Megasquirting a 3.5 Classic

[MikeAK]

Hi all,

After being persuaded by Fridge to go the Megasquirt route with my 3.5 classic back in early Feb I'm back with many questions as promised!

I've just received my Megasquirt V3 kit. Ordered it early Feb but its been sitting in customs since mid Feb till now, no explanations as to why!!

Anyway I now on with building it and have a few questions for the megasquirt experts here.

Since the standard air cleaner looks quite restrictive and the airflow meter is no longer required I am thinking of putting a short pipe(75mm ish) onto the plenum to mount the air temp sensor with a "performance" pancake style air cleaner mounted on that. Sound reasonable?

For idle and cold fast idle control I think I have 3 options.

Option 1 Just keep the existing extra air valve for cold idle control and not bother with warm idlespeed control.

Option 2 Fit an idle speed control valve from a 3.9 (which I have) the plenum seems to have the mounting on the casting so would just need drilling and tapping to mount it. This would give cold idle speed and warm idle speed control via megasquirt.

Option 3 Use a rotary style idle valve as fitted to fords and early cavaliers etc using the existing extra air valve pipes. Again this would give idle control via megasquirt.

Anyone got experience/recommendations?

For lambda sensors megasquirt can use 1 or 2 sensors. Is there any real advantage in using 2 sensors, one on each down pipe over one sensor after the Y joint. I happen to have 2 brand new 4 wire heated sensors and mounting bosses.

I will be using EDIS to provide the spark, but as I have a P38 coil pack I would prefer to use this rather than buy 2 ford coil packs. From measurements the inductance, resistance and turns ratio are practically identical to the ford specs. Any reason why it wouldn't work?

I have a 3.9 fuel rail and injectors. These look like they should go on in place of the existing fuel rail and injectors. Anyone know if this is the case? If they do fit it it means I don't have to bother with PWM drive in megasquirt and can ditch the power resistor pack.

Also 3.9 injectors have the same flowrate as the 3.5 injectors as far as I can tell from googling around (185cc/min @ 2.5bar 202cc/min @ 3bar) so I shoud be able to use these with the exiting 4cu ecu if I link out the power resistors. Looking at the output stage circuit of the 4cu it should have no problem driving the high impedance injectors. The reason for this is I want the RR to be on the road as much as possible during the conversion so I could fit the fuel rail and injectors and continue to run using the 4cu while building up the megasquirt and new loom.

I also have a refurbished set of Bosch 0280 150 718 injectors (181cc/min @ 2.5 bar 199cc/min @ 3.0 bar) same physical fitting as the lucus 3.9 ones could I use these instead? These are supposed to give a finer fuel dispersal pattern which gives better combustion or is the more "pointed" Lucas pattern required because of the inlet tract design?

I want to be able to put the original injection system back on if I get rid of the RR at some point in the future so I don't want to hack up the loom. So I am looking for another preferably 3.9 loom to use as the basis for my new loom so if anyone has one they want to sell and would be prepared to post please PM me. It could be one thats been hacked of at the bulkhead, I don't need the ecu connector, just the engine end of loom and conectors.

Has anyone got a fuel and spark map for a 3.5 I can use as a starting point. If someone could send me one I'm sure it would save a lot of time getting started.

Sorry about the long post but thought I may as well get it all asked at once!

Regards

Mike

[Bull Bar Cowboy]

After being persuaded by Fridge to go the Megasquirt route with my 3.5 classic back in early Feb I'm back with many questions as promised!

I've just received my Megasquirt V3 kit. Ordered it early Feb but its been sitting in customs since mid Feb till now, no explanations as to why!!

Where is your location ? ……………..

Anyway I now on with building it and have a few questions for the megasquirt experts here.

Since the standard air cleaner looks quite restrictive and the airflow meter is no longer required I am thinking of putting a short pipe(75mm ish) onto the plenum to mount the air temp sensor with a "performance" pancake style air cleaner mounted on that. Sound reasonable?

The filter is very restrictive, but also very effective in getting clean air into the engine. I am using this filter and can on my 3.9 which is circa 240 bhp. On the rollers we can see a distinct power roll off at 4600rpm which is the snorkel / filter combination, mainly due to the lack of ram air effect on the rollers, as on the road, the roll off is not noticeable.

You need to be quite careful with the position of the IAT, as heat soak is a problem, especially when the engine is stationary after a run. Significant heat from the engine rises back through the inlet tract. I now have my IAT mounted in the canister cover of the air filter and this seems OK. Originally I had it mounted in the inlet pipe to the plenum after the ait filter…….. here latent heat soak was an issue. This is mainly due to the calculation that MS uses to determine the correct VE for the engine ........... very hot IAT leans off the mixture, however, once on the open road it soon settles down. For me this is was an issue when slow moving off road, and long period of idle when winching............. but moving to the current position has fixed these minor issues.

For idle and cold fast idle control I think I have 3 options.

Option 1 Just keep the existing extra air valve for cold idle control and not bother with warm idlespeed control.

Option 2 Fit an idle speed control valve from a 3.9 (which I have) the plenum seems to have the mounting on the casting so would just need drilling and tapping to mount it. This would give cold idle speed and warm idle speed control via megasquirt.

Option 3 Use a rotary style idle valve as fitted to fords and early cavaliers etc using the existing extra air valve pipes. Again this would give idle control via megasquirt.

Anyone got experience/recommendations?

Option 1: Yes, you can do that, but its not ideal............ also if you use a 3.9 inlet manfold it will not fit due to the fuel rail.

Option 2: MS1 will not control a 4 wire stepper motor …………MSII will, but you will not require much of the other functionality that comes with it. also I get the impression that even with MSII the stepper control code is very much in its infancy. OEM ECU's use a look up table based on CLT & IAT to quickly determine where the valve should be ............ I dont think MS had enough memory to do this.

Option 3: This is the preferred option with MS1. You need to make some small changes to the ECU (best to do it during the ECU build). The Ford valve unfortunately will not easily fit the plenum……… I looked into that option, hoping to be able to utilize the old stepper motor position. I have successfully used a Bosch 2 wire PWM valve from a Volvo 940 Turbo (as have a lot of others), but most of the 2 wire valves will work OK. You have to option of warmup only or closed loop………….. I am running in closed loop so I get fast idle warmup and engine load idle control.

For lambda sensors megasquirt can use 1 or 2 sensors. Is there any real advantage in using 2 sensors, one on each down pipe over one sensor after the Y joint. I happen to have 2 brand new 4 wire heated sensors and mounting bosses.

No point in 2 sensors and it is troublesome to implement. I have used a 4 wire sensor mounted in the Y pipe outlet, just before the centre box.

I will be using EDIS to provide the spark, but as I have a P38 coil pack I would prefer to use this rather than buy 2 ford coil packs. From measurements the inductance, resistance and turns ratio are practically identical to the ford specs. Any reason why it wouldn't work?

There is no reason why you cannot use the P38 coils ………. However, they are known to fail with monotonous regularity (the coil pack is a known fault with the P38 & 4.0L Disco). The Ford coils are not only waterproof, but also fairly bombproof, however, be wary of aftermarket imitations. Personally I would go for the Ford coils

I have a 3.9 fuel rail and injectors. These look like they should go on in place of the existing fuel rail and injectors. Anyone know if this is the case? If they do fit it it means I don't have to bother with PWM drive in megasquirt and can ditch the power resistor pack.

The 3.9 rail is not a straight bolt on with the 3.5 inlet manifold ……… the injector fitting is different and some metal needs to be removed from the front of the casting. IIRC the injectors can be made to fit with a little machining to accept the injector O ring. Also the 3.9 fuel rail will need to use the 3.9 fuel regulator as it is slightly different from the 3.5 flapper reg.

Also 3.9 injectors have the same flowrate as the 3.5 injectors as far as I can tell from googling around (185cc/min @ 2.5bar 202cc/min @ 3bar) so I shoud be able to use these with the exiting 4cu ecu if I link out the power resistors. Looking at the output stage circuit of the 4cu it should have no problem driving the high impedance injectors. The reason for this is I want the RR to be on the road as much as possible during the conversion so I could fit the fuel rail and injectors and continue to run using the 4cu while building up the megasquirt and new loom.

The output of the 4CU was one of its biggest failings ! ………. The output is a pair of RCA18483 transistors (TO3 case) driving 4 injectors each and driven by a pair of BC214’s which are fed directly from the Ferranti LFC1041AE LSI chip…… i.e. banked injection. The output pair can be changed for Philips BDX65B transistors that are better suited to the job. Much of the trouble was due to heat dissipation and the cracking of the Base / Emitter soldered joints. The RCA transistors had a habit of developing a slight collector / emitter leak and this was the source of bad idle, hunting, and running rich.

Once all the sensors are in place you should be easily able to complete the MS install within a day and have the car in a drivable condition ………..

I also have a refurbished set of Bosch 0280 150 718 injectors (181cc/min @ 2.5 bar 199cc/min @ 3.0 bar) same physical fitting as the lucus 3.9 ones could I use these instead? These are supposed to give a finer fuel dispersal pattern which gives better combustion or is the more "pointed" Lucas pattern required because of the inlet tract design?

With banked ‘port’ injection the spray pattern is not of great importance as the fuel is laying on the port walls until such time as that cylinder produces an inlet stroke, however, it is important that each of the injectors deliver the same amount of fuel. If these injectors are the same as the 3.9, then they will not fit the 3.5 inlet manifold…. See above

Has anyone got a fuel and spark map for a 3.5 I can use as a starting point. If someone could send me one I'm sure it would save a lot of time getting started.

I have my old 3.5 map & MSQ file here somewhere ………… I will try to look it out and post it up.

HTH

Ian

[Hybrid_From_Hell]

The LR 90 V8 Airbox is HUGE and will flow more than enough air, I would not advise a "Pancake" stylee one really, esp if ever you go off road

Try a read here : Megasquirty Clicky mine is one of the air boxes mentioned above

Nige

[MikeAK]

Thanks for the comprehensive reply Bull Bar Cowboy.

I probably should have said I'm using a Megasquirt V3.0 PCB with MSII processor module.

I'm located in Darwen in deepest Lancashire

So reading your advice this is the conclusion I have come to:

Keep the existing air cleaner and mount the intake air temp sensor in it. My engine is otherwise standard so if its OK for your 240bhp engine it should be more than good enough for mine.

Go for the two wire style idle speed valve, had a google round and the volvo one you mention looks identical to the cavalier one I was considering.

Fit the 3.9 fuel rail, along with the inlet manifold I also have. I thought the rail might have fitted the 3.5 manifold but swapping it will give me the chance to see the state of the cam and followers. Looks like one of the coolant pipes enter the maifold at the front in a different place but that shouldn't be too difficult to overcome.

Use one Lambda sensor mounted in or just after the Y joint.

I will go for using the 3.9 coil pack for now since I have it, If (when) it packs up I will change to ford packs then.

Now for the bit I'm still unsure about regarding injector choice. what I meant (but didn't ask very well) is would there be any detriment in using the Bosch injectors rather than the Lucas ones? The reason being that the Bosch set is refurbished and cleaned and the condition of the Lucas set is unknown other than the car was running when they were removed.

Does the coolant temp sensor have the curve expected by the standard Megasquirt SW or will I need to recalibrate (easytherm SW)?

It would be great if you manage to find your map and MSQ file.

Thanks for the suggestion about the LR90 airbox Hybrid_From_Hell but since it seems the stock item is up to the job I'stick with that.

Thanks again

Mike

[Bull Bar Cowboy]

Mike,

The Bosch injectors will be fine ...... IIRC the Lucas injectors are just re badged bosch items, like all the other injection parts (apart from the ECU)

The coolant sensor data will need to be entered into the ECU using easytherm .................we can post up the info .............we have an S19 file (ECU Firmware) with all this info, but it is onlt for MS1.

I will post up the 3.5 spark and fuel maps as the full MSQ will will be of no use for MSII....................

If fitting the 3.9 inlet manifold, you will need to blank off one of the water pump outlets with a core plug (dealer part - a few pence) and the heater pipes then run externally around the out side of the plenum, as opposed to under the manifold and through the valley...............

The resistor pack is quite easy to cut out ............ use the two brown orange feeds for +12 to each injector bank. The injector feeds all went back to the 14CU where they were commoned for bank firing within the 14CU PCB ........ on the header plug pins.

Yes its common to use the Vauxhall valve .............. the same valve is also fitted to VW & Audi

All straight forward stuff really ........................

Ian

[FridgeFreezer]

I think MS2 has enough memory that you don't need to use Easytherm, you can just enter the values in MegaTune or similar (I think). Either way, we have the data

Looks like my apprentices have answered all your other questions

[gn3dr]

Ian

Could you post up your maps anyway as I will be squirting a standard 3.5 using V3 MS1 so hopefully it should work for me.

On your description of the water pipes - was there a changeover period on how these were routed - mine ('89 engine) are routed back to the heater outside the plenum (over the drivers side rocker cover) but I have the older type injectors - connected to the fuel rail with little lengths of pipe.....

One other question. There is a water heated plate underneath the throttle body on the 3.5 I have. Do you think this is necessary when converting to megasquirt? I guess it's for preventing icing or something like that in cold climates but my logic tells me cold air = better performance (in our relatively mild climate)?

[FridgeFreezer]

I have run a couple with no plenum heater connection and they seem OK, not sure why it's there.

[MikeAK]

Ian

On your description of the water pipes - was there a changeover period on how these were routed - mine ('89 engine) are routed back to the heater outside the plenum (over the drivers side rocker cover) but I have the older type injectors - connected to the fuel rail with little lengths of pipe.....

That sounds exactly like mine. Mine is a an 89 and if it was a month younger it would have been a 3.9. I think there must have been a changeover period, mine also has metal heater pipes with the "filling tower" running down LH side of plenum. The only difference I can see is that one of the rubber pipes goes to the front of the manifold behind the dizzy on the 3.5 and to LH front on the 3.9. My 3.9 manifold has a blanking plug fitted where the pipe would go on a 3.5. So hopefully its just a case of swapping over the blank and the stub pipe and the 3.9 manifold will go straight on

Mike

[Bull Bar Cowboy]

Here are the 3.5 maps…………..

The fuel map used these constants………

The VE map………..

Spark map………….

[gn3dr]

Excellent. Thanks for those maps. Much appreciated. Should help me a lot when I get ready to start up.

[MikeAK]

Thanks alot for the maps - should save quite a bit of time

Mike