Excuse the length but I'm gonna try and be through in my description of the cars behaviors.


I had a local shop change the oil today in our 1996 Jaguar XJS 4.0L in preparation for a long trip next week and after I left and got on the road I noticed a few water droplets blowing up on the windscreen but didn't think much about it since it appeared as though they had also cleaned the windscreen, then about 15 miles down the road the car cut out like someone had just instantly grounded out the ignition.

I coasted off the road and looked under the hood and it became clear they had WASHED under the hood, I called the shop and they admitted to their spout coming out of the oil fill hole and shooting oil all over the top of my engine, so after they was done they backed it out and over to their pressure washer and washed it, all under the hood, thoroughly they said (something they seemed proud of). The engine would have still be fully warm when they washed it, I wasn't there long enough for the engine to cool off.

I tried to start it and it just cranked, occasionally it would "hit" but only for a moment, or even make a mild back-fire. A few times even started but ran really rough and quickly died again, after about 45 minutes with the hood up it finally started but idled rough and I just let it sit there idling hoping it would warm itself up and clear up and about about 5 mins it kinda coughed once and after that returned to normal idle. The check engine light was on by this point.

I let it idle a bit longer then got on the road, it would occasionally "buck" but kept going for the most part though in addition to the check engine light the transmission light also came on. Once it seemed to loose all power and I shifted into neutral and it actually never died and then I was able to push it back into gear and it went on fine. About 4 miles down the road I stopped at a place and grabbed a coke and wash up (I'd been checking connections under the hood in 95 degree temps) and after I came back out it started up again fine, the check engine light was still on but the transmission light had gone off. I drove 15 more miles and stopped and filled up with gas, again it started fine, I got on the highway and made it about 20 miles when it bucked a couple of more times and then quickly died again. After an hour I called someone to come get me with a trailer, took them two more hours to get there, during all those three hours it never would start and run again even at idle for more than a few moments. I let it sit and sit and would then try it again and after a long sit it sometimes would start for a moment but idle rough and quickly die again.

After he picked me up we stopped for dinner, drove the 50 miles home, and when we got home (now 6 hours after the last time it died) I reached in and tried it and it started and at first I thought it was gonna run right but it quickly started idling rough again and after 20 seconds died again and did not restart again.


On the road-side I unplugged every connector I could get my hands on looking for water in them and never found anything. Unplugged and re-plugged every relay, even swapped positions of all the relays which had the same part number on them, pulled and checked every fuse. The shop said they only washed under the hood and claim that they washed it thoroughly but that they didn't get "too close with the spray wand".

I'm seriously out of places to look, if it was under my hood or in one of the under-dash fuse boxes and I could get at it I did and never found anything wet but there has to be some water somewhere.


Anyone have any ideas on what I could be overlooking?

~

 

I would guess at the coil packs having packed up; can you tell if you are getting a decent spark?
Try spraying them with a contact cleaner or water displacement spray.

 

Sounds like you touched all the bases but you'll have to go back in and repeat the entire process. There's surely still a water droplet or two lurking in of the connections. Or perhaps some water worked its way *into* a relay?

Cheers
DD

 

Oh man!! I hate people taking liberties with my cars. That is the very reason I always feel like I have to be a a-hole anywhere my cars go and spell out every single little thing "don't wash the car. It causes swirl marks" "don't go run errands in my car while I have entrusted it to you". "Don't test drive my car without me being present" "don't change the dial on my radio" "I just came in for tires. I am not interested in your complimentary check. Do not open the bonnet"".....,and so on.

Well with this I think you are looking at a crank sensor or a TPS. I don't think the coils would have gotten that wet considering they have that cover......number one thing is the crank sensor. This is not the first time a XJS AJ16 has been washed and has resulted in that particular part going out and causing exactly what you are describing

 

This morning it started but only ran about 2 mins then died. Checked it with a scanner afterwards and have two codes I have are P1775 and P0727 which are no doubt still left over from last night since I had no scanner or way to clear them so I cleared them both and tried cranking it, it didn't start (though kinda backfired lightly) and I checked again and the codes didn't come back. I put a battery charger on it on low, showed only 56% battery power remaining so now the first thing to do is let the battery charge up fully.

The look up on the codes says one is transmission failure but is more likely caused automatically by the other which is the engine speed sensor; I don't know if they are referring to the crankshaft or camshaft position sensor or not. Some dodge trucks have a camshaft position sensor AND a crankshaft position sensor AND a separate engine speed sensor (which often does little more than run the tach) where other makers sometimes use "engine speed sensor" as another term for one of the other two, particularly the crankshaft sensor.

 

SouthernGypsy,

You have a crankshaft position sensor but you don't have a camshaft position sensor on an AJ16 car. What you do have is an engine position sensor (in the place where the distributor used to be mounted on the front right side of the block on an AJ6 engine. This sensor is only used to identify the engine position to facilitate starting. It's not used after that.

Even though they are theoretically under cover, I would pull the coils and check for water in the head recesses where each coil / spark plug is. The gasket on the overall coil cover is not that good and it's easy for water under pressure to get under there and fill those wells.

Disconnect the coils and then see if there's water in the wells.

I also remember you saying that most of your coil gaskets were missing and wonder if this may have exacerbated the water problem?

Good luck

Paul

 

Thanks, and actually I ordered new gaskets for all my coils and put them on right after I had mentioned that when someone said they was supposed to have them.

 

Does anyone know why the Engine Speed Sensor (aka Crankshaft Position Sensor) seems to have a sight glass on it in a removable cover? Is there supposed to be a gasket under that cover, and what's the point of the sight glass? It almost looks like it maybe supposed to have oil of some kind in there and the sight glass is to make sure you have enough oil but I have no clue.

Anyone?

 

SouthernGypsy,

that's not the Crank sensor. The crank sensor is mounted on the front timing cover above the crank. The sensor you refer to is the Engine Position Sensor. It is used by the engine to know when Cylinder one (or six?) should be firing as the crank sensor naturally doesn't know the difference between firing stroke and exhaust stroke. The sight window is available to set the engine up but really has no value after that. The EPS helps the engine to fire initially but then does nothing once the engine is running. I don't know if there is a gasket under the cover. If you're worried about water ingress, I suspect it's more likely to happen at the wiring plug point.

Because the EPS is only used for starting, I don't think it could cause a car to cut out whilst running, but I might be wrong!

Hope that helps

Paul

 

Odd they'd use 2, because what you just described the engine position sensor doing is also an almost perfect description of a basic (ie. circa 1990s) crank position sensor.

Anyways, maybe a good point on the other thing but it's been my experience (a particularly argumentative Jeep Wrangler comes to mind) that just because a circuit is only used when starting doesn't mean that grounding it out (like water could be doing) when the engine is running wont cause the ignition to instantly cut out as well.

First thing I did was charge the battery fully again today but this morning noticed that sight glass had moisture beads on the inside of it this morning when I was looking the car over, first time I have ever seen that. So I took the cover off, blew it out with filtered dry compressed air, and the car starts and idles with the lid off. I notice what looks like faint glue residue in a ring on the underside of the metal cap with the sight glass in it as though there once may have been a gasket that's gone now. I let it idle awhile and warm up (to evaporate any water the air dry didn't get) while the cap was off and when I put it back on in lieu of a gasket I used a q-tip and put a VERY LIGHT coat of RTV around the very outer edge of the inside of the lid. That may be a worthless act though because that sight glass itself I notice is not really tight in there and if someone sprayed water at it looks like it'd go right around the edges of the sight glass.

I haven't road tested it yet and drying the moisture out of that spot may only be a coincidence in fixing it (though it still wouldn't run right first thing this morning but does now) so only a road test will find out for sure I guess but I only just came in from finishing out re-securing that cap.

 

SouthernGypsy,

Hopefully the problem might have been with the moisture in the EPS. Let's hope you've now solved it.

I suspect the reason that Jaguar fitted that EPS was because when they developed the AJ16 which didn't use a distributor but had coil on spark ignition, they had:

a. a need for the engine to easily know when it needed to start the spark sequence, because the crank sensor can't tell the difference between firing stroke and exhaust stroke

b. They had a ready-made pedestal in the block where the distributor used to be fitted on AJ6 engines, so it was a fairly simple engineering exercise

Fingers crossed that the problem has now gone. (But i'd check each spark plug well anyway!)

Paul

 

The lesson is...change the oil yourself and spray all that is wet, which should not be with WD40 Glad its sounds like you sorted it

 

Yea just got back from a test-drive and it ran fine the whole time.