extra air valve ?
Discussion
I think it opens on start up Ug, a little more air, a little more fuel, a few more revs when cold, I aint sure though, Wedg1e will be along in a bit, he will know.
Its the thing sat above No2 Inj, behind flame trap, front right of plem
This is my old 350, wish i still had it, Snap, crackle,
POP. The original BadRedWedge
Its the thing sat above No2 Inj, behind flame trap, front right of plem
This is my old 350, wish i still had it, Snap, crackle,
POP. The original BadRedWedge Edited by badred on Tuesday 5th December 07:24
OK
It's described in the EFI manual on the wedge pages..
The older EFI system with the flapper air meter and additional
cold start injector on the drivers side of the plemum.
The extra air valve - just puts extra air in when the engine is cold.. this just increases the engine revs - combined with extra fuel this stops stalling when the engine is cold.
My system is the hot wire - this does not have an extra injector - insread it just puts more fuel in via the 8 injectors.. and the extra air gets into the engine via the stepper motor mounted on the back of the plenum.
It's described in the EFI manual on the wedge pages..
The older EFI system with the flapper air meter and additional
cold start injector on the drivers side of the plemum.
The extra air valve - just puts extra air in when the engine is cold.. this just increases the engine revs - combined with extra fuel this stops stalling when the engine is cold.
My system is the hot wire - this does not have an extra injector - insread it just puts more fuel in via the 8 injectors.. and the extra air gets into the engine via the stepper motor mounted on the back of the plenum.
uglymug said:
When does the extra air valve work? Is at start up or on full throttle ?
It starts off open when the engine is cold, allowing air to bypass the throttle plate and artificially hold the revs high. With the ignition on, a bimetallic strip inside the EAV heats up and gradually forces a blade to close off the aperture and thus the air, bringing idle speed back down.
When you crank the engine, the combination of extra air from the EAV and fuel from the cold-start injector (fired by the thermotime switch seeing cold coolant) acts like the choke on a carb and gets the engine running.
Once the engine is warm, heat-soak through the EAV casing keeps the blade closed, so a warm restart will see the EAV closed, while the thermo-time switch seeing warm coolant prevents the cold-start injector from firing.
HTH
wedg1e said:
uglymug said:
When does the extra air valve work? Is at start up or on full throttle ?
It starts off open when the engine is cold, allowing air to bypass the throttle plate and artificially hold the revs high. With the ignition on, a bimetallic strip inside the EAV heats up and gradually forces a blade to close off the aperture and thus the air, bringing idle speed back down.
When you crank the engine, the combination of extra air from the EAV and fuel from the cold-start injector (fired by the thermotime switch seeing cold coolant) acts like the choke on a carb and gets the engine running.
Once the engine is warm, heat-soak through the EAV casing keeps the blade closed, so a warm restart will see the EAV closed, while the thermo-time switch seeing warm coolant prevents the cold-start injector from firing.
HTH
I have a flapper type 400 which will not idle, from cold, unless you sit with your foot on the accelerator until the needle on the temp gauge is at least horizontal. Gets worse the colder the air temp gets. So putting 2 and 2 together could there be a problem with the "extra air valve" not being open on my car?
Or am I just putting 2 and 2 together and getting 22 ?
KJR
Mine was suspect so I took it off (*) and cleaned it through with carb cleaner, though any similar solvent would do. Squirt some in, slosh it round a bit then tip it out into a cup. Observe the colour in the cup and repeat until what comes out looks the same as what goes in. Finish by spraying some light oil in to replace any lubrication that has been washed away.
Tested it by heating using a hot air gun, though any heat source would do and then peering through the orifices, like using a telescope, to see how much light comes through.
These are quite simple devices so you should be able to get it going easy enough. I would guess that 99.9% of failures are down to varnish buildup gumming up the works.
BTW When the engine is running you can tell if the EAV is still open by squeezing the attached pipe flat and observing the revs change. But be warned as doing this too much will bugger the pipe. I wonder how I know? Said pipe is still held together with self amalgamating tape some four years or so later on! Note to self must replace all rubber pipes instead of making notes to self!
(*)bit fiddly but no real complications. one or two bolts (think it might be only one?) plus the pipeworkery.
Tested it by heating using a hot air gun, though any heat source would do and then peering through the orifices, like using a telescope, to see how much light comes through.
These are quite simple devices so you should be able to get it going easy enough. I would guess that 99.9% of failures are down to varnish buildup gumming up the works.
BTW When the engine is running you can tell if the EAV is still open by squeezing the attached pipe flat and observing the revs change. But be warned as doing this too much will bugger the pipe. I wonder how I know? Said pipe is still held together with self amalgamating tape some four years or so later on! Note to self must replace all rubber pipes instead of making notes to self!
(*)bit fiddly but no real complications. one or two bolts (think it might be only one?) plus the pipeworkery.
The best EAV to get is from a Jag, this looks the same as the rover one but it holds the revs up when the engine is cold, i think its from a 4.2 mkII jag, you should get one from a jag breakers for around 20 quid, thats what ive got fitter to mine as recommended by Mr Adams.
The rover one dosent hold the revs up, its only due to to the little air it allows past and the jag one has an opening 3-4 time the size of the rover part, still it they are clean then they should work ok.
KJR, you say the car dosnt idle, dose the car smell rich with fuel when starting, have you replaced the cold start sensor, also you could put a 10k omega resister accross the temp sensor, this will fool the ECU in thinking the car is over 50 degrees and reduce the fueling, if there is no diference then the car is under fueling..
Is the 9th injector connected? they are bad at leaking fuel into the system, they can be removed the car will start ok with out it.
If under fueling you may need the ECU looked at, or it could have a dry joint, if you arnt great with a sodlering iron get it to a electronic shop for them to redo all the joints..
Cambelt
The rover one dosent hold the revs up, its only due to to the little air it allows past and the jag one has an opening 3-4 time the size of the rover part, still it they are clean then they should work ok.
KJR, you say the car dosnt idle, dose the car smell rich with fuel when starting, have you replaced the cold start sensor, also you could put a 10k omega resister accross the temp sensor, this will fool the ECU in thinking the car is over 50 degrees and reduce the fueling, if there is no diference then the car is under fueling..
Is the 9th injector connected? they are bad at leaking fuel into the system, they can be removed the car will start ok with out it.
If under fueling you may need the ECU looked at, or it could have a dry joint, if you arnt great with a sodlering iron get it to a electronic shop for them to redo all the joints..
Cambelt
campbell said:
KJR, you say the car dosnt idle, dose the car smell rich with fuel when starting, have you replaced the cold start sensor, also you could put a 10k omega resister accross the temp sensor, this will fool the ECU in thinking the car is over 50 degrees and reduce the fueling, if there is no diference then the car is under fueling..
Is the 9th injector connected? they are bad at leaking fuel into the system, they can be removed the car will start ok with out it.
If under fueling you may need the ECU looked at, or it could have a dry joint, if you arnt great with a sodlering iron get it to a electronic shop for them to redo all the joints..
Cambelt
Is the 9th injector connected? they are bad at leaking fuel into the system, they can be removed the car will start ok with out it.
If under fueling you may need the ECU looked at, or it could have a dry joint, if you arnt great with a sodlering iron get it to a electronic shop for them to redo all the joints..
Cambelt
Campbell,
Thanks for the info. The 9th injector, cold start, was disconnected years ago.
The car may be overfueling as I have been aware of needing to get it out of the garage asap after starting because of the strong smell of exhaust gases.
re: cold start sensor - where is this located ?
re: temp sensor - I assume this is the one fitted to the side of the radiator ? Or is it the one on the thermostat housing ?
KJR
HI all, Playing around with the EAV last night. It is working to some extent as I have got it set up on the bench with 12v going to it. The quadrant plate is moving! , but when it is cold it looks like it does not return to its fully open position with the cut out in full view, only half is showing. This could mean why its not fast idling when on waem-up. After 1/2 hr this has moved slightly but has still not fully closed. This could mean why I am having a slight over-run?.
Your thoughts gentlemen please.......
Your thoughts gentlemen please.......
Applying 12v to it on the bench will not shut the gate, It needs heating at the same time as if it was bolted to the engine. To check if it is closed when the engine is is hot, disconnect and plug the output pipe to plenum (or clamp it off), no change to rpm then its not that. Inconsistant idle when warm on mine was a badly seating over-run valve (tightend the nut a bit and problem solved), check by clamping the rubber pipe, again if rpm does not change that too is OK. All the over-run valves I have only show a slit in the moving plate when cold, none of them have a large open hole when looking down the bore.
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