god damn shunt is killing me

[PapaButch]

Hey guys been a long time since I've been on here - Hello!

The chimaera 4.3 has had a lot of work on it and is now back in action!

But before it goes, it is shunting so bad low speeds 10-50mph are just killing, constantly having to depress clutch as the backlash on the diff is going to kill it again after it has just been done!

car is tuned, remap, trumpets, decat straight through exhaust, smooth bore, injectors, camshaft etc

but can i do anything with the timing by twisting the distributor to help it at all? if i can, which way do i turn it ?

Regards

Chris!

[mike-v2tmf]

Moving your distributor will undo the good work of your mapper , assuming its been mapped correctly

[TV8]

are you still using plug extenders?

[Dr Mike Oxgreen]

TV8 said:

are you still using plug extenders?

If so, get rid of them!

Mine wasn’t shunting as such, but getting rid of the plug extenders made the throttle response distinctly smoother, less snatchy.

Try removing them and wrap the ends of the HT leads with tinfoil to protect them temporarily while you do a test drive. See if you get any improvement.

I did find that the heat socks I used were insufficient protection though, and after a year the ends of the HT leads had burnt through and caused a misfire. I’ve now replaced them with leads that have angled ceramic ends.

[PapaButch]

I have these on at the moment.

[PapaButch]

Those cheap metal things were long gone. Car does have a lt77 gearbox and old style diff...but the backlash on the diff sometimes is to much for me to bear when it starts jumping around.

[jojackson4]

Map or chip?

[PapaButch]

Same thing on the rv8 unit you need a new chip for the new map

[blitzracing]

Who remapped it (assuming it still 14CUX ?) . If this has been done properly it should have picked up an major issues with the fuelling on the rolling road. Large amounts of shunting can mean the ECU is trying to sort the fuelling out with big corrections if something is wrong in the first place. Best bet on the 14CUX is to run it on the green tune as you can add more fuel at the shunting point.

[spitfire4v8]

Sounds bad if as described. Take it back to whoever did the work. Its only fair to give them another chance at improving it.

[jojackson4]

PapaButch said:

Same thing on the rv8 unit you need a new chip for the new map

You can buy a chip
Or you can remap there is a lot of difference

[bobfather]

Shunting and plug extenders? Different issues, plug extenders cause miss fire, shunting is not miss fire it's a fuel air mixture problem. I agree that removing the extenders is a good thing to do but it's not going to solve shunting

[PapaButch]

I’ll find out who done it as I gave the car to Kent Tvr (Paul) to sort out lots of bits and he done a great job but he took it somewhere for remap

[PapaButch]

[PapaButch]

Have spoken to Paul and because I wanted max power he has tuned it as so. So when foot is down or cruising at 70 the car is absolutely fine it’s just getting to that point!

[PapaButch]

Have spoken to Paul and because I wanted max power he has tuned it as so. So when foot is down or cruising at 70 the car is absolutely fine it’s just getting to that point!

[wuckfitracing]

Something is clearly wrong, it shouldnt shunt that badly. Mine doesnt and its all 100% standard.

[Sardonicus]

Mapping for max performace at top end should not compromise cruise/low RPM behavoir unless advance total figure is some how too much advance at low RPM, stock dizzy compromise if so and total advance may need taking down a tad unless you want to start playing with duzzy advance plate , bob weights, springs etc

[MPO]

Try taking off your vacuum advance pipe and temporarily block the metal pipe on the plenum.

Have a drive and see if this reduces the shunting. If so, this could indicate a vacuum advance problem…

MPO

[PapaButch]

But the car dies when that rubber hose is taken off that spaceship looking saucer next to the dizzy