under the hood - these look like a great solution.

Just used an infrared thermometer on the top hose and with the car sat after a run the temp reading is 85 - 90C. Guess the gauge is out by 30C and I should stop worrying about it!

Bassfiendnoideawhathp

5,530 posts

249 months

Monday 2nd May 2016
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JJREED said:
It fires up instantly every time (or so it seems, I've only done a couple of trips in it and it's done it on both trips)

If it's 'running fine' when I fire it back up it just pulls away fine.

If it's still 'running' bad' when I fire it back up it idles OK (but lumpy) but when I pull away it just dies (i.e. no power)

When i'm driving and it starts misbehaving, if I pull over and park up it continues to idle (but won't rev as readily / llumpy) but has no power to pul away agin.
In some ways very similar to the symptoms I used to get ... have you seen whether your main cat bucket in front of the engine is getting so hot it actually starts to glow red when it's misbehaving? Mine did and it killed the cat too so just be aware of that if it is.

For me it turned out to be a break or dodgy connection in the loom somewhere around where the loom enters the connector that attaches to the ECU ... I didn't get any further in diagnosing or rectifying it than that because I had the whole lot ripped out and replaced with a CANEMS and complete new harness as much for my own peace of mind as anything as I was driving it constantly looking for my "exit" route for in case it started to bugger about and was no longer a pleasure to drive.

Phil

Edited by Bassfiendnoideawhathp on Monday 2nd May 08:56

QBee

20,903 posts

143 months

Monday 2nd May 2016
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JJREED said:
Just used an infrared thermometer ......
Just checking - you do know how to locate a misfire with one of these, I assume?

ClassiChimi

12,424 posts

148 months

Monday 2nd May 2016
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If you have a misfire you might see a drop in temps in the corresponding exhaust manifold just as it leaves the head from that chamber. wink

JJREED

Original Poster:

56 posts

107 months

Monday 2nd May 2016
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Well, I've done a hundred miles or so this weekend, and it's done it only once, on the same left hand bend/bump/drain cover again. Looking at the loom it might be one of the relays tapping against the positive terminal of the battery???
I wasn't able to ge relays but have ordered a couple for collection onTuesday and we'll go from there. Intermittent every 100 miles or so I can live with, but I'll probably strip back the first portion of the loom, check terminals and give a good clean etc. etc. while I'm doing the relays.