Discussion
Hi all, I haven't posted on here before but I do enjoy reading this forum and so hopefully deepening my understanding of these beasts. One thing that I always question every time I see it is my ecu. It seems fairly obvious that that it is not the original (my car being a 5 liter) and the computer having 4.5l and a date in 2003 on it. The car runs faultlessly and regular checks with rovergauge show no problems. My question is can anyone tell me wether this ecu is fundamentally identical to the original or should I try and track down a 5l one cheers. 
As far as I know they are similar if not identical. The only thing that gets changed on an engine change is the main chip.
If you want to explore further, take the ECU out of the car and carefully undo the screws and open it up. Don't touch anything, just see if the main chip inside has any labels on it. I think it's a 28 pin chip IIRC, but could be wrong on that. It plugs into a holder rather than being soldered in.
If you want to explore further, take the ECU out of the car and carefully undo the screws and open it up. Don't touch anything, just see if the main chip inside has any labels on it. I think it's a 28 pin chip IIRC, but could be wrong on that. It plugs into a holder rather than being soldered in.
Someone will be along with the reason why it's fine. It ain't broke, so don't fix it!!
I upgraded my engine from four litres to five and was told I could keep the same ECU, just change the chip. When we had running issues I did try a five litre ECU, but it actually ran worse.
However we had not just changed the engine, but also:
Injectors
Plenum
AFM
Cam
Inlet manifold
Decatted
Decatting makes no difference so long as you leave the lambdas in the exhaust manifold.
I upgraded my engine from four litres to five and was told I could keep the same ECU, just change the chip. When we had running issues I did try a five litre ECU, but it actually ran worse.
However we had not just changed the engine, but also:
Injectors
Plenum
AFM
Cam
Inlet manifold
Decatted
Decatting makes no difference so long as you leave the lambdas in the exhaust manifold.
Thanks sounds about right to me also but as you say someone may come back with some different advice, I've been toying with the idea of de-catting but don't know how much there is to be gained, I suppose it depends on how blocked they are, presumably if there is no blockage then there will be no gain removing them. However here in N.Z. I don't have to worry about emission testing come w.o.f. Time so some would probably say its a no-brainer?
Decatting makes the car about 8-10 decibels louder and much harsher sounding. It also adds about 20 bhp.
You have to remove both precats and the main cat.
My decatted 5 litre car, with the Clive Y piece, is 105.8 decibels at 4500 rpm. If you want to test yours and have an IPhone, download an app called Decibel 10th. Hold your phone two feet from the exhaust, at 45 degrees up, out and back from the tailpipe. Get someone to start the car and rev it to 4500.
Precats can be bashed out of the exhaust manifolds. It can be done on the car, but you risk bits of cat ending up in the engine. Perhaps more sensibly, they can be taken off the car, put in a vice, and the cats bashed out with a big long screwdriver or crowbar! Even more sensibly, take the manifolds off the car and get a welder to cut them open around the big tube, just downstream of the 4>1 union. Take the cats out, and check the 4>1 unions from inside. They almost always start to fail at that union, so you are saving a job later. The manifolds must be accurately welded back up, both or length and orientation.
The main cat is removed by cutting the Y piece around its middle, having marked it first vertically so that it can be accurately welded back up, otherwise the Y piece won't fit. The only snag is that I have been told that the sound of the big empty Y piece is a bit dustbin-like. I fitted a Clive Ford Y piece. ACT also sell one. Both are about £350. Both sound a lot better.
If you need to quieten it for track days, you can buy bolt on silencers, again from ACT. They knock about 5 decibels off and soften the sound.
HTH
You have to remove both precats and the main cat.
My decatted 5 litre car, with the Clive Y piece, is 105.8 decibels at 4500 rpm. If you want to test yours and have an IPhone, download an app called Decibel 10th. Hold your phone two feet from the exhaust, at 45 degrees up, out and back from the tailpipe. Get someone to start the car and rev it to 4500.
Precats can be bashed out of the exhaust manifolds. It can be done on the car, but you risk bits of cat ending up in the engine. Perhaps more sensibly, they can be taken off the car, put in a vice, and the cats bashed out with a big long screwdriver or crowbar! Even more sensibly, take the manifolds off the car and get a welder to cut them open around the big tube, just downstream of the 4>1 union. Take the cats out, and check the 4>1 unions from inside. They almost always start to fail at that union, so you are saving a job later. The manifolds must be accurately welded back up, both or length and orientation.
The main cat is removed by cutting the Y piece around its middle, having marked it first vertically so that it can be accurately welded back up, otherwise the Y piece won't fit. The only snag is that I have been told that the sound of the big empty Y piece is a bit dustbin-like. I fitted a Clive Ford Y piece. ACT also sell one. Both are about £350. Both sound a lot better.
If you need to quieten it for track days, you can buy bolt on silencers, again from ACT. They knock about 5 decibels off and soften the sound.
HTH
That's a good point, I wonder how different the two maps are at full throttle, I hadn't been too concerned about fueling thinking the ecu would keep it correct (with feedback from the o2 sensors) but I seem to remember the o2 sensors are ignored above 3/4 throttle leaving it to run on the map+coolant temp+rpm+air flow (which is probably maxed out at that piont anyway) maybe I need to get it on a rolling road/dyno to confirm?
If you can dyno it easily, its not a bad plan.
Shouldn't be too difficult to get a standard 500 chip from the UK.
Just tell me what makes you sure yours is a 500? Does the engine number and size match the documentation, for example? That very very low mileage perhaps suggests the engine has been changed and the odometer reset? 10,000 miles on an 18 year old car with aircon (reading your profile) sounds very unusual. The TVRCCJ in Japan may be able to tell you more about the car - try contacting Yoichi by email - you will find him regularly posting on the Random TVR pics thread. His most recent is the penultimate post on this thread:
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Shouldn't be too difficult to get a standard 500 chip from the UK.
Just tell me what makes you sure yours is a 500? Does the engine number and size match the documentation, for example? That very very low mileage perhaps suggests the engine has been changed and the odometer reset? 10,000 miles on an 18 year old car with aircon (reading your profile) sounds very unusual. The TVRCCJ in Japan may be able to tell you more about the car - try contacting Yoichi by email - you will find him regularly posting on the Random TVR pics thread. His most recent is the penultimate post on this thread:
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Edited by QBee on Sunday 8th September 03:39
Thanks for the contact qbee, I too have questioned weather or not my car is a genuine 5l. it was certainly sold to me as a 5l and the import papers that came with it support this.it has the purple tappet covers and the Griffith style wheels.
I understand the "5" in the chassis no. and the "50" in the engine no should mean its a 5l? (only going on info. i have picked up on the internet)re. the mileage, while the body isn't perfect (clear coat lifting and carpets fading)the engine is very clean inside (had the sump of) and has used about 1/2l of oil in the 7k kms i have done. it also has an "odometer verification" sticker on the windscreen which you pay extra for when importing.I don't know how they do this other than checking previous inspection reports throughout its life to confirm that the mileage hasn't gone backwards at any point? Also during the compliance process all the brake rotors and pads were measured all of which showed very little wear. All that said i still wouldn't be surprised if the car in fact has covered more miles than indicated it is very low after all. It was something i weighed up when i purchased the car and i decided it didn't mater to me so much everything else about the car was what i wanted and there's not too many of these beasts around to choose from in this corner of the world. Cheers p.s. gotta go for a drive now all this talking about it has got me all fizzed up.
I understand the "5" in the chassis no. and the "50" in the engine no should mean its a 5l? (only going on info. i have picked up on the internet)re. the mileage, while the body isn't perfect (clear coat lifting and carpets fading)the engine is very clean inside (had the sump of) and has used about 1/2l of oil in the 7k kms i have done. it also has an "odometer verification" sticker on the windscreen which you pay extra for when importing.I don't know how they do this other than checking previous inspection reports throughout its life to confirm that the mileage hasn't gone backwards at any point? Also during the compliance process all the brake rotors and pads were measured all of which showed very little wear. All that said i still wouldn't be surprised if the car in fact has covered more miles than indicated it is very low after all. It was something i weighed up when i purchased the car and i decided it didn't mater to me so much everything else about the car was what i wanted and there's not too many of these beasts around to choose from in this corner of the world. Cheers p.s. gotta go for a drive now all this talking about it has got me all fizzed up.
![](http://thumbsnap.com/sc/UxpGcY9l.jpg[/img]</a> <a href="http://thumbsnap.com/dRJXefgC" Target="_blank">[img]http://thumbsnap.com/sc/dRJXefgC.jpg)
Glad you are enjoying it. The only other thought I have is that it has either had an ECU failure or an engine failure in its life.
The 5 litre lump is less robust that the 4.5/4.6 litre engine, and can suffer from broken crankshafts. It was an engine developed by TVR by taking the 4.5 Range Rover engine and increasing the stroke. They then externally balanced the engine rather than internally, and didn't cross bolt it. The later 4.6 Range Rover lumps are pretty well unbreakable.
A friend of mine broke his 5 litre of similar vintage to yours, and replaced the bottom half of the engine with a 4.6 short engine, keeping the same heads. That could just possibly explain the 2003 4.5 ECU. The BHP is similar - with mods his 4.6 makes 20 bhp more than my 5 litre.
Its just possible that the ECU broke (unlikely) and was replaced with what was available in Japan. A boiling battery can do a lot of damage, and the ECU is rather too close to the battery for comfort.
The 5 litre lump is less robust that the 4.5/4.6 litre engine, and can suffer from broken crankshafts. It was an engine developed by TVR by taking the 4.5 Range Rover engine and increasing the stroke. They then externally balanced the engine rather than internally, and didn't cross bolt it. The later 4.6 Range Rover lumps are pretty well unbreakable.
A friend of mine broke his 5 litre of similar vintage to yours, and replaced the bottom half of the engine with a 4.6 short engine, keeping the same heads. That could just possibly explain the 2003 4.5 ECU. The BHP is similar - with mods his 4.6 makes 20 bhp more than my 5 litre.
Its just possible that the ECU broke (unlikely) and was replaced with what was available in Japan. A boiling battery can do a lot of damage, and the ECU is rather too close to the battery for comfort.
NZ fan said:
That's a good point, I wonder how different the two maps are at full throttle, I hadn't been too concerned about fueling thinking the ecu would keep it correct (with feedback from the o2 sensors) but I seem to remember the o2 sensors are ignored above 3/4 throttle leaving it to run on the map+coolant temp+rpm+air flow (which is probably maxed out at that piont anyway) maybe I need to get it on a rolling road/dyno to confirm?
You can either put on the rollers, or if you have test meter to hand, run a couple of wires to join the black and white wires on one of the lambda connectors, get a passenger to read the meter from inside the car under full load / peak RPM. Ideally you want about 1.1 to 1.2 volts, but as long as it does not drop below around 1 volt it will be it wont be leaner than lambda 1 (14.35:1) on these probes. The voltage drop of to 0 volts is very sharp on these probes as the mixture leans off, and should never be seen under full load. The probe outputs are still active in open loop.Hi,
some possible ways to identify the engine size, without fully stripping.
Genuine 5.0L sump has several round indentations at the front to allow crankshaft clearance.
Drop sump and view crankshaft, rover crankshaft will have "Rover" and engine capacity i.e "4.6" cast into the back counter weight. The TVR 5.0 crankshaft has more distinctive rear counter weight shape than the rover item, more squared off is the best way I can describe it.
Check engine number on the block, located in 2 places. 1st down on the plinth where oil dipstick enters block, 2nd on a raised pad at the front top of the block (n/s) where block meets head. Numbers should match vin plate.
Ozstyle
some possible ways to identify the engine size, without fully stripping.
Genuine 5.0L sump has several round indentations at the front to allow crankshaft clearance.
Drop sump and view crankshaft, rover crankshaft will have "Rover" and engine capacity i.e "4.6" cast into the back counter weight. The TVR 5.0 crankshaft has more distinctive rear counter weight shape than the rover item, more squared off is the best way I can describe it.
Check engine number on the block, located in 2 places. 1st down on the plinth where oil dipstick enters block, 2nd on a raised pad at the front top of the block (n/s) where block meets head. Numbers should match vin plate.
Ozstyle
Hi, thanks for that. more info i was unaware of. I have recently had the sump off but didn't know what to look for.However i have found the engine no. and although not very accurately stamped, it is a match with the body tag.
Just need to confirm now that it is not lean at full noise. Cheers.
Just need to confirm now that it is not lean at full noise. Cheers.
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