Engine surging. Advice anyone?

[Bellyj43]

Hi All, I just changed a snapped throttle cable on my otherwise healthy and recently serviced T350. It all seemed fairly straight forward but when I started it up, the throttle surged about 4-5 times before staying at high throttle!
During the cable replacement I did touch metal against the alternator '+' which sparked, but I've checked the engine related fuses and they appear to be ok. I've started it 4 times and it does the same every time.
At the moment I switched the ignition off I get a 'warning code 245 Power Supply' but this may be because I've switched it off at high revs?
I've also tried starting it with some throttle but it just surges from higher initial revs. I can't think of anything else I've done or touched or even how the throttle can surge without the throttle bodies being open ie hardly any air is getting in.
Any suggestions would be muchly appreciated.
Belly

[VARLEYHYD]

245 is possible damage to diode in alternator, but not related to hunting/ surging

Hunting can be problem with front & rear 3 sets of throttles not balanced between

G

[Bellyj43]

The throttles were balanced last month when it was serviced. It must be something I've touched during the air box removal but I can't think what. Code 245 wasn't in your manual Graham. Do you know where the diode is situated?
Thanks
Belly

[Robertjp]

you sure the throttle isnt just too far open? Ie the new cable been set shorter? Its sounds a bit like the ecu soft limiter which can be a bit unnerving if you have not had it before but it hunts up and down, its an oscillation in revs
if the throttle is set too far open it would hit this immediately on start.
The comical thing is when i think of engine surge its the type when rotors slam into each other and you get flames out the front of the intake and has the potential to scrap an engine!

Edited by Robertjp on Thursday 13th September 22:51

[Bellyj43]

Good suggestion Robert. I did adjust the length of the bar at the back of the accelerator pedal to improve the throttle response as the first cm of pedal movement did nothing. Maybe I've adjusted it too much.
I'll adjust it back to how it was as see how it goes. There's no chance of comparing cable lengths now as it had snapped.
Any idea how open the throttle butterflies should be open at idle? They look like about 2-3mm.
Thanks. Belly

[clive f]

at idle you shouldn`t see hardly any gap on the butterflys at all, as mentioned earlier, check your throttle cable adjustment , sounds like you`ve taken so much slack out and now opened the throttles, also have you tried to adjust the tickover on the throttle linkage, there are 2 adjuster screws between 3 and 4, one for tickover, the other for 4,5,6, have you moved the wrong one?

[Bellyj43]

Thanks for the great advice chaps. I disconnected the throttle cable at the engine and fired it up..... It started fine.
The butterflies were definitely too far open so I've adjusted the cable at the bracket to increase its length by about 6mm. The throttle butterfles are almost closed now at idle and it runs smoothly.
Thanks again.
Belly