1989 BMW E32 730i help needed

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Mouse
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1989 BMW E32 730i help needed

#1 Post by Mouse » Wed Oct 30, 2019 10:01 pm

Hi there. I'm new to the board, but not to lpg.

My father used to convert cars to lpg back in the 70's and 80's. My first few cars, as a result, were running on lpg. I trained as a mechanic, and the premises directly beside was, and still is, a lpg installer, but on houses, rather than cars. Although most of the workers cars ran on lpg.

Recently I was offered a 1989 E32 BMW 730i, and as an avid classic car fan, I was interested. If I was to buy it, it would be with the iintention of converting it to lpg, as I would use it every day. However, my problem is that technology has changed so much since I, or my father, were in the habit of converting to lpg.

So can anyone point me in the correct direction? I've done some research on the conversion, and have some ideas that would work, but some things I don't fully understand. Like, what is my best option in regards to a full kit? I've read about the Zavoli multi point conversion, and it sounds like that is what would suit. Or is there better options?

Thanks in advance.

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Re: 1989 BMW E32 730i help needed

#2 Post by Gilbertd » Thu Oct 31, 2019 3:41 pm

You could just keep it simple and stick with technology that matches the age of the car (and your experience) and fit a single point system. Much cheaper than a multipoint, far simpler and will work just as well.
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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Re: 1989 BMW E32 730i help needed

#3 Post by Mouse » Thu Oct 31, 2019 9:00 pm

Thanks. I was assuming that the more modern system is better, as regards, more improved fuel economy, and power, and easier to use. I don't mind learning new tricks with the multipoint system.

Does the single point system use an ecu?

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Re: 1989 BMW E32 730i help needed

#4 Post by Gilbertd » Thu Oct 31, 2019 9:21 pm

Yes, it takes an input from the existing lambda sensor and adjusts the gas flow from that. So it is a mixer system that you will be familiar with but instead of the manual power valve between the vaporiser and mixer, it uses a stepper motor valve controlled by the ECU. Unless you intend running it down a drag strip, you won't notice any difference in performance between running on LPG or petrol. The multipoint system slaves off the existing petrol injection system so depending on what system is fitted now, may mean you can't fit a multipoint anyway. What injection system does it have fitted?
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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Re: 1989 BMW E32 730i help needed

#5 Post by Mouse » Thu Oct 31, 2019 9:53 pm

I haven't the car yet, but I'm think it's Bosch Motronic. It being a 1989, I doubt it has a cat, so I can't say it would have a lambda sensor or not.

I won't be doing the drag strip thing, more like a driving Miss Daisy, handy go slow, kind of driving

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Re: 1989 BMW E32 730i help needed

#6 Post by Gilbertd » Thu Oct 31, 2019 11:05 pm

If it's running Motronic, I would have expected it to have a lambda sensor although according to http://www.ecolambda.co.uk/main/bmw.htm it doesn't until 04/92. Maybe it isn't Motronic or maybe an early version that didn't use one. Not really a problem to add one though, it just needs a boss welding into an exhaust downpipe. My Range Rover runs 5-0V Titania lambda sensors instead of the more common 0-1V Zirconia sensors. The 5-0V ones stop giving an output at idle which confuses the LPG system so I've got an additional boss in one downpipe for a 0-1V sensor purely to drive the singlepoint LPG system.
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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Re: 1989 BMW E32 730i help needed

#7 Post by Mouse » Thu Oct 31, 2019 11:20 pm

Yeah. I stand to be corrected on this, but I think new EU reglations on emissions didn't come into effect until Aug 1992. Prior to that cats weren't needed. Us cars, depending on the state, meant it did need a cat well before that. And Japan too, and probably other countries as well.

Either way, as you say, it's not the end of the world to retro fit a new sensor.

So which system make am I best looking at? Zavoil, or Lavato or whoever? No point in fitting a cheapo system that's just going to be constant trouble, although I'd like to think a single point system would have less to go wrong with it.

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Re: 1989 BMW E32 730i help needed

#8 Post by Mouse » Thu Oct 31, 2019 11:59 pm

In part of my looking across the interwebs, I found this thread in bimmerforums. https://www.bimmerforums.com/forum/show ... 0i-big-six . On the third post he posts pictures on the install. No need to go any further as regards the install of lpg. As you can see he has a multipoint system fitted. Zavoli. I know I'm asking questions on a specific vehicle, and I'll need to do more research, but from those pics, do you think I'd need to go multipoint, or is it a case bt case basis?

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Re: 1989 BMW E32 730i help needed

#9 Post by Gilbertd » Fri Nov 01, 2019 9:19 am

Best wait until you get the car and see exactly what petrol system it has. In Italy, where many of the LPG systems come from, all components must come from the same manufacturer. Rather than each one going their own way and designing everything there's a lot of badge engineering. AEB manufacture the ECUs for Bigas, Zavoli, King, OMVL, Emer and probably a few others for instance. They are all the same ECU just with different firmware (and label stuck on the outside). Simon on here (LPGC) will be able to advise on the best reducer and injectors for your engine. There's pros and cons for both single and multipoint. With the dedicated lambda sensor on my Range Rover, I have two totally independent fuel systems the original petrol system and the singlepoint LPG system, so if one develops a fault, I've still got the other. It will also run on LPG from stone cold so the petrol in the tank is treated the same as the spare wheel, something to be used only in case of emergency. Downsides are that the fuel metering, while good, isn't optimum and the mixer in the intake will restrict airflow at full throttle. With a multipoint, there's a lot more work involved in the install (drilling the inlet manifold, lots and lots of wiring) and once installed it needs to be calibrated. It can't run on LPG from cold it needs to warm up on petrol first before it switches over, so if you do lots of short journeys you'll still use a fair bit of petrol. It slaves off the petrol injection system so if that develops a fault, then the same fault affects the LPG system too. However, the fuel metering will be more accurate so the economy will be better (although even if accurately calibrated, maybe only by 1 or 2 mpg) and the power output from the engine will be only fractionally down from petrol. In fact, if you can advance the ignition timing, you can get more power due to LPG having an Octane rating of 105 allowing you to run more advance.

While it isn't state of the art, I bought my car with the singlepoint on it almost 10 years ago and was intending changing it for a multipoint. I never have as the simplicity of the singlepoint and the fact that it is a stand alone system means I've got belt and braces when I set off on one of my 3,000 mile round trips around Europe (which I do regularly). In the time I've owned it, it's needed 2 replacement lambda sensors (because the first one I bought was a cheapo Chinese generic that lasted less than a year) and a vaporiser as the original one was getting very tired after 150,000 miles.
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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Re: 1989 BMW E32 730i help needed

#10 Post by Mouse » Fri Nov 01, 2019 8:21 pm

Thanks a lot for that info. From what you're saying the singlepoint will suit me best. More simple all 'round. I'll wait until I get the car, if I get it, before I'll settle on what system to use. It'll need some work anyway, so I'd be in no rush to make a decision.

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Re: 1989 BMW E32 730i help needed

#11 Post by Mouse » Fri Nov 08, 2019 10:58 pm

Just as an update to this.

I viewed the car this week. Turns out that despite I being told it was in storage for a few years, it was "in storage" under a tree for 13 years. If you wanted a proper project car, it would have been ok, but for me I was not interested. However, it got me well interested in old Skool BMW's, so I think I'll keep an eye out for one.

So, so far, thanks for everyone who answered my questions.

As governer Schwarzenegger would say, I'll be back.

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Re: 1989 BMW E32 730i help needed

#12 Post by Mouse » Sun Jun 14, 2020 11:28 pm

I told you I'd be back :) .

Well I did buy a car, a 1990 735i. I bought it just before lockdown, so there has been no hurry for me to do any conversion on it since. I won't be putting the car on the road for other reasons until October, so I've got plenty of time to do any work I need to do to it.

Anyway, it's a straight 6, with Motronic 1.3 injection system. Because it's a 1990 car, it does not have a catalytic converter, or a lambda sensor. The ignition system is also electronically controlled with the use of a crankshaft position sensor, so the ignition timing cannot be altered. From my research, and the advice here, the single point closed loop system is the better option for me. Although, it seems the multipoint systems seem to be favoured on this engine, on any of the few pictures I see across the internet.

So, am I correct in saying I need a system that can provide sufficent lpg to a 3.5 litre, that requires a lambda sensor, and an adapter to fit into the intake tube after the airflow meter? I believe that this system is susceptible to backfiring, which would blow the airflow meter, but there's a backfire protector for that it seems. Does anyone have any experience with this system, that has that protector in? Or do you think it is even necessary?

Here is the car

Image
Image

You can see the pipe from the afm to the manifold. I'm assuming that is where I need to fit an adapter, or is there a different solution to that?

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Re: 1989 BMW E32 730i help needed

#13 Post by Gilbertd » Mon Jun 15, 2020 1:23 am

This https://tinleytech.co.uk/shop/lpg-parts ... -flow-mtr/ is what you'd need to fit. That, and weld a boss into a downpipe so you can fit a lambda sensor. Backfires only happen if the mixture goes very lean or you've got a poor spark (well worn plugs or iffy HT leads) but something like this https://tinleytech.co.uk/shop/lpg-parts ... ype-v0080/ (they come in different sizes) between the mixer and AFM would give you the protection you need. Vaporiser would need to be an OMVL R90E or BRC AT90E, both would be up to the job (I'm running an OMVL on a 4.6 litre Range Rover and a BRC on a 4.0 litre Range Rover). Then all you need would be the controller, like this https://tinleytech.co.uk/shop/lpg-parts ... ol-system/.

Very tidy looking motor from the days when BMW built real cars.
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.

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Re: 1989 BMW E32 730i help needed

#14 Post by LPGC » Mon Jun 15, 2020 11:04 am

Check to see if your AFM is the hotwire (MAF) type or flap type. If it's the flap type it can cause extra vacuum at an LPG mixer which can make the mixture too rich at low loads but I'm pretty sure it'll be the hotwire type.

I had a couple of V12 Beemers this shape, they had 2 x hotwire AFM's, 2 dizzys, 2 fuel pumps, 2 fuel pressure regs, 3 ECUs to manage the engine. The engine was managed as 2 separate straight 6's, the 3rd ECU acted to sync the other 2 ECUs. If any component failed that would usually disable an engine the V12 could still run on 6 cylinders. Wish I'd still got them!
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Mouse
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Re: 1989 BMW E32 730i help needed

#15 Post by Mouse » Tue Jun 16, 2020 12:36 am

Thanks Gilbertd. I had a look at the items you listed. I looked at the BRC AT90E on tinleytech and it lists it as up tom 190 bhp. My 735 is rated as 211 bhp. Probably not that anymore, but would you think I'd be better off with the OMVL R90E as a result?
The mixer plate you listed looks like it will bolt directly onto the inlet manifold, although the venturi looks very small compared to the inlet pipe. Is there different sizes do you know? Or is there a single injector that can be fitted to the manifold instead?
It's 6 cylinder, and has 2 banks of exhaust pipes all the way from the manifold to the rear of the car. Will I need just two lambda sensors, one on each pipe? The exhaust manifolds have predrilled holes with what looks like 6mm bolts blanking them, which would be handy to fit a lambda sensor. But I'm assuming lambda sensors are larger than that.
It is a very tidy motor, alright. Back when BMW made top quality cars.

LPGC, It has the flap type AFM. I'm not certain that it gets totally destroyed in the event of a backfire, but it bends the gubbins inside of it instead. Still not good. But regardless, I'd still be left with the extra vacuum making the mix rich. If that is the case, is there a simple solution to it?
The V12 engines are really something else, but if you're feeling flush, you can by as close as you'll ever get to a brand new 1992 740i here . https://www.catawiki.pl/l/14714755-bmw- ... l,jh;jgkjw . It's in Poland, but is RHD, and had less than 500miles on the clock. A nice road trip ahead for you :)

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Re: 1989 BMW E32 730i help needed

#16 Post by Gilbertd » Tue Jun 16, 2020 1:27 am

Yes, I noticed the listing for the AT90E when I got mine. I needed to replace my old OMVL and at the time the OMVL one wasn't available, Tinley Tech advised that the AT90E was good for over 250 bhp so quite why their site says 190 I've no idea. The R90E is slightly smaller too so now it is available again, it's probably a better bet.

The venturi in the mixer has to be smaller than the throttle body bore as it generates the suck that draws the gas in, so while you would expect it to be a restriction, it isn't as the venturi causes the airflow to accelerate. The gas isn't injected, it is sucked in by the airflow. As the gas is introduced into the intake at one point, if the mixture is correct on one cylinder, it will be correct on all the others, so fitting a single lambda sensor in one of the downpipes that will do fine. My Range Rover has two manifolds (being a V8) but uses 5-0V lambda sensors rather than the more common 0-1V types. The LPG system doesn't work too well with the 5-0V sensors so I have an extra 0-1V sensor in the RH downpipe solely to drive the LPG system. If the 4 cylinders on one bank are receiving the correct mixture, the ones on the other bank will be too. Standard lambda sensors have an M14 thread although you can get them with smaller M12 and M10 thread but they aren't cheap
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.

Mouse
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Re: 1989 BMW E32 730i help needed

#17 Post by Mouse » Tue Jun 16, 2020 12:45 pm

Thanks for that. The venturi just looked so small, it looked as though there would not be enough air passing through without losing significant power. I don't mind some loss. I won't be gunning the car, but I don't want it to struggle either. But if the mixer is designed to work, then that should be good enough.

I was pretty sure with the lambda sensor on one pipe would be enough, but asked just in case. I suppose if there's a missfire or something wrong with one of the three cylinders it's connected to, there could be a problem, but then again, it would be pretty obvious there's something wrong if that's the case. I was hoping I could get away without fitting a lambda boss by using the existing blanked holes in the manifold, as it would save me the hassle of taking the downpipes off. No such look by the sound of things. Is there any particular lambda that is needed or will a generic one do?

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Re: 1989 BMW E32 730i help needed

#18 Post by LPGC » Tue Jun 16, 2020 1:29 pm

There used to be a version of the R90 that featured an extra high pressure gas outlet designed to be connected to a gas pressure operated servo that kept flaps open during running on gas but Iirc it was designed for KJetronic rather than inline flap airflow meters.

Worth seeing if you need a flap opener before trying to source and fit one, maybe the extra vacuum at the mixer venturi at low loads due to the flap in front of the mixer will be slight enough not to be a problem. Even if it is a problem maybe you could re-arrange components so the flap meter was closer to the the throttle body with a mixer between air filter and flap.

Simon
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Re: 1989 BMW E32 730i help needed

#19 Post by Gilbertd » Tue Jun 16, 2020 3:28 pm

Generic lambda sensors from the Universal Chinese Lambda Sensor Company seem to last about 9 months for me, so I've been using NTK ones intended for a 1.8 Ford Focus. Went to a scrappy and got the plug and about 4 inches of wire so I can just plug in on a proper waterproof connector rather than having to solder them in.
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.

Mouse
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Posts: 12
Joined: Wed Oct 30, 2019 9:32 pm

Re: 1989 BMW E32 730i help needed

#20 Post by Mouse » Tue Jun 16, 2020 11:00 pm

LPGC wrote:
Tue Jun 16, 2020 1:29 pm
There used to be a version of the R90 that featured an extra high pressure gas outlet designed to be connected to a gas pressure operated servo that kept flaps open during running on gas but Iirc it was designed for KJetronic rather than inline flap airflow meters.

Worth seeing if you need a flap opener before trying to source and fit one, maybe the extra vacuum at the mixer venturi at low loads due to the flap in front of the mixer will be slight enough not to be a problem. Even if it is a problem maybe you could re-arrange components so the flap meter was closer to the the throttle body with a mixer between air filter and flap.



Simon
I suppose I won't really know until I put it all together if I need something extra or not. It crossed my mind after you mentioned about the vacuum pressure that maybe putting the mixer between the air filter and afm would do, but then again, it looks designed to be bolted directly onto the inlet manifold, behind the throttle plate. Surely if that's the case there must be another solution around the vacumm pressure, if it does increase. Mind you, the one Gilbertd linked mentions that it'a a "Plate mixer for BMW with flap-type air-flow mtr". That sounds like it's built specifically for that job.
Gilbertd wrote:
Tue Jun 16, 2020 3:28 pm
Generic lambda sensors from the Universal Chinese Lambda Sensor Company seem to last about 9 months for me, so I've been using NTK ones intended for a 1.8 Ford Focus. Went to a scrappy and got the plug and about 4 inches of wire so I can just plug in on a proper waterproof connector rather than having to solder them in.
Oh, I thought the lambda sensor had to be one that was designed with the lpg system. Will any decent 0-1v sensor do, or was there a particular reason you went for a Focus 1.8 one?

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