I've had got Jenvey DTH throttle bodies on a rebuilt ABF motor. Goes really well and the map on the DTA ECU is just about right through the rev range. It's very hard to drive though in town with light throttle inputs. It either revs its socks off or starts kangarooing down the road. It's all a bit embarrassing and I think I'm someone who can be gentle on the pedals! Is there any way of slowing down the throttle opening? It will be great on track but I have to get it there Any advice appreciated.
I put an extra throttle return spring on mine so that it required more pressure on the throttle, for me it gave better control of light throttle inputs
It just needs road tuning to get that right. It seems to me the calibration was developed on dyno and you got the WOT bits tuned in and more time was needed on the road for light throttle openings.
Is the throttle pedal travel similar to what it would be as standard or is it really short travel? A really short-travel throttle pedal could make normal driving difficult.
That sounds reassuring - I was beginning to worry that there was nothing more to be adjusted. Full power is only partial throttle travel so it's pretty sensitive. The extra return spring sounds interesting - was that easy to do?
I think you should get it mapped again where are you as there maybe somewhere nearby that can help, do you know who set it up
Not a problem with mapping - I've got someone locally. It's on the road mapping that's needed as the rolling road can't replicate no throttle or light throttle driving.
They should if they are good at it! But you can't beat road mapping, my old 3dr cosworth road mapped was much better than one mapped on rollers I still miss the 380bhp!
I had the same issue, but I was running bike ITB`s which are a little worse. Sounds like there are a couple of things you can do. First off, as already said, get the midrange / low down stuff mapped. Secondly, I drilled a second hole in my accelerator pedal arm to reduce the lever length. Foot the the floor was still enough to fully open the butterflies, but it made the pedal quite a bit less sensitive and much easier in the paddock / slow speed See the throttle cable, top left. it goes through a hole partway down the accelerator arm, rather than at the end. Small cable tie required to stop it pulling back through and I needed to bend the pedal slightly to regain my H&T position.
I had my Mk2 on throttle bodies running Citroen/Pug Ecu and mapped by Wayne at Chipwizards on rollers By far the most drivable car i had EVER ! Get it mapped properly and ensure throttle pot is functioning correctly as that is probably most important sensor when running Itb-s
It is 'kangarooing' as the engine is experiencing an oscillation from low torque to high torque. This can be very unpleasant. If you are using a decent throttle spindle/cam, similar to what badger 5 sells and the tps sensor as mentioned is fine, then the area of the map at tip in loads, at a guess without seeing the car, 0-30% throttle loads and idle to 2500 rpm, needs to be addressed. As said above you can address this condition on a dyno in a road simulation, however I have found over the years the conditions you described occupy areas in the ECUs lookup tables, that occur in real life. Therefore to set the engine torque or drivability, is usually best done on the road. Some of my best calibrations were 80% developed on the road with the other 10% on a dyno for WOT tuning
Thanks everyone, some good suggestions. I've got Bill's throttle mechanism which is well proven. It's very sensitive though. Sounds like I need to spend some time mapping on the road and adjusting the throttle, possibly fiddling with the pedal linkage as suggested.
