crankcase ventilation problem

[richy]

i all,i have a twin plenum 1986 rover sd1 vitesse,i have had a lot of trouble with idle,with cutting out & and stalling.but now i have found the problem,to much crankcase ventilation,i found this when i discovered the breather pipe broken in half,now its got no breather pipe it ticks over perfect no stalling and starts of the key with out using throttle,but when i put a replacement breather pipe on,it stalling again wont tick over properly,now i have been reading up on the PCV valve and also i have ordered one,do any one no will that sort the problem out.or can i just hang the breather pipe down under the car and just put a filter at the throttle body were the breather pipe connected to.be great full off some help please,richy

[DaveEFI]

i all,i have a twin plenum 1986 rover sd1 vitesse,i have had a lot of trouble with idle,with cutting out & and stalling.but now i have found the problem,to much crankcase ventilation,i found this when i discovered the breather pipe broken in half,now its got no breather pipe it ticks over perfect no stalling and starts of the key with out using throttle,but when i put a replacement breather pipe on,it stalling again wont tick over properly,now i have been reading up on the PCV valve and also i have ordered one,do any one no will that sort the problem out.or can i just hang the breather pipe down under the car and just put a filter at the throttle body were the breather pipe connected to.be great full off some help please,richy

Allowing extra air into an injection engine plenum results in an increase in idle speed. That's how the cold start idle control works. But the idle speed valve should allow more than enough adjustment. So sort the breather system first before going any further.

The breather system consists of a flame trap on the front of the right hand side rocker cover and a pipe from that to the plenum. The air inlet to the crankcase is a small hole on the rear of the left hand side rocker cover with a foam filer on top.

Remove the flame trap - it unscrews. It is packed with wire wool and gets blocked. If you can't blow through it easily, clean it or replace. You can replace just the wire wool, or try burning out the gunge with a blowlamp.

Next remove the pipe the hose from the flame trap fits to on the plenum. It is a tight push fit into the casting. Insert a suitable sized drill to prevent it collapsing and use some grips to twist it back and fore to extract. You can them get access to the drilling that pipe feeds into - clean that. A suitable drill helps here, turned by hand. The far end of that passage has a smaller hole at right angles into the air intake - clean that too. These jobs are easier done by removing the plenum.

Note the hole in the side of the pipe and align that with the passage when replacing.

Check the intake is clear with a bit of wire.

The crankcase operates under a slight vacuum when everything is correct and a clear breather system will cope just fine - even with a worn engine.

[richy]

hi Dave thanks for your reply,i have done all these jobs,i had even had the plenum off and the inlet manifold,and cleaned,i put new belly gasket on,i am just sick,just can not get the idle spot on,just were i think i am getting somewhere it goes back the same again,i have nearly replaced every thing,ecu,afm,all sensors,air pipes,new steal wool in flame trap and so on,but as soon as i take the breather of it, perfect,blip the throttle doesn't cut out,ticks over perfect every time,if i had the breather connected and blip the throttle it would cut out every time.been on this now nearly two months,that's how long i owned it,thanks any way,richy

[DaveEFI]

hi Dave thanks for your reply,i have done all these jobs,i had even had the plenum off and the inlet manifold,and cleaned,i put new belly gasket on,i am just sick,just can not get the idle spot on,just were i think i am getting somewhere it goes back the same again,i have nearly replaced every thing,ecu,afm,all sensors,air pipes,new steal wool in flame trap and so on,but as soon as i take the breather of it, perfect,blip the throttle doesn't cut out,ticks over perfect every time,if i had the breather connected and blip the throttle it would cut out every time.been on this now nearly two months,that's how long i owned it,thanks any way,richy

Sorry if it's stating the obvious, but what is the CO reading at idle? It can be difficult to set by ear as it were. If it's not between 1.5-2% with the adjustment screw about 1.5 turns out from the stop that needs investigating.
The snag with this EFI is it is open loop - so any number of slight faults can give grief. For example, the wrong fuel pressure will have a drastic effect at idle, as will a weeping injector. But may not notice when driving.

[richy]

hi Dave,i just fitted a adjustable fuel pressure regulator,and i have that set at 36psi, the C,O i did go to the garage and had it set,but still doing its idle thing,i have just taken the extra air valve off as its the only thing i haven't tested yet,and that's sowing 33ohms,and there is voltage at the plug when i turn the engine over.so thats all good, i think were all stuck on this dave.its a mystery,thanks.richy

[DaveEFI]

hi Dave,i just fitted a adjustable fuel pressure regulator,and i have that set at 36psi, the C,O i did go to the garage and had it set,but still doing its idle thing,i have just taken the extra air valve off as its the only thing i haven't tested yet,and that's sowing 33ohms,and there is voltage at the plug when i turn the engine over.so thats all good, i think were all stuck on this dave.its a mystery,thanks.richy

Is it a rising rate reg? if so, try setting it for the best idle. That usually means about 38 psi engine running vacuum pipe disconnected and blanked off.

The extra air valve should only have an effect with the engine cold/warming up. It closes slowly under the influence of coolant temp and an electric heating element, from the wide open cold position. If it jammed, it would increase the hot idle speed.

[richy]

hi Dave,its Is it a rising rate reg,and it set like you said to do.what about the butterfly,if that's not completely sealed shut on idle,can that course to much suction for the breather and could be chocking up on idle,is that possible,because why i think back,when the breather pipe Brock in half i stuck my finger up the end of the pipe and their was quite a pull and the engine revs went up,any ideas,richy

[ramon alban]

Allowing extra air into an injection engine plenum results in an increase in idle speed.

That's how the cold start idle control works. But the idle speed valve should allow more than enough adjustment. So sort the breather system first before going any further.

You sure about that Dave? In the context of Richy's prior post that you were addressing he had not mentioned the Extra Air Valve, so if any air is entering the plenum from a non-metered source the effect will be a randomly variable weak mixture, most likely causing the stalling reported.

Richy, because of the uncontrolled nature of any rogue air, the idle screw will be ineffective, even more so if the two throttle plates are also not sealing properly when closed.

Everything you report smacks of an unusual rogue air leak associated, one way or another, with the fitting/unfitting of the breather tube. Worse, by playing with alien PCV valves and hanging breather pipes below the engine, you may well invent a new Efi breathing process but the Efi system will be so compromised only a clairvoyant will be able to offer help.

You must do as Dave describes, exactly, and sort out the Efi breather system as designed. Sure, the car may not behave as you want, tough, but that is because you are not chasing a faulty breather system once it is correctly refitted. Only then can you move on with finding the real problem

Expressed another way, the Efi breather system is simply a wire filled flame trap, a clear pipe and a clear plenum breather gallery - plus that clear little hole at the rear of the LH rocker cover. It just needs to be right, dont worry about testing it. Having got that put right, you now have to seek out the malfunction.

Your loss of control over the idle speed does indicates a significant leak , in all probability, somewhere associated with the crankcase environment, so first off, I recommend you look at the integrity of both rocker cover gaskets.

If they are not perfect - loads of air will get into the controlled crankcase environment - this is especially a problem with our Efi system as Dave explained, it normally operates under a slight vacuum, so that would be royally messed up by leaking rocker gaskets thereabouts.

For example, if one removes the oil filler cap when an Efi engine is idling normally, the idle speed becomes flakey and unreliable. Exactly the same effect happens if a rocker gasket fails or is not sealed completely - both sides.

If you find that the rocker gasket sealing is dodgy, then fix it. If they are OK, come back and we look elsewhere.

[richy]

thanks Ramon for your reply,i will have the rocker covers off to morrow morning and replace the gaskets and will let you know if that works.thanks richy.

[richy]

hi,i done the rocker cover gaskets today,and also checked for air leaks,and it is a little better,it does tick over now about 850 rpm,when it i blip the throttle it does continue to idle,so that's good,but when starting using no throttle,it starts but cuts out,so i still having to use the throttle on start up for the engine to idle,and i think its some thing to do with the throttle discs,as they are worn,i have tried to seat them as best as i can,but still got gaps. and i can not buy them anywhere, and its still smells if its running rich,witch i will sort out,i will buy a co analyzer,that's a must. thanks for your help to Ramon & Dave,never thought that the rockers would of caused so much trouble.thanks again.richy

[ramon alban]

Hello Richy, One problem solved, more to discover! Was it ever any different? Have you read my twin plenum throttle disc setup process?

http://www.vintagemodelairplane.com/pag ... ing01.html

If yes, study it again in depth, you must be missing something!

The discs can be dressed to take off any edge bumps and unless bent, I'd be surprised if they were unrepairable.

Because they are brass, any dinks in the edges can be fluxed, solder blobbed and dressed like new.

As you will read, the discs must be centred correctly in their tunnels using the process recommended. 8th bullet page 2.

Ill fitting discs will cause a higher idle speed, they do not cause overfuelling.

If your smells are indeed due to overfuelling, you should address that separately.

Doubt if a CO analyser will tell you any more than you already know or can discover by plug colour test - both banks and then deal with the components that may cause overfuelling.

Set the AFM CO screw to 2.5 turns out from fully home and then test the temp sensor, correct fuel pressure , throt pot and weeping injector possibilities, by observing if the fuel pressure holds up ok after switch off.

[richy]

hello Ramon.i had my plenum off last month to do the throttle discs,and i did take to much off with wet & dry paper,on the throttle discs.i got them as best as i could and in line in the plenum.but it did stop the high idle which what i was getting before. so it did improve,but then i was getting the opposite,hard to keep idle.but we sorted that out now,its just starting up with out using throttle,you mentioned holding fuel pressure when engine of.i have fitted a adjustable fuel regulator,when at idle it reads 36psi.as soon as i tern the engine off it goes to 0,almost strait away,but their is pressure holding in the injector rail.their is no pressure from the fuel filter to the (FPR) when engine is not running.i am not shore if it suppose to be or not,with the (AFM) i did adjust to 2.5 turns from fully home,but would hardly idle at all and also smelling very rich,so at the moment i have got it about 3.5 from home,i have now ordered a co analyzer.that will arrive here till next week,richy

[ramon alban]

I really dont know about how adjustable or rising rate FPR's work, but the pressure in the fuel rail is what I was referring to and on cars with stock FPR that pressure goes all the way back to the pump non return valve and the pressure should hold for a a goodly while, few hours even overnight is possible.

Its clear you still dont have control over the idle speed even with the idle adjust screw so if you have indeed eliminate all sources of rogue air then I'd have to say maybe the opposite, and the idle air gallery is still blocked despite your reported plenum off cleaning session.

So lets recap?

# Your fuel rail pressure holds up at 26 to 36 psi with engine off.

# Your breather system is now back to normal, as Rover intended.

# You can only just start the engine without feathering the throttle.

# The engine smells very rich.

Conclusion you still have at least two problems - idle air control and rich mixture.

1 find out why you cant adjust the idle speed with the idle control screw

2 go thro the whole list of tests why your engine runs rich.

plug color, temp sensor, throt pot, fuel pressure, weeping injectors, etc.

[richy]

hi ramon
going back to your recap

" the fuel rail pressure holds up at 26 - 36psi with the engine ON "

"when the engine is OFF there is NO FUEL PRESSURE at all "

"yes the engine smells rich "

"i CAN adjust the idle speed "

i pulled the fuel pipe off that leads to the cold start injector and there was no fuel pressure at all,also it takes a little bit of cranking to get started (about 5 seconds) after turning the key.thanks.richy

[DaveEFI]

hi ramon
going back to your recap

" the fuel rail pressure holds up at 26 - 36psi with the engine ON "

"when the engine is OFF there is NO FUEL PRESSURE at all "

"yes the engine smells rich "

"i CAN adjust the idle speed "

i pulled the fuel pipe off that leads to the cold start injector and there was no fuel pressure at all,also it takes a little bit of cranking to get started (about 5 seconds) after turning the key.thanks.richy

If there's no pressure when the pump stops, you have a fault in either of the one valves, one in pump, one in regulator, or a leaking injector or leak in the line. Clamping a hose can sometimes isolate where the fault is.