Engine hunts when hot

[LenChim]

blitzracing said:

It tells you the map number in the RoverGauge screen shot- just above the map table, I could not quite read it on the photo. Id drop the ECU out and split the case and check the chip then. It should have a label on it something like 4.5 cat if its TVR. I dont know the maps as well as Spitfire, but its worth checking if he does not recognise it as well. Also check your tune resistor- its poking out of the ECU loom in the footwell- its in a small clear plastic case, and should have white insulation wires on it (white tune). This should tie up with Map 5 shown in RoverGauge.

OK it seems as though we may have found some of the problem, The chip has a 4lt sticker on it. I can not find the resister as yet, I do not know how much of the loom I have to take apart to find it? Is it likely to be behind the battery box? As you can see from the pic I have undone some of the insulation from the loom.


As can be seen from the last pic:-
Current fuel map :-5
Multiplier:- 0x56CC
RPMLimit:
Row Scaler:- 0xB9

Right across the top of the screen it says:-
Tune No:-R2967
Tdent :-1A17
Check sum fixer :-FF
I Do not know what any of that means.

[LenChim]

It seems not to have liked two of the images I put up so lets try again:-

[LenChim]

And again:-

[LenChim]

blitzracing said:

I cant see it in your loom, its not on all looms, as in the USA looms they dont want people changing maps, so the resistor is missing. It looks like this if you can find it, but as long as you are showing map 5 thats fine.




Im surprised the difference between 4 and 4.5 would kill the engine that badly, but I guess the 4.5 has much improved higher RPM breathing over the 4 ltr when it needs more fuel.

Maps here if you want to blow another chip or drop me a mail if you want me to do one for you.

http://www.remap-14cux.uk/bins/

Ok It says Tune:- R2967 as I have but I notice some thing else about altering the voltage on the AFM by turning a screw. When cleaning the AFM I turned that screw so have I screwed up the AFM literary?

The picture should be of the AFM with an 7/32 allen key sticking out the side.
TVR Griffith 400 & 400HC Precat (R2422)
TVR Griffith 430 & 430BV Precat (R2422)
TVR Chimaera 400 CAT (R2967)
TVR Chimaera 430BV CAT (R2967)
TVR Chimaera 450 CAT (R2967)
TVR Griffith 500 (1995on) (R2967)

RoverGauge shows the CO trim voltage for non cat vehicles in real time but you first have to start and stall the engine before RoverGauge displays any adjustment of the CO trim screw. Please make a note of your CO trim voltage before making any adjustments so you can revert back if required.

The CO trim voltage & AFR table on the left was created by turning the CO Trim screw in half turn increments clockwise which increases the CO trim voltage and fuel. For all Precats 13.5 AFR is best for smoothness and reduces shunting.

CO Trim for Precat vehicles
Precat owners wishing to change firmware revision may have to adjust the CO trim screw on the AFM with a 7/32 Allen Key. The Co Trim voltage should 2.3 volts for a 4.3 running it’s original factory ECU and 1.4 volts when running TVR’s later code R2967 or Land Rovers final code R3652.

R2967 & R3652 idle AFR (4.3L)
Clockwise increases volts & fuel

Co Trim Volts AFR
0.04 Lowest 16.5
0.55 15.7
0.8 14.8
1.05 14.3
1.25 14.1
1.42 13.5
1.6 13.3
1.75 13.1
1.92 13.0
2.05 12.8
2.20 12.7
2.35 12.5
2.50 (8 turns) 12.4

[LenChim]

davep said:

spitfire4v8 said:

I did suggest this just over a month ago .. you can give the advice Dave but it's pot luck whether anyone actually acts on it

Frustrating isn't it! Horse to water and all that ...

Hopefully there will be another TVR running to its full potential at the end of it.

It's all very well guys but if you think that the fault was not there originally you would first look at all the things that could change i would suggest. I have corrected many other faults with the car e.g. the shunting, excessive fuel consumption, tick over all over the place, etc. Personally did not think that the chip was incorrect as I thought it was a new fault but having done all the obvious we now come to the chip, lets hope that fixes it. You do not normally go around at 5400+ rpm on your Sunday run out.

[LenChim]

Well I have now ordered the 4.5 chip so I will soon find out if that is the solution to the problem. Question, re removing and replacing the chip, do you need a tool, are there any do's and don'ts? Should I disconnect the ECU from the wiring loom etc?
Many thanks Len.

[LenChim]

blitzracing said:

I've grabbed one of Steve Sprints 450 maps with later base code, extended fuelling and a few other tweaks. I've heard nothing but good for Steve work, and its in the post box now.

Many thanks.

[LenChim]

LenChim said:

Many thanks.

OK I have put in the new chip, got it warm and let it tick over above 90C so all reset. Took it out for a run goes very well up to 5400 ish rev's then hit a wall, looking at the out put from the lambada's the voltage drops to zero after about 3300. So whats new? Found I had a vacuum in the petrol tank so left the cap of, no difference. I am going to swap out the coil and see if I can blag an AFM from some one after that I am devoid of ideas. Does any one know of some one with a rolling road in west Sussex that is not going to cost me an arm and a leg? I will try and get some screen shots of the car under power if it ever stop raining.

[LenChim]

blitzracing said:

The Rev limit should be about 6200. I've yet to hit it on a TVR map, it makes my eyes water thinking of those pushrods and valves trying to keep up. The landrover limit was around 5400, but it's a serious brick wall when you hit it, quite terrifying if you are trying to overtake something in third, and it simply cuts the injectors. None of this accounts for the drop in lambda voltage so early on.

Ok, I changed the HT coil gave it a run and it will rev over 6000 rpm as you said it sounds very excited so it would seem that the coil was breaking down despite passing all the resistance tests. The lambada voltage still drops to zero but what the hell. I could only glance at the matrix but the black square was over to the right on the screen so it would seem to be ok, I honestly cannot say if it was near the top or the bottom I think?? it was about mid way. If I get a mad passenger at some time in the future I will get a better reading from them.
Many thanks for your knowledge and help over the past few months. Len