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

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

Post by macaddict » Thu Mar 12, 2009 9:36 am

Yes, the 6CU and 16CU are definitely a little primitive, I noticed the accel squirts happening even when the engine was off (it was actually how I found out my TPS was wearing out!) I keep the 16CU in the trunk as a spare just in case I fry something in the Megasquirt, fortunately I haven't had a reason to plug it back in.

Adding MAP-based accel enrichment has definitely helped, right now it's set for a 50/50 split. I had basically over-fueled it to prevent backfiring with the TPS-only setup, the MAP-based enrichment has improved the response considerably once the car is moving. I still need to do some tuning for off-idle enrichment, but it's pretty close.

As far as the cold air setup goes, I think I'll have to have a couple beers to steady my nerves and then start cutting holes in the old girl. With as heavy a beast as she is, any increase in power is always helpful. =)
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 » Fri Mar 13, 2009 12:24 am

I finally got around to doing some empirical testing of the default IAT-based fuel correction this evening by letting the car idle for extended periods of time to heat things up under the hood. The results were interesting, the default IAT correction was off by quite a bit at intake temperatures over 130 deg. F/55 deg. C. Adjusting this with the IAT correction table solved most of the problems I was having with accel enrichment and hot starts, yet another compelling argument for a cold air intake. Cruising at 65 MPH the IAT is around 100 deg. F with the outside temperature around 60 deg. F, at 35 MPH the temperature jumps to about 130 deg. F. At idle it peaks around 160 deg. F, which is where I was having most of the accel enrichment issues. With the A/C on the radiator fan runs at about 60%, which keeps the intake temperature from going above 140 deg. F. I'd done most of my tuning sitting in the car with the A/C on, which is probably why I hadn't noticed how lean things were getting when the air intake temperatures got high.

Thanks again everyone for your help, I've posted the latest msq files if anyone's interested:

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

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

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

Post by StevenD57 » Tue Mar 17, 2009 10:28 am

OK, a friend here in Phoenix with a 1987 XJS-C is going to order the MS-II surface mount pre-assembled unit so we can at least do the EFI change over part of the job. Do you have any sort of wiring diagram or other information so we can see how you hooked the factory EFI bits in through the MS input? As I understand it you actually placed the MS unit inside the OEM Lucas EFI ECU case. Is that correct? Do you have any photos of that?
Jaguar E-Types, modified Merkur XR4Ti, Jensen-Healey
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Re: 1984 Jaguar XJS V12 5.3L HE (11.5:1 CR)

Post by macaddict » Thu Mar 19, 2009 9:56 am

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

The case and connector are from a junk 6CU, I unsoldered the connector from the board and used barrel wire splice connectors to crimp aircraft grade wire to the pins. I then soldered the crimp connector and wire to the pin and put heatshrink tubing over each splice. Here's where I got the wire:

http://www.aircraftspruce.com/menus/el/wire.html

I just connected things up logically, I'm using the full load switch wiring for the ignition control (which I haven't hooked up yet) and I had to change the reference for the IAT sensor from +5v to GND by disconnecting it from the fuel rail temp switch and running a jumper wire to ground. I'm only using the injector "on" wiring, the hold wiring isn't connected.

One thing to be aware of is that the trip computer will stop working properly if you're driving the injectors in peak and hold mode. The trip computer fuel interface unit expects the B bank injector "hold" line to be low the entire injection event which isn't the case now. There are several options I've been exploring, but haven't had time to work on it recently:

- Use a spare I/O port to generate the required signal
- Build a filter circuit
- Use a PIC or some other microcontroller to provide the correct signal to either the FIU or the trip computer itself

I really want to switch to Delphi injectors and the 6.0L fuel rail, which would solve that problem as I could drive them in saturated coil mode. Still no luck finding the new fuel rail though.

I'm still fiddling with the parameters for cranking and afterstart enrichment, and have noticed that every once in a while things suddenly go rich causing a bog. It's only apparent during steady cruise so I suspect I am having noise problems somewhere, I'm going to scope the sensor inputs and try switching to MAP based enrichment in case it's noise on the TPS line causing an accel shot. I did find some other cruddy ground points in the system, so this weekend I'm going to try and pull all the connectors and ground lugs apart and clean them. An 87 XJ-S in Arizona is probably likely to have fewer corrosion problems than an 84 XJ-S in San Francisco, so you'll probably be OK! =)

- 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 » Thu Mar 26, 2009 9:54 am

So, it appears I'm somewhat of an "misinformed person" and had the injector PWM duty cycle set too low. After trying to dial in the IAT correction and accel enrichment this evening, I noticed that I kept having to add fuel the longer I let the car sit idling. I thought it was just the IAT adjustment being out of whack, but after hitting adjustment figures over 90% at 180 degrees I figured something else had to be wrong. It occurred to me that it might be the injector PWM control as I was also having problems with the AFR varying quite a bit at full load when hot. I bumped it up from 21% to 25% and voila, problem solved! I hadn't noticed this before today as I normally don't let the car sit idling for extended periods of time, and I'd set the PWM value using the method listed in the manual. Of course, I forgot how warm things get under the hood of a V12 Jag!

The latest bins are up at http://crosstalk.atomz.com/~ross/jagstuff/megasquirt/ if anyone is interested. It's working pretty well now, I think I'm ready to try controlling the ignition this weekend if I have the time. I bought a 7-pin HEI module to swap in place of the existing 4-pin module so I can try playing with things using the VR sensor in the distributor, if I can get that working then going to a crank mounted trigger shouldn't be that hard. I bought the Marelli VR sensor and had tried to get a Marelli damper, but the seller on eBay I'd purchased it from turned out to be less than reliable. I managed to get a refund through PayPal, but sadly no damper. I'll keep an eye out for another one, but for now just trying to get it to work with a 7-pin HEI module is likely to keep me busy for a bit!
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 » Sat Mar 28, 2009 12:03 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

The case and connector are from a junk 6CU, I unsoldered the connector from the board and used barrel wire splice connectors to crimp aircraft grade wire to the pins. I then soldered the crimp connector and wire to the pin and put heatshrink tubing over each splice. Here's where I got the wire:

http://www.aircraftspruce.com/menus/el/wire.html

I just connected things up logically, I'm using the full load switch wiring for the ignition control (which I haven't hooked up yet) and I had to change the reference for the IAT sensor from +5v to GND by disconnecting it from the fuel rail temp switch and running a jumper wire to ground. I'm only using the injector "on" wiring, the hold wiring isn't connected.
Yes, I am very familiar with the stock EFI wiring diagram. But I am more interested in knowing what stock OEM wires connected up to which pins on the MS inputs. I guess I need to look more closely at the MS wiring pigtail to see if I can figure out what bits go where.
--
Steve
Jaguar E-Types, modified Merkur XR4Ti, Jensen-Healey
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Re: 1984 Jaguar XJS V12 5.3L HE (11.5:1 CR)

Post by macaddict » Sat Mar 28, 2009 9:40 pm

Ah, I believe this is what you were looking for, I pulled the ECU out of the car to verify the pinout:

Function Megasquirt-II Lucas 6CU/16CU
---------- ---------------- ----------------------
Ground 7,8,9,10,11,19 1,16,17,19,23,34,35
+12V 28 22
Tach 24 18
Spark Out 36 3 (Full load switch)
CTS 21 5
ATS 20 21 (make sure to change the reference for the Jag's ATS to ground, by default it's TPS Vref)
TPS 22 7
TPS Vref 26 20
Inj A 32,33 13,14,31,32
Inj B 34,35 8,9,27,28
Fuel Pump 37 15
O2 23 6

I wired the sensor ground (19 on DB37) to it's own wire to ground (pin 1 on the 16CU harness) and the TPS ground reference. Only the A side O2 sensor is being used, the B side has a WB 02 installed for monitoring but isn't connected to the MS-II. I am planning to use the B side O2 wire to drive a PWM idle valve but haven't gotten around to it since the original idle valve is more or less working.

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 » Sat Mar 28, 2009 9:46 pm

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

Function | Megasquirt-II | Lucas 6CU/16CU
Ground | 7,8,9,10,11,19 | 1,16,17,19,23,34,35
+12V | 28 | 22
Tach | 24 | 18
Spark Out | 36 | 3 (Full load switch)
CTS | 21 | 5
ATS | 20 | 21 (make sure to change the reference for the Jag's ATS to ground, by default it's TPS Vref)
TPS | 22 | 7
TPS Vref | 26 | 20
Inj A | 32,33 | 13,14,31,32
Inj B | 34,35 | 8,9,27,28
Fuel Pump | 37 | 15
O2 | 23 | 6
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 » Tue Mar 31, 2009 11:42 am

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

Function | Megasquirt-II | Lucas 6CU/16CU
Ground | 7,8,9,10,11,19 | 1,16,17,19,23,34,35
+12V | 28 | 22
Tach | 24 | 18
Spark Out | 36 | 3 (Full load switch)
CTS | 21 | 5
ATS | 20 | 21 (make sure to change the reference for the Jag's ATS to ground, by default it's TPS Vref)
TPS | 22 | 7
TPS Vref | 26 | 20
Inj A | 32,33 | 13,14,31,32
Inj B | 34,35 | 8,9,27,28
Fuel Pump | 37 | 15
O2 | 23 | 6
Thanks, that should help a lot. I am sure we will have a lot more questions as we get going.
--
Steve
Jaguar E-Types, modified Merkur XR4Ti, Jensen-Healey
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Re: 1984 Jaguar XJS V12 5.3L HE (11.5:1 CR)

Post by macaddict » Wed Apr 08, 2009 1:02 am

I finally had some free time tonight, so I decided to play with the X-tau enrichment settings and see what kind of difference it made. Long story short, it seems that even conservative X-tau table values largely eliminated the need for TPS and MAP based enrichment. It still needs a little tweaking but it's close enough that it already works better than the standard enrichment table values I'd spent a significant amount of time dialing in. There's still a bit of lag when you mash the throttle, but it doesn't go too lean or rich enough to cause problems. It also keeps things from swinging way rich when closing the throttle abruptly.

The other problem I'd been having was an occasional bog due to the MS-II adding too much fuel. I'd thought that the problem was related to TPS and MAP noise, but despite the considerable amount of jitter present there it really didn't make much of a difference when I compensated for the noise. I then started poking around at the log files and discovered that I hadn't been paying attention to the system voltage. There's enough noise in the electrical system on this beast that the voltage the MS-II was reporting occasionally spiked high or low, just quickly enough for the injector PW voltage compensation to kick in.

The oscilloscope didn't show much noise at all on the 12V line feeding the MS-II so the spikes are either being induced internally or being picked up through one of the sensor inputs. I do notice some unusual voltage spikes on the negative side of the coil when the ignition system fires, there's a zener diode in the ignition module that's supposed to filter those out before they get to the tach or ECU (there's also a resistor in series with the tach and ECU ignition signal lines) but it doesn't appear to be doing anything. I'm going to try adding a shunt zener at the terminal block near the MS-II to filter out any spikes that make it all the way back, but the current fix of adjusting the voltage compensation and sensitivity values is working great. This will all be a waste when I finally get a crank trigger mounted I suppose, but with my current work schedule I have no idea when I'll get around to it.

I'd left the voltage compensation in because the Delco CS130D and 4" v-belt racing pulley I'd been using could only manage about 12.8V at idle with the A/C on. I managed to locate a smaller 1/2" wide v-belt pulley (from a Ford tractor of all places) that fit perfectly, and now the system voltage is 14.1V more or less all the time. I could probably disable the injector PW voltage compensation completely at this point and not worry about it, but I do want to know what is causing the MS-II to pick up the occasional spike. No resets though, which is a good sign.

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

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