Advice please!

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Gilbertd
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Re: Advice please!

#221 Post by Gilbertd » Wed Jul 29, 2020 7:31 pm

It will zoom from 250 to 0 and back when you tweak anything, that isn't what you are trying to achieve. What you are trying to do with the manual valve is get the bias set so the lambda is around correct for a specific opening of the PV in both idle and out of idle. Think about what it is trying to do. The mixture is lean for the given PV and bias settings meaning the actuator is wide open (250), so you tweak one or other to richen it up. The controller now sees that it is running rich so it closes the actuator to lean it off a bit but no matter how far the actuator moves, it is still rich so it keeps on going until it reaches 0 and it is still rich. So you lean it off a touch, lambda then reports lean mixture and the actuator adjusts to try to get it rich but no matter how far it moves, it's still lean. You can ignore what the actuator is doing as it is doing nothing other than opening and closing, it isn't affecting the mixture no matter how far it moves.

You need to get it so that the lambda is on the verge of switching (aiming for 0.5V) for a given PV and bias setting at idle, then open the throttle and see if it goes rich, lean or stays roughly the same without touching anything else. If you've got it so it goes slightly lean (lambda goes from 0.5V to 0.4V) when you open the throttle, then you should be able to tweak the bias very slightly so it goes slightly rich (lambda moves to 0.6-0.7V). That will be ideal. Then when you put the actuator in, the lambda switching point at idle will be slightly higher than out of idle so you don't get a momentary lean mixture when you open the throttle while the actuator is opening, as it will be closing slightly. All the time you are using the PV, the actuator will be thrashing up and down as it is trying to correct but having no affect.
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
98 Ex-Police Range Rover 4.0, AEB Leo, daily motor
96 Range Rover 4.6HSE Ascot, AEB Leo, my spare


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Pinger
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Re: Advice please!

#222 Post by Pinger » Thu Jul 30, 2020 1:20 pm

With the actuator in place, bypass fully screwed in actuator positions are:
Default circa 160.
Idle 80-100
Out of idle 150

When I release the throttle from say 3000rpm and as the fuel is reinstated below the 1300rpm ORCO the actuator goes to circa 160 and very slowly closes to 80-100.
I set the 'below steps for idle at 60 but as it was constantly idling on the rich side I progressively changed it so it is now at 80 - the lowest it wants to go and pretty much where it was with the old reducer.

It is taking throttle from idle but the actuator immediately opens to 150-160. Because of this I haven't provoked an inlet backfire by 'snapping' the throttle open and, as these are pretty much the settings I had yesterday and it drove OK I'm not in fear of a backfire. When I 'squeeze' into the throttle, the actuator appears to respond quickly.

At one point opening the bias screw to try and richen the out of idle, the screw came out of the body of the reducer so it is a fair way out. In any case, more richening there further pushes down the actuator at idle (at one point down to 40-60).

It is taking a little more cranking than yesterday to start when hot.

Conventional wisdom then says I have a mismatch between reducer and mixer.
The reducer is as we know a new R90E (incidentally the old was marked the R90E - no Super or S markings) and by all accounts is compatible with the engine.
The mixer I assume must be small enough as it appears to be 'over drawing' at idle and, is sensitive to bias adjustment at idle (witness also when the bias screw unwound itself 1/4 turn on the old reducer the engine refused to start as overly rich from the bias side). What I don't understand is how it can lose sensitivity at higher rpm and throttle opening (bearing in mind also that it is not being asked to flow anything like it would at WOT and high rpm with the engine loaded). For the same reason, the reducer can hardly be working at maximum flow.
Do I need a larger mixer (I can measure it - from memory it is less than 3'' ID) to reduce the sensitivity at idle?

What am I missing? Why cant I get the actuator to be at broadly the same opening at idle and out of idle? As with the previous reducer (which was spewing gas past the bypass) my in idle and out of idle settings differ by circa 50 steps - the in idle always being the more closed.

(As the petrol side is currently functioning again, during all the above I had the fuel pump relay removed just in case a leaking injector was influencing results).
The other difference from when the previous reducer was in use is that I have disconnected the EGR so its valve is permanently closed. Were it still enabled, at out of idle conditions when it opens, it would further reduce the signal to the mixer drawing exhaust gas from below the throttle plate as it does. When previously enabled with the old reducer, the disparity in actuator positions were similar.

Pinger
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Re: Advice please!

#223 Post by Pinger » Thu Jul 30, 2020 6:35 pm

I've been looking for images of the type of mixer I have and the nearest I can find is as per the linked photo below.
Mine doesn't have small holes that most mixers seem to have. With mine, the round hose connection goes to a rectangular cross section protruding very slightly into the area that is open and its end is cut at a slant.There is some attempt at a formed venturi profile but it is pretty crude. If you can imagine the rectangular duct on the other side of the linked photo and assume you are looking at the photo from its air entry side, you'll probably get the idea.

https://galleryplus.ebayimg.com/ws/web/ ... 000010.jpg

Pinger
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Re: Advice please!

#224 Post by Pinger » Thu Jul 30, 2020 10:11 pm

I need to go back and do it all again with the PV and a functioning lap top. Tomorrow.

Gilbertd
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Re: Advice please!

#225 Post by Gilbertd » Thu Jul 30, 2020 10:59 pm

I'm intrigued by you saying the bias screw fell out? What was on the end of it, a simple cone or a spring and roller? If it was a cone, you're tweaking the wrong one, that's the idle bypass. The symptoms are the same as a mixer that is too large so not generating enough suck when you open the throttle. You are pouring more gas in at idle but as soon as it is expected to give more, it goes lean.

I bought a 4.6 Range Rover with a Leonardo system already fitted but not working. There was a wad of invoices for work that had been done on the LPG system and a brand new R90E on it. That would idle with the actuator sitting around the middle but as soon as I opened the throttle it went lean, very lean. When I checked the mixer I found that the centre had fallen out so it looked much like what you have now.

Give it another go but I'd be suspicious of that mixer now you've described it.
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
98 Ex-Police Range Rover 4.0, AEB Leo, daily motor
96 Range Rover 4.6HSE Ascot, AEB Leo, my spare


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Pinger
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Re: Advice please!

#226 Post by Pinger » Fri Jul 31, 2020 7:55 am

Gilbertd wrote:
Thu Jul 30, 2020 10:59 pm
I'm intrigued by you saying the bias screw fell out? What was on the end of it, a simple cone or a spring and roller? If it was a cone, you're tweaking the wrong one, that's the idle bypass. .
It is as below - confirmed by Tinley.
Gilbertd wrote:
Thu Jul 23, 2020 6:39 pm
If the mixer has been correctly sized for the engine airflow, it will be about right straight from the box. It might need the top screw adjusting slightly but not by much. If I remember right, one screw is marked Idle so you would expect it to be the idle bypass but that is wrong and it isn't (obviously lost something in translation from Italian). Simple enough to identify which is which, the idle bypass, the one that dribbles a small amount of gas in at idle, will be the one that is screwed fully home (and wants to stay that way).
When it arrived, the upper screw, the bypass, was screwed fully in. When opened slightly (with the solenoids hot wired) it hissed gas.
The lower screw marked IDLE but controls bias when it came out had a cone at its tip.
Tinley confirmed the screws both by markings on reducer casing and orientation when my reducer is fitted with solenoid uppermost.

Pinger
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Re: Advice please!

#227 Post by Pinger » Fri Jul 31, 2020 8:09 am

I am genuinely confused as to if there is any point in reinstalling the PV again.
All I can see happening is that I will open the PV for out of idle so that I can weaken with the bias in order to weaken the idle and thus move the idle default position closer to the current default of 160.
But, weakened, the actuator when out of idle will on account of the weakened mixture via the screwed in bias emulate the new PV setting and have to open even further thus the number of steps between in and out of idle will remain the same.

I also don't understand why, when I release the throttle from say 3000rpm and as the fuel is reinstated below the 1300rpm ORCO the actuator goes to circa 160 and very slowly closes to 80-100. I mean so slowly it takes 5 seconds or so.
If, from out of idle when the actuator is around 150 I close the throttle and within 1 second I go back on the throttle, the actuator is still where it needs to be for out of idle. Only if 5 seconds or so elapses does the actuator close right down and then oscillate between 80 and 100.

Have I reached the best that can be achieved with what is reckoned to be an incompatible (oversized) mixer?

Pinger
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Re: Advice please!

#228 Post by Pinger » Fri Jul 31, 2020 1:25 pm

PCV system under investigation as potential source of disparity of actuator settings idle and out of idle.
Recap. My PCV inlet is now independent of the induction system upstream of the throttle plate after crankcase explosion. The PCV valve should be closed during idle (mine is passing a slight amount of vacuum) but open with opening of throttle (which does create a reasonable vacuum).

Gilbertd
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Re: Advice please!

#229 Post by Gilbertd » Sat Aug 01, 2020 9:45 am

Releasing the throttle from higher revs will cause the cut off to operate but, after a period of not a lot of gas going in, the actuator will need to open up to get the mixture correct. The lambda will tell it that it is now a bit rich so it will slowly close to get it correct. It closes down slowly as a rich mixture is less likely to cause any problems than a lean one so it doesn't want to close quickly and risk going lean.

One way of proving a too large mixer is to blank off part of it (to reduce the size of the opening and generate more suck) with a bit of duct tape stretched across one side of it. That might be worth a try just to see if that gets you closer (or the other way round so it becomes lean at idle). What is the diameter of the throttle body and the hole in the middle of the mixer? Normally the bypass is fully closed and the bias is set about midway, not almost fully out as you have it so you've got a mismatch there.
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
98 Ex-Police Range Rover 4.0, AEB Leo, daily motor
96 Range Rover 4.6HSE Ascot, AEB Leo, my spare


Proud member of the YCHJCYA2PDTHFH club.

Pinger
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Posts: 131
Joined: Tue Feb 11, 2020 5:08 pm

Re: Advice please!

#230 Post by Pinger » Sat Aug 01, 2020 10:27 am

I think the problem (as it is but I can probably live with) is in the PCV.
Recall I disconnected the PCV inlet tune from the inlet tract where it was drawing gas through the crankcase and it now draws from atmosphere. The PCV valve is a shuttle valve with three modes. Closed (engine off and/or inlet backfire), slightly open (idle), more fully open (normal on throttle driving). This is where I think I am losing my signal to the mixer on throttle opening.
I blocked off the inlet side (of the PCV sysstem) but as it was still drawing vacuum at idle (where I expected it to be closed) it didn't make much of a difference. Later today, I will isolate it from the manifold at the PCV valve side and if that makes a difference I think I have a solution to it.

Pinger
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Re: Advice please!

#231 Post by Pinger » Sat Aug 01, 2020 10:31 am

Gilbertd wrote:
Sat Aug 01, 2020 9:45 am
Releasing the throttle from higher revs will cause the cut off to operate but, after a period of not a lot of gas going in, the actuator will need to open up to get the mixture correct. The lambda will tell it that it is now a bit rich so it will slowly close to get it correct. It closes down slowly as a rich mixture is less likely to cause any problems than a lean one so it doesn't want to close quickly and risk going lean.
Makes perfect sense.
I did consider disabling ORFCO just to eliminate the actuator dropping down to 40 but as I could keep up with it I didn't. I could though to prove the above correct.
Gilbertd wrote:
Sat Aug 01, 2020 9:45 am
One way of proving a too large mixer is to blank off part of it (to reduce the size of the opening and generate more suck) with a bit of duct tape stretched across one side of it. That might be worth a try just to see if that gets you closer (or the other way round so it becomes lean at idle). What is the diameter of the throttle body and the hole in the middle of the mixer? Normally the bypass is fully closed and the bias is set about midway, not almost fully out as you have it so you've got a mismatch there.
See above post. PCV (given I modified it) needs to be checked. The workaround is simple if it proves it be the culprit.

Pinger
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Re: Advice please!

#232 Post by Pinger » Sat Aug 01, 2020 12:35 pm

Pinger wrote:
Sat Aug 01, 2020 10:27 am
I think the problem (as it is but I can probably live with) is in the PCV.
Recall I disconnected the PCV inlet tune from the inlet tract where it was drawing gas through the crankcase and it now draws from atmosphere. The PCV valve is a shuttle valve with three modes. Closed (engine off and/or inlet backfire), slightly open (idle), more fully open (normal on throttle driving). This is where I think I am losing my signal to the mixer on throttle opening.
I blocked off the inlet side (of the PCV sysstem) but as it was still drawing vacuum at idle (where I expected it to be closed) it didn't make much of a difference. Later today, I will isolate it from the manifold at the PCV valve side and if that makes a difference I think I have a solution to it.
The above.
Blocked completely it pulls the actuator from 150-160 down to 130 at out of idle while not overly affecting the idle position thus closing the gap between the two.
More to be done with this.

The above was on the driveway when I got back after driving 15 or so miles on the existing set-up with new reducer and it was driving quite sweetly. I could live with it as it is but the above suggests there's improvement to be had.

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