standard tvr cam

[daz the plumber]

can any one tell me what the factory fitted cam is for the 4l tvr chimaera 1996 thanks

[V8 Animal]

daz the plumber said:

can any one tell me what the factory fitted cam is for the 4l tvr chimaera 1996 thanks

Mine
Sorry daz could'nt resist

[daz the plumber]

my wallet is empty , im out of cash lol. spent 1400 quid on a new cam still not happy .15 mpg and ive been adviced to spend another 600 plus quid on a re map .its a joke .don`t know why i did not go for a standard factory cam .i dont want to knock of another tenth of a second off 0 to 60 i just want to burble around enjoyiong the summer .i was aware of these cars being a little expensive to run but thats not a problem . ive owned a mg rv8 in the past so i have an idea what they are about .i feel like dumping it in the river ... i feel sick when i turn the key . daz

[rev-erend]

If it's doing 15mpg - then I think it's unlikely to be the mapping.

Before any mapping takes place - you have to have sure everythink else is OK first ..

My suspisions would be -

Throttle pot
Wires loose or frayed
Air flow meter
ECU

These are the usual causes of fuel over usage.

For example - my cable to the airflow meter was just hanging on - I did a tank of fuel in 60 miles

[Dave81]

Are you saying that since the new cam install (MC1 right?) that your fuel consumption has dropped to 15mpg???
Can't see that if your car was making average 4ltr consumption rates before that it would have dropped that much due just to the cam???? What else have you had done to the car since you've last seen decent fuel returns???

[900T-R]

Something weird going on and indeed, I'd be going through the fuel and ignition systems with a fine toothcomb.

The RV8 is quite relaxed about its fuel requirements at WOT/high rev operation and below that, the lambda control system should keep things in check -surely going from the TVR 51 (I think) cam to a mild 'upgrade cam' like the MC1 should not get things 'out' by as large an extent that the O2 sensor feedback loop wouldn't be able to do its work. I've got my engine rebuilt and upgraded and it's in effect a completely different engine inside - bigger valves, different pistons, ported, re-shaped combustion chambers, different cam - and ran spot on from the day it was returned to me!

[Ab Shocks]

My 4L with MC1 cam gives about 300 to a tankfull on a run but drops down to 200 miles if I'm hooning.
Probably AFM I reckon Daz

[penno]

Might sound a daft one but have you checked for petrol leaks?

[daz the plumber]

no petrol leaks, when i slowly lift the throttle from tick over its very lumpy all most as if its running on 7 cylinders .at 2100 the car runs perfect and i must say it goes pritty well . a local dyno center had a look at it , im not saying there experts but they said the car runs very rich then rights its self at 2100 revs .if i put the car on any load meaning not reving it clatters . the noise is there mainly up to 2100 . for some reason the vacume advance is capped off .the fse fuel regulator as been set at forty psi and it stinks of petrol .in the past ive dropped the fuel presure with out any results .its a lovely car tell you the truth its spoilt my summer .i thought when having work done , its a one fix job and if it costs more ok , can`t see why its up to me to sort it out .it should be back to me working some where near .if i go for a remap the cost as gone up to buying a short engine ..

[daz the plumber]

im getting fifty miles on £20 so work that one out at £1.14 a litre . ive tried the higher octane but its worse .im not even reving the car .

[lesstatt]

i think thats 13 to the gallon if my maths is right............. ouch, what about taking it to the guys in Melton and letting them look at it, quite reputable by all accounts

Edited by lesstatt on Tuesday 29th July 19:07

[Konrod]

I still suspect that the engine thinks it is cold and is over fuelling, as the lambdas will be over-ridden in that state.

I recall that there are two temperature sensors, one for the gauge and one for the ECU. What's the betting that a connector got knocked off during the cam swap...... Once any revs are reached the engine would smooth out but consumption would be horrible.

Check the wire is connected to the manifold temperature sensor under the dizzy.

Editted for poor spleingt

Edited by Konrod on Tuesday 29th July 19:10

[GreenV8S]

Running with the vac advance disconnected will reduce the part-load economy (and make the engine hotter).

If you still have the standard fuel map then the FSE pos will result in either too much fuel under full load or not enough fuel on part load. If you then raise the fuel pressure to get the part load fuel back to where it should be then under full load it will be massively rich.

Who measured the fuel pressure and how?

[rev-erend]

The advice given sounds very wrong.

I would seriously think about going to someone who knows TVR's .. not sure where you are ..

You could end up spending money on a remap and then still not solve what is probably something else malfunctioning.

For instance the throttle pot costs about £10 (ebay) and takes 2 mins with a volt meter to check, change and re-set-up can can give just that kind of problem.

[That Daddy]

rev-erend said:

The advice given sounds very wrong.

I would seriously think about going to someone who knows TVR's .. not sure where you are ..

You could end up spending money on a remap and then still not solve what is probably something else malfunctioning.

For instance the throttle pot costs about £10 (ebay) and takes 2 mins with a volt meter to check, change and re-set-up can can give just that kind of problem.

Or new about £50 from Land Rover dealers dont buy s/hand its a rapid wearing item,and dont just test once but a few times,my one was giving nice linear scaling on 2 tests until it failed on the 3rd when it was warm(all seperate occasions)just for your information my fault with this divice was intermittant dieing on constant throttle openings(cruising)but Daz thats not your overfueling fault,i think i would remove that adjustable fuel reg and try a stocker,try and get the car near to standard before getting to involved with other stuff,i must say you have been getting some sound advice on hear so far,dont dispair remember if its not the fuel reg you can just refit it,but that overfueling at low throttle openings i smell something fishy and would have to loan a Air mass meter if the former dont change a thing(i once left mine unplugged by accident while testing and it overfueled like a bd,i got about 100m before i realized,it was that bad)sadly your to far away,if i was in your area you could gladly lend my Chims gear

Edited by That Daddy on Tuesday 29th July 21:03

[clive f]

agree with That Daddy, my AFM somehow got water inside it, and didn`t want to run at all at low rpm, practicaly threw the petrol out the back, try and borrow one and swap them over

[That Daddy]

clive f said:

agree with That Daddy, my AFM somehow got water inside it, and didn`t want to run at all at low rpm, practicaly threw the petrol out the back, try and borrow one and swap them over

Thats weird Clive because this happened to my brothers car after about a few months of ownership and his car lives garaged and he had not powerwashed the engine,judging by the gungy mess in his AFM we thought it may have been from a breakers yard lieing around or something before being fitted to his Chim but the history of the car does not tally with this he cleaned it out and it still works oh yes the symptoms he had was severe lurching and very poor running at low speeds(its a vital part of the system)to the point of being undrivable,it still as the dreaded lurch at low speed but thats another matter,Blitz knows i am on this and with his knowledge and help is getting closer to being resolved sometime soon,bloody time is my enemy i just got to put what i have learned from Blitz into action

Edited by That Daddy on Tuesday 29th July 21:31

[coetzeeh]

Daz, I had a quick look through your profile and previous posts and found this. I note you said you fitted a rising rate fuel regulator...the response is from "Blitz"..

"The problem with rising rate is the ECU's fuel mapping is worked out with the fuel pressure being fixed at 37-42 PSI above manifold pressure. When you boot the car the ECU puts a set amount of extra fuel in to maximise the power increase when its needed. If you use a rising rate, it then quickly "boosts" the fuel pressure to put even more fuel in. Combine this with what the ECU's already doing, and it simply over fuels, so you get no more (possibly less) power, and it wastes fuel. The ultimate continuous power is not controlled by the boost rate during acceleration, but by the final air fuel ratio, that is controlled by the ECU, together with the final settled fuel pressure, that is now no longer "boosted". You can still get a good final BHP, but no better than a linear unit thats set correctly. I have closely looked at the fuelling with a rising rate unit, and it’s almost impossible for the ECU to control the mixture as it should, and makes the fuel consumption worse. The rising rate units are really a relics of trying to get the best out of the older mechanical fuel injection systems. Personally my eBay unit is working just fine.

Mark"

[daz the plumber]

its not a riseing rate .its a 1:1 fuel regulator works the same as standard but you can tweak the presure up .i did not fit it , was fitted with the cam and advance unit plugged off .

[That Daddy]

daz the plumber said:

its not a riseing rate .its a 1:1 fuel regulator works the same as standard but you can tweak the presure up .i did not fit it , was fitted with the cam and advance unit plugged off .

But is it working? have you checked or had the fuel rail pressure checked Daz?