I know this has been covered but iv exhausted all avenues so far lol and this is my last resort..

Alrighty, over the last few days i have been modding away at a spare throttlebody i had. Didnt increase the bore or anything, basically just a light sand to smooth out the entrance to the throttlebody and a real good polish job on the bore aswell as a little mucking around with the butterfly to make it flow a little better but made sure not to alter the diameter of it in anyway



Today i fitted it to the EF (its auto by the way) and started her up. The throttle screw was in too far and was idling at about 1500 and when you tap the accelerator it would keep accelerating and take an age to drop . So i turned the screw out to drop the idle down a bit. Got it to idle in neutral at about 800rpm and about 700rpm and reset the ecu. Only issue is that i have a real bad case of rev hang. I can rev it and the revs takes a while to come back down to idle. Sometimes i rev it and then it'll drop down to 850-900 like its okay then it'll just pick the revs up to 1100rpm again by itself before settling down to about 800rpm again. Took it for a drive and it jerks quite bad going back to first gear when you slow down to a stop, on the upside it seems to have a bit more go in the midrange lol which i found quite weird in a good way

Have checked all vac hoses and everything is connected, renewed the t/b gasket and the isc gasket and cant hear any hissing noises so im pretty sure the vac side of things is sorted. Tried a spare isc i had and still had issues. Sprayed wd40 on the butterfly shaft on either end just to make sure it wasnt sticking, checked the throttlecable, and the return spring which works with the throttle lever all to no avail.

Im thinking its isc related as I tried using an isc gasket made with smaller holes, it kind of helped i think but it still has bad rev hang. Will the isc still operate properly if it is blocked off completely? Im guessing ill have to bump up the base idle a little to make up for it being blocked, i just dont want to have issues with cold starts. Ill probably make up another gasket with smaller holes or no holes tommorrow and muck around with the idle again, maybe drop it a bit lower reset the ecu again and see if it makes any difference.

Any ideas or suggestions would be greatly appreciated though.

Cheers.

You need to perform the correct base idle reset procedure of the EF ecu. First get the engine too operating temperature..

1) Unplug the ISC and place a 0.75mm feeler gauge between the adj screw and stop tab on throttle body.
2) Short the far left top and bottom pins on the diagnostic plug.
3) Start the car, revs should rise then fall
4) Now adjust to 700rpm (+-50rpm)
5) Turn car off, remove shorted pins, remove feeler gauge, replug in ISC.
6) And Have a nice day...........

Cheers.............

Last edited by EL__Fairmont on Mon Apr 13, 2009 8:33 pm, edited 1 time in total.

ah the dreaded rev hang.... make a new isc gasket with 4mm holes, and turn in the throttle body screw in just enough so that it doesnt stall or surge when cold.

you wanna still have the isc conencted & functioning for cold idle settings or will have to turn base idle up to 1000rpm when warm, just so it runs ok when cold

Cheers EL Fairmont, might give that a go first thing in the morning and see how it goes. I hate following procedures, i just went ahead and adjusted the idle while the car was running, did it when i first got the car and it worked a treat. But i had a good reason to change the T/B over so it was a little bit of fun despite the way it turned out.



Haha tell me about it, it feels weird driving around and the revs are so high when you come to a stop. I really just wanna piss the ISC right off the T/B right now, it gives me the s**t.

He hasn't increased the throttle bore/butterfly diameter so this method shouldn't be required???

This method you describe is only generally used when running big cams and bored out throttle bodies.

May sound stupid, but can you over adjust or completely remove the cruise control cable from the throttle for a little while and see if it is still happening.

Cheers fiend, will try that tomorrow while im at it. Cruise control is another thing i would like to piss right off along with the ISC, it not like i use it anyway . This rev hang thing really got me stumped lol, doesnt seem to be an easy fix like it was the first time round

Yeah the throttlebody came up mint, photos dont it justice, especially the paint job on it, its red anodize over a metalflake silver base. Not bad for a home job eh lol. You can all the metal specs shining in the sun, matches my new matching rocker cover well which i also mucked around with over the easter weekend

Let me know how you went on this... When you get near the computer with a free moment...

I am sitting on this site hating the search functions missing in action status as I am looking for a bible on how to set idle. If I simply pull the Idle Solenoid Control off and set idle to 500, as soon as it is put back on it goes up to 1100 and stays there which would suggest a number of things to me.......... Never mind, am buggering off to look for the way to set base idle properly... Although - hey, wasn't it listed just above? On this thread? Low and behold, there is a gawd.



I use cruise control a LOT. Even around the bays at 55km/h. I use it when being followed by the plod, that gets them. 53km/h in a 50km zone for about 10 continuous kilometres and they get bored.

Having the cruise control cable stiff in the slightest acts in the same way as having your base idle set too high, other than that it can "bounce" a little, so idle would possibly be hunting up and down from 800-1300 when warm...

Either way, you have too much air getting into the system at idle!!!! That is easy to diagnose, but harder to point a definite finger at any single component.


I will be doing another rocker and BBM sometime. Going for the ceramic heat deflecting coating thing when it does happen... Could be a long long time $$$$$$! The heat deflecting ceramic stuff looks like an anodized finish too...

Alright had a go with the little f**k today and still havent had much luck. I tried resetting the base idle using the procedure listed up above in this thread although i initially thought that was only for checking base timing? I know it says thats how you set the idle too in the workshop manual but i usually just adjust it with or without the ISC connected, anyways... Basically shorted the 2 pins, disconnect the isc, started the car and it was idling at around 500rpm (wish i could let it idle at 500rpm, its sounds awesome, nice deep note - its amazing how just a couple hundred rpm's can change the exhaust note haha) adjusted it up to around 750 rpm. Disconnected the bridge from the 2 pins and idle goes back up to 950 . Although the first thing i did was make another gasket with smaller holes, fixed the rev hang issues instantly. No more rev hang now, just high idle. Lowest i can get the bastard to idle at is about 800 in gear and around 1000 in park/neutral and thats when its warm. Its a lot better than it was yesterday though, no rev hang, but the high idle makes it just as bad, the car jerks when coming to a stop, and just wants to keep going when you brake

So came home and mucked around with the idle again. Then i noticed that i could keep undoing the throttle screw and the idle would not go any lower than 800rpm. So either ive got a leak somewhere that i havent picked up on, or ive sharpened one end of the butterfly to much and theres the slightest gap in the t/b bore letting in air. Anyways, the modded t/b is getting ripped off tomorrow morning and ill be chucking the old one back after i replace the throttle screw on the old one which is totally munted at the moment, it has been tampered with in the past by someone thoughm noticed it when i first got the car and looks like it been adjusted with a useless set of pliers which kept slipping and f**k it

Now i know what its like for guys with t5 conversions that disconnect their isc's in hope to fix the rev hang issue. Fix the rev hang, now you've got issues with cold starts.. Bloody fustrating i tell ya

Yeah man, there is some air getting through where there shouldn't. When I last had my throttle off I actually had very similar issue having cleaned the throttle body properly it no longer sealed 101% like it did when it was dirty! Heheheheh, never mind. Other times this has happened was caused by cruise control being caught on a fraction and an air gap left around the ISC.

That's all my findings out the way. This afternoon reset base idle to stop it stalling on using neutral down hills and now have rev hang myself. Have a Christmas wish list already - J3 chip, programmer and a spare weekend please.

I am crossing fingers that a computer that actually knows what a manual is will work with the manual! Call me stupid if you want.....

just wanna no how u got it that nice red colour wat steps did u take

Just about guarantee the original poster's problems are cause by the TB inside polish + messing with the butterfly plate (ie. = excessive clearance in the bore - that's the air leak). I'd chuck an untouched (except for a good scotchbrite scrub) std butterfly plate in and see how that goes.

Finally got the idling issues sorted once and for all. Took off the throttlebody as i had my doubts about maybe taking off too much when sharpening the butterfly. Had a look on the inside of the T/B and noticed there was a gap at the top where the butterfly sits inside the bore. No gap on the bottom and it appeared as though it would not close completely as i could push the lever back and it would move slightly to close completely. So took out the butterfly out and checked that the edge hadnt been grinded/sharpened too much, which it hadnt still had it original little markings around the edge so i put it back in and managed to re position it which was very strange as i thought that it would only go in one way and centre itself when it was screwed in. Got the butterfly to sit dead centre in the bore this time. It now had only the slightest little gaps around the butterfly which could only really be seen when held up in the light. Compared it to the old untouched T/B and it was the exact same both had tiny gaps around the butterfly. Put the modded T/B back in and added a second gasket to in between to make sure there wasnt any air leaks. Removed the isc gasket i made up with smaller holes, chucked the original one back in with normal sized holes. Fired it up, adjusted the idle, took it for a spin and now its sweet. No rev hang and idles about normal now too . Idles at about 650-700 in drive when warm and about 800 in park. Will wait to see how the ecu relearns everything but so far so good

how did u go about making a new gasket with smaller holes?

Just used a piece of thin cardboard, like from a cereal box (thats what i used lol) and traced the old gasket onto the cardboard. Trace the holes for the 2 screws which bolt it to the T/B and then create 2 smaller holes for the air passages. Would of been a hell of a lot easier if i had a hole punch to use to make the holes though, instead i ended up using a drill. How weird is that, using a drill to make holes in cardboard

First time round i made the air passage holes about 8mm diameter each and it didnt make any difference at all. Then i made another gasket with holes about 3-4mm diameter and that seemed to work best. It was like i had the ISC disconnected, it had no rev hang at all. Only problem was it didnt like cold starts, it would fire but didnt idle where i would of liked it, it was idling around 600-700 when cold and it would hunt a bit. When its warm though, no problems, idles normally.

Dont know how it would of idled without the ISC connected when cold, i imagine it would be worse though, probably wouldnt hold idle well