Stupid me.... wtf have I done!

[arbee]

Grrrr, did the PCV system the other day, had the manifold off throttle linkage etc - now got a problem, basically its idling too fast - around 1200 rpm

Thought first of all that I had cracked the pipe from the MAF to turbo therefore more air coming in - faster running? That is not the case - the 'crack' is actually the seam for the pcv heater thing! No air is getting in.

Throttle seems to be operating ok and i never adjusted the 'stop screw' that adjusts the throttle postion on idle. At rest there does seem to be a little slack in the throttle cable tho, is that normal?

Any ideas? is it just a matter of adjusting the screw? what would have changed and what have i done!?

Ta

Rich

Also noticed exhaust fumes leaking where the pipe from the IC joins the turbo, although I will sort this could it have any effect on idle?

[t5owner]

Rich,

Did you put the throttle cable back on the same spool as it came of if you look at the unit u will see there are 2 differant spools for the cable to go on and it must go back on the same one as it came off otherwise it will remove any slack that the cable needs and cause your idle speed to rise as the tension in the cable will wind the spool without touching the accy pedal

As for exhaust fumes from the ic pipe near to the turbo yes it could affect the idling as there is obviously a leak and as well as exhaust gases escaping it could be letting in unmetered air which could give rise to ilde speed fluctuations

Cheers

stuart

[volvotuning]

Indeed, a leak anywhere after the MAF can affect the idle. See if you can hold the revs at 2500 rpm while in neutral. If the revs keep wanting to climb, it's almost certainly an air leak.

Adam.

[arbee]

yeah the throttle cable is in the correct position, if i disconnect the linkage the spring loaded cable returns to its screw stop postion so on thinking about it, i don't reckon its that. Gonna have to check the all the hoses tho i'll be buggered if I'm taking the manifold off again lol.

Adam it does seem to hold the revs at idle tho not tried yet to hold it further up the range. I hate to think of the dirty unfiltered air is being sucked in! If there is an air leak does the ecu increase fueling to compensate then or is it gonna run lean?

[volvotuning]

Adam it does seem to hold the revs at idle tho not tried yet to hold it further up the range. I hate to think of the dirty unfiltered air is being sucked in! If there is an air leak does the ecu increase fueling to compensate then or is it gonna run lean?

It will always hold revs at idle, even though it may be slightly higher than 1000 rpm.

Fueling at part throttle is always kept under control by the ECU using the lambda sensors which tell it to add more or less fuel based on the current mixture readings. It's therefore always lean at idle and off load, ie lambda 1.

Adam.

[arbee]

i know nothing about lanbda senmsors at all Adam but cheers - it makes sense to my non mechanical brain :) will report back after a decent looky over tho got too little time!

[volvotuning]

i know nothing about lanbda senmsors at all Adam but cheers - it makes sense to my non mechanical brain :) will report back after a decent looky over tho got too little time!

lambda sensor = device which tells the ECU about the air/fuel mixture, ie if it's rich or lean. The ECU can then add more or less fuel to keep the mixture at stoich AFR, which is lambda 1.0 (14.7 AFR for normal petrol). The lambda sensor therefore allows the ECU to control the fuel trim.

In reality, fueling control is actually a little more complex than that, but in terms of the lambda sensor itself, that is what it's function is - fuel mixture measurment.

Adam.

[SaffronC70]

Idle control valve a bit sticky/dirty ?

[t5tart]

silly question did you replace the manifold gasket and tighten the bolts up properly didnt miss one did you ????

[arbee]

nope there all torqued up (best i can remember but will check!) and yeah, used a new gasket. Tried what adam suggested and it does indeed try to climb the revs if i try to hold on part throttle, so i'm guessing an air leak somewhere. If for some dumb reason one of the pcv hoses isnt secure under the manifold then that would have the same effect as air would be drawn in there yes??

i've a feeling i'm gonn have to dismantle it again when i get the chance. away tomorrow and down in cornwall next week til the BH monday (not in the Volvo) gonna be at the lasty minute before trax as i'm reluctant to take it all the way up there with an air leak :( Apart from dirty air entering the system what other hazzards are the if i run it as is?

[t5owner]

nope there all torqued up (best i can remember but will check!) and yeah, used a new gasket. Tried what adam suggested and it does indeed try to climb the revs if i try to hold on part throttle, so i'm guessing an air leak somewhere. If for some dumb reason one of the pcv hoses isnt secure under the manifold then that would have the same effect as air would be drawn in there yes??

i've a feeling i'm gonn have to dismantle it again when i get the chance. away tomorrow and down in cornwall next week til the BH monday (not in the Volvo) gonna be at the lasty minute before trax as i'm reluctant to take it all the way up there with an air leak :( Apart from dirty air entering the system what other hazzards are the if i run it as is?

Just a thought on the hoses as it could be that stupid fiddly one that plugs into the bottom of the manifold i had the same probs with mine came off twice whilst i was trying to put the manifold back on as there isn`t much slack on that hose

Cheers

stuart

[nobananas]

When I did the pcv pipes on mine the large plastic one under the manifold was so brittle it just kept breaking up. I seem to remember it's wrapped in foam insulation. Is there any chance you've cracked it on reasembly and not noticed ?

[Jod T5]

When I did the pcv pipes on mine the large plastic one under the manifold was so brittle it just kept breaking up. I seem to remember it's wrapped in foam insulation. Is there any chance you've cracked it on reasembly and not noticed ?

the pipes should only crack when they are dry... the new ones supplied by volvo (part no 9471644 later 850') whilst stiff are flexible although the smaller pipe will need to be "jubileed" to the pcv valve....

Rich, your car was running fine before you changed the pcv....i would be sure you removed the throttle housing from the inlet manifold instead of removing it all as a whole...have you checked (tightened) the four throttle body to inlet bolts maybe you have a air leak between the throttle body and the mainfold....i would have that off as a matter of course, give it a good clean with a toothbrush refit with a new gasket (or instant gasket lol) and re-torque...ensure while you are doing this you clean the throttle position sensor on the housing as this reports the throttle valve position to the ecu and this in turn can effect the idle by sending false signals to the ecu....
as i explained before the idle control valve in my experiences only really plays a part when the engine is under load with the throttle closed...ie approaching a r-a-bout or slowing for traffic lights etc with the butterfly closed...etc....with the butterfly closed the idle control valve will allow a certain amount of air around the butterfly to maintain a steady idle....
if you are not experiencing problems at these instances i would discount the idle control valve and concentrate on the unmetered air intake theory...
as time has passed since you origional post i assume from your recent one on the voc forum the issues have not been resolved....
what checks have you carried out??
have you checked your codes...??
rich if you are still having issues i am at home on the weekend of the 28th october so if you fancy a little m11/a14 drive you can pop over to see me and we can have a fiddle...lol
btw i also have a code reader and a service light reset tool if you need to borrow them....
cheers
jod

[arbee]

cheers for the post Jod - I'd completely missed it! tbh the not getting it sorted thing is completely down to me having fek all time. In the middle of selling/buying a house so have very little time with the car at the mo :( Done no real checks other than remove the throttle cover and check the hoses I could see. I reckon I'll probably resolve it when i get a chance to dismantle/reassemble the lot again. Got no lights on, but not checked for codes - my old 850 has the built in diagnostic wotsit anyhow :haha:

really appreciate the offer of a fiddle mate lol, tho reckon I'll have to pass - weekends are a bit precious at the moment :)

cheers
Rich

[Jod T5]

In the middle of selling/buying a house so have very little time with the car at the mo


ahh...i remember that one....knightmare.....


Got no lights on, but not checked for codes - my old 850 has the built in diagnostic wotsit anyhow :haha:



thats the only things that really annoys me about the phase2...poor abs units aside...lol




really appreciate the offer of a fiddle mate lol, tho reckon I'll have to pass - weekends are a bit precious at the moment :)



no worries....just give me a shout.....

cheers :Handshake
jod

[swordy21]

The bottom part of my PCV system, where the 2 plastic pipes join the turbo induction hose was where my airleak was.

See here http://www.vpcuk.org/forums/showthread.php?t=7285

Just a thought