We all know TVR electrics have their moments, and the Griff ECU and dizzy are certainly a few years behind the times. Not to mention on ours with 90+k miles on the clock, they're a little worn.
So, on a budget of about £1000 and whatever parts I find in my workshop, I'm going to see what I can do to improve things. The goals are for easy maintenance & fault diagnosis, more power, more fuel economy, a smoother drive and tolerance for all future engine mods.
Note that the current spec list doesn't fit into the budget. I failed miserably on that goal.
Adjustable fuel pressure regulator What the software can do...
VEMS is a Speed-density based ECU, with support for fully sequential operation of v8 engines
Thanks to the wideband lambda support, it can run closed loop fuelling for much of the time, and also has a nice "Autotune" feature for the VE fuelling map.
The ignition isn't yet quite so clever, but there is a knock sensor input, so it can do some tuning of ignition advance by itself, but it's nothing like putting the car on a dyno and listening with det cans.
How the parts fit together - Not in build order!
I chose a 36-1 trigger wheel with a standard Ford VR sensor for ease of replacement if necessary. A kit of parts specifically for my engine was available at a reasonable price. Since I don't have time to fabricate such things and can't take the car off the road for that long (The car is a daily driver), this was the best option. | |
Fitting the trigger wheel took a whole day, as the crank pulley was held together with Imperial bolts in very awkward positions! (They were supposed to be M8 according to the literature) A tool to remove them was fabricated and they were replaced with M8 cap screws.
Nicely made and the missing tooth position is easily adjusted when fitting.
Since the cam is difficult to get at, I thought I'd use the (now redundant) distributor body and a hall sensor instead of the camshaft wheel. They both turn at the same speed (more or less) so I see no problems. 
| First experimental cam trigger. A modified "points type" dizzy shaft, somewhat redesigned... The Hall sensor is G-clamped to the case at this stage. | |
Unfortunately, this didn't work reliably when tested - I think there was too much ferrous metal spinning round - , so my new idea was to remove the plate completely and make a thin tapered blade with a M6 bolt in the end to fit on the dizzy shaft. This was much more successful and worked well on the test bed. (bench power supply, volt meter and pull-up resistor) 
"Final" version of the dizzy-based cam sensor. Note the attempt to balance the shaft by tapering the bar. The hammer is used for fine adjustment... It's back in the engine now, and I just need to align it and do the config. The nice thing about using the dizzy is that the camsync pulse can be positioned anywhere in the cycle to suit both hardware and firmware.
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The fuel regulator had died shut and replacement seems inevitable. I've always tried to see such things as oppertunities for upgrades, so I have found an adjustable regulator.
The standard TVR reg was set to 2.5 bar. This simply isn't enough for good atomisation, so the new one should have 2 benefits - apparently bigger injectors and a better burn.
Note the addition of a pressure gauge for easy testing in the future. It's certainly cleaner, but it's a bit obvious that the car's modified now. The snag is that the fuel pump sounds a bit strained being asked to pressurise the rail to 3.5 bar. Oh well, maybe that Bosch 044 pump is in order.. Note -6AN fittings... Bench testing the ECU - Essential first steps! | | |
I've bench tested the NTC sensors and they work in pots of water at varying temperatures. Here's a picture of my "lab" (kitchen)
Calibrating the resistive sensors to produce the sensor profiles for VEMS
The first job is to get some brackets made up to support the coils. They will be placed on the left hand rocker cover, as this is the only flat space I have left in the engine bay! (The right hand side will be used for the twin throttlebody plenum) coils_sml.jpg - Coils and wiring harness built up on the bench. Note home made HT leads. | | |
I hope to get the brackets machined from aluminium this week. This didn't happen, so I had to resort to plan B - making them out of what I could buy from the local DIY store. It won't look too bad when all the wires are arranged neatly. Coils now in car. They're all held in an aluminim cradle mounted on the rocker cover using rubber bushes to damp vibrations
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First fitting of VEMS in car. What had I started?
Injector wiring completed & tested. It looks better than the factory wiring! Also took the time to hoover out the soil and powdered grot from engine. (Best not to ask how it got there...) It looks a whole lot cleaner now and will be much easier to work on.
I removed the old engine wiring loom after the injectors were shown to work. This might be considered rash. Indeed it was, because it stopped the fuel pump and starter working! Even though they weren't supposed to be connected to that part of the loom!! It seems TVR re-used part of the Rangerover loom, including where the rangerover immobiliser plugged in. (This was bypassed for the TVR immobiliser) It took 3 hours in the cold and dark evening to trace the 2 all black wires I needed to reconnect as they were mixed in with grounds and all sorts.
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Now the hazzard lights and heater have stopped working. I haven't even touched those systems! (Maybe a 2nd genboard to control the heater & stuff???) I suppose the moral here is don't do anything like this if you need the car the next day!! starting_wiring.jpg - measuring up the wiring harness.  First bits of the wiring loom are fitted under the bonnet. Much neater than the old loom. Note that everything is colour coded. | |
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I found some well priced 600cc/min injectors, flow matched to 1%. They're monumentally huge for my engine, but this gave me an idea or two... Such as ethanol based fuels.
So I bought them without much hesitation. The flow matching really shows. They were also supplied with a datasheet of opening and closing parameters. This helped me get VEMS set up very well. The engine runs so smoothly! The idle pulsewidth is 1.35ms, so I wasn't far off on my estimate of 1.4ms... 
Engine mostly tidy. A few things left to do, but they can wait... This is the state the car was in when it went to the 2006 Growl.
Recently, the exhaust caught a speed bump. This has started to split the flexi-joint under the car. It's been patched up with gun-gum but it's only a matter of time before the sports exhaust goes on!
It turns out that there was a serious problem with the exhaust manifolds too - some of the bolts have "worked loose" and the flange on one bank has been etched by the exhaust gasses so that they now won't seal.
New performance manifolds have been bought to fix this. Built to my specs with proper wideband and EGT ports fitted. The primary length also suits the engine better than the standard one, making this an all-round improvement.
Fitting the new manifolds was a headache. I had to enlarge some of the holes to get them to fit properly and I found some of the threads had stripped out of the head! No wonder the bolts had worked loose. Thankfully there's enough thread for slightly longer bolts. It's a bodge but it only needs to survive until December when the engine comes out for a new cam and the manifolds get ceramic coated. 
Drilling and tapping the plenum for the air temperature sensor. All looks neat and tidy.
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| Inside view of the air temperature sensor. |
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| Revised air temperature sensor. When located in plenum, the sensor became heatsoaked far too easily. |
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VEMS adds about 5 new fuses, and possibly adds or removes a relay or two (depending on your car). Instead of just having these extra bits kicking around loose, I thought I'd put in another small fuseboard.
This quickly became an excercise in rewiring the whole car, since a few wiring gremlins had been discovered. A useful modular fuseboard was acquired from A company called "Vehicle Wiring Products". It is considerably smaller than the old one so will allow me to gain an extra couple of inches of legroom in the passenger side.
The engine, cooling fans and headlamps have been put on to the new fuseboard, along with the main ignition relay now. The rest of the wiring is taking a lot of time to figure out!! 
Order of work
The order of work was designed so that the car could be used for as much of the time as possible while the conversion was in progress. This wasn't always plain sailing and sometimes resulted in having to repeat work. It's much easier if you can take the car off the road and get on with it - unfortunately this isn't an option for most of us...
manifolds First Outing Problem
The last Lucas part fights back...
A warning to everyone that sometimes no matter how carefully you check the new bits you add, it's the old bits that get you...
Having got a reasonably set up car, I thought we'd take it to a Piston Heads meet near London so I could optimise the "motorway" bits in the map (ie high speed cruising). I shouldn't have bothered as it was a total nightmare.
We filled up with fuel, and the car wouldn't start leaving the petrol station. Caused by a dead battery and poor terminals I think. (The battery was replaced after we got home and this problem went away.)
All was going fine after that - all settings on the laptop and LCD were perfect until the engine died without warning. I got it started again, but it was running rich (lambda at 0.75 to 0.95) and very rough. Since we were parked on the M-way hard shoulder, we had to move on, so I thought we'd be able to limp home - it was only 7 miles or so. The rich condition got worse and worse until the back fires got so bad I thought we'd kill the one remaining cat. After the wadding from the backbox exited the car at reasonable velocity on fire, I saw sense and got towed home.
The cause was that the fuel pressure regulator has failed. Note from Marcell: With an LCD and keyboard (and some experience using the menu), it is possible to change req_fuel to limp home. See - VEMS can cope with anything if you have the cribsheet of commands!
Second outing - The Growl 2006 + 1000 mile UK tour
All worked well - car achieved 30mpg on a run down the M6.
Did I achieve my Objectives?
Yes, apart from the budget! Well, once the shiny bits started to appear it was only a matter of time befer the small budget project changed into a big budget project... I didn't intend to have new injectors at this point (but they were a bargain) or new manifolds (but they too were a bargain...) I see a pattern emerging! [Add more] The whole story can be found on my section of the VEMS website.
What's next
Cam change 
