1984 Jaguar XJS V12 5.3L HE (11.5:1 CR)

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StevenD57
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Re: 1984 Jaguar XJS V12 5.3L HE (11.5:1 CR)

Post by StevenD57 » Wed Apr 08, 2009 5:36 am

macaddict wrote:Overall the car is running better than it ever has. Even the fuel economy has significantly improved, she's been averaging around 16 MPG per tank in mixed city/highway driving which is much better than the 12 - 14 MPG she used to get on the best of days. If I stick to the freeway (about 65 miles round trip to work) she'll get close to 20 MPG per tank. Definitely the best $400 ever spent on this car, I don't think a commercial aftermarket injection system could do any better.

I think you should make another post to the XJS and V12-engine lists on Jag-lovers with the above information. The idea that a $400 EFI change with only a little bit of re-wiring could make this much difference in fuel economy is a significant piece of news that others should be interested in.
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Re: 1984 Jaguar XJS V12 5.3L HE (11.5:1 CR)

Post by StevenD57 » Wed Apr 08, 2009 9:25 am

macaddict wrote:Steven,

There are photos of the install at the link below:

http://crosstalk.atomz.com/~ross/jagstuff/

I don't have a wiring diagram other than the diagram for the original ECU:

http://crosstalk.atomz.com/~ross/jagstu ... Pinout.gif


- Ross.

Ross:
I just tried to look at the msq files in the megasquirt directory and I got the following message:

Forbidden
You don't have permission to access /~ross/jagstuff/megasquirt/megasquirt200902111942.msq on this server.


Is there a permissions problem on the megasquirt directory or the files located there?

It seems none of the files in that directory can be d'loaded. They all produce the above message.
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Re: 1984 Jaguar XJS V12 5.3L HE (11.5:1 CR)

Post by StevenD57 » Wed Apr 08, 2009 9:55 am

Ross:
What is this purpose of the stuff in the photo in the following URL?

http://crosstalk.atomz.com/~ross/jagstu ... 046037.jpg

I see there is an HEI module in that photo but it is not clear what all that is doing.

Also you stated in your first post here that:
macaddict wrote:The stock injector resistors are bypassed and the Megasquirt is running in peak and hold mode.
How did you bypass the stock injector resistors? Any more details and/or photos of that would be a big help too.

Also you said:
macaddict wrote:Right now the system is handling fuel injection only with the timing signal coming from the output of the stock Delco HEI ignition.
Where exactly did you pickup that timing signal from the OEM ignition?

Another question... is the wiring block you have bolted onto the bottom of the OEM EFI ECU case in the following photo a standard off the shelf wiring block or is that something you got from diyautotune too?

http://crosstalk.atomz.com/~ross/jagstu ... 999857.jpg
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Re: 1984 Jaguar XJS V12 5.3L HE (11.5:1 CR)

Post by StevenD57 » Wed Apr 08, 2009 10:18 am

macaddict wrote:Ok, so the formatting didn't quite survive the posting process, here it is again:

Function | Megasquirt-II | Lucas 6CU/16CU
Inj A | 32,33 | 13,14,31,32
Inj B | 34,35 | 8,9,27,28
Does this mean that instead of firing the injectors in banks of 3 each as per the OEM strategy, you are firing all six injectors in each bank at once?
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Re: 1984 Jaguar XJS V12 5.3L HE (11.5:1 CR)

Post by macaddict » Sun Apr 12, 2009 2:59 am

Steven,

Sorry about that. I fixed the permissions on the files, you should be able to download them now.

The injectors are wired up in two banks of six, with bank 1 matching cylinder bank A and bank 2 matching cylinder bank B. The Lucas 6CU and 16CU are wired in the same manner but appear to fire both banks at the same time. Much like the Megasquirt there is only effectively one injector driver per bank in the Lucas setup, the two groups of three injectors on each bank are run to the same pair of transistors (one peak, one hold) inside the original ECU. I believe the only stock EFI setup on the XJ-S to do alternating batch fire was the Bosch D-Jetronic on the non-HE engine and it still fired 6 at a time, three on cylinder bank A and three on cylinder bank B.

The stock injector resistor block has four resistors, one for each group of three injectors. If you look at the rather confusing wiring diagram Lucas saw fit to inflict upon us, you can see that the A bank injector hold resistors are wired to pins 12 and 30 on the Lucas ECU and the B bank injector hold resistors are wired to pins 11 and 29. The pins for each bank are tied together internally and are routed to the collector on the hold transistor. I simply neglected to hook these up to anything as the Megasquirt only has one transistor per bank, the only thing I connected were the "on" injector pins, namely 13, 14, 31, 31 for bank A and 8, 9, 27, 28 for bank B. I left the original wiring to the injector resistor pack in place in case I need to plug the original ECU back in.

The timing signal is currently coming from the stock ignition module heading back to the original ECU (pin 18.) The 7-pin HEI module in the photo you referenced:

http://crosstalk.atomz.com/~ross/jagstu ... 046037.jpg

is to allow the Megasquirt to control ignition timing using the stock distributor VR pickup. I modified a junk CEI distributor to lock out the mechanical advance and removed the vacuum advance can. I then modified the VR sensor mounting plate to allow me to lock it in an arbitrary position (basically added a setscrew that holds it in place.) This makes the distributor rotor position adjustable so that in the base timing position (about 8 degrees advance) the trailing edge of the rotor tip can be just passing the contact on the distributor cap to give the maximum range possible for ignition advance. I haven't tried installing it yet, but if Easter weekend turns out to be quiet I may have a chance to give it a go. Ideally I'd like to install a crank trigger and do away with the distributor entirely, but this does allow for a limp-home mode if I had to use the original ECU. I'll take some photos before I install it, and let everyone know if it actually works.

The wiring block bolted to the bottom of the gutted 6CU case was just something I had lying around, I don't think DIY AutoTune sells them. Here's something very similar from Digikey:

http://search.digikey.com/scripts/DkSea ... =CBB112-ND

Hope this helps!

- Ross.
1984 Jaguar XJ-S HE (Rosie III) - Megasquirt-II v3.57 fuel+spark
http://crosstalk.splunk.com/~rdykes/jagstuff

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Re: 1984 Jaguar XJS V12 5.3L HE (11.5:1 CR)

Post by macaddict » Sun Apr 12, 2009 3:41 am

Woops, didn't notice the comment on fuel economy earlier. The Megasquirt really isn't the only change I made, there are others that are probably contributing slightly to the improvement that I should have mentioned:

- Electric fan from a 2000 Jeep Grand Cherokee with a Flex-a-Lite PWM fan controller.

- Custom lightweight aluminum fan shroud, no provision for the original auxiliary electric fan to save weight. A/C on causes the Jeep fan to run at 60%.

- Delco CS-130D alternator in place of the original smog pump, removed the Lucas alternator. Voltage at the battery now 14.1V instead of 12.8V which probably helps out the ignition system.

- Synthetic lubricants (engine oil, transmission fluid, differential gear oil and wheel bearing grease.)

- Removed the mostly broken ignition vacuum advance control system and connected the advance can directly to ported vacuum. The retarded timing at idle allows the O2 sensor to stay warm enough to go closed loop at idle now. The timing is now steady at cruise, before it used to bounce all over the place.

- "Rebuilt" the distributor (ie, whacked the rotor carrier a bunch of times with a screwdriver until unstuck, then flushed the thing with solvent and a quart of synthetic engine oil. Been working fine ever since.)

- Replaced the failing Lucas ignition coil with a slightly hotter MSD Blaster coil. Kept the secondary coil in front of the radiator. Throttle response and fuel economy improved, but that could have been because the original coil was starting to die.

- New spark plugs (the cheapest Delco's I could get my hands on, hey it takes 12 of them!) with a .030 inch gap.

- New spark plug wires (custom made from Taylor cables and boots/terminals from Napa.)

- Ignition timing advanced as far as I could go before it started pinging.

- Removed the inlet fuel pressure regulator. You can hear some whining from the fuel rail at times due to the increased flow, but the problem I was having with hot starts seems to have gone away.

When she's fully warm on a warm day with the A/C off, she can get 21 MPG at 65 MPH on level ground with the original ECU. With the A/C on it's usually 20 MPG. Puttering around at 45 MPH she can hit 24 MPG, more if I disable O2 sensor feedback and run it lean. She has a tendency to ping when I do that though, so I haven't really played around with lean cruise much on the Megasquirt. The most I've averaged on a tank that I can verify (going by the odometer and how much gas I put in) was 18.5 MPG round-trip from Palo Alto to Morgan Hill, CA. Removing the mechanical fan, two extra belts and the mechanical smog pump made the single largest difference, fuel economy jumped by about 2 MPG overall.

I think one of the bigger improvements in fuel economy the Megasquirt has made is due to improved transient fueling. Both the 6CU and 16CU I have seem to go far richer at times than is called for, especially during accel enrichment. With the X-tau tuning on the Megasquirt the AFR stays pretty consistent unless I really stomp on it, then it doesn't go richer than about 12.5:1. The O2 sensor cross counts are much higher with the Megasquirt as well, the 6CU/16CU seemed to be really lazy about O2 sensor correction which was probably wasting fuel.
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http://crosstalk.splunk.com/~rdykes/jagstuff

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Re: 1984 Jaguar XJS V12 5.3L HE (11.5:1 CR)

Post by StevenD57 » Sun Apr 12, 2009 5:45 pm

macaddict wrote:Steven,


The timing signal is currently coming from the stock ignition module heading back to the original ECU (pin 18.) The 7-pin HEI module in the photo you referenced:

http://crosstalk.atomz.com/~ross/jagstu ... 046037.jpg

is to allow the Megasquirt to control ignition timing using the stock distributor VR pickup. I modified a junk CEI distributor to lock out the mechanical advance and removed the vacuum advance can.
Hope this helps!

- Ross.
I am confused. At the start of this thread you wrote:
macaddict wrote:Right now the system is handling fuel injection only with the timing signal coming from the output of the stock Delco HEI ignition. I have the ignition output of the Megasquirt connected to the full load signal line coming from the vacuum switch mounted in the engine compartment, that way I can drive a MSD ignition box or possibly another HEI module to control ignition timing at some point.
So you do have the MS2 unit controlling the ignition timing as well or not?
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Re: 1984 Jaguar XJS V12 5.3L HE (11.5:1 CR)

Post by macaddict » Tue Apr 14, 2009 2:51 pm

The MS-II is not currently controlling ignition timing, the ignition system is mostly stock at the moment. The original full load switch wiring is connected to pin 36 on the MS-II so that I can hook up the 7-pin HEI module and modified distributor when I get around to it.

I advise getting the fueling dialed in before playing with the ignition system. The Lucas CEI system is really a Delco HEI system in disguise, and works fairly well compared to the rest of the electronics on the car. Use the opto-isolator ignition input on the Megasquirt, it should work fine with the original ignition system.


Cheers!

- Ross.
1984 Jaguar XJ-S HE (Rosie III) - Megasquirt-II v3.57 fuel+spark
http://crosstalk.splunk.com/~rdykes/jagstuff

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Re: 1984 Jaguar XJS V12 5.3L HE (11.5:1 CR)

Post by macaddict » Sat Apr 18, 2009 11:40 pm

Ok, I spent some time this evening cleaning up the VE tables, the updated msl files have been uploaded. I effectively added a DFCO feature by setting the bottom row of the VE table to 0 where you never spend any time unless you're decelerating. It's not really noticeable when driving, but the WB O2 sensor indicates it's kicking in when letting off the gas on the freeway or downshifting on downhill run. I also adjusted the injector cranking PW and ASE values, it was still a little hard to start when cold.

I think I'm done tuning it for a while, there are a lot of maintenance items on the to-do list that I need to get around to finishing. I'm going to try and rig up an interface circuit to get the trip computer working again, if I can cobble something together that works I'll post the schematics.


Cheers!

- Ross.
1984 Jaguar XJ-S HE (Rosie III) - Megasquirt-II v3.57 fuel+spark
http://crosstalk.splunk.com/~rdykes/jagstuff

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Re: 1984 Jaguar XJS V12 5.3L HE (11.5:1 CR)

Post by StevenD57 » Sun Apr 19, 2009 5:57 am

When are you going to start looking at replacing the AAV with some sort
of other type of idle control mechanism controlled thru the megasquirt?
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