Thought the problem was the PCV. It isn't the PCV...
 

Evening Everyone,

A little bit of help if you'd all be so kind.
1993 240 B200F running a little rich since i got it in November, keep getting a pop from what seems to be the front end of the exhaust / manifold on overrun at about 2,200rpm, not everytime I drive it, but certainly once or twice a week of daily commuting. I am also experiencing clutch judder when engine gets warm in start stop traffic, only in first whilst pulling off fine anytime else.
Little bit rich, using a little oil, but nothing i'd class as horrific or upsetting I've topped it up with the total of a litre in the 9 months I've had it. After reading all the helpful stuff I could off here (Thanks soooo much), I figured it might be the Flame Trap. Just had it off and to my suprise seemed pretty clean. Back on, engine runs as before.
So i'm at a loss. If the trap is clean, does that mean it could be a blockage somewhere else in the PCV gubbins or something else entirely? There is a buildup of sludge under the flame trap, but it seems old and crusty not fresh, but the bonnet lining has got a big oil mark just above the valve cover which is still wet to the touch if you drag yourfinger across it.
I'm not an utter amateur, but i'm not far off, so be gentle with me!
Thanks in advance!

You could check or replace the vaccuum lines in/out the manifold.
Have you checked your sparkplugs for condition?
This engine have an O2 sensor?

Car was really rough in November, changed the plugs and leads, 88 degree thermostat (all oem Volvo) and yes, it ran a lot better, but still getting these problems.
Oxygen sensor looks pretty new (I'm starting to see a pattern here:( ), but I do have a somewhat modified exhaust pipe fitted by the previous owner. It's a Simmons back box attached to basically a straight tube which splits at the down pipe and goes straight to the manifold. Is it possible that these problems are being caused by the removal of the cat without the LH knowing? If it helps, pick-up is a bit stuttery, but otherwise the engine seems to pull very well and is nice and smooth if not a bit tappety / noisy, but what 240 isn't!?
Thanks for your help, I'll check the condition of the vac hoses at the weekend.
:D

LH should learn fine even de-catted (1992-1993 is the changeover time)
but you can disconnect the battery for an hour which definitely resets the ECU and let it learn again : I had similar problems to yours (mine's a 1992 turbo 940) when filled up with some dodgy fuel. Got better fuel and reset, was fine after that, but not fine until resetted.
Try Shell v-power-whateveritscalledthismonth for the octane boost and see if that helps.

Popping on the overrun and a lambda sensor over fuelling sounds much like air getting in the exhaust piping somewhere, are you certain you don't have any leaks in the home made exhaust system?

It will only affect fuelling if there is an air leak between the engine and the sensor. Anything on the exhaust after the sensor has no effect. Which is why a missing cat won't be the issue as all the sensors I've seen have been either just after the manifold or just before the cat. As yours is a 93 it should be tested as having a cat, so I'm surprised that you don't have one.

Dave A

Good point,
did you (OP) buy it with valid MOT test remaining?

Did it maybe have Pulsair at one time which has now been removed? Maybe sucking air in through those connections if one of the blanks is loose?

Maybe an F doesn't have Pulsair...

on a 93 injection? That really would be reverse engineering :)

You haven't mentioned if you have any fault codes logged???

Dave A

I learn a little more....