I'm at a loss and need some advice to troubleshoot why my 4.4TDV8 is struggling to start. Once started it runs fine. Here's the symptoms:

- I always have a USB cigarette socket with a voltmeter plugged in whilst driving to monitor the volts. I initially noticed that the voltage when entering the car was very low, like 12.0-12.3 low. When I tried to start the car, nothing happened other than a click, and the draw on the battery would send the volts down to low 11V, sometimes even high 10V. I did find, however, that I could start the car turning the ignition on, turning the a/c and radio off, waiting for the fuel pump and whatever else kicks in during the first 20s or so to settle down and let the voltage across the battery stabilise. I could start the car then, often with as little as 12.1V showing. So, I thought that the battery was on the way out. Cue a new battery - a 90Ah 850cca AGM, exactly the same as originally fitted to the car. This hasn't fixed the problem.

- Next I bought a Topdon AB101 Car battery tester after seeing a Ben's Garage test - nice and simple bit of kit and only £32 delivered. I tested both the new battery and the old battery (after charging up with a proper charger for a few days) and both are reading fine. The Topdon also runs tests of cranking and then charging - both came back ok (but more on charging in a moment). Anyway, I'm thinking that it either had to be started motor or alternator. After reading a lot on starter motors and how low voltage would struggle to get the solenoid to engage, I bought and fitted a brand new Denso DSN1207 (a pig of a job but I got it done). On the very first start, it shot into life and I thought that was it. I still wasn't sure why the voltage seemed to be a little lower than the 12.6V that I would expect, but put the 0.3-0.4V difference showing on my USB cigarette lighter thingy down to battery draw differences between across the battery and at the cigarette lighter, plus the fact that it's cheap tech so not super accurate. Anyway, I fitted the new starter motor on Monday and it started first time every time, without having to wait for the voltage to settle, on Tue and Wed on multiple short trips. However, I went to start the car today and...nothing. I had 12.0V on the USB thingy with the ignition on. I got it started with my Noco Boost and went for a drive for 15 mins, also giving it some proper beans to the redline a few times to really get engine (and hopefully the alternator) working properly. I got back, switched off, and it's showing 12.6V on the USB thingy.

So, to recap, i have a new battery and a new starter motor. Now I need help troubleshooting and would really appreciate some advice.

Batteries - I have two available (the original and the new replacement). I doubt either is a dud, they seem to charge fine and the Topdon AB101 is giving a 75%+ SOH on both.

Alternator - I am seeing wildly varying voltages when driving, anything from about 11.7, all the way up to approx 14.8 ish. There doesn't seem to be consistency on this, according to speed or load. I had initially thought I need a new alternator, but before I shell out for one I need to nail down whether this is normal behaviour - there are threads on here, citing the manual, that say the vehicle has smart charging and can [I'm paraphrasing] vary the voltage dependent upon the needs of the vehicle. What I also want to understand is the current output needs from the alternator as well as the voltage output. I assume that a low current means it won't be enough to charge the battery properly, even if the volts are 12.6 or higher? I recorded a 20+ minute log at motorway speed using my IID and the link to the log, showing Alternator Current, Alternator Load, Battery Current and Battery Load on that drive is below.
https://drive.google.com/file/d/1uZV0drdWn...sp=sharing

Battery Management - is it possible this is something to do with the vehicle's sensors not getting correct information? How could I tell if the battery and alternator are fine, and it is something else?

Parasitic drain - I checked already with my multimeter and got 0A from the disconnected negative battery terminal and lead, but I was expecting to see something, even if only a few mA, so I am going to have to investigate that a little further to rule that out. Should I have the car locked or unlocked for this? should i be switching things on or turning them off whilst running this test?

Please help...anyone! I really would appreciate an ordered list of try this, try that etc to help me troubleshoot this problem away!!

Sounds to me your first battery was fine

I also run an LED voltmeter from the cigarette socket. 12.0 to 12.3 is quite normal upon entry
Mine drops to 9v, maybe 8v even, when starting
I have no starting issues

As folks say, the battery management ECU is quite clever on the MY11s onwards that use AGM batteries.
Installing a new battery usually requires a reset of the battery management ECU - as the charging needs of an old v new battery are different

But it doesn’t sound like the old AGM was in bad condition

Maybe my memory is poor, but I thought my old MY10 had a lead / acid battery
I don’t think your battery is the problem

On parasitic drain, workshop manual says anything up to 20mA is fine

On charging, I see normal charging voltage between 14.4 and 14.8 on tick over. No need to excessively rev the engine to get full beans out of the alternator

I don’t hear my fuel pump when turning on the ignition before starting. I thought the fuel system was a primed system / pressurised system and didn’t need to be re-pressurised on each start up.

Personally my guess would be the issue is poor contact / intermittent earthing in the starter relay somewhere. Maybe starting with the starter button, and the starter motor (the bushes on these are known to go)

Am just guessing really, sharing thoughts.

ignore me Cheers, Greg
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2011 Vogue SE 4.4 with lots of toys in Stornaway

I have had the same issue and I think I am at the tail end of it.

I have replaced:
Starter
Alternator
Battery
Relays

I suggest you clean the engine to chassis strap and observe, this has made a massive difference. I still have occational starting issues but the car starts with the same procedure you have used.

I suspect it is a design issue where the relay circuit degrades over time, poor contact means spark/buildup/resistance resulting in poor starting.

I am currently going down the path of"GraemeS" and add a high current relay for the starter solonoid.

Click image to enlarge

ffrr14 - thank you for this 🙏

I spent yesterday doing some fettling. I thoroughly cleaned the contact points on battery -ve terminal and the chassis ground at the end of the cable so know that’s now fine. However, I couldn’t locate the engine-chassis Earth strap. Do you know where that is on the 4.4TDV8? In lieu of this I made up a new strap that I was able to bolt to the engine in an unused threaded M8 hole I found on the top-front of the block and then connected it to the Earth point on the top of the osf suspension strut. That should do a better job than the original strap but I’d still like to locate the original to do a scrub/clean of that regardless!

Also, you mentioned you’d changed relays - plural. Please can you tell me which & where? I’m aware of relay 6 in the engine fuse box and have swapped that with the fuel one next to it as a temporary measure (both relays same spec). However, are there more relays and where can I find them?

I’m awaiting a motorcycle relay to arrive next week but I already have the cabling and connectors to do the job, so that will be next weekend’s fun to do the GraemeS upgrade.

I am determined to get to the bottom of this and am very hopeful that the GraemeS relay upgrade will be the end of it. Any help you can offer would be very much appreciated! Andy

2010 4.4TDV8 Vogue SE in Santorini Black with Ivory interior
2017 Audi SQ5 3.0 V6T Quattro in Volcano Red
2001 Audi Allroad 2.5 TDI manual with low-range in Highland Green. Currently SORN whilst undergoing some serious restoration!

I found an earth strap near the bottom of the right side rear (looking forwards) of the radiator, found when R&R'ing the fan shroud.

So, I did the GraemeS mod yesterday and added a high-current relay into the circuit between the engine compartment fuse box and the starter motor. It has started without hesitation every time since and in as many different scenarios as I could try. It's only been 24 hours (but quite a lot of starts) so I need to keep an eye on this for longer to be certain, but I am quietly confident that this might well have done the trick. I will try and do a proper write up with some photos and a how-to that might get wiki-fied but, in the short-term and for this thread, here's what I did:

- I chose to mount my relay at the top of the engine bay near the fuse box, rather than down near the starter as GraemeS has done. I found a spare M6 threaded metal post on the bulkhead just under the pollen filter housing bolt on the drivers side that is perfect. I wanted it up high for water-resistance and easy access for future maintenance, plus the engine heat will dry it out if it does get wet.

- I went a little over the top with wiring choices in the hope of reducing resistance to minimise voltage drop as much as possible. I used 10AWG/6mm2 between the fuse box (starter motor trigger wire) and the relay, and also to earth the relay switching circuit. I then used 6AWG/16mm2 to go from the battery 12V feed in the fuse box (the big red cable coming in at the rear of the box) via a 80A midi fuse to the relay, then the same size cable from the relay down the side of the engine to the starter solenoid terminal.

- I sourced a connector from a scrapped fuse box to go straight into the plastic plug connector in my own fuse box, allowing me to remove the original red 4mm2 starter cable and replace it with my new 10AWG/6mm2 cable. This meant no cutting of cables or splicing into the loom which was something I wanted to avoid so I could return the vehicle to stock if I needed to (or remove the mod easily if it doesn't work).

- The next step is to drill 2 holes into the side of the fuse box to route the 6mm2 and the 16mm2 cables properly. I haven't done this yet as I wanted to run it as is for a few days to make sure the mod worked and is reliable before I started drilling into something that I can't undo. I have a load of rubber grommets to be able to get the best seal possible on the fuse box and will probably add some silicone sealant on both sides of the grommet to be 100%.

My initial thoughts are that this is a really easy mod to do if you have the right cabling and some basic tools. After doing a ton of research into this mod online (it's really popular in the US and Australia, particularly in the trucking and farming communities on big engines), it seems to me like this is an absolute no-brainer, even if you don't currently have starting issues. The original cable from the fuse box to the starter solenoid is over 6m long and a pathetically small diameter; meaning it is barely up to the job in perfect conditions, i.e. good battery health, no corrosion of terminals and earthing points, good relay contacts, good starter solenoid contacts etc. Now, I am getting 12V directly from the battery to the starter solenoid and if that doesn't hold the solenoid closed to initiate the starter then nothing will. I spoke with GraemeS about choice of location and he was extremely helpful (thanks mate!) but he had different reasons for his choice of location near the starter, which is an equally valid location and a LOT easier to do than my choice of location. However, I am very OCD about these things and I wanted to have easy access to the new relay, so I chose to mount mine in the engine bay. I also wanted to keep the relay 'trigger' circuit as short as possible for reliability, so not continue to use the 6m-long existing cable, even if it was only being used for a relay and not the starter solenoid which draws a lot more power.

When I get a chance I will write up a new thread with this as a how to for others to follow but, in the meantime, I am now praying to the L322 gods that I have FINALLY overcome my intermittent starting issues and that this job is jobbed!  Andy

2010 4.4TDV8 Vogue SE in Santorini Black with Ivory interior
2017 Audi SQ5 3.0 V6T Quattro in Volcano Red
2001 Audi Allroad 2.5 TDI manual with low-range in Highland Green. Currently SORN whilst undergoing some serious restoration!

Its a common fix for starting issues on tvr chimaera and griffiths which seem to suffer from the same issues especially when hot...

Yes, I can vouch for a hot engine seemingly making it worse. I often found that the vehicle would start when cold, even with a slightly lower battery voltage. I could drive for an hour so assumed my battery would be at full charge for its state of health, but then get a no start! It was infuriating! Anyway, no non-start issues so far and hope it continues that way long-term![/quote] Andy

2010 4.4TDV8 Vogue SE in Santorini Black with Ivory interior
2017 Audi SQ5 3.0 V6T Quattro in Volcano Red
2001 Audi Allroad 2.5 TDI manual with low-range in Highland Green. Currently SORN whilst undergoing some serious restoration!

Can remember more than once filling up the chimaera with fuel and being unable to restart the damn thing, having to go back to the garage cashier and get a push out of the way of the pump until it had cooled off a bit, then discovered the relay mod.

I must be a glutton for punishment TVR then range rovers 😂😂😂😂