Weird Wedge fault? (Might be battery we think)
Weird Wedge fault? (Might be battery we think)
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wedgeinald

Original Poster:

1,314 posts

220 months

Monday 6th April 2009
quotequote all
Got the wedge put back together at the weekend, but was unable to take it far as its developed a weird fault.

I think its just the battery (so charging the old one and getting a new one anyway) but here goes......

Car has been laid up since about oct/nov with the alarm switched OFF completely, turned the alarm on (so it wasn't "imobilising" the car) and tried to start the car....engine turns over but instantly all hell out of the alarm....so turn it all off and back on again...same thing.

Set and unset the alarm so its DEFINATELY off.....still no joy.

So jump the car from another and get it started (suspect the drop in battery vlts was triggering the alarm?) runs fine whilst connected to the other car/battery but when disconnected the engine ticks over fine but will not rev properly (and eventually at all!) I think this is just because the battery is low as the car will not re-start on its own again afterwards.

The fault co-incides with the battery voltage gauge going "haywire" as well.

Re-Jump it and all is well for a short time.

I think the battery is possibly screwed or just low on charge, but thought i'd ask and see if anyone had seen this fault before?

The engine does not die (but it will if any load applied) but does not rev at ANY throttle setting by the end.

When connected to the other car will rev freely to 5k (and beyond i assume) but as soon as disconnected it will rev only on part throttle to about 3k and the amount of throttle it will take and the revs acheiveable drop off. IF you hold it on say 2k it will sit there "forever" until you let it back to tickover then it will not rev again.

I'll know on Tuesday if I'm right but any ideas gratefully received.

Norman

B-Reight

905 posts

232 months

Monday 6th April 2009
quotequote all
Once the car is started, the alternator should be providing the power to run the car. If its working fine with a decent power supply from the jump car, perhaps your alternator is shot. (or associated earth/wiring)

Might be worth sticking a mltimeter between gnd and coil positive to see if you have adequate supply to the coil. Tis about 13.5v on mine with the engine running.

Edited by B-Reight on Monday 6th April 13:10

jeff m

4,066 posts

288 months

Monday 6th April 2009
quotequote all
Set your multimeter to AC volts go on big red wire.

wedgeinald

Original Poster:

1,314 posts

220 months

Monday 6th April 2009
quotequote all
B-Reight said:
Once the car is started, the alternator should be providing the power to run the car. If its working fine with a decent power supply from the jump car, perhaps your alternator is shot. (or associated earth/wiring)

Might be worth sticking a mltimeter between gnd and coil positive to see if you have adequate supply to the coil. Tis about 13.5v on mine with the engine running.

Edited by B-Reight on Monday 6th April 13:10
I did suspect this but will the alternator run the car with (in effect) NO battery? When the car is revving the voltage does seem to indicate the alternator is running (reading appx 14V on the gauge)

I'll check it all out on tuesday but might get an alternator lined up to be on the safe side. Hoping to be at the mid essex meet on sunday.

Cheers for the sugestions so far.

Trickie Dickie

2,399 posts

264 months

Monday 6th April 2009
quotequote all
When my battery goty completely drained and I started to charge it
the alarm just kept going off as I think there is such a low charge
that the alarm thinks the battery is being disconnected

I simple disconnected the battery and then charged the battery for a while
before re attaching the battery and hey presto it was all ok again

I may be wrong on the theory but that is what happened in practise

HTH

Richard

Jonny weggie

1,607 posts

221 months

Monday 6th April 2009
quotequote all
Had a problem like this once,to cut a long story short,[battery] i had bought a new one,it was charged but not fully charged, so charged for 2 full days and touch wood it's worked ever since. good luck.

wedgeinald

Original Poster:

1,314 posts

220 months

Monday 6th April 2009
quotequote all
Cheers for that guys.....I might try and fit the battery tonight if I get time.

Hopefully will save me the expense of the alternator.

Other than that the car is looking/sounding goodsmile

adam quantrill

11,679 posts

272 months

Tuesday 7th April 2009
quotequote all
Check the alternator earth (from casing to engine block), even a 0.1V drop will cause all sorts of wierd stuff. It's very easy to clean up, just clean off the bottom bolt.

wedgeinald

Original Poster:

1,314 posts

220 months

Tuesday 7th April 2009
quotequote all
Ok further info....

Its NOT the battery, its not the Alternator.

Its HT related. when the problem occours there is a weak or no spark.

However the spark is fine (and the engine will rev etc) while the starter is engaged.

We suspect the coil (being weak) or the ignition electronics. We did find a poor contact in the wiring but the fault persisted even after that was cured.

How easy (cheap?) is a new (or used replacement) ignition module aquired?

Anyone had a similar fault? any tests we can run? it "settles out" if left turned off for a while but the fault returns quite quickly. It is definately much more of a problem with the engine hot than cold.

I'm planning to get a new coil ASAP as a precaution anyway.

Might stop us taking the car to the Mid-Essex meet this Sundayfrown

jeff m

4,066 posts

288 months

Tuesday 7th April 2009
quotequote all
The 12v during starting comes from the key being in the start position as it is a ballast resistor car.
Once you release the key to the run position then the 12v is via the ballast resistor. The big blue wire.

The module is just a trigger that switches off the coil current.

The module does use different inputs when in the start position than the run position but if it runs in the start position I would not suspect the module switching, it is more likely to be either the module plug between the key and the module or the ballast wire/wiring.

wedgeinald

Original Poster:

1,314 posts

220 months

Wednesday 8th April 2009
quotequote all
Got the RAC guy to check out the wiring and balast wire etc.

He did find 1 bad (intermittant) connection but the fault was still there after.

I'm thinking coil at this stage so chasing round to find a replacement to double check.

I'm hoping to still have the car out at the weekend if I can cure the fault.

Norman

jeff m

4,066 posts

288 months

Wednesday 8th April 2009
quotequote all
http://www.tvrwedgepages.co.uk/maint_parts.html

Norman,
The link above is parts list which includes the coil.
Coils can get cooked if there is a problem, esp if they get a higher low side voltage than they expect.
Low side of the coil is expecting around 8 volts in the "run" position.

Is your tach moving in sync with the revs?

wedgeinald

Original Poster:

1,314 posts

220 months

Wednesday 8th April 2009
quotequote all
Hi that page only shows the "enhanced" coil replacement. (which I might fit in due course)

I think I've managed to source a coil so will get it tested later today (hopefully).

The rev counter works just fine.

Joys of classic motoring?

Norman


wedgeinald

Original Poster:

1,314 posts

220 months

Thursday 9th April 2009
quotequote all
Was the Ignition "box" in the end.

One happy wedge and an even happier owner.

Norman

wedgeinald

Original Poster:

1,314 posts

220 months

Wednesday 15th April 2009
quotequote all
Was out and about in the wedge on Sunday went to the Mid Essex meeting. (about 250 miles with no dramas at all!)

http://www.tvr-nomads.co.uk/midessex.htm for pics

Lovely run despite light rain at the start and some chilly bits along the way.

Would have been nicer if only we'd had Monday's weather.

Great bunch over there and the Carvery was great.

Norman.