throttle hassles 16v

[colinstubbs 0]

I've got a Webber Redline throttle body fitted, same size as the fabled Firebreather, but it's got 924 stamped on the actuator arm, so i think it's same as fitted to 2 litre porsche 924.

 

When I fitted it, the spring was dead light so I used a small bungie cord to give it some feel and help it return to idle, but it always seemed to stick a little and left me having to blip it 'a la chav' at junctions. :oops:

 

I changed the throttle cable as it was also sticking at various other revs and found a few broken strands on the old one that were catching - sorted! But no! :x Sticking throught the range was sorted, but idle was still ar$e.

 

I finally bit the bullet the other day, took off the TB and had a look. I thought that when I polished it a bit, prior to fit, that I could have made it too good a fit as it closed thus holding it off closing completely, so I carefully took a piece of emery paper to the butterfly and chamferred it to reduce the friction.

 

At the same time I cleaned the oily residue from the butterfly and the body 'down-stream' as it were. Suffice to say it cured it for awhile but it's doing the same thing again. I'm wondering if the oil vapour heading up the breather pipe is gumming up my butterfly valve and causing it to stick? Doesn't seem likely to me but the motor's done 162k, piston rings could probably be better! :roll:

 

I don't know whether I should source a stronger spring or simply redirect the breather pipe as kevHaywire mentioned in flusted's diy catch tank thread. Or both! Where could I get the spring from for instance? It is starting to pee me off a bit!

 

I dunno how to do the piccy thing but on flusted's webber firebreather thread mine is the bottom pictured TB which incidentally operates the opposite way to the standard TB , opens anti-clockwise looking down on it.

 

Any help/suggestions greatly appreciated!!!!

[flusted 0]

have you fitted the isv micro switch?

[colinstubbs 0]

yes mate, got a bracket for that, that's fine!. The idle is stable in that it doesn't hunt about and isn't lumpy, it just doesn't always drop to 1000rpm. if I get out and pop the bonnet i can just move the quadrant that extra half a knats cock that seats the butterfly properly closed. As i recall i had a mate look at it as i killed the engine and it seats as the manifold vacuum drops! Like the running engine is holding it off somehow? Seems daft to me, I'll have another check today after I've driven to my brothers, seems to happen more when it's hot. Cheers

[flusted 0]

mine had a very small hole drilled in butterfly to aid on/off throttle transitions

[colinstubbs 0]

I think I see what you're saying there, the hole reduces the suction effect of the manifold allowing the butterfly to shut. In that case, what size was the hole and whereabouts was it drilled?? If this is all I have to do to fix the problem I'll be well happy :D Cheers

[colinstubbs 0]

Good news, I went to check out the ISV, looked at it and thought ,"Isn't there a leckie connection?" removed unit to find the plug had come off!! Obviously a complete twat had touched it last! :oops: :D

 

~I cleaned it anyway, and surprisingly enough seems to have cured my idle and slowly dropping revs problem! It's so nice when it's that simple :lol:

[bcstudent 0]

Bonus!

 

Can you describe what you meant by 'slowly dropping revs'? I know it's difficult to describe these things but I'm interested to know how bad the problem was.

[colinstubbs 0]

It was taking about 5 sec to drop from 3k to wherever it decided idle was gonna be. Sounded like I wasn't lifting off for gearchanges, Very frustrating.

 

All in all it was pretty bloody bad! Still seems okay though, so I'm happy with that :)

[Phil K 0]

Glad you got to the bottom of it mate :D

[bcstudent 0]

Yeah, mine is nowhere near as bad as that so I'm guessing that's just the way it runs!

[colinstubbs 0]

Cheers Phil,

 

LOL