lockie

just rebuilt my cosworth engine & refitted it but when i try cuise along at low revs (under 2.5kish) it sometimes judders/kangaroo's & when throttle applied it keeps on doin it?????

any idears???

if u change downa gear so revs pick up its ok or if u shut throttle off & re apply its ok

never done this before i remove engine???

tps??? as i cant seem to get it to go any higher then 4.2 volts on idle & then drops to 0.2 on full throttle

atm i think its set to 3.7 on idle as it must have moved when tightening it

any other idears???? as car used to cuise along smooth at 30mph in 5th gear!

cozmeister

iTrader: (1)

Be thinking about the TPS - they wear out just at the sweet spot around cruising speed. And it's not so much the voltage dropping, it's the way it drops and rises - it should be a linear change. When the TPS is opened slightly, it signals to the ECU that it should start adding fuel, and shuts the idle control valve. When it reads as closed (by you or a dodgy TPS), the fuel is cut off, hence the lurching, which can be quite violent when you're not expecting it!

Changing down a gear or up a gear just makes your foot move the TPS to a different position, out of the bad zone, making the symptom "go away".

If you're on an L6 ECU, the TPS must be aligned properly after it's fitted to the throttle body.

lockie

changed tps & air temp sensor, loadsa better but still sometimes jumps about at 2k.

ive had 2 set tps to 3.7 volts on idle (closed)
best i can set it to is 4.3 but when started it idles at 3k! & it cant be dropped any lower so ive had 2 rest to 3.7 & it idles fine

Guinnless

Check the engine mounts are properly tightened!