What 2 do next ? HELP !!

[dubweiser 0]

Go easy on me cos i'm new here, but i'm having problems with my C idling and holding revs at bout 1500 revs.Hav done all the things such as changing plugs, leads ,rotor arm, dizzy cap, cleaned isv, and reset the computer but it still runs like bag 'o' sh**e.When the isv is unplugged it idles perfectly except slightly higher on't revs and tends to dive a bit after revving it up high.Took pipes of isv and it seems to be working.All the breather pipes look okay too.Anyone got any thoughts as to what to try next cos am going mad and got an itchy lighter hand !!!!

PLEEZ HELP !!!!!!!!!!!!!!!!!!!! :mad: :? :lol: :roll:

[Neocorrado 0]

Did you try the iddle stablelizer ? that might be a posibility

[dr_mat 0]

Temp sensors?

[Linus Van Pelt 0]

Do you mean the car idles at 1500? Seems awfully high to me if that's the case... Mine idles at about 900 - 950.

 

I had all manner of idle troubles when I got mine, the final cure involved a throttle switch and temprature sender (as dr_mat, rightly points out). I can dig up part no's if you need them.

 

The ISV could still be the problem, I guess (mine improved slightly with cleaning, but improved more when I slapped a new one in), unfortunately they're not cheap ,about £100 from euro car parts or German & Swedish.

 

Other possible candidates (clucthing at straws though) include a sticky throttle cable or blocked fuel filter.

 

I used to have an excellent article on fixing and adjusting 16V idles, only the link is dead now... :( if you have the patience you could try going through the VW FAQ for answers...

 

Failing that I'd get it to a Bosch Service Centre, they have all the diagnostic kit and won't charge the earth like a $tealer would.

 

LvP.

 

Update:

 

Just e-mailed the chap who was hosting the article (Andrew - Volkswizard) and he kindly e-mailed it back to me ;)

 

Admittedley this is aimed at the Golf 16V engines (i.e not the one that's in the 2.0) but it should hold true in most parts (I would expect...)

 

Firstly make sure the idle stabilisation valve is operating

normally.

With the ignition on position 2 (the instrument warning lights flashing

but

engine not running), the valve should buzz. You should be able to hear

it or

if not touch it and you should be able to feel it vibrating slightly.

If

this isn't happening then check the connection of the wiring plug.

Connecting a 12v directly to the valve should make the flap inside the

valve

open fully and should help distinguish if the problem lies with the

valve or

its wiring.

 

It is quite common for ISV's to become clogged up by oil vapours

from

the air that passes through them. This can make their action rather

lethargic meaning that the car wont maintain idle and instead will

stall e.g

when coasting to a stop. I had this problem on a 1990 Mk2 16v, it was

solved

by soaking the ISV overnight in petrol (carb cleaner is equally as good

but

costs more than £4 per gallon!) so it's worth trying if this sounds

familiar. Incidentally after the soaking period, the petrol was

significantly darker than previously confirming just how much gunk it

had

removed.

 

It's also worth fully unscrewing the idle bleed valve in the

throttle

body and cleaning it as well as all the inlet tracts and airflow flap.

 

The next step is to set the idle and CO. Mk2 16v's run best at

2.0% CO

which is significantly higher than the 1% +/- 0.5% recommended by the

factory. The added enrichment insures adequate fuelling when the 16v is

on

full song and is what the tuning companies aim for. When Ray Partner

last

took his famous red concours 16v that AmD had set-up for an MOT, the

tester

commented that it was running richer than normal. It passed though as

3.5%

is the upper limit for an MOT pass for a post 1986 car without a

catalyst.

 

I recently set the CO on my 1991 Jetta GTI 16v using the method

below

and when later rolling road tuned by Vince Saiya of Stealth Racing, the

reading was "spot on", so here goes;

 

With the engine fully warmed (above 80 degrees on MFA), turn off

the

engine and disconnect the white cased spade connector on the red and

black

lead from just to the left of the coil (click on thumbnail for a full

size

image).

 

This lead connects the coil to the idle stabilisation valve and

sends

an rpm based signal that determines the rate at which the ISV pulses

(the

duty cycle).

 

Disconnect the breather hose from the side of the airbox and

block the

hole. This should always be performed on most engines when setting the

mixture as it prevents crankcase gases being fed back into the engine

and

giving an untypically rich reading.

 

Start the engine and the idle revs should be lower than normal,

if

they aren't, the idle valve is not working properly and the idle speed

is

incorrectly being determined by the idle bypass screw alone.

With the engine running, turn the idle screw up until you get

950rpm

+-50.

If the idle wanders/hunts or is lumpy/misfires (engine visibly

rocking), insert your 3mm allen key into the CO adjustment screw in the

fuel

metering head and turn it anti-clockwise to weaken the mixture. Do not

rev

the engine with the 3mm allen key in position as you run a serious risk

of

damaging the airflow flap.

 

With the engine now idling very jerkily and just prior to the

engine

cutting out, turn the key clockwise in 1/8th turn increments until the

idle

smooths out. Eventually, the engine should settle to a nice, steady

idle

with no misfiring or jerking. This will be 2.0% or very close to it. If

the

revs have wandered away from 1000rpm in the meantime, adjust the idle

bleed

screw accordingly to restore them and return to adjusting the CO as

described above. When idle speed and CO are correctly adjusted, switch

off

the engine and reconnect the breather pipe and the red lead.

Take the car out for a run and when you dip the clutch, the rev

counter needle should gently fall to 1000rpm, not plummet. Also examine

the

exhaust gas, even at 2.0% there should not be any tell tale signs

suggesting

that the engine is running overly rich.

If after all that it's still missing and rough, investigate air

leaks

as these will cause the mixture to run lean and all the above will not

apply

until rectified.

 

If there is anything you are unsure about, take the car to your

local

Bosch agent for setting up, mine charges £25 + VAT or a rolling road

tune at

Stealth Racing is money well spent at £45 + VAT.

 

Thanks to Kevin Hayward and Gary Bocking of the excellent Club

GTI

e-list for these tips.