WesBrooks

Using Gems 4.6 Flywheel and Cam Sensor

26 posts in this topic

Morning.

May have my hands on a Gems 4.6 in the next few months. I'd like to include cam and crank position sensing even if I do use wasted spark & batch firing initially.

I'll be using MS3x.

There appears to be three options for me:

1) Fit trigger wheel to front pulley and use interim timing cover from old 3.9 using adapted dizzy for cam angle sensing.

2) Consider using exising encoder wheels on flywheel and cam and at best stock sensors.

3) Mix of above.

I prefer the idea of 2, but as there is no chance of me running this engine on the original GEMs ECU I guess there is little point pitching this battle if there is no point. Only bad thing that I can see for 1 is that there is play in the gears that may introduce a timing error where as the cam wheel encoder is rigidly linked to the cam. Probably not enough to cause a noticable issue?

Any one used the stock GEMs encoders?

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Do you need a cam angle sensor?

They should work with MS no problem, they are simple VR sensors.

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55 minutes ago, WesBrooks said:

 I'd like to include cam and crank position sensing even if I do use wasted spark & batch firing initially.

I'll be using MS3x.

1) Fit trigger wheel to front pulley and use interim timing cover from old 3.9 using adapted dizzy for cam angle sensing.

 

It is my understanding that you will not need the cam sensor for batch firing - however you did say initially and if you want to go sequential later then it will be needed.

Why do you need to use a 3.9 timing cover - why not use the 4.6 cover which has the cam sensor in it and use either a trigger wheel or the 4.6 flywheel with its crank sensors for basic timing.

 

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I've the luxury of this project not needing to be on the road any time soon and I'm aware that overall my enjoyment of the project will be just as much in the tinkering as the driving. With that if it takes a little longer, but eases work for others later who are less inclined to tinker then great. If it is likely to be a hell of a fight to use the stock sensors then I'll move on! I'm not shy of coding either so may be able to help in that respect.

I'd be interested to know if people have done it. I've seen the details for the sensors and yes, they are typical from the electronics side of things. What isn't clear from my scan through (granted not a detailed read!) the MS manuals is whether or not the feedback pattern from the cam sensor is a standard pre programmed pattern or whether I would have to code a new encoder pattern. The gems cam angle sensor appears to work off the varying widths of the 'spokes' on the cam pulley.

Fitting the interim cover feels like a little bit of a bodge and adds more mechanical parts. This does however appear a standard MS way of detecting cam angle. It allows you to modify a distributor with a hall effect sensor so that MS can detect crank angle and the engines position it the full cycle.

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I am building a 4.6 to use MS3x - I am using an older flywheel so not crank sensor.  I am using the 4.6 timing cover and have put a trigger wheel on the front to tell the MS3 where the crank is.  As I am going sequential I will use the standard cam position sensor in the timing cover.

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That's great to hear. Would you mind updating the thread (or point me to a build log/thread) if you uncover any tricks to get it playing well? ...or all going well just to say it is plug and play!

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I am going this way as that was recommended in various forums including the V8 Owners forum and the Megasquirt Forum.  They all said that batch firing would be OK and it will probably be but as the engine was sequential and MS3 can take input from the standard cam sensor I can use it - also MS3 can used the standard crank flywheel sensor but as I sis not have one I went the trigger wheel route.

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Here's a RV8 running full sequential from ExtraEFI:

I've been discussing this with Nige (be it with a few months between emails due to me!) and am currently trying to detail out my plans so that I know what bits I'm buying from who.

From what I can see it doesn't look like it will be too challenging running using the standard flywheel and crank sensor. I'll be using VAG logic level input coil packs as I've heard horror stories about the cost of the Gems coil packs! Are these logic level too?

I'm planning to run this up on an engine test stand before getting it in the car so should have great access to swap sensors about and make it nice and easy to do quick checks like spinning it over to check sensors and timing. This is also a measure of keeping the engine out so I don't have to move it again later!

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If memory serves the crank sensor is only needed once at startup so the ECU can work out the position, after that it knows the cam is locked to the crank so it'll always be where you think it is (unless something goes terribly wrong).

Pretty sure GEMS aren't logic-level, they're also not as common as VAG ones so harder to find & more expensive.

I'm curious as to why you want to go sequential, what benefits you think it'll give?

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If I wire it from the start as batch fired then in order to migrate to sequential I would need to start again with the loom. If I want to batch fire with sequential wiring then I'm guessing it is very simple. If there were no benefit I'm guessing the ECUs for the GEMs and Thor systems would have been cheaper to wire as batch fired? What benefit did they see and the non direct injection systems between then and now? From an electrical point of view staggering the injection events could smooth the current loading on the electrical system and reduce noise. Noise being quite a serious concern for other bits of my project - but having said that making sure the electrical system doesn't fall over due to a lighting strike within a mile is probably a tougher requirement to achieve.

The CAM sensor allows me to use sequential ignition and when combined with the VAG coil packs allow me features like rev limiting and drops the number of igntion events per cycle which can't be a bad thing for spark plug reliability and electrical noise. While time consuming I'd rather wire the injectors in and allow the freedom to try additional features later.

Main aims for the MS are:

  • Comfortably achieve emissions for MOT and maybe IVA.
  • Tuned for 80C Coolant temp.
  • Optimum balance between fuel economy at cruise and keeping from going too lean.
  • Attempting to knock sense with stock sensors to allow safer ignition tuning.

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The reasons manufacturers have for going sequential are not necessarily considered "useful" aftermarket or in engine swaps - for example, slightly lower emissions at idle. I was just curious which benefit(s) you're going for. Sequential systems tend to drop back to batch-fire at higher RPM anyway, not sure if that's any different with MS3.

The wasted-spark setup doesn't usually fire two plugs per event as the one in the "other" cylinder is harder to arc over, so once the target plug strikes up most of the energy will go that route.

I'm slightly perplexed by your concerns over electrical noise and lightning , I've never known vehicle electrics to be upset by it, never had an MS upset by it and never seen any noticeable noise coming back from it - do you have some sensitive kit in your truck? I've never known a vehicle be upset by lightning either :huh: and I've driven a squirted vehicle through a lightning storm more than once.

I'm also not sure why you want to tune for 80deg coolant temp as that's less efficient and worse for emissions? If the cooling system can't cope, running a lower stat is just a sticking plaster. If your system is from the V8 Disco then it should be more than up to running at standard 92deg temperature, and be perfectly happy and reliable at that.

I'm not having a go at you, just curious about the reasoning behind some of your decisions.

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I wecome the discussion.

Regards lightning it causes an over voltage situation on mosfet gates. This along with ringing needs to be controlled if you've got any homebrew electronics in there.

Thermostat advise is from Des Hammill's how to power tune rover V8s. It relates to dropping the thermostats back to the level used in the 3.5 before control was potentially sacrificing longevity in favour of emissions. Every bit hotter the engine gets increases the problems relating to differential expansion of the Alloy block and steel main caps. This doesn't help the main fretting, something my 3.9 suffered from.

The rover V8 has a carp BHP return compared to the amount of fuel it consumes. I believe this is mostly down to the head design, which indicates air flow issues. This will get worse the faster you run the engine. Therefore I am tuning for torque and economy from idle which should give me a good benefit when greenlaning or generally playing off road.

If I see a substatial benefit from sequential injection low down and start to head towards batch firing due to flow limits on the injectors then I can change for higher pressures (thor) or search for higher through put injectors.

I realise my choices are comprimises, but so are most projects in some way.

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I will be watching with interest (in a positive way)!

Sequential - From what I have read over the years there physically isn't enough time to inject the quantity of fuel required during the tiny window available at higher rpms, which is why systems drop into batch fire mode. Changing injectors or upping the pressure may by you a few more rpm, but I can't see it being much.

On the flip side, if you fit massive injectors or use super high pressure in the pursuit of raising the upper limit of the sequential rpm window then you are possibly going to run into problems injecting a small enough amount of fuel at idle.

 

 

 

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Looks like the injector timing resolution for the MS3 is 1 microsecond which equates to about 0.03 of a degree at 5000rpm.

I'm not building my truck for fast road, I'd go locost or buggy if I wanted good road manners. It's got and auto, and if I remember rightly 70mph will be about 3000-3500rpm. I'm not sure what the shift points are on the ZF box when you kick down, but will look into it. I expect I'll be cruising around 65.

I'm not so interested in top end performance because this needs head work and increasing the red line to fully realise, which would add £500-1000 per bank onto the engine build cost. I'm reading through guides like Des Hammil's to see what I can cost effectively do.

I'm hoping to get a few years service out of the 4.6. If I get a lust for more power rather than say improving the trucks off road capabilities with lockers etc then I'll seriously look at an LS3 lump and take the MS3 over to the LS3. If however the 4.6 proves reliable and in good fettle then I'm fully expecting the stock 220bhp to be plenty (the MS may free a few extra ponies!), and the tuning will focus on low end torque and economy (or more to the point efficiency).

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Hi Guys,

I am very interested to read of your electronics issues when converting to run on Mega Squirt systems. I am in the process of building rear engined off road buggy using a P38 Gems 4.6 as the donor vehicle for drive line. I know I am bucking the trend but what is wrong with using the original gems ecu (emc). I have found a company that will free the engine ecu (quite cheap) so it no longer needs input from the BECM and figure with a new power supply and fuse board (something like what they run in the Morgan plus 8) I can basically use all the standard sensors and engine loom. Not sure if I will be able to run the auto box and transfer case direct from the manual inputs and the 6 pin connection to the engine loom but I am currently laying out the controllers and bits I have salvaged from the p38 loom (with pin description inputs from the manual in RAVE) to see what inputs I need (earths power signal, comms and comms direction etc).

I may need something like Ashcroft's compushift or fit a manual valve body (and hi lo control) but I am hoping the stock system can be made to work (without input from the BECM or ABS controller). I think road speed signal can be obtained from the speedo output (if not done as standard).

I am a bit of a newby at this so the learning curve is steep but I wanted to learn something about electronic control while I build this project (other wise I could have bought a loom and ecu kit from the like of Lloyds or RPI).

 

Has anybody else out there tried to do it this way? I wold love to get my hands on simplified wiring diagrams. Also pin references from the manual are great but it would save me some work if they also had wiring colors so I can identify the tails on the bits of stock loom I need. Any help and advice greatly appreciated. Also looking for non locked maps that I can get loaded on the original PROMS for injection and timing mapping to remove the mid range lean/over heating issues with the stock maps. I may yet stump up the cash and buy Tornado chips but I think there will loads of folk out there with maps that may be worth a try. If it all works I may develop the engine a bit but agree that, bang for buck, the LS engine conversion is probably the way to go for over 250HP. Currently it just a play thing but if I can make it light enough it may worry a few of the tail enders in the Scottish Comp Safari scene.

Yet to find a stock wiring diagram with wire colors and would appreciate any links or leads, even simplified block diagrams (I will endeavour to post a block diagram of what I am trying but I think it will look like a Morgan +8 without the security input but these are all manual so no auto box controllers).

Wes, I hope I am not hijacking your thread. What sort of off road toy are you building? Mine only needs a few lights (for the dark northern evenings), usual engine gauges, fuel pump, etc, and a big stop, go and crank buttons. If I get really keen I will make an independant front end for it a bit like Mathew Lee's earlier buggies (maybe a bit longer). 

I run mostly 2wd offroad rails (VW powered) but also play with a modified diesel rag top 90 for trials, orienteering and some winch events (like yr Southern Challenge trophy trucks). After dipping my toe in Landrover club Comp Safari racing I find myself drawn to V8's - mostly for the noise! Plus in my old age a 2 seater toy is bit more sociable in the local 4x4 scene.

 

Bob Tail

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There is no reason if you dont want to play around with ecu tuning.  However if you are using the P38 gearbox you may have issues as its ECU needs to talk to the engine ECU.  Not knowing exactly what you are building can have a front driveshaft on the drivers side instead of the passenger side (as per P38) then I would go with a Disco 1 auto which is fully autonomous and a LT230 transfer case.

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Thanks Gary,

With the engine in the rear the drive shafts will be on the wrong side. Current plan is to cut the front diff housing and flip the mid section and reweld, Flip complete rear diff and re fit mountings maybe for a late disco J radius arm (simpler under the engine than using the top link and A arm set up from a disco 1 or 90) Thought about a few different combinations including shelling out for a proper reversing transfer case (Milner maybe) as not likely to need 2 ratios or using defender axles and just flipping nuggets (bit of redrilling required) but want the strength of the P38 gear to save buying uprated CV's etc. Have not read enough about the wear issues about flipped diffs yet. Apparently they don't like being run backwards for any length of time. Is this caused by gear profile or old wear patterns or spacial relationship between crownwheel and pinion? High pinion shaft will mean they need more oil or a splasher for lubrication.

For the gear box there is also an option to fit the manual valve body from an earlier ZF box but keeping an open mind till I see if I can get the engine ecu to talk to the gearbox and transfercase controllers. There is a 6 pin connector from the engine loom to to the gearbox loom which I think has the relevant links.I think the BECM just supplied power and a comms path but this can be replicated. 

I will lay out what I have salvaged from the donor. Check the pin outs from RAVE and see what I have and what I need (running without the BECM) and make a block diagram and post the results. Would like to hear if anyone else has done anything similar and maybe learn from their wiring diagram? In the process of getting ecu unlocked and considering re mapping at present. Will get it running first before I dive into chassis (eventually will be a full tube fabrication after some testing on ladder chassis) and driveline.

Maybe I should start a build thread for this project? First I was hoping to learn a bit more from folks who have gone down some of these paths - simple Gems ecu management first, then gearbox control.

Wes' project seemed a bit similar but not to keen on MS and it seems I have a pretty capable ecu already so why replace it?

Eventual use in comp safari events (like short course racing but timed 5 to 10km runs over 2 days. Maybe 100km of fast rough stuff) if I can make it light enough to be competitive with higher powered land rover derivatives (Bowlers, Tomcats and Simbugginghis). I actually still think a light rear engine 2 wd buggy will do the trick but want 2 seater so weight goes up and 4wd becomes more desirable (but possibly lighter options than LR live axle). It is really falling over a good coscast 4.6 that has drawn me along this path other wise it could have been a Lexus V8 mid engine onto a Fortin transaxle (or a cheaper Renault transaxle). Also the events are run by Land Rover clubs so its not such good form bringing exotic kit along. Its more social and about thrashing similar kit around the hills than balls out performance.

Hope Santa was kind.

 

Bob Tail

 

 

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The RAVE electrical manual has all the wiring colours.

8 hours ago, garrycol said:

However if you are using the P38 gearbox you may have issues as its ECU needs to talk to the engine ECU.

Eh, only on the later Bosch ECUs. The GEMS just has a whole lot of wires sending info.

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7 hours ago, elbekko said:

The RAVE electrical manual has all the wiring colours.

Eh, only on the later Bosch ECUs. The GEMS just has a whole lot of wires sending info.

Thanks for that information :-)

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I run my MS (with edis) using the standard crank sensor on the fly wheel. No trigger wheel fitted. Just had to adjust the angle in the settings and from memory, rotate the ring 90 degrees. Search my old posts.

G

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There is a whole topic on reverse running diffs, speak to Nige though as I understand it LR never made seperate front rear diffs so one always runs reversed? Of course for the money there are replacement ring/pinion designed to be run reversed.

Flipping a diff does not change the side of the crown wheel being driven, the rotation is still the same (sorry realaised that this is not true as the engine will drive the reverse way which is the whole point!) but as the pinion is now on the other side effectively you are driving on the top of the wheels not the bottom so it drives the other way! I think the issue comes from the change in oil location as the top of the diff is normally in free air/oil mist and the bottom in oil, flipped it is the other way around so the diff floor is now the roof!

Edited by missingsid
Error in brain!

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On 26/12/2016 at 0:03 AM, Bob Tail said:

Maybe I should start a build thread for this project?

Sounds good, that's exactly the sort of thing we like to see round here!

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Happy New Year to all,

I have made some progress with identifying all the inputs required and so far it all looks doable, maybe a few bugs to sort with road speed signal from speedo and not sure if diagnostics will work without the BECM but will hook up the K and L lines and take some advice from a local OBDII guru (who is mostly into VAG stuff but has a good understanding of the control and comms systems - I am more of blue spanner man!).

Any links to other threads talking about reversing diffs? Is the P38 running gear worth preserving? I have all ashcroft running gear in my trials truck but not to keen to shell out on another set of CV's and axles to convert/reverse defender or disco axles if the p38 stuff is tough enough. I hear at least the rear diff is a 4 spider unit and supposedly the front open type CV's are strong enough. Any comment on this appreciated as have heard various accounts. Extra strong P38 gear is hard to find but I hear on the grapevine there was some purchased from a US company for a Whitbread racer.

 

I will get my wiring diagram on paper over the next few days and post it for comments - it will be a combination of block layouts with just the tails of interest in any detail (the wires that used to interface with the P38 body and controls). Engine and gearbox looms will be standard. It won't be beautiful but I will try make it useful (if it works). 

 

I figure that since no one has come back with anything similar - maybe I am the first to go down this route? or maybe I am too naive to see the dragons!

Keen to hear if anyone has remapped the original EPROMs in the GEMS ecu for better (richer mid range) injection map (rather than the rechip route).

Just been to visit a mate who is doing something similar with a 4.6 in a winch trials truck but with aftermarket loom and ecu kits, He has binned the original MS set up after much frustration (and £) and is now on plan B with an Emerald system which has better local support from the rally fraternity. I think he would like to know more about ZIM's set up using the original bellhousing crank sensor. I will try searching the old posts.

 

All the best for 2017.

 

Bob Tail

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16 hours ago, Bob Tail said:

not sure if diagnostics will work without the BECM

Should be fine.

16 hours ago, Bob Tail said:

Extra strong P38 gear is hard to find but I hear on the grapevine there was some purchased from a US company for a Whitbread racer.

Lucky8 do some IIRC. Your eyes will water.

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