M20B27 on LPG - Developments

[e301988325i]

Your Vap is mounted behind the left headlight IIRC, whereabouts is it fed with hot water, are you still using the same 39mm mixer as before?

Have you had to adjust the leo setting for driving, how does it fuel at high load?

Sounds to me like your Vap is suffering wind chill when driving, do you have inner headlight covers fitted? I guess what's happening when you're stationary is the VAP heats up and boils more gas forcing it out through the mixer.

[StuBeeDoo]

Your Vap is mounted behind the left headlight IIRC, whereabouts is it fed with hot water, are you still using the same 39mm mixer as before?

Have you had to adjust the leo setting for driving, how does it fuel at high load?

Sounds to me like your Vap is suffering wind chill when driving, do you have inner headlight covers fitted? I guess what's happening when you're stationary is the VAP heats up and boils more gas forcing it out through the mixer.

You're right with the vap location Alex. The water feed is from a t-piece between the cylinder head outlet and heater matrix inlet. The outlet from the vap goes into the header tank outlet.

The Leo is and has been fine when driving. The stepper is fairly stable at 125 +/- 10 when on the move. Even accelerating hard uphill in 2nd it doesn't go above 140. Yes, I'm still using the 39mm venturi as IMHO it's the best compromise for power with a relatively decent idle. The idle was better with the 36mm venturi, but the engine felt as if it was holding back above 4k. With the 42mm, the car positively flew from 3k upwards, but I could never get it to idle nicely - plus, the stepper maxed-out on a regular basis. OK, so now you're going to say that I'm an ideal candidate for a BLOS, aren't you?

Do you reckon I should try shielding the vap then?? When I was initially researching before doing the LPG install, I read somewhere that 50deg is the right temp for the vap. I'm sure I've seen thermostats that go in the hoses to keep the vap at the right temp.

[e301988325i]

Here's one I made earlier. I've never heard of 50C operating temperature, or the thermostats, but I'd like one. I think it would be a good idea to try and stabilize the temperature of the VAP.

I'll wait for results of the BLOS before reccommending it!!

I fitted some pre-facelift engine bay headlight covers to my facelift car today, had to cut holes in to allow the outer headlights to poke through but it still looks s a lot tidier than before.

from:
http://www.e30zone.net/modules.php?name ... highlight=

mention of thermostat here, rich and poor running when it got hot
http://mark-lawton.com/diy-lpg-conversion/

[StuBeeDoo]

Right! Getting away from the vap for a while...........

I'm not confident about my soldering on the AFM plug. I want to do something different. I'm thinking about getting some crimp-on male spade terminals to push straight into the loom socket.

Any thoughts, anyone??

[Ant]

get a section of loom from the breakers, or get you local dealer to make up a repair loom for you dude, they'll do the crimps for you and assemble the plug, that leaves you the easy bit

[StuBeeDoo]

Thanks for that Ant.

I've been thinking. Am I right to run the set-up in this ^^^^ sequence - MAF into mixer - or would it be any more efficient, in terms of airflow through the MAF, if I put the mixer before the MAF? I can't find the venturi thread from a while ago, or I would have read through it again and posted this question there if necessary.

I've now got the petrol mixture set-up so that in a dire emergency, I could drive on petrol before I get on the dyno. Hopefully that means that I won't need to spend too long on the dyno getting it all mapped.
The plan is to get the fuelling and ignition maps spot-on, and then tweek the ignition map for LPG running.
By the time I get on the dyno I'll still have Tesco 99ron in the tank, so once that's all gone I'll pop back on the dyno and get another map done for regular unleaded. TBH, I'm unlikely to need normal regular very often but as I've got 4 maps, I may as well use as many as I can.

[e301988325i]

That's a tricky one, on one hand it's better to have the mixer closest to the TB.

On the other, with the MAF measuring air volume to get a load signal, ie 100% on petrol say, but on gas the MAF will only ever see 90% volume because LPG is taking up say 10% inlet charge volume because it is being added after, in truth your custom map should sort this IMHO.

[StuBeeDoo]

Sort of update..........

I hope that getting the mapping sorted does something to improve the fuel consumption.

Before the W.A.R chip and MAF conversion with LPG at 59.9p/ltr fuel was costing 15.6p/mile
Last week, with the W.A.R chip and the AFM and 68.9p/ltr it cost me £21.75 to do 115 miles - 18.9p/mile
This week, my local is 73.9p/ltr and I've done 135 miles. This has all been with the MAF fitted. Cost? 23.5p/mile. In terms of MPG, which I know isn't really an accurate way to calculate LPG conusmption, I've gone from about 18mpg to just over 14 since I started this experiment. OK, so the car's going like a rocket, but for what it's costing me now I might as well run it on petrol.
It doesn't take much working-out to see that my costs are rising in disproportionately to the cost of the gas.

I'm going to give it the benefit of the doubt until the mapping has been done, but if that doesn't improve my running costs I'll refit the AFM, remove the W.A.R chip and sell it, rip all the LPG off and stick it on eBay and sell the car. I can't justify running it at what it's costing me now. It looks like I'm going to be looking at modern diesels.

[e301988325i]

You cant give up until the maps done, the MAF is probably way out of whack, and it sounds like you're enjoying the power too, where have you gained extra?

[StuBeeDoo]

It seems better right through the rev-range Alex.

I'm not making any irrevokable decisions for another couple of weeks. I've got a trip to Hampshire and south Wales planned over the weekend of 25th-27th and I'll see what the consumption works out at once the mapping is done. But TBH, I've got a bad feeling about it.

I don't have room to keep a third car (just keeping the touring for weekends and holidays), so if the touring can't be fettled, one way or another, it will have to go - probably to make room for a Smart ForTwo for me to commute in and we'll have to get a bigger, better car on Wor Lass's NHS staff lease package.

I've just about spent all my savings now, trying to get the touring right. Some form of car is a necessity for me to be able to work, but being on NMW and unable to find another job due to age not being on my side, with possible redundancy always lurking in the background I have to be realistic. It looks like the time is approaching where the E30 is a luxury I won't be able to afford much longer. To justify keeping the touring, I need to get the fuel cost per mile as far below 20p as I can. At current prices that's equivilant to a petrol car doing better than 30mpg.

[StuBeeDoo]

Last weekend I re-enabled the "full throttle mode" on the Leo.
This morning I've been reading back through old posts and read that I had done this in the past and noticed a considerable worsening of economy. So I've just been out diasbled it again and there isn't any noticable effect on performance.

[StuBeeDoo]

I'm thinking seriously about putting the mixer before the MAF rather than after. I'm not sure if this will achieve much in the way the engine runs, but it should make it all fit together a bit better.

[e301988325i]

I can't imagine how your leo gets full throttle signal Stu, there is only one throttle input into the leo, and the full throttle function requires a variable TPS signal?

[StuBeeDoo]

I can't imagine how your leo gets full throttle signal Stu, there is only one throttle input into the leo, and the full throttle function requires a variable TPS signal?

Doesn't somehow it work off the WOT bit of the TPS??

[e301988325i]

Normally, the leo is fed +5v from the idle part of the TPS switch, all the leo knows is the difference between idle and not idling.

Unless it's wired differently to above, or the leo has a fully variable 0-5V throttle feed, to measure load with, there is no way for the leo to register WOT.

I thought you were running a leo, or do you have a different system?

[StuBeeDoo]

On mine, when you enable the full throttle function, you have to enter a TPS voltage value between 0.1v-4.9v. I've been putting in 4.9v and as soon as the throttle is opened, the stepper shoots straight to what ever point I've entered. I usually put in the stepper figure that it's at when running on the road (currently around 125).
If I disable the full throttle function, the stepper still moves up to 125 as soon as I accelerate, just not as fast.

I take it from your post, what I'm doing is wrong, then. That's probably why, when I do use the function, my consumption goes through the floor.

Wouldn't you have thought that after nearly 4 years I'd have found my way around the Leo and be able to use it properly??

[e301988325i]

There's 4 bars for the throttle position on the Leo IIRC, yours should only be able to switch between idle and not idling, is it doing that? That's how the leo knows to switch between the idle stepper limits and the running stepper limits.

The full trottle function jumps the stepper to a preset value, but after that jump it then aims for stoich, unfortunately because of this the WOT function can't be used to increase the mixture under high load, for more power!

[StuBeeDoo]

There's 4 bars for the throttle position on the Leo IIRC, yours should only be able to switch between idle and not idling, is it doing that?

Yes.

The full trottle function jumps the stepper to a preset value, but after that jump it then aims for stoich, unfortunately because of this the WOT function can't be used to increase the mixture under high load, for more power!

The function's definitely working (or it was before I disabled it) because the other day while I was out on the road I set it at 225, rather than 125, by mistake. I wondered WTF was going on when it shot to 225 then dropped back to normal......... Then I realised my input error.
While I was faffing-on, I also discovered that (unless I'm mistaken) with the cut-off function enabled the full throttle function doesn't work even though it says it's enabled.

[e301988325i]

The cutoff function uses the 5v signal from the idle switch to detect TPS idle position with revs above 1300 or whatever you set it at, if you're telling it 5V is full throttle the two contradict and I gess one won't work. I have noticed the overun cutoff saves fuel, but I wanted to give the stepper a rest.

Stu, you've confirmed that your leo is normal, wired up normally with only idle signal feed, you can't use the WOT function unless you install a variable TPS.

Thinking this through, I actually now believe that the AFM signal, (0-5v fully variable, fairly constant at idle, and the AFM is effectively always fully open at WOT giving the voltage required for the WOT function) should be fed to the LEO TPS input instead of just the idle tps signal. And I have wasted my time installing a fully variable switchable TPS. Of course this won't work with your AFM jammed open, but for those of us with the mixer in front of the AFM this is fine. Stu, you should feed your MAF output signal instead of TPS idle to the Leo for better functionality.

I can imagine that with the WOT enabled you have been wasting loads of fuel IMHO.

[StuBeeDoo]

Thanks for that Alex.

I don't know where I'd be without this place. I'd probably have given-up on the E30 years ago.

[e301988325i]

Do you see where I'm coming from, our cars all have a fully variable 5v load meter, perfect for LPG. Why didn't I think of this before.

[Gunni]

a 100kpa map sensor would be more ideal then the AFM as the AFM doesn´t reach WOT reading until at a certain point. The map sensor would go 4.5v at WOT at any rpm.

[e301988325i]

You can specify the voltage point at which the WOT function enables the leo lpg ecu, which would cover the low rev, not fully open period you describe, my point is that no extra sensors are needed. You can also specify idle hysteresis which allows the idle voltage to fluctuate whilst still registering idle.

Of course you are correct that the MAP sensor would work, you're input is appreciated, as we're all bumbling along, teaching ourselves!

[StuBeeDoo]

Right! Back to the excessive fuel consumption issue.

As I posted somewhere above, my soldering skills are non-existant. Bearing this in mind, I bought a crimp-on "Autobar disconnect plug" kit from ECP for the princely sum of £3:49 - just in case.
I wasn't really happy about cutting the AFM plug off my engine loom, but needs must, I suppose.
This afternoon I went out to have a look. As I unravelled the loom tape from the plug where I'd done the soldering, it all fell apart. Only 1 cable was still attached and that was one of the IATS ones.
So, after a few minutes hyperventilating, I cut the AFM plug off the loom and fitted the plug kit.

Now, I don't know that the ECU does with the ignition timing if it gets no load signal whatsoever, but that's what must have been happening.

I KNEW there was no point in me throwing money at a soldering iron kit. I should have just cut the AFM plug off in the first place.

[StuBeeDoo]

Do you see where I'm coming from?

TBH Alex, I'm not sure I do. I'm not the brightest of sparks.

Are you saying that the load output from the MAF could be sent to the Leo via the wire that taps into the TPS?
Would this be done in place of the TPS wire, or in addition to?
.... And doing this would enable the Leo's full throttle function to work solely when the engine is under full (or near full) load??


I have to be honest, this is getting well beyond my capabilities and understanding now.

[e301988325i]

I think your may get higher MPG now , there are some good youtube soldering guides. . .

[StuBeeDoo]

there are some good youtube soldering guides. . .

I know, I watched 2 or 3. My problem is that I don't have steady enough hands. I even tried gripping the iron in my Workmate and holding the wires in my fingers but that didn't work either.

[StuBeeDoo]

I think your may get higher MPG now

I certainly hope so. I've had the Leo connected to the laptop again, just in case I need to make more adjustments, but I didn't.

The stepper is even steadier now (fluctuates between 110 and 125 max). The idle seems a little smoother, and it doesn't seem to need as much throttle pedal for a given speed.

Time will tell.

[StuBeeDoo]

I've topped-off the LPG again today. The latest consumption figure (after disabling the full throttle function, but before finding the disconnected solder joints) is back to what I was getting with the AFM fully open. So, all is not lost.

[e301988325i]

That's good news!!

[e301988325i]

That's good news!!

[StuBeeDoo]

Something Alex relayed to me today by PM gave me the feeling that I should publish the costings for this little engine management upgrade caper.
W.A.R chip - £270
Second-hand M50B20 MAF - £40
Dyno time - £TBA (but it's £72/hour)

I have bought other second-hand parts (the air filter case and AFM) and some tools and electrical items, but in the case of the former it was a necessity for me because I can't have the car immobile for more than a few hours at a time. The tools will probably be used again at some time in the future and the terminals I class as "consumables". Therefore, I won't include any of these items in my costings.

[e301988325i]

Are you saying that the load output from the MAF could be sent to the Leo via the wire that taps into the TPS?
Would this be done in place of the TPS wire, or in addition to?
.... And doing this would enable the Leo's full throttle function to work solely when the engine is under full (or near full) load??


I have to be honest, this is getting well beyond my capabilities and understanding now.[/b]

From what I understand the AFM would be better then the MAF for signals because it is maxed out earlier in the rev range.

Yes you could, if you fancy another experiment, swap the idle TPS feed to the the LEO for the output of the MAF, giving the leo a fully variable load input, not quite as perfect as fully variable TPS, but IMO better than the simple, 'idle +5v' or 'not idle 0v' switch that's in place at the moment.

[StuBeeDoo]

OK, today's mapping day. I'm leaving for Motoscope within the next hour.
175bhp and 185ftlb on petrol would be nice, but the most important thing is to get it running as efficiently as possible. TBH, I wish now that I'd had a power run done on petrol at the same time as the LPG one just before Christmas.

Update later.

[e301988325i]

How did you get on?