Low Idle

Installed my polished manifold and throttle body the other day and now my idle seems to be at about 500revs. Is there a way of changing this manually or is it done through the ECU??

yes you can do it manually.

Not very good at explaining and I am sure someone will come along and correct me.

what you have to do it adjust the screw by the throttle cabling in your engine bay.

You no where you can rev the engine from the engine bay by pressing the latch front, there are 2 screws near by that you will see, adjust them to suit the idle you want.

I had to do this on my car.

hope it helps. like I said im rubbish at explaining,

Sounds perfect. I thought it would have been something similar, but as we all know things are never easy on the sup. Thanks again

thats cool anytime.

might be worth checking for vaccum leaks around the throttle body and manifold. before you go adjusting things.

If you need any help come round mate..

Thanks for that Chris. I did check the hoses, but wouldn't hurt to double check.

Its the grub screw on your throttle body u need to look at..

Anyone know what the idle speed should be?

6-700rpm is "normal" though some idle fine even lower!

omg! I wouldnt touch that screw! not sure about yours tho being non vvti, but I thought the ECU generally controls the idle speed especially on the VVTi models?

The idle is NOT set by adjusting the screw, fiddling with that will also move the throttle pot closed position. It's ecu controlled. if you have to readjust the butterfly closed position via the stop screw you need to correctly and accurately reste the throttle pot setting, or the maps the ecu will read from will be skewed.

Chris, is the VVTi's TPS - that is setup in the same way as a non VVTi yes?

Honest answer is I don't know, that info for the VVTi has never been available to me.

Cheers Chris. I did have a feeling it was ECU controlled but wasn't 100%. Must be a leaking hose then.

It's not incrediably bad, but i did sound like it wanted to stall this morning.

Correct me if I am wrong but I would have thought a leaking hose vented to atmosphere would actually increase the revs?

I'd clean the Idle Control Valve, reset the ECU and test again. Might be fuel related as well...maybe it had a batch of the good stuff and set itself a lower idle?

An ECU reset isn't a bad idea. May have got upset when swopping them over.

Yeah, on a MAP based car a leaky or missing hose actually raises the idle as it introduces more air to the intake plenum and it's actually measured and fuelled for.

If the low idle is due to the ECU needing to learn it should suss it out if left to idle for a couple of minutes. Also blip the throttle a bit and let it settle back to idle, it should get better at it each time you do it. Pretty much the procedure you should go through after resetting the ECU anyway.

I'd never move that screw fitting though - if your idle is off it's the sign of a problem. Moving that screw simply masks the problem's symptoms and causes other changes in itself...

-Ian

Well all hoses seem in tact. I'll let it idle for 5-10 minutes tomorrow and if there's still a problem i'll do a reset.

When you say manifold and throttle body you mean the whole intake side ..which means the TPS would have been taken off to polish it ????? is this set corectly? Fuel for thought

I had that problem (too low revs at idle) and it turned out to be a single faulty spark plug. Maybe check em

When you say manifold and throttle body you mean the whole intake side ..which means the TPS would have been taken off to polish it ????? is this set corectly? Fuel for thought

Ooohh, don't know. Sorry Mig but what does TPS stand for and how do i tell??

Could be spark plugs but i only changed them about a month or 2 ago. Saying that i did put 27's in and it's been the coldest wetaher lately for a while.

Well i changed the hoses due to this thread, and she's now idleing fine. Not 100% sure why as the hoses all seemed to be fine, plus tomorrow is always another day so will have to keep an eye on it.