Gsxr Bodies - Erratic Idle

[chipstick 382 1 Cars]

Trying to get my engine to play ball and idle properly.

 

The issue I am having is when blipping the throttle the revs increase and drop but remain higher than they should be. It's as if the higher you rev it the higher it stays when it does drop.

 

I haven't changed my rev counter for a soldered one yet so not exactly sure what figures we are talking.

 

It's done this since the bodies and ECU have been on my car.

 

Initial thoughts were that the spring to the centre of the bodies could be stiff as if I push the throttle cable wheel back home it drops to a steady idle. I greased it and it's no better. I moved on to the cable adjustment, so I slackened it right off so the spring would be gaurenteed to go fully back, but it still does it.

 

I'm reluctant to adjust too much incase I've missed something obvious.

 

Is the TPS perhaps a bit iffy holding the butterflies open too much? Air temperature sensor, would this cause similar symptoms if it was playing up?

 

When driving it the revs stay high when you go to change gear, so I'd like to get it sorted before Sandy gets back from Holiday and the thing goes off for mapping.

[chipstick 382 1 Cars]

No matter what adjustments I make to the springs, cable etc it doesn't improve the actual idle post revving. I've adjusted it so it hardly has enough air to run at all, to plenty so it idles high yet still idles higher when you blip the throttle.

 

I'm sure it must be TPS related - yet it was fine when fitted on the other engine.

 

Any mechanical adjustments don't even make it slightly better or really any worse, which is making me think it may perhaps be something else.

[stu8v 68 1 Cars]

I guess at an air leak.

[chipstick 382 1 Cars]

I'm unsure what sort of 'seal' there is between the bodies and the satchell inlet. Ive never disassembled them so it's all new to me. Are there individual gaskets?

[welshpug 1,626]

O rings iirc

[chipstick 382 1 Cars]

Been giving the air leak idea some thought.

 

If I am infront of the car revving it by hand, when the revs remain high after blipping the throttle and I push the throttle wheel whatsit closed it goes back to a low idle. It's as if the butterflies are being held open ever so slightly resulting in a high idle after revving.

 

Is an air leak likely to cause the butterflies to be reluctant to fully close? As I say when you push the throttle wheel whatsit fully home it stops. When the engine is off the springs allow it to shut with a satisfying 'ting' on the stopper.

 

Forgive my ignorance but obviously when an engine is running the butterflies must allow a certain amount of air in to combust, hence the ports not fully closing, but it's the amount it allows which seems to be an issue. Perhaps an air leak behind the butterflies where the manifold joins to bodies could be increasing this rev yet the ECU is under the impression that the butterflies are only marginally open hence not doing anything about it.

 

Time for a beer

Edited August 11, 2012 by chipstick

[kyepan 291]

Try turning the idle adjustment screw down a little, mine did the same when it was set to allow too much air through. Additionally, helper throttle return spring would be sensible to help close he throttle up.

[chipstick 382 1 Cars]

Adjusted both springs from one extreme to the other and as expected it adjusts the idle from stalling to jet fighter. Either end of the scale still gives the issue of the idle not returning to its original position. For example if I adjust it so the idle is high on tick over - the return point after blipping the throttle is higher than that. If I adjust so it ticks over even higher, the revs remain higher again after blipping the throttle.

 

So I think I've ruled out the adjustment issue as no matter how it's adjusted the problem remains.

[kyepan 291]

so helper spring then?

[chipstick 382 1 Cars]

Adjusted the middle one to high heaven also. Unless it's worn and when running isn't strong enough to close the butterflies enough?