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

[macaddict]

I found a cruddy looking but otherwise intact Marelli damper/pulley assembly on eBay for $75, I bought it so I can use it to test fit a trigger wheel. If it works out I can get it rebuilt and install it, then figure out how to mount the vr sensor onto the front engine cover. Thanks Steven!

[StevenD57]

I think if you neatly mount the EDIS coil packs like Philip did I don't think your average emissions test facility wouldn't notice a thing.
If you are really worried about it you could get one of those plastic covers off of a 6.0L car that fits over the top of the engine.
That would give you a good excuse to switch to a later fuel rail design (the plastic cover bolts to the later fuel rail directly) that would eliminate the little rubber hoses between the rail and the top of each injector. If you did not want to do that you could probably make some brackets to hold the 6.0L plastic engine cover so it looked normal to the car.

[Philip Lochner]

Ross, I've been meaning to ask, did you have any issues with injector flyback currents causing noisy MAP signals or somesuch?

Some guys had serious issues with LoZ injectors until eventually it was found that running the flyback currents back to the injector 12V supply by lifting the collector legs of Q9 and Q12 and running wires from these legs stright back to the 12V injector supply solved the problem. I did this too - but as a precaution, not because I was having the problems.

Just wondering if I'm going to have to do this on my DD6 and the V12 cobra I'm doing...

[macaddict]

Hmm, good idea with the plastic 6.0L cover. I was actually planning on replacing the injectors with 17 lb. Delphi saturated coil units so I could switch to more modern fuel rail, it looks like those would fit the 6.0L rail just fine. The last time it was smogged the mechanic took one look under the hood, said "oh, wow" and just clicked "PASS" on every visual test. He also didn't bother disconnecting anything when running the timing test and when he noted the discrepancy between actual and specified timing (due to the vacuum advance) I just said that the timing pointer was off. He shrugged, and typed in the timing value on the underhood label. Passed with flying colors, even with a dead smog pump and sticky mechanical advance mechanism.

I have had surprisingly few electrical noise issues with the Megasquirt, especially considering it's on a Jag. =) Before I installed the MS-II I cleaned up all the ground points on the chassis and engine and ran another ground strap directly from the alternator case. That solved a number of issues I was having with the original injection system and gives me a steady 14.1 at the battery with a Delco CS130D alternator. I haven't seen any noise-related issues, the MS-II has never reset unexpectedly and scoping the sensor inputs doesn't reveal anything out of the ordinary. That's not to say that there isn't some effect from the flyback current being dumped into the PCB, I just haven't noticed a problem because of it.

One thing that might be helping to keep flyback-induced noise at bay is the fact I'm running in 4 squirts alternating mode, so only 6 injectors fire at a time. I noticed that fueling became more consistent, presumably because the fuel pressure fluctuates less.

[StevenD57]

Are you running a MS-II that you built yourself or one of the pre-assembled surface mount units?

[macaddict]

Steven,

I'm running a v3.57 unit I bought from Diy Auto Tune. I thought about building it myself but I really didn't want to introduce too many unknowns into the system at once. I figured that buying a pre-assembled unit would at least ensure that the ECU itself was working properly.

After a few weekends of fiddling with the tuning I think I finally have the old girl dialed mostly in. The latest datalogging run shows that EGO correction is within 10% in most places, and WOT fueling is between 12.5:1 and 13:1. Starting is also much improved (I was actually giving it too much fuel during cranking) and acceleration enrichment is much closer to being correct. Still leans out a little just after changing the throttle angle, but that may be due to the fact that the ECU's in the trunk and the MAP sensor pipe has to run the entire length of the car. When I move the ECU to the front I expect I'll have fewer problems, although I've yet to find a really good spot to put the ECU other than the glove compartment.

I've noticed that the air intake still proves to be a restriction, above about 4000 RPM the manifold pressure starts to drop at WOT and levels off at around 90 KPa. Drilling a few holes in a spare set of air filter housings helps a bit, but not as much as just taking them off and zip-tying the air filters on. Time to trim the air intake snorkels and find a way to route some cold air into them!

[Philip Lochner]

Time to trim the air intake snorkels and find a way to route some cold air into them!

Here's how I did it:
http://www.jag-lovers.org/snaps/snap_vi ... 1177702011

You will also have to make sure that you have your MAT correction table well tuned. This can mess you around big time. Have a look at this:
http://www.msextra.com/viewtopic.php?f=89&t=30599

PS: If your TPS signal is clean, you can use that for your AE or balance it with MAP based AE. I never used TPS based AE because my signal had a lot of noise but now its sorted.

[macaddict]

Philip,

Nice work on the air intake hoses, we'll see if I'm brave enough to take a hole saw to the Jag. =) So far I've only drilled 4 holes in the entire car, one to mount the cruise control actuator under the cowling, and the other three to mount the Flex-A-Lite fan control module to the underhood fuse box. I don't plan on ever trying to show the car though, so I guess I shouldn't be squeamish about it.

I hadn't considered that the default MAT correction might be too aggressive, since it's still breathing hot air from in front of the radiator and the weather's been fairly consistent I hadn't noticed much of a deviation when tuning the VE tables. I'll look into that before I try to route cold air into the beast.

Where do you have your ECU mounted, in the original location? I was concerned that using MAP based AE would be defeated by the long vacuum pipe running to the stock ECU which is mostly why I want to move the MS-II to the front. I'll try playing with it and report back with the results.

[Philip Lochner]

Where do you have your ECU mounted, in the original location? I was concerned that using MAP based AE would be defeated by the long vacuum pipe running to the stock ECU which is mostly why I want to move the MS-II to the front. I'll try playing with it and report back with the results.

I've got my MS sitting in the glove box because I wanted easy access to it. The 16CU ECU uses only TPS based AE and it squirts fuel even if the engine is not running!! The long pipe to the back might in fact be a good low pass filter in itself by virtue of having to move so much air in such a narrow pipe over such a distance thus filtering out the higher frequencies. I found that I could not use the centre tap on the balance pipe by having too much resonance there so I'm tapping off the back of one of the manifolds.

[Philip Lochner]

I hadn't considered that the default MAT correction might be too aggressive, since it's still breathing hot air from in front of the radiator and the weather's been fairly consistent I hadn't noticed much of a deviation when tuning the VE tables. I'll look into that before I try to route cold air into the beast.

If this does not convince you to implement cold air feed, nothing will....

http://www.msextra.com/viewtopic.php?f= ... 42#p203642