I've got hot start woes too!
Discussion
I can go to my car cold after a couple of weeks and it will start on the button. If I drive somewhere then go back to it in less than about 45 minutes, it doesn't want to know. The fuel pump primes, but it doesn't even try to turn over. Go back to it a bit later on and it starts with no problems. It had the Carl Baker new immobiliser and remote boot release not that long ago. The problem used to be occasional, but is now pretty much constant. If I go anywhere in it I have to be staying for at least an hour or leave it running! 
slippery said:
I can go to my car cold after a couple of weeks and it will start on the button. If I drive somewhere then go back to it in less than about 45 minutes, it doesn't want to know. The fuel pump primes, but it doesn't even try to turn over. Go back to it a bit later on and it starts with no problems. It had the Carl Baker new immobiliser and remote boot release not that long ago. The problem used to be occasional, but is now pretty much constant. If I go anywhere in it I have to be staying for at least an hour or leave it running!
Interesting. I thought the Carl Baker install was supposed to fix this problem. I fitted the Mod-Wise kit over 12 months ago and have had no problems since. You need to check the two circuits.
1) The low amp circuit that engages the starter motor SOLENOID
2) The current drop in the battery to starter cable at the starter motor
TBH as you're not hearing anything at all from the starter solenoid its sounds like the low amp side to me.
When the car is hot and exhibiting its DNS symptoms, jack & support on the O/S to get to the starter solenoid wire, remove it and test it with a meter.
You'll need an assistant up top to put the key in the sprung start position so the low amp circuit is energised.
My bet is you'll see next to no voltage & amps, if any at all.
People often fail to fully understand just how much resistance in a wire increases with temperature, but remember the same rules apply to the windings on the solenoid coil too.
Observing what you have at the removed solenoid wire will point you in the right direction, something in the low amp circuit or in the starter solenoid itself.
If the issue is in the solenoid wire you then need to establish if it's resistance in the wire itself or another component that makes up the low amp circuit.
Think: Ignition switch, immobiliser, or a non standard relay if one has been added (IE A hot start kit).
If the disconnected starter solenoid wire is showing good readings on your meter, then suspect the starter solenoid itself which in most cases can be replaced as a unit in it's own right without the need to replace the complete starter motor.
However, if the solenoid is at fault and your starter motor is getting on a bit you may find it more logical just to replace the starter motor with a new one which obviously will give you a new starter solenoid too.
You should also check all your earths while your at it, and take a meter reading at the high amp starter motor connection (big red wire) too.
This thicker red wire is the high amp feed directly from your live battery terminal to the back of your starter motor, it's very long & TVR uses a rather feeble gauge, both mean that resistance in this wire was quite high even from new.
Over the years & after many heat cycles the weedy 7ft long TVR starter cable becomes internally corroded & brittle raising its resistance still further, when it's hot things are even worse to the point where there's such a drop in voltage & amps at the starter motor it will only turn the engine over very very slowly or often not at all.
Some will tell you all this is nonsense, but I've witnessed it on my test meter & on my very own car, a new heavier gauge starter cable saw all the current delivered to the back of the starter right where its needed, and it'll do that every day all day long cold or hot as hell!
More recently Alex AKA GasMonkey was suspicious of his starter lead so cut it open, what he found was that half the strands were burnt & blackened, no surprise to me but further conclusive evidence to the doubters out there that this is definitely an area of weakness on these cars.
But all the above is pure speculation, the real key to solving your problem is the same as anything else:
1) Understand the system & how it works
2) Test each element carefully of the system in a systematic way
3) Replace only what is necessary to effect a repair
Don't just guess & throw replacement parts at it in the hope you'll solve the problem, sure you may get lucky every now & then with this method...
But the proper way you fix your car is to follow the above three steps.....
1) The low amp circuit that engages the starter motor SOLENOID
2) The current drop in the battery to starter cable at the starter motor
TBH as you're not hearing anything at all from the starter solenoid its sounds like the low amp side to me.
When the car is hot and exhibiting its DNS symptoms, jack & support on the O/S to get to the starter solenoid wire, remove it and test it with a meter.
You'll need an assistant up top to put the key in the sprung start position so the low amp circuit is energised.
My bet is you'll see next to no voltage & amps, if any at all.
People often fail to fully understand just how much resistance in a wire increases with temperature, but remember the same rules apply to the windings on the solenoid coil too.
Observing what you have at the removed solenoid wire will point you in the right direction, something in the low amp circuit or in the starter solenoid itself.
If the issue is in the solenoid wire you then need to establish if it's resistance in the wire itself or another component that makes up the low amp circuit.
Think: Ignition switch, immobiliser, or a non standard relay if one has been added (IE A hot start kit).
If the disconnected starter solenoid wire is showing good readings on your meter, then suspect the starter solenoid itself which in most cases can be replaced as a unit in it's own right without the need to replace the complete starter motor.
However, if the solenoid is at fault and your starter motor is getting on a bit you may find it more logical just to replace the starter motor with a new one which obviously will give you a new starter solenoid too.
You should also check all your earths while your at it, and take a meter reading at the high amp starter motor connection (big red wire) too.
This thicker red wire is the high amp feed directly from your live battery terminal to the back of your starter motor, it's very long & TVR uses a rather feeble gauge, both mean that resistance in this wire was quite high even from new.
Over the years & after many heat cycles the weedy 7ft long TVR starter cable becomes internally corroded & brittle raising its resistance still further, when it's hot things are even worse to the point where there's such a drop in voltage & amps at the starter motor it will only turn the engine over very very slowly or often not at all.
Some will tell you all this is nonsense, but I've witnessed it on my test meter & on my very own car, a new heavier gauge starter cable saw all the current delivered to the back of the starter right where its needed, and it'll do that every day all day long cold or hot as hell!
More recently Alex AKA GasMonkey was suspicious of his starter lead so cut it open, what he found was that half the strands were burnt & blackened, no surprise to me but further conclusive evidence to the doubters out there that this is definitely an area of weakness on these cars.
But all the above is pure speculation, the real key to solving your problem is the same as anything else:
1) Understand the system & how it works
2) Test each element carefully of the system in a systematic way
3) Replace only what is necessary to effect a repair
Don't just guess & throw replacement parts at it in the hope you'll solve the problem, sure you may get lucky every now & then with this method...
But the proper way you fix your car is to follow the above three steps.....
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