The V8 Owners Forum -

It has been cured by trying a second ECU. It's still a bit of a mystery but the theory is (offered by Mark Adams) that between 92-93 Rover changed the ECU and that TVR meanwhile may still have been fitting the older chip in the newer ECU's

This means he's saying that I've had the wrong chip from ...

...I mean to see what the pressure is doing at 6k..

That I havent checked. Checked it static but not revving to 6k (didnt think it'd be this hard to diagnose back when had the pressure tested)I still have an adjustable FPR sitting around would that work to try?

Standard TVR 4.0 idle is a bit lumpy. Dont know what cam exactly but I dont think they're that wild. There should be an equivalent cam available but obviously it depends what your vehicle is. I wouldnt have thought a TVR cam would be any good in a LR/RR?

Hi guys

I thought I should start a new thread because my old one was a dead end so seeing as I'm back to square one, may I ask any gurus out there to have a read of this one.

It's a '94 TVR Chimaera with 50k I bought it with 38k. I havent revved it hard until the last few months but I'm pretty ...

Thanks Dave

AFAIK the resistor only absorbs/helps stop ECU seeing too many spikes, ECU is quite happy with 12v there but anyway, it didnt do anything and you were right that my initial voltages were fine. Steve Heath, I'm afraid your book led me down a dead end! I say that bearing in mind it is an ...

Okay I gave it 12v by removing the resistor and it didnt solve it.

Oh this is weird.

I've swapped the ECU (from another 1994 car) and again, it didn't solve it.

I read that some -1993 cars had the limit at 5,600 but if mine was somehow one of those (it's a '94) why would it revv to 6k once? And ...

Hi Spend.

I found the resistor.

Well here's what we've got: 12.66 volts on coil side all the way to the resistor. The resistor it's self seems to be reading 7140 ohms - bit high?

With ECU plug disconnected we have the same 12.66v at pin 39 and with it connected it drops to 9.4 varying slightly ...

Okay cool. I've just remembered where I think the resistor is so off to investigate now the various things.

Cheers guys will post back what I find.

Sorry but have to ask his question. Are you sure the engine is not reaching 6000 and it's just the rev counter reading which is at fault?


Problem is it will revv to 6k ONCE (either under load or at idle) then it will only go to 5k or thereabouts

I did consider that but sadly it's not because ...

Yep, that was my next test today!

Thanks for the replies btw

So if it's down to the resistor I should see the same voltage at pin 39 even with the ECU plug disconnected right?

And if it suddenly hits 12.66v then it's the input impedance of pin 39 it's self?

Okay. Need to do some further tests

Yeah, sorry I should have said what the standard 4.0 TVR uses. Hotwire I believe it is yes.

I realise an oscilloscope is needed to see properly what is going on in terms of spikes etc but according to Steve Heath's book (''the bible'') it is supposed to have 12v there at pin 39 with ignition on ...

Hey guys I'm new here.

I'm in the process of tracing a high RPM misfire. Quick background on this issue: everything is new - Coil, cap, rotor, leads, plugs, ign module. Dizzy also rebuilt/checked. Swapped for another known good ECU as well, nothing cured it. Also tested fuel pressure reg, pump and ...