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T O P I C    R E V I E W
BorstlapPosted - 07 Jun 2013 : 22:16:24
This topic is about a programmable ignition I built in my Sonett, but the story begins with something different: an inlet manifold.

After having bought my Sonett in 1999 and browsing the www for Sonett-fan websites and parts suppliers, I found two pictures (on the site of the no more Motorsport Sweden) of an engine that looked very exciting because of all non-standard parts that were attached to it.

They were pictures of a race engine built by Jack Lawrence, one of the V4 gurus in the US. I had vague plans and wishes for a better running and more powerfull engine (the one in the Sonett didn't run that well in those days) and became quite intrigued by the carbs installed. After some detective work I discovered that they were Weber 40 DCNFs. It turned out that these were also used by Saab before they changed to DCOEs, so these were the ones I should go after. After some time I managed to buy a set (with accompanying VW-Beetle manifolds) on Ebay and then I could get started with hacksaw and sanding machine on a standard single throat V4 manifold; DCNF manifolds are made of either unobtanium or veryexpensium so one needs to be creative. What's more, they are unsuitable for use in a Sonett.

The engine in my Sonett lies horizontally instead of that it tilts backover as in a 96/96, so a manifold like the one in the picture is not really an option. So I started measuring and came to the conclusion that the dizzy was a major obstacle for getting the rear carb positioned properly; this is quite critical because of the bolts that screw down the manifold, as seen here below.

The motorcycle ignition contraption as used on the Jack Lawrence engine was out of my league, so my project ground to a halt. Then about a year or so later someone here on the forum put up the question if it was possible to use the fan pulley for use in conjunction with a Megajolt ignition. This got negative advice of course, but my interest was aroused and after some websearching I found the site of the makers of Megajolt, This looked interesting, but would it be possible to use the balance shaft pulley as a mount for the needed trigger-wheel that is essential for the operation? Not long after I found on the Swedish Saabclub site a topic from a Finnish guy who had built a 96-Turbo and had used a Ford ECU for controling ignition and fuel injection. The ECU used a trigger wheel mounted on the balance shaft pulley for crank position information. The only thing that kept me from getting started was my personal financial crisis. Starting in 2009 I collected the not too expensive parts bit by bit and started after a while I could start tinkering with the trigger-wheel and metal profiles in order to get the VR-sensor in position. I have a spare engine block, which was very convenient for this purpose.

For starters the trigger-wheel and sensor. The bracket is bolted down by using two of the bolt holes used for screwing down the engine's front plate. The threaded rod makes positioning very easy. From above it looks as follows (apologies for the unsharp pictures; autofocus can be a curse ).

After this dry testing it was time to test for fitment on an engine that could run; enter the 96:

For this purpose I removed the cooling fan from the pulley; it is quite in the way and I could do with some space. The long ago bought original electric 99-Turbo fan was tie-wrapped to the front of the radiator and kept things nice and cool. The test run went well, so then it was just to get started with getting the electr(on)ics in place for testing. After a while things looked like this:

Left from the red screw driver is the Edis-module. This receives positioning information from the trigger-wheel, sends out a signal to the ECU, receives a signal back from the ECU and sends a signal to the coilpack, here standing on fresh air duct. From there it is down with to the plugs. I managed to grab the plug cables on Ebay for less than a fiver; brand new and originally meant for use on a Fiesta. The Edis-module has a limp-home mode that comes alive when it doesn't get a signal from an ECU. Trying this I got sparks on the plugs, so I was on track. Last year I managed to get an old no longer in use laptop with an old fashioned COM port from work and finally during autumn the Megajolt itself.

Soldering the Megajolt together went ok, but there was a snag that costed more than a month to sort out. Megajolt sells in two versions, one that works with a MAP-sensor and one with a TPS-sensor. Mine is the MAP version. When testing I got a weird pressure reading, stopping up everything. Finally it turned out that one of the pins of a processor had folded up during pushing it into place , resulting in a wrong signal. After this was sorted out I got issues with the vacuum due to the carb of the 96; it is a worn out and air leaking Fomoco. As this would not change I decided to take the plunge, remove the nose from the Sonett and start installing. There was a nice weather period at the end of March which I used for getting the car out of the container and remove the nose. Things got serious now .

To be continued.
15   L A T E S T    R E P L I E S    (Newest First)
BorstlapPosted - 22 Aug 2015 : 23:24:18
Some progress in the project again. I had the nose off in July and decided to install electric cooling fans. A guy on the Swedish Saabclub website inspired me by having installed two 10' fans on his Sonett. He put both in front of the radiator. I prefer to have them behind but in order to get both there means that the bearing of the mechanical fan has to be removed and that (in my case) the trigger wheel and sensor for the Megajolt had to be repositioned. As this was too much work for now I installed one fan in front and one behind.

Current for the fans is drawn from the B+ connection at the alternator, secured by a 25 Amp fuse. The switching relay is tucked in nicely between the voltage regulator and the coil. The additional wiring goes partly through the extra flexible tube I put in place for the required MJ loom.

I started programming the activation threshold value as used on the 96, but this was too low; the fans kept going while the needle of the coolant temperature gauge had dropped a bit under horizontal. A small adjustmend solved the problem. Works like a charm ..

BorstlapPosted - 11 Jul 2014 : 22:27:29
The Megajolt project is coming to a close. One of the last issues to try was hooking up the electric fan to one of the output channels. The four available output channels start or stop conducting to ground when triggered by a chosen value of rpm, engine load or Aux input value. During a calibration session I picked a value where the needle of the dashboard coolant temperature gauge started to get over the horizontal position. This became the triggering point for the cooling fan. Another nice option of the MJ is that advance can be influenced by Aux input values. As Aux input is in my case regulated by the coolant temp sensor I added a degree or two advance for coolant temps under normal and put in a degree retard for temps over normal; same principle as the mechanical device that was used in the latest model years.

I spliced the Aux Input channel of the MJ into the wire that runs between the coolant temp gauge in the dashboard and the sensor. For security I put a diode in the connection to the MJ; I didn't want to take the risk of blowing up something with the 12 volts from the dashboard gauge into the 5 volts earth side of the MJ.

All this testing resulted into the first drive on own power in more than 20 years

though for the wrong reasons . All the testing was done with the front wheels off the ground so that I was able to have the wheels spinning and get some load on the engine. Unfortunately the right hand side inner CV dust boot got a tear and flying grease began to muck up the engine compartment and even the bonnet of the Sonett. As the car was parked with the right hand side to the wall of the container I had to get it out and turn it. Only these few metres made me eager to get the car roadworthy again so instead of only swapping the dust boot I decided to start the battle of the rust removal again. First out is the front wheel suspension. So maybe I'll start another project thread here about an opal green 96 and its long way to roadworthiness

BorstlapPosted - 12 Jun 2014 : 17:52:21
So here they are, first the map I started with:

And here the most recent one:

I found out after the first test drive that I needed to extend the range both towards lower and higher KPa values. The engine pulls quite a vacuum going downhill without moving the throttle and at WOT pressure sometimes may creep up to 102KPa; ram-air in a confined engine compartment ? So at WOT advance went down. I haven't been at the dyno, but I have the feeling that the changes improved performance. The improvement compared to the old setup with the dizzy is dramatically: no more hesitation at low speed when the throttle is opened up, markedly better responce between 2800 and 4000rpm and even stronger pulling at high revs.

BorstlapPosted - 12 Jun 2014 : 16:57:54
The 20-100 list is pressure in the manifold measured in absolute KPa. 100 KPa is ambient air pressure (= 1 bar), 0 KPa is total vacuum. I started the map by trying to stay as close as possible to the mechanical advance curve of the dizzy. Then it is just to use mechanical advance only at WOT and adding vacuum advance at various levels of vacuum.

By extending the range between minimum and maximum advance you can improve performance. It has been a year since I started with making and adjusting maps for the Sonett and if I remember correctly I made som downward adjusments at higher load. In addition I added a degree or two at higher revs and I can't help feeling that the engine's response to that is positive. I will take a look at the old maps I saved and post them, just to see the difference. The map that is up here is for the 1700 engine in the 96 and should have (according to an official Ford manual)less advance than a 1500 engine.

DerekPosted - 12 Jun 2014 : 15:04:05
What does the 20 - 100 list on the left represent? with most standard engines advance usually max's out around 3500 and some people find that near max revs the engine can make more power by reducing the advance by a degree or two. Any comments on that?
DirtbikerPosted - 12 Jun 2014 : 09:11:43
Hi Alex,

This is really interesting - keep the updates coming!

James RanaldiPosted - 10 Jun 2014 : 22:09:34
Thanks Alex,

I think I understood the logic there

Very interesting.


1968 V4, LHD
1984 99 GL
1992 900i Convertible
BorstlapPosted - 10 Jun 2014 : 21:04:05
Hi James,

As a picture says more than 1000 word I took some screenshots to make the explanation a bit more lively .

First a picture of the standard map I programmed in on the 96:

As is shown here, ignition timing depends on load (in this case vacuum in the inlet manifold) and rpm.

The MJ has an Auxiliary Input that can be used to influence timing. Voltage is between 0 and 5 volts, going up in steps of 0.02 volts. The extra window shows the connection between each step (ADC voltage) and the measured voltage (Voltage). The column Scaled Value can be filled out with anything you like. Often a coolant temp sensor is used, just as in my case. When you know the connection between temperature in degrees Celsius or Fahrenheit you could fill these values out, but as I don't know I didn't bother to do so. To the left is the row with 10 bins where corrections can be programmed. Both bin values and corrections can be filled out after own preference. I found out that normal operation temperature equals a value of about 112 units. When the value goes up to 116 units the needle of the dashboard gauge begins to creep up. MJ has four ouputs that can be programmed to either conduct or not conduct at a set value of rpm, load or Aux Input (I will make a screenshot and post that later). What I saw is that when the fan is activated is that the Aux value goes up for a short while (it takes some time before the cooled coolant fluid reaches the sensor) and then starts to go down again. The fan stops at a value well under 116, somewhere around 110.

When an engine is under operational temperature it can do with some extra advance in order to burn a colder mixture. When the engine gets too warm it can do with less advance, especially at idle. The same was done on the last model years of the 96 where there was a gizmo installed on the thermostat housing that operated a valve that regulated vacuum advance. When coolant temperature went up the valve opened, switching from a vacuum point under the throttle plate to a point above. This killed any vacuum advance, making the engine run slower and maybe burning less mixture. Biggest influence will be at idle; I saw that idle went down when advance got down. To decrease advance does influence performance of the engine, but preventing an engine from overheating is worth the small sacrifice (I've once been stuck in traffic with an engine beginning to overheat and a cabin heater at full power ).

James RanaldiPosted - 09 Jun 2014 : 10:32:20
Hi Alex,

Great stuff.

I understand that ignition timing can influence the engine running temperature but I am not clear about using the temperature to change the ignition timing How does this work ?

Does the resulting change to the timing not influence the engine running ?



1968 V4, LHD
1984 99 GL
1992 900i Convertible
BorstlapPosted - 08 Jun 2014 : 22:50:52
I thought Youtube videos were streamed and that there was no inbetween storage, but I am not too familiar with the technicalities. What it shows is that the Aux gauge is rising up to a normal operating temperature and that the cooling fan is switched on and off by the MJ. In addition ignition timing below normal operating temperature is advanced (at start +2 degrees, then +1 en finally 0) and retarded when temperature rises above normal. The fan kicks in when the needle of the dashboard gauge only goes slightly over N, so overheating is dealt with at an early stage.

Today I connected the MJ in the Sonett to the temp sensor. First hookup was a no-no. I had connected to the wire of the oil pressure sensor ; after the meltdown I had in 2006 I replaced a good deal of the wiring and as I was short for brown wire I used a lenght of yellow. I assumed that the 3 on the insulation was an 8 that had lost some of its ink, so I hooked into it. Of course the correct wire was well hidden, so it took an hour or so to correct matters. But the test drive showed good results, so I am a happy man .

James RanaldiPosted - 08 Jun 2014 : 21:44:04
Great stuff Alex. Unfortunately I can't make much of the video.

Huge file so my I pad may not be happy.

I can't run the video



1968 V4, LHD
1984 99 GL
1992 900i Convertible
BorstlapPosted - 07 Jun 2014 : 09:27:49
Slow but steady progress since the last posting. The coolant temp sensor is hooked up and calibrated. After that it was also possible to dial in extra advance and retard based on the temperature of the coolant fluid. A short video clip to show the final result (warning: put the sound down, the audio recording was horrible ):

As I wasn't sure how the MJ would influence the reading of the temperature gauge in the dashboard I started by separating them with diodes. This had an effect on the dashboard gauge so I removed it in that line. As the MJ ouput is 5 volts I kept it there for security; would be a bit dumb to blow it up with the 12 volts coming from the dashboard gauge.

BorstlapPosted - 23 May 2014 : 20:27:31
So last weekend I took the final step and created a vacuum point. As drilling in the manifold is quite a hassle when it is in place I decided to use the intermediate plate with the connections for the brake booster and crank case ventilation. To get things in place the first thing to do is to remove the centre:

Four mm aluminium tube does the trick; a good deal softer than brass tube, but as it doesn't bear any weight that is no problem. It is also much easier to bend. Because I don't have a drill standard I had to drill handheld, resulting in ending up a bit too high:

Next was fixating the tube and sealing on the outside by using low-temperature melting Techno Weld. On the inside where I drilled through the vacuum channel I dripped in a few drops of thread sealant:

Finally it was closing up the underside of the tube by pincing it down and making two airslits:

Then it was time to get everthing in place again and have a test run using the dizzy for checking if the vacuum was working and getting the engine warmed up. All was well so then came the big moment of changing the spark plug leads. No fun doing that on cylinder 1 when the engine is warm ; the Edis leads meant for use on a Ford Escort or Fiesta don't have a 90 degrees cap and have a long rubber sleeve for keeping moist out, making it hard to push it into place on cylinder 1. Last check, all leads connected correctly? No, cylinders 3 and 4 might be wrong. Changing these two and then the first try: no starting and after a few seconds a loud bang . Double check spark plug wiring on the Sonett for reference: the swap on cylinders 3 and 4 was the wrong thing to do . Swapping back again, giving it a go and: bingo . Strong running and idle suddenly 300rpm higher than with the dizzy, so the sparks must be working better.

That was the rambling for now . Next stage is connecting and tuning the cooling fluid temp sensor for extra advance during cold startup.

BorstlapPosted - 04 May 2014 : 11:08:58
Time for an update. I have done some changes to the timing settings and run the car now with this setup:

The 600rpm range was of no use, so I dumped it and added a 5500rpm range.This gives a better response at higher revs when flooring the throttle during acceleration.

Last year I started to revive the 96 that has been standing idle for far too many years. First job was to change the worn FoMoCo carb to the Weber DGV I bought years ago. Now it starts without hesitation again. However, it still left room for improvement on the ignition side so I decided to go Megajolt here as well. As I wanted to convert to an electric cooling fan I had to reposition the trigger wheel sensor; the changed pattern of the fanbelt makes this necessary. Finally, in order to get rid of the problem of finding a long enough bolt for the balance shaft pulley I chose for a trigger wheel with a larger centre hole, so that the big washer can get trough. The pulley-triggerwheel combo now looks like this:

Biggest problem is getting a good centration of the trigger wheel. This was done at the workshop at work where they have the proper equipment. Drilling holes connected to my feeble attempts to do this myself at home are stille visible . The arrow points at the TDC marking, the blackened tooth is where the sensor must be.

After I managed to get the cooling fan bearing out unharmed I filled up the hole with metal repair putty and screwed on a bracket for the trigger wheel sensor:

The bracket itself was a piece of predrilled profile I picked up at the local hardware store, nothing special:

In order to get it secured as tight as possible I screwed in bolts from the backside of the front plate with a smear of thread lock to secure that they won't screw loose and end up in the oil sump:

The screws are M6, mut M5 will do. It will make screwing down the various parts easier when the four bolts are a bit further out, but I worked with what I had lying in order to keep work and cost down.

With everything in place it looks like this:

Detail of how the sensor is bolted in place:

Yesterday I had a first start with the Megajolt connected to the test rig with spark plugs; then you can see whether you get a spark or not. An earlier attempt failed due to a faulty ground in the Edis-connector. Yesterday, after rectifying the problem the plugs sparked up . A test with a timing light showed that the trigger wheel sensor is exactly where it should be; no need for correction.

Last thing to do before a real live test is to make a proper vacuum point in the inlet manifold. I just ordered aluminium tube of 3 and 4mm diameter, so this will hopefully be on next weekends to-do list.

x96Posted - 17 Jun 2013 : 19:24:13
Yes, the fuel pump of that injections goes in the tank. Surely is high pressure.
The idea came thinking about modern cars similar to 96 in engine capacity, a bit more heavy but with 5 speed transmision (both weight and transmission could compensate) can increase the fuel consumption from 8liters/100km (35MPG) to 6liters/100km (47MPG) thanks to the fuel injection.
That improvment is not too much and the transformation a bit complex. but the engine could run smoother.

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