Hello XJSers,

So today I bring you another problem that I seem to have with my kitty (see sig below for specs). Apparently, now it has no power at low RPMs. Seriously, there are heavy duty haulers full of sand/rocks/concrete passing me when taking off from a red light. However, one I get to about 2000 RMPs, I suddenly get power back and I can once again move quite fast. Once I come to a stop and have to accelerate, there is again no power until I each 2000 RPMs. Vehicle is NOT overheating, it's running at normal temperature. No smoke coming rom exhaust, not leaking oil.

I did recently change the pickup coil and the vacuum advance. I do seem to be able to move the rotor quite a bit side to side, and it does return to its position when I let it go, so I'm thinking it's not the centrifugal advance (i.e., stuck distributor). Current suspects include a stuck pickup coil or non-working vacuum advance (it did have vacuum when I tested prior to installing it, did not test after installing it) or possible stuck EGR valves. It might also be clogged catalytic converters, but at this point I have not disconnected them to find out, and there does seem to be good airflow. Gas pressure seems good to the fuel injectors and rail line, if you are wondering.

One of the things I am not sure of is whether the pick-up coil needs to be greased for it to work. I can easily move it by hand, so I assume that the vacuum can move it too (if it is working). I o plan to test it this weekend, and I have a feeling it will be working just fine.

Any of you have suggestions about other areas where I might be able to look? Car did not have this problem before I changed the pickup coil, it just wouldn't run at all before I changed it).

 

Only thing that comes to mind is a sluggish centrifugal advance, sticking until 2000rpm is enough to unstick it.

 

Agree with Per.

The fact it kicks in at 2000rpm, which is 1000rpm distributor speed, kind of makes sense.

Other items I have had issues with ove rthe years are:

1) Vac hose TO the ECU, not in good shape, and a delayed signal to the ECU.
2) The infamous "Blue/White" vacuam full fuel capsule is toast, VERY common. It is located tucked into the inlet manifold at about 5A. This enriches the fuel by about 15% on acceleration. This capsule works in conjunction with/as well as, the capstan micro switch which enriches fuel at about 60% throttle.
3) AAV is NOT closing 100%, so a huge vac leak is sensed, and acceleration suffers.
4) The 2 throttle rods are not synched 100%.
5) The 2 rubber bushes at the rear of the inlet manifolds where the throttle linkage pivots/rotates, are missing. Terrible lag in ACTION if that is so.
6) Initial ignition timing is waaaay off. This I doubt to some degree, due to later performance happenings.
7) TPS is having a hissy moment in the lo range readings, very common again.

I'll keep thinking.

 

You know, a sluggish centrifugal advance makes more sense. I didn't lubricated the sucker when I changed the pickup coil, I should have. It sounds like I need to take out the distributor, clean it out, and lubricated it.

Two questions, though. First, is it okay to drive the vehicle home? It about ten miles away, and I read that this can cause major problems. Only drove it twice since I noticed this problem. And second, what kind of lubricant should I use on the distributor? I have some Castrol lithium, high-temp grease here, but I've read that engine oil can also he used. Suggestions?

Thanks.

 

A couple more tidbits.....

Even a new vac advance capsule won't work right if it isn't getting vacuum.....and there's a complicated scheme of delay valves, timers, etc that might be causing a problem.

It would only take a few minutes to bypass the controls and run a vacuum hose from the distributor to a ported (throttle edge) vacuum nipple. If the performance suddenly changes then you'll know you're on to something.

Next, do you sense any weirdness in the transmission?

Year ago, when I bought my 88 XJS, I had a problem with sluggish off-the-line performance. Sometimes I could nail the throttle and peel rubber. Others times....blahhhhhhhhhh. Eventually, the blahhhhhh behavior became constant.

It ended up being a trans problem or, more specifically, a torque converter problem. The details escape me but the trans had been overhauled just a couple months before my purchase and a seal installed backwards (or something like that) and the torque converter wasn't convertering

Cheers
DD

 

Synthetic engine oil is the preferred, due to the heat.

Drive it home, by all means, just drive super quietly, no drag racing, just triple your age and drive accordingly, HAHA. The harm/damage that is real is due to hard driving with these issues.

 

Earlier you said that you can turn the rotor and it returns back when released. That's probably as good as it gets....although, to be specific, it should snap back *smartly* when released. Does it?

From your description I'm not sure a full tear-down would be called for. I'd be tempted to carefully and sparingly spray some solvent (brake wash, WD40) into the mechanism and exercise it vigorously. After that, another careful and sparing spritz with a very light aerosol lube. Personally I wouldn't want anything thick that might become sticky when constantly exposed to heat.

The mechanism is typically oiled with a 3-4 drops of light oil into the center of the shaft every couple years. After your sure everything works this should be all that's needed to keep it working.

Cheers
DD

 

Doug: I don't think it's the transmission at this point, as it had been working just fine before the whole pick-up coil had to be changed. However, it may be contributing to it, as it was having trouble shifting out of first when first driven in the morning. It worked well once the car warmed up. This bbllaahhh you describe feels more like it's coming from the engine.

Oh! And I forgot to mention. I filled it up on Wednesday, and by Thursday it had gone through 1/4 of the fuel. It is ANYTHING but fuel efficient at this time, like things just aren't firing quite right. I mean, I know it's a V-12 and all, but for the amount of miles it was driven, this was way off kilter.

Actually, the rotor doesn't "SPRING!" back into place. It sort of more or less moseys it's way back into place, but it does return. (As a side note, the first time I moved it like this, I just about went into a panic thinking I had broken the rotor shaft). Anyway, I will once again remove the distributor cap, rotor, and dust cap and spray some WD-40 into it. Where exactly should I be spraying? Doug, you stated that 3-4- light oil drops into the center should be enough. Is there a hole in the center shaft?

Grant: I will drive it home like an old man, possibly also pulling the seat all the way forward and looking directly ahead at all times. Any advise for all those Mustang and Camaro owners that like to rev their engines next to me at a stop light? Why the heck do I always seem to attract those? It's an 89, guys!

Aside from the distributor, I also have to change ALL the hoses. I can't think it's any harder than changing the transmission filter and pan gasket. Almost got myself killed with THAT job there, let me tell you...

 

UPDATE

Well, I worked on the distributor, didn't take it out. The rotor now "SNAP"s back into place when released, tested the vacuum advance and it works. I replaced MOST of the coolant hoses, cleaned out the side tank for the radiator (I forget what it's called), and cleaned the front of the radiator. It's running cool, though temperature in and of itself was never a problem, really.

What IS a problem, is that it STILL doesn't have any power at low RPMs. It does great in the 40-60 MPH range when driving, and it will absolutely not do above 60 MPH unless I'm on a steep incline. It seems to love running only between 40 and 60 MPH, anything less and it seems to BBLLAAHHH and nothing above 60 (as in, "nope, not giving you any more power").

At this point I'm thinking it might be a vacuum issue. It could also possibly be a fuel pump issue, I guess, but I removed a fuel injector and it seemed to be spraying. I am not sure of a few things.

1. How can I test where a vacuum problem might be? This is new to me, and I am not sure what I should even be asking or what I should do at this point.

2. How can I test the fuel pressure? I do know it's getting fuel at the fuel injectors since I took out 1A and it was spraying as I believe it should. I'm just not sure how to see it there is enough pressure when accelerating. I'm a little skeptical this is the issue, as the car runs well between 40 and 60 MPH.

3. Where the heck is the ECU? I am getting to know my vacuum hoses pretty well, haven't noticed where or which might run to the ECU.

Grant, thank you for all the suggestions. Doug, your input is useful.

Just want to get Morris back and running right, and it's a bit frustrating to not have it running right. However, it is teaching me quite a bit about the V-12!

 

The ECU is in the boot, on the RH side, behind the trim panel that simply slides out.

I know this is against the grain of normality, but are the 2 coils OK. I am well aware the "normal" issue here is none revving above 3500, but I recently had an '85 here that had been fiddled with, revved fine in "P", bugga all in "D", and the main coil had gone very high on the primary ohms, as in 2.9K ohms, in lieu of the 1.2K required. I only had a crappy old coil lying around to use as a tester, but it read 1.4, so tried it, good as, peeled the tyres easily.

Also suspecting the timing. The centrifical was gooey, OK, and I wonder if the actual timing of this engine was done with this thing hissy, so now it would be as retarded as hell. A proper retime of the engine would be ABOVE #1 on my "too do" list at this point.

Fuel pressure is tested by "T" joining a gauge into the hose between the rail outlet and the LH FPR. Generally you will be sacrificing that hose for this test.

Removing the RH FPR also is a pretty standard "upgrade" to these, and may be worth considering.

 

Update time!

I FINALLY had some time to look under the hood, was able to go over a few things. I checked the timing by checking the left camshaft through the oil cap at about as close to TDC as possible. The rotor was pointing to about 1A. Right now I don't think it is the timing, though it MIGHT be possible that the right side is off. I hope not!

The hose to the ECU looks good. Actually, all the hoses on the car look good, they all seem pliable, bendable, and in good condition. Tested the coils, also seem to be giving a nice blue spark. Even removed and tested with another coil I have laying around, no difference in performance of car.

Two things I want to check:

1. That "infamous "Blue/White" vacuum full fuel capsule" that Grant Francis mentioned earlier. I found an orange vacuum part under 5A, was orange and metal, has one port on one ide and two ports on the other. One of the two ports goes to the vacuum advance and the dump valve, the other of the two ports goes to the intake manifold. From what I have read, the piece is called the vacuum regulator. Is this what Grant Francis was referring to? And how do I test it?

2. Grant Francis said "3) AAV is NOT closing 100%, so a huge vac leak is sensed, and acceleration suffers." What is the AAC? Where is it? And how would I test it?

3. Lastly, and also Grant Francis, "TPS is having a hissy moment in the lo range readings, very common again." What is the TPS? Where is it? And how would I test it?

I also noticed today that now the idle seems to be moving up and down ever so slightly when not in Drive, so whatever is going on, it seems to be getting worse. Car continues to get hot in stop and go traffic, as it's in those low RPMs a lot. Still does wonderful between 40-60 MPH, and won't go past 60 MPH. I wish I could drive and be able to see the vacuum capsule advance in action, I have a feeling I would not see it move.

 

One of the members at a snowmobile forum I follow had a funny post.

If you worked on it right before the problem started, re-check your work, chances are you messed something up.

I think it's more likely that you fixed something - the advance mechanism. As Grant says, the timing was likely adjusted with the bad advance and is now badly out.

Checking the timing would be number one on my list.

 

OK, Jack poured on ice, lets start.
Not in your order above, my brain works differently. Tooooo many hours sorting V12's, HAHA.

1) You have spark, GOOD.
2) That timing check is inaccurate, the only thing I see via the oil cap is the chain and sprocket, unless your oil cap is somewhere different?. The timing plate (if still fitted) is under the engine, attached to 2 bolts of the sandwich plate. NOT easy to see, but it should be there. Some serious cleaning may be required to find IT, and the timing marks on the crank pulley.
3) The TPS is under the throttle capstan, rear centre of the engine with 2 rods going to each bank. It is set at idle position, Ignition ON, engine OFF. Probing the Red and the Yellow (memory here so dont quote me), and 0.32v - 0.36v is CRITICAL. Then a SMOOTH rise in volts to somewhere near 5v, as the TPS is opened to full throttle. Many of this age will be erratic at best. replacements are expensive. Many have used other brands, etc. I used an XJ40 unit for $5 s/hand, sweet as, 15 years ago.
4) The Blue/White fuel switch is still used on USA cars to the best of my knowledge. It is a vac capsule, attached by 2 wires, to the micro fuel switch on the throttle capstan, so one or both of these switches will enrichen fuel by "about" 15% for acceleration, and then again at WOT to stop lean burn. The vac regulator you found, we did not get. I would by-pass it for now to sort this thing.
5) The AAV, man you are about to learn something amazing. It is the alloy casting thingy on the rear of LH cylinder head. NOTORIOUS for jamming, and generally reeking havoc. Fluctuating idle is one of the issues. Low cold idle is another. High hot idle is another. General lousy performance is another. I rebuild them. I remove them totally, which is my preferred method.
6) You state it gets "hot" in stop go traffic. This is a worry. The fan hub "may" be getting weak. The thermostats may be getting old, and not operating as designed. Many other items may also be contributing. Timing being retarded, as I said before, is quite high on the list here. DO NOT overheat a HE V12, you will pay dearly for that misadventure.

Either way I have a "Word paper" on it that I can email direct to you if wanted. Tooooo large to add here, I have tried in the past. I also have "papers" on the TPS setting, etc, if of any use to you or others. PM only, coz as I said, too large to add here.

 

OK, more thoughts to keep you busy.

I would be seriously inspecting the fuel SUPPLY circuit.

The small "sump tank" under the battery has a fine plastic mesh sock over the outlet pipe TO the pump. These block frequently, and the pump starves for fuel, the engine runs crappy, and will not perform well at high speed, and/or under acceleration. Eventually it will block sufficiently to allow idle ONLY.

Clean it out, change the main EFI filter, the one behind the spare wheel. That way, the fuel system is basically sound and can be kept out of the troubleshooting scenario for now.

I will keep thinking.

 

Grant Francis said "That timing check is inaccurate, the only thing I see via the oil cap is the chain and sprocket, unless your oil cap is somewhere different?. The timing plate (if still fitted) is under the engine, attached to 2 bolts of the sandwich plate. NOT easy to see, but it should be there. Some serious cleaning may be required to find IT, and the timing marks on the crank pulley."

So here I am, looking at the alignment notches and the timing plate. Haynes manual doesn't state WHERE the notches should be at, though. What number does the notch go at to get TDC? I'm thinking it might be the 0 (zero), but one can never be too sure, right?

 

Just another update. I asked in the previous post as to where the alignment notch on the crankshaft should be set to. I set it to 0 (zero) today, no problem. Then I looked at aligning the rotor.

Problem! I'm not sure what marks or how I'm supposed to know exactly what to align the rotor with. I noticed that a side of the distributor has some lines on it, but I am not sure if they are for alignment or just a decorative part of the distributor casing. Also, as the rotor can be turned a little before it springs back (I re-oiled it), I'm not quite sure how to make sure I would be aligning the rotor where it's supposed to be at. I imagine that at some point I'll have to use a light gun to make sure it's timed right. Not sure where to point the gun at or how to set it up (have never had a car that needed one).

Ideas or suggestions?

 

OK, been a work, Bugga.

The distributor rotates in an anti-closkwise direction. Remove the rotor for now, it is obviously clouding thought.

With the timing mark on the crankshaft pulley set on TDC (or zero), the pointing of the rotor to anything is of little consequence at the moment. I say this due to the fact the engine is running, so the "basic" timing is spot on, the timing is on the correct stroke, etc, and just the "fine tuning" bit is maybe amiss.

This is where it gets messy, coz I have done this 100+ times and think nothing of it, but putting it into words for someone else to follow is not easy, due to me usually assuming too much.

I will state MY way, follow if you wish, or ask away and I will fine tune my scribbles if needed.

Now you know where the timing mark is, rotate the engine by hand until the 10deg mark is against the notch. It has been years since I have done this, so the actual layout of the plate etc is fuzzy now, and none of my V12's have that timing plate installed anymore.

NEVER EVER ROTATE THIS ENGINE BACKWARDS. if you go past the make, suck it up and go around again.

Once this mark is aligned, go back to the distributor.

Now look at that star wheel under the rotor. One of the points of it SHOULD be directly AT the pick up point in the reluctor.

If this is NOT so, unlock the 13mm locknut at the front of the distributor, and rotate the screwdriver slotted bolt so as to align these 2 items. This will SET the base timing, and is usually so close as to what is needed for proper running that further adjustments may not be needed.

If the available adjustment is insufficient, the distributor mounting socket cap bolts will require loosening so the base section can be rotated to allow proper adjustment.

Once this is done, relock that nut, NOT super tight, it will break that slotted bolt and you will not be happy.

Refit the rotor and cap. Remove you big spanner from the front pulley nut.

Start the engine and observe if anything as to running quality has changed. Further "tweeking" of the timing may be needed, but this can be done via that slotted bolt, and with the engine running.

2ND note re this issue.

The very long timing chain on these engines can stretch with age. This will result in the RH camshaft being retarded. Some I have retimed over the years, have been as far retarded as ONE whole chain sprocket tooth. The engine was very DULL, and lifeless prior to this retime. Once done, the whole engine came back to life.

 

Thanks Grant Francis, you have no idea how helpful you've been thus far.

So I used the 0 mark for the crankshaft, which is apparently incorrect. The engine seems to be running a little better, though, but now it's overheating when it's going fast. Still no power between idle and 10 K rpm, which is better than when there was power between idle and 20 K rpm.

Looking at the timing plate, there are numbers going up, one set called "Before", and another set called "After". It seems to go up to about 28 either side, the 0 is right in the middle. Do I set the crankshaft to 10 Before or 10 After?

Now that I know this piece of information, I can go and redo my timing better. Hopefully it will take car of this issue and I can go forward and start working on the power steering system. It's leaking something awful, and hopefully it's just hoses and not the rack and pinion itself.

 

OK, good sort so far.

I am impressed, trust me..

The timing you have done has effectively timed the engine in a retarded state, which is indicated by the high temp when running faster scenario.

The mark you need is the "Before" side of the Zero.

Whilst you are doing this I suggest loosening that locknut on the distributor adjuster, and move that adjuster so as to allow you some more "advance" motion if so needed later in the tuning process. Reset the "base timing" after adjusting that lockscrew. That way you have plenty of timing advance up your sleeve.

These engine like a goodly amount of advance timing, up to about 18+deg in our market, if using our 98 octane fuel. However toooooo much advance will punch holes in pistons, so be careful what you do after this base setting. Fine tune the timing by all means, but do not too far from teh base line I have given you.

There is a timing procedure for the V12 (basically 3000rpm, held, climb under the car, timing light on the plate, mate moving the dissy), but it is messy, too many items rotating very fast in front of your face/nose, and can be scary/dangerous if you are slightly careless.

It can be got spot on without this, and I have done it my way for a very long time.

Once it is "SET" correctly, there is no need to go back there, it will not move.

 

Alright Mr. Francis! At least I got the "10 at Before" alignment right! Woo-hoo!

Now, here's the issue I seem to be running into in a video format. I did not even know what the question was, because I don't know what I don't know. So, without further adieu...

VIDEO0127 - YouTube

Let's see what I'm supposed to do here, I am baffled!