I have found a new kickdown switch on the net but I can not find the fuel injection enrichment switch. Is it called something else? I don't believe it to be bad though. Just wondering in case I need one at some point. Just have no idea what could cause the rough idle and hard start, then out of nowhere it just runs fine for almost an hour until I shut it off and leave it for a few hours. Then back to rough idles and hard starts.

 

I have done some reading on the site about idle issues and so forth... Some have replaced their coil and fixed their issue. Could my coil be the issue?

 

It's the same as the kickdown switch. To be clear I wasn't suggesting that you needed an enrichment switch but was simply pointing what it was.



The 'could be' list is long and there's a good possibility you have a stack-up of various faults, not a single fault. But with these cars it's a good idea to *very carefully* check for loose/dirty/weak connections, frayed/burnt wires, poor grounds before buying new parts. That's a good place to start.

From there it's mostly inspect and/or test, then repair whatever needs repairing as you go, until you find the find the problem. One often overlooked area is the vacuum hose connection at the back of the engine (on the aluminum balance tube between the intake manifolds) which supplies the MAP sensor...which is in the ECU wayyyyy at the back of the car, in the trunk

There are many quirks and areas that always seem to need attention on these cars: crispy-fried injector wires, worn out throttle bushings, dirty throttle bodies, leaky vacuum hoses, mis-adjusted throttle linkages, general lack of maintenance (plugs, wires, cap, rotor), stuck AAV, dangerously old fuel hoses (like yours) and others things that escape my memory at the moment. If you're a pretty decent DIY mechanic and can take good notes and pics, the best way to approach this is "Do it all, do it right, do it once"...and then you can forget about for a few years. A couple weekend's worth of work, at least, for a V12 first timer, but it actually ends up easier in terms of overall labor than doing each item individually

Cheers
DD

 

No worries Doug. I wasn't thinking you were saying I needed a new one. I just figured I would order both and now that I know it's the same thing I can just order 2.


I work at Lowe's so I'll just get myself some tough vacuum tubing and some clamps when I get payed. I do plan on changing the plugs/wires/cap/ and rotor as well. Might as well hit the coil while I am at it. Does the spark amplifier ever have issues? Might test that some how.

 

Also where can I find the brackets to replace the factory air-boxes? I can do the tubes and filters myself.

I'm talking about the 4 bolt flange that goes on the intake so you can attache a pipe. Or are there decent priced intake replacement kits?

 

Pull the distributor cap and inspect for moisture, this reeked havoc with my idle and running under throttle in drive a month ago, drove me bonkers, wouldn't idle for squat, would rev fine in park but would stumble badly in Drive, worth checking since the car sat for some time. Also mine would every now and then work fine, then go right back to crap.

 

Right on. Thanks for the input. I'll look into that. I also watched a video on youtube about an xjs owner havin idle issues. His ended up being the coolant temp sensor connector. I'll be checking that as well. I know this manhunt for issues is going to take some time unless I stumble upon it with blind luck. I just need to stop being so anxious. lol

 

CTS is about $16 on eBay,worth replacing as it's cheap and one less thing to fret about in the future, if it's down right "bad" the car won't start, it's it's on the blink it can cause rough idle and stumbling and can get "right" just as fast and go south the next start.

 

Yeah. Gonna change the sensor and the connector both.

 

Good!

The majority of the much-ballyhooed electrical problems on these old Jags come down to poor/loose/dirty connections....and poor/loose/dirty ground points.



Sometimes blind luck, yes. Other times you discover the fault as a result of methodically going thru a process of elimination. That's not a bad thing, as the process of elimination inevitably uncovers other things that need attention along the way. Fix those as you find them, and keep going.


Good, you've recognized that early on.

Slow and steady is the name of the game with these cars. Never try to rush thru anything. The car will fight you. Trust me

Cheers
DD

 

Yes.

Inside the amplifier is a generic GM ignition module (AC Delco D1906, GM 19810771) like this:

ACDelco Ignition Control Modules 19180771 - Free Shipping on Orders Over $99 at Summit Racing

'Tis this module that so often gives trouble. The other parts inside the amplifier fail much less frequently.

Most typically they give trouble when hot....like after 45-60 minutes of driving....but they can fail in any number of ways. Many owners carry a spare in the glove box. Most prefer the genuine GM/Delco replacement.




I'm sure there are some testing tips out there on the internet but they might be useful only to determine module is dead or alive. A merely sickly module is harder to test, as you must do the test when the fault is actually occurring...which isn't always possible.


Cheers
DD

 

That goes inside the black box that is located to the left ( U.S. driver's side ) of the TPS?

Also, at some point I am going to tackle the making of my own injector harness.
When I re do my vacuum connections, each piece that I take off, I think I am going to lightly sand the surface to where they look a lil more appealing. Might even do a once over on the intakes eventually as well when I take all that stuff off to do the injector harness.

 

Right. Inside the black box that is mounted on the LH intake manifold.

http://www.justjagsuk.com/uploads/im...08_DAC4104.JPG



The TPS is mounted underneath the throttle capstan, hidden from view, so let's not use that as a reference


Cheers
DD

 

Way to check GM ACDelco amplifier.


I have no reason to do so, neither of my cars have one, that I am aware of.


As I somewhat "understand" the principle, if "increases" the signal given by the units in the distributor so that the coil sees a "make and break signal for the coil to "convert: to HT and fire the spark.


Same idea as the older "point and condensor" did, but electronically.


So, if my hypothesis is correct, a Dwell meter should see that. Dwell, yes, OK. Dwell, no, might be a bum amp.


Carl

 

Ok sorry I have been busy today. Had to call into work because my passenger window was busted out and a bunch of stuff was stolen out of my avalanche. I have an update on the jag....

 

So, I replaced the coolant temp sensor and connector today it idled a little bit better that normal but still falling on its face left and right.... The other day when it ran perfect, I remember that I saw 2 connectors that were unplugged and matched one another. So, I plugged them in and went about my day. So when trying to start it yesterday and couldn't I was irritated because I had it running perfectly fine.

So today after I taped up my window and made a police report about my broken window and the theft, I tinkered with the Jag a little. As I stated earlier, I replaced the coolant temp sensor and the connector. Idled like crap still and didn't have the power to even put it in gear and hold the idle, and would still die while giving it gas. Cleaning the air flow sensor the other day helped but when I plugged these wires in together, it kept the car from starting. Also another note. I have a massive coolant leak from under the center fan somewhere. I can squeez the hoses when the car isn't running and hear a girgle and when I look under the car it's coming from the center of the car. So it died, probably because the coolant sensor couldn't detect coolant. Maybe, i'll have to remove the cap and look to see if there is coolant visable in the main coolant fill. I'll have to check the water pump and the lower radiator hoses at some point too. But below is a pic of the 2 connectors that were disconnected the day I brought it home and then connected yesterday. Today I retraced my stepps, disconnected them and she ran fine. Until she ran out of coolant.

Does anyone know what they go to? I was so mad about my Avalanche, that I didn't bother tracing the wires.



The wires with the arrows pointing at them, cause the car to not even want to start and if it does, the idle is rough as hell and very low. Not to mention idle is so low that the alt doesn't even give enough juice, because the alt dash light stays own.

With them unplugged it runs fine.

 

The starting fluid ruined the mass airflow sensor, I did the same thing, Get a new mass airflow sensor.

 

The V12 does not have a Mass Airflow Sensor.

Whatever you guys are talking about...it isn't a MAF!

A pic would be helpful.

Cheers
DD

 

I'll snap a pic of it when I get home an a couple hours. It's the sensor on the drivers side air inlet tube to the air box.

 

I don't know if it has one or not, I was referring to my Mercedes I thought the fuel pump had gone out so I sprayed some starter fluid in and it started for a few seconds but found out when I disconnected the battery I forgot to hook up the fuel pump wire anyway after spraying the starter fluid it got on the mass air flow sensor and would start and die and the whole car would shake,replaced mass air flow and runs perfect.