Intermittent Starting Problem
Discussion
I've got an intermittent starting problem which I'm struggling to diagnose. It seems random and it doesn't matter whether the engine is hot or cold.
I turn the key and the fuel pump primes, but the starter solenoid either doesn't click at all or clicks faintly. Sometimes the starter will make a momentary attempt to turn. If I wait a few seconds and try again, it will sometimes start. It may take as few as 3 or as many as 10 attempts before it will crank and start
.
It's a 98 car which I've owned for 12 years with no previous issues like this. The starter motor, alarm and all starter circuit wiring are original. The battery is less than 12 months old , the 100amp fuse is new and the charging circuit is healthy.
I've read all the threads I can find on the Hot Start issue, but as I've said this doesn't appear to be heat related. From what I've read, the problem would appear to be in the low current side of the circuit but the frustration is that I can't get it to replicate the problem now I've got it jacked up and I'm stood here with my multimeter in hand.
I know if I set off to go anywhere, Sods Law dictates that the bloody thing will undoubtedly play up again, and the worry then is that it won't start at all.
I'm tempted to just take off and inspect the starter motor and solenoid, and look for anything obvious to eliminate any faults with those but any other suggestions would be welcome.
I turn the key and the fuel pump primes, but the starter solenoid either doesn't click at all or clicks faintly. Sometimes the starter will make a momentary attempt to turn. If I wait a few seconds and try again, it will sometimes start. It may take as few as 3 or as many as 10 attempts before it will crank and start
.
It's a 98 car which I've owned for 12 years with no previous issues like this. The starter motor, alarm and all starter circuit wiring are original. The battery is less than 12 months old , the 100amp fuse is new and the charging circuit is healthy.
I've read all the threads I can find on the Hot Start issue, but as I've said this doesn't appear to be heat related. From what I've read, the problem would appear to be in the low current side of the circuit but the frustration is that I can't get it to replicate the problem now I've got it jacked up and I'm stood here with my multimeter in hand.
I know if I set off to go anywhere, Sods Law dictates that the bloody thing will undoubtedly play up again, and the worry then is that it won't start at all.
I'm tempted to just take off and inspect the starter motor and solenoid, and look for anything obvious to eliminate any faults with those but any other suggestions would be welcome.
Edited by sparkythecat on Saturday 24th May 13:22
tty contacts behind the key?Check the low current wire to the solenoid ( physical inspection as well as electrical test )
It could be the ignition switch on the way out - these are about £15 and a ten minute job to change
Hot start kit again not expensive and can't hurt to have fitted
When/if it happens again try the thump the dash underside whilst cranking method (usually passenger side, but found one on drivers side yesterday - this just gives the immobiliser relay a jolt and makes the proper connection)
It could be the ignition switch on the way out - these are about £15 and a ten minute job to change
Hot start kit again not expensive and can't hurt to have fitted
When/if it happens again try the thump the dash underside whilst cranking method (usually passenger side, but found one on drivers side yesterday - this just gives the immobiliser relay a jolt and makes the proper connection)
Edited by ukdj on Saturday 24th May 13:44
Well, the starter motor and solenoid have been taken off, cleaned up and bench tested. They appeared to be working fine and the teeth don't show inordinate wear. The the crimp on the switched wire to the solenoid wasn't as tight as it may have been, but it is now.
In the absence of any better suggestion, I'll just have to keep running it until the problem shows again. It seems pointless speculatively replacing any components until I can identify which one is causing the problem.
Can anyone tell me the way to bypass the immobiliser circuit, to test if this cures the problem next time it happpens? PM me if necessary.
In the absence of any better suggestion, I'll just have to keep running it until the problem shows again. It seems pointless speculatively replacing any components until I can identify which one is causing the problem.
Can anyone tell me the way to bypass the immobiliser circuit, to test if this cures the problem next time it happpens? PM me if necessary.
QBee said:
+1 for solenoid. But I agree that the starter switch can give similar symptoms and has been found to be the cause on at least one case recently reported on here.
Is the starter switch behind the dash or in the steering wheel shroud?Edited by QBee on Saturday 24th May 13:53
Your problem almost certainly resides inside the immobiliser.
The circuit from the start terminal on your ignition switch to the starter solenoid on the starter motor is looped through a relay buried inside the immobiliser.
This relay is notoriously unreliable, partly because it was never man enough for the job TVR made it do, & partly because of the way TVR wired it.
Given this relay is buried deep inside the immobiliser you only have two practical options to solve the problem:
1) Fit a new alarm/immobiliser system (costly)
2) Complete a bypass (free)
You could fit another relay to take some load of the worn relay inside the immobiliser and indeed the truth is this is all the Hot Start kit is, but a Hot Start kit will just mask the problem for a while.
The Hot Start kit is a temporary solution as it cannot repair or reverse the contact damage that already exists inside the relay within the immobiliser.
The immobiliser bypass will permanently solve your problem because unlike fitting a Hot Start kit the worn out problematic relay that's the cause of many Chimaera & Griffiths starting problems is completely removed from the starter circuit.
The only downside with the bypass is your starting circuit is no longer protected by the immobiliser meaning the car can be cranked on the starter motor without the need for the immobiliser/alarm fob to be pressed.
This isn't as big an issue as you may think because the car still won't start due to the immobiliser also controlling the live feed to the fuel pump, fortunately while operating in the same way as the starter solenoid circuit the fuel pump immobiliser circuit/relay seldom gives trouble.
So simply bypass the immobiliser on the starter solenoid circuit only and you'll have a reliable starting TVR that's secure too, best of all a bypass costs nothing if you do it yourself.
It's also extremely easy to do, just find the right wires that pass through the immobiliser using a multimeter, then join them together.
Job done
Or another common cause of a slow turning stater motor/intermittent starting is high resistance in the rather inadequate gauge battery to starter motor cable.
This cable was not only under specified by TVR in the first place (especially for its considerable 6ft length), but TVR then chose to drape it over the bell housing trapping it behind the hot cylinder heads & exhaust manifolds where there's also little or no air flow to cool it.
During its life this feeble cable gets heated up and cooled down literally hundreds if not thousands of times, add all this to the fact it's now probably anything from 15 - 20 years old & suffering heavy internal corrosion and it's not hard to imagine how much the resistance will have increased over time.
If you are having trouble imagining it, just take a look below
The circuit from the start terminal on your ignition switch to the starter solenoid on the starter motor is looped through a relay buried inside the immobiliser.
This relay is notoriously unreliable, partly because it was never man enough for the job TVR made it do, & partly because of the way TVR wired it.
Given this relay is buried deep inside the immobiliser you only have two practical options to solve the problem:
1) Fit a new alarm/immobiliser system (costly)
2) Complete a bypass (free)
You could fit another relay to take some load of the worn relay inside the immobiliser and indeed the truth is this is all the Hot Start kit is, but a Hot Start kit will just mask the problem for a while.
The Hot Start kit is a temporary solution as it cannot repair or reverse the contact damage that already exists inside the relay within the immobiliser.
The immobiliser bypass will permanently solve your problem because unlike fitting a Hot Start kit the worn out problematic relay that's the cause of many Chimaera & Griffiths starting problems is completely removed from the starter circuit.
The only downside with the bypass is your starting circuit is no longer protected by the immobiliser meaning the car can be cranked on the starter motor without the need for the immobiliser/alarm fob to be pressed.
This isn't as big an issue as you may think because the car still won't start due to the immobiliser also controlling the live feed to the fuel pump, fortunately while operating in the same way as the starter solenoid circuit the fuel pump immobiliser circuit/relay seldom gives trouble.
So simply bypass the immobiliser on the starter solenoid circuit only and you'll have a reliable starting TVR that's secure too, best of all a bypass costs nothing if you do it yourself.
It's also extremely easy to do, just find the right wires that pass through the immobiliser using a multimeter, then join them together.
Job done
Or another common cause of a slow turning stater motor/intermittent starting is high resistance in the rather inadequate gauge battery to starter motor cable.
This cable was not only under specified by TVR in the first place (especially for its considerable 6ft length), but TVR then chose to drape it over the bell housing trapping it behind the hot cylinder heads & exhaust manifolds where there's also little or no air flow to cool it.
During its life this feeble cable gets heated up and cooled down literally hundreds if not thousands of times, add all this to the fact it's now probably anything from 15 - 20 years old & suffering heavy internal corrosion and it's not hard to imagine how much the resistance will have increased over time.
If you are having trouble imagining it, just take a look below
Thanks for the detailed reply ChimpOnGas. I was hoping you might post on this thread.
Just a couple of questions.Does the dash have to come out to access the immobilizer circuit?
Can the battery cable be inspected properly in situ or does it need to removed and does it pull through easily or is it a pig to remove?
Just a couple of questions.Does the dash have to come out to access the immobilizer circuit?
Can the battery cable be inspected properly in situ or does it need to removed and does it pull through easily or is it a pig to remove?
Edited by sparkythecat on Monday 26th May 22:33
sparkythecat said:
Does the dash have to come out to access the immobilizer circuit?
Yes, well the dash top has to come off.sparkythecat said:
Can the battery cable be inspected properly in situ
No, sadly not.sparkythecat said:
Does it need to removed
Yes.sparkythecat said:
Does it pull through easily
No, and don't forget to tie some strong cord to the end of the old cable so you can pull your new one back.sparkythecat said:
Is it a pig to remove?
Yes.But before you start all this do some tests to establish exactly where the problem is, don't just assume it's the immobiliser or starter cable until you've proved it.
To this end a decent quality long jump lead & a good multimeter are your best friends.
Edited by ChimpOnGas on Monday 26th May 23:20
I left the immobiliser circuit alone and wired in a heavy fused supply to a relay then switched the relay via the ignition switch, I ran a heavyish [30A] wire from the relay direct to the starter solenoid and have not had problems since. I just left the original light wire to the solenoid tucked away so easy to reconnect.
Edited by Aussie John on Tuesday 27th May 06:09
Edited by Aussie John on Tuesday 27th May 06:10
Aussie John said:
I left the immobiliser circuit alone and wired in a heavy fused supply to a relay then switched the relay via the ignition switch, I ran a heavyish [30A] wire from the relay direct to the starter solenoid and have not had problems since. I just left the original light wire to the solenoid tucked away so easy to reconnect.
Well that's another way to do it Aussie John and no doubt would be/is 100% effective, in effect you've still bypassed the damaged Meta relay though, which is exactly what you want to do.Does your engine crank on the starter with the key in the sprung start position without disengaging the immobiliser?
If so you've bypassed the immobiliser, you've just done it a different way.
The root cause of he problem is that TVR chose not to fit a dedicated relay to the starter solenoid circuit which as we know is far from best practice, my guess is they decided to do this in the misguided belief that the Meta relay was sufficient.
The problem is the Meta relay was actually never designed to take the level amps fed to the starter solenoid, its merely a little low amp switching relay.
You will find the little Meta relay system works reasonably reliably on the fuel pump circuit because the fuel pump draws considerably less amps than the starter solenoid and (unlike the starter solenoid circuit) the fuel pump also benefited from a second dedicated relay from day one, this is the metal one on the blue connector hanging in the passenger footwell.
Running the starter solenoid circuit through the little Meta relay worked for TVR for a while, even years in many cases, but eventually it will fail giving the well documented starting fault nearly all Chims & Griffs eventually suffer from at some point in their life.
If owners had fitted the Hot Start kit (a relay) from day one, it would have solved the problem permanently because the little Meta relay would have never ever seen all those amps so would have never ever been damaged in the first place.
The problem is people typically fit the Hot Start Kit (HSK) after the problems start indicating that the little Meta relay has already been damaged.
The HSK doesn't bypass your damaged Meta relay it'll merely take some load off it, which admittedly can have a positive result for a while, but because the damage has already been done the problem still lurks in the background waiting to catch you out.
You can add as many relays as you like, if the circuit still includes the damaged Meta relay it will always remain the weakest link.
And as we know any chain is only as strong as its weakest link, only fitting a new link (new alarm/immobiliser system) or bypassing that weak link will solve the problem.
The bottom line is however you choose to do it, you need to bypass that damaged Meta relay.
Just fitting a HSK is not the complete answer
Not sure you know how that Meta alarm relay is incorporated into the starter circuit Dave 
the TVR/Vaux ign switch when cranked in no way energizes the Meta relay it just uses the already closed relay contacts 
the alarm unit does this when you dis-arm the alarm, this so called relay must be well underrated for the job because strictly speaking once those contacts are closed it should easily be able to pass enough current to energize the starter solenoid 
I have used 15A fuses on 4 hot start conversions and to date none of them have blown so that Meta relay must be pretty poor especially seeing as when its needed the contacts are already shut 
the TVR/Vaux ign switch when cranked in no way energizes the Meta relay it just uses the already closed relay contacts the alarm unit does this when you dis-arm the alarm, this so called relay must be well underrated for the job because strictly speaking once those contacts are closed it should easily be able to pass enough current to energize the starter solenoid I have used 15A fuses on 4 hot start conversions and to date none of them have blown so that Meta relay must be pretty poor especially seeing as when its needed the contacts are already shut Edited by Sardonicus on Tuesday 27th May 10:10
This thread is brilliant.
Many thanks to those who have posted and those who have PM'd me.
I know that logicallly I should be trying to diagnose the problem when its occurring and car won't start and I could then more accurately pinpoint the cause.
But, ironically it's starting easily whether hot or cold just at present, but with a trip to France due in a few weeks I need to engineer out the most likely causes.
A new ignition switch is less than a tenner and given the sheer volume of them for sale on eBay, there must be a very high attrition rate so I think I'll replace that any way
I will also bypass the immobilizer relay as suggested by ChimOnGas, but if i do,should i put another relay in the starter circuit? as when I bench tested the starter, the solenoid was drawing around 8 amps when engaged.
Many thanks to those who have posted and those who have PM'd me.
I know that logicallly I should be trying to diagnose the problem when its occurring and car won't start and I could then more accurately pinpoint the cause.
But, ironically it's starting easily whether hot or cold just at present, but with a trip to France due in a few weeks I need to engineer out the most likely causes.
A new ignition switch is less than a tenner and given the sheer volume of them for sale on eBay, there must be a very high attrition rate so I think I'll replace that any way
I will also bypass the immobilizer relay as suggested by ChimOnGas, but if i do,should i put another relay in the starter circuit? as when I bench tested the starter, the solenoid was drawing around 8 amps when engaged.
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