"Loping" Idle - please help

[brettu26]

Help me please

I have Aspec VR4, car has standard ecu K&N air filter (factory replacement) and exhaust from cat back, no other mods

Idle started surging last Thursday on one of those nasty cold mornings!
Is ok under any load but as soon as clutch is in its loping. Once I come to stop at lightsa or intersection it flattens off back to normal most times
Also Idles excessively high (just over 2k) when cold now

Today at lucnh i opened it up a little, then as i pulled in to work it was trying vey hard to stall on idle <1000rpm

Also has a slight missfire under load

Related? or 2 seperate items?

and how do i fix?

im leaning in the direction of airflow meter or coil?
but was hoping just plug(s) or leads

cheers Brett

 

[Yushman]

A faulty idle speed motor would probably be causing the idle problem

 

[CLuTZ]

A faulty idle speed motor would probably be causing the idle problem

+1

as for the misfire, might pay to check the condition of your ignition leads, and plugs

 

[brettu26]

ok cheers guys, I actually searched the forum and printed the post out from way back about faulty idle speed motor; thanks.

having checked it again & having it start, but not run after work. I discovered the idle adjustment screw is missing!!!! wtf?!!!
i am guessing it has somehow vibrated & worked its way lose, causing the vacuum leak and shitty idle, then when I boosted it, it blew out?
didnt hear it hit bonnet or anything and no marks...

so i taped up the hole to get me home and will fit another screw today.

anyone had this happen before?
and no i have never touched or played with the idle

 

[brettu26]

late update: I found the idle adjustment screw - sitting in the recess of the inlet manifold

still have the occasional 'lope' so assume idle stpper is knackered. but its only an intermitant problem.

I have replaced the leads with some new Magnecore's which are fantastic!!!

 

[Entaran]

Block your FIAV. Wax pellet in it is rooted. Check extremepsi.com or ffwdconnection.com for the FIAV Bypass plate to do it. Once done you will also be able to remove some coolant lines to your throttlebody which will make everything neater.

Problem solved (after you replace the BISS screw)

 

[mattrat]

is the fiav needed??
or is it just a waste of time

 

[Entaran]

It's only needed if you live where it snows.

 

[mattrat]

yer always thought the coolant lines into the TB were just useless and further heating up the air

 

[Jonson]

FIAV stands for Fast Idle Air Valve, it is a bypass valve. Your not gonna gain much from removing it, it's just a band-aid solution.

 

[Entaran]

It's also the cause of a problem when the wax pellet decides to get all fuxxored.

My silver one did this exact thing (except ejecting the BISS screw) and blocking it fixed it permanently.

 

[mattrat]

could it be the reason my car hunts from 1 -1400 all the time, or one of* lol

 

[brettu26]

thanks guys will play with that next

 

[nate108]

to keep the biss screw safe put a tiny bit of silastic ontop of the hole where the screw sits in.

also set your base idle using this guide:
http://www.vfaq.com/mods/BISS-1G.html

clean and test your ISC with this guide:
http://dmtalon.v8eaters.com/ISC.html

goodluck

 

[brettu26]

yup those are really good faq's have been reading over them too. unfortunately the one for the FIAV has goneski...

 

[nate108]

also replace your FMIC it solved 90% of my idle issues

get a jspec FMIC and jspec in and out pipes to the cooler
you will need to cut your front support a bit

best mod u can do - IMO - for the aspec VR4

 

[brettu26]

I actually have a j-spec cooler in the garage ready for install! and jdm bumers to fit it behind

 

[milkandoj]

also replace your FMIC it solved 90% of my idle issues

get a jspec FMIC and jspec in and out pipes to the cooler
you will need to cut your front support a bit

best mod u can do - IMO - for the aspec VR4

It that fixed you issue it would'nt be the size or the efficency of the intercooler it would have been you had some problem that the new piping fixed like an air leak

 

[omad]

to keep the biss screw safe put a tiny bit of silastic ontop of the hole where the screw sits in.

also set your base idle using this guide:
http://www.vfaq.com/mods/BISS-1G.html

clean and test your ISC with this guide:
http://dmtalon.v8eaters.com/ISC.html

goodluck

Also recommend the BISS adjustment to be done on any car that hunts before looking at the ISC. I had done a few ugrades to my car and lastly changed the air filter to a new one as it hadn't been changed in a while and the idle started hunting. It's cause was that the base idle was too high. (I may also have played with the BISS in the past)