Sooty Plugs, judder at low revs
 

Hello all:party009:

I've been out to check the my new set of plugs and they are really sooty as per the last set. I presume it's running rich (better than the dreaded lean!!).

When I boost at low revs the cars seems to give out a high frequency judder until 4KRPM then she takes off.

What can cause rich running on these cars and what the best course of action
??

For your info,,,, It's had new plugs/dizzy/rotor/leads/fuel filter/air filter so far. Last year she had new PCV system/injectors/dump valve/blanking plate etc etc.

I'm running out of money!!!:music-smiley-019:

george, clearly you have a boost leak from somewhere, i have no doubt you are experienced enough to have checked the usual areas...
what gap are you using, try 6mm....
juddering is sure sign of this, i expect you have a leak either at the lower i/c hose or at the throttle based on the fact that you sorted the inlet elbow when you did the pcv....
with the stock 7mm setting i too had overfueling issues which were sorted with the plug gap reduction....
ecu upgrades often run rich, try a mbc to counteract this....
IMO the shelf chips/remaps are set very safe and overfuel rather than underfuel....of course some custom remaps underfuel to prevent this!!.....
cheers
jod

how many pipes am i looking for re the boost leak is it the main one that runs'under' the block,or is there any more?? i had simlier probs this week,the old juddering trying to stall business,im sure its a boost leak but having checked it and rechecked it i cannot for the life of me find it,so do i just replace the elbows and the hose ??? can it run over top of the block or does it have to be re routed to where it was???
help!!

the main culprit on the later 850's is the elbow at the side of the inlet manifold, i have mentioned before that this elbow does leak boost and is ubdetectable as you can see the split due to its location, nor can you hear it leak as it will always be at vacuum when the car is at idle....to check security remove the elbow at the other end of the pipe from the PCV valve and put your thumb over the end..There should be a definate suck
if there is not a good suck then it is likely either your elbow is split or your pipework has broken behind the inlet manifold..both eventualities means loss of boost...
The solution is of course to redo the PCV system which may not be practical at the time so you cab rig a temporary feed using 4mm hose from the inlet manifold elbow (heat elbow in water first to expand) fixing it on with long nosed pliers, the elbows come with a fitting sleeve with goes inside your 4mm hose and can be secured with cable tie
http://i35.photobucket.com/albums/d1...e/04a39cdd.jpg
running the hose under the fuel rail, round the block, below the dizzy and onto the PCV valve nipple...
http://i35.photobucket.com/albums/d1...e/4c65c5f8.jpg
Pipes to change....
Inlet to Pcv...
compressor to BCS
actuator to BCS
Inlet manifold to recirc-valve
Intet manifold to EVAP...would be a good start.....
Give your actuator arm a good tug to make sure its working ok...a weak spring will lose your boost...try moving the arm back and forth towards the turbo.....you may want to fit a MBC to test the arms efficiency....
cheers
jod

Cheers Jod

I have changed the throttle body and top IC hose Part of the high pressure system but that's it. I may fork out for a Samco kit. Hopefully Santa will bring me one:party009:

hope he brings you what you want george....
as a first off, get a new set of plugs and regap to 6mm, this should help the spark compensate for the "extra" fuel.....i cannot stress the difference this has made to my car....:cyclops:
cheers
jod

Will do jod:party009:

I have a plan!!! Now bare with me on this...LOL>>>>>>

I plan to plug up the drain hole at the bottom of the IC and spin top metal 'S' hose from the turbo through 90 degs which will allow me to fill the system up to the top of the IC and test for leaks.

The reason for this is that I think my IC may be leaking as it's loose and may have rubbed trough at some point causing a leak, also this will check my bottom hose and intermediate hose too. It wont check out my top IC hose or throttle hose but these are new anyway.

I will of course drain it fully and vent overnight before starting her up after the leak check.

Has anyone got any other points I may have missed which this method??

Forgot to mention, , I'm thinking of using petrol for the leak check.

It would be much safer and cheaper to use air!

True, but I can't think of how I can charge he system, and what is the acceptable leak rate. If I do use petrol I will vent it for a good 24 hours before I rebuild it. Also the petrol should clean the oily 'gunk' out of the IC, shouldn't it?:swoon: