I know better, so I was very careful not to use any high
pressure while washing the engine bay. Immediately after
washing I now have a crank, no start condition. I have
narrowed it down to no fuel as I can spray some starting
fluid into the throttle body and it fires briefly. I can
hear the fuel pump coming on so I have to believe that the
injectors are not firing. I have checked every fuse and
relay on car and everything is good. I unplugged every
connector under the hood that could have gotten wet and made
sure it was dry. What in the world could I have gotten wet
that caused this? Could I have shorted out the computer
somehow?? Everything seems to work on the car except it
won't start.

Rob

 

damn- I would open and leave open to dry the distributor cap- and do not wash engines anymore- I learned that years ago...the hard way...good luck hope it helps.

 

It will start....eventually

Repeat after me.... "I will never wash a Jag engine again.... "


silly boy

ukcat

'90 xjs
'00 xj8
'02 x-type
'72 mustang fastback

 

Hi, sorry to ressurect an old thread but I have the exact same issue with my Aj16 XJS, I washed the engine bay with a hose and degreaser and now I have the exact same condition you had. What was the issue for yours, was it a simple fix? Thanks

 

Sorry this happened.I also have the same model as you Seems like one of these wash episodes every six months. Usually the crank sensor and connector has gotten wet. If you where particularly generous with the water it could have gotten into the coils and even dripped down the ECU. Start by drying the crank sensor and connector and never, wash the engine again. You want to just take your rag wet with cleaner and take your time. Let us/ me know if you need guidance as to where things are located

 

Thank you for your reply! I have washed the engine of my other XJS plenty of times with no issues but after this ordeal I will make sure not to do it again! Luckily I have a perfectly running XJS so I've been trying each sensor and part from it on the non runner to no avail! I'm in California and everything appears bone dry, I've cycled and cleaned the connectors and cycled and changed the relays. One thing I've noticed is that, with the ignition on, the coils are only receiving roughly 5v,could this be an indication to a particular issue?

It cranks strongly, starting around 500rpm and then down to 200 - 300rpm, there is fuel at the rail but no dissernable clicking from the injectors. It starts, albeit roughly, with starter fluid. I've been at this for three days now so any help would be greatly appreciated!

 

If you had not changed the cps, on your car, my advise is to do it now. The CPS is a maintenance item and should be replaced on all AJ16 cars by now if it hasn’t. If it turns out to not be the problem, you can rest assured the car won’t leave you stranded because of a decrepit CPS anytime soon. So both your cars are AJ16’s ? Have you already tried the CPS from the other?

Something else to think about is if you happened to turn the car on and immediately turned it of right before you washed it, like maybe to back it out of the garage into the driveway. AJ16’s don’t like that and are notorious for flooding and not starting after that type of scenario. I always let mine get warm and drive it at least around the house a couple of times around the house. The solution to that for me was to push that pedal all the way and try to crank until she caught on.

 

I would have thought the CPS too, it was one of the first things I changed over to test, the sensors from both cars worked fine! I also swapped the MAF sensors and throttle bodies incase either had malfunctioned but both were functioning fine.

I have been trying to figure out the 'washdown' incase the car is flooded. I'll keep put foot on the pedal fully depressed for as long as I can crank it before the battery starts to struggle. Unfortunately, this hasn't produced any results. One thing I've noticed is that the voltage varies on all of the coils. The coil most forward is now registering around 6v whereas the further back you go the lower the voltage until 0v. The ECM relay holder reads 12v and I've put a working relay in there just incase that might have been the issue but that didn't change anything.

I'm checking for voltage at the CPS plug, with the ignition turned on should it read anything or would power only be supplied when cranking?

To summarise what I've done incase it might help narrow things down:

Change CPS sensor
Changed MAF sensor
Changed throttle body and the two sensors attached
Cycled relays
Checked fuses - all OK
Checked fuel at the rail and regulator - both OK
Changed batteries - strong voltage on both
Cleaned and dried all accessible connections
Checked for injector tick - nothing
Checked for flooding by pulling the spark plug and coil - seems dry
Starts with starter fluid
Plugged in OBD 2 - connects fine but shows no error codes

It's a case of the car running perfectly prior to the wash, with it only having 30,000 miles on it, to cranking strongly but not firing.

​​

 

Hi to any guys having a problem Starting their 4.0L engines after washing them

XJS Engines and Water do not mix and are a great big NO! NO! but of course you know that now, so please never do that again!

If possible get your Car outside with the Bonnet/Hood open, so the Sun can hopefully help to dry it out

If you have an AJ6 then any damp plug leads could be Shorting out against each other and so a 'Hair Dryer' may help

In the Case of an AJ16 Water could have got down inside the Tubes that house the Coil Packs, so pull all the Coil Packs out and let them dry but don't pull the Spark Plugs out at this stage, at least until you can be 150% sure that no Water can trickle down into the engine, or that could be a disaster that you won't want to go near

As has been mentioned the Crank Sensor may have got wet and if so could then well result in a No Start Situation and may need removing to dry out, unless you can find a way that you would be able to do that in situ

As for Cranking the Engine the Battery needs to be 100% Fully Charged, as with a half charged Battery then you could be wasting your time, as those Engines need a Full On Spin over

And any Wet or damp Engine could easily take two or three days to dry out, so lots of patience and or Beer, may then be required!

 

Bruh!!!….. so much for outlining what you have done on this fashion so we are not guessing. Great!

So, did you dry out the connectors as you swapped sensors?

Other thing I can think of is that water made it down to the ECU. The bulk wire entry port is directly behind the ball accumulator ball .

 

Haha always helps to lay things out!

I like to think I did but honestly probably not long enough, that's been my aim today, to dry things out. The bonnet has been open all day for the past three days in the Californian sun which sires everything else out! I didn't find water down any of the coil passages, I always cover the main block and alternator when washing engine bays, to which I will no longer be doing!

I took the panel off to glance at the ecu and it looks clean and dry, there's dust all around it so it doesn't appear to have seen any water.

I'm definitely at a loss. One thing that is peculiar is that after I will try and start it a few times, if I open the gas cap it will be eager to release pressure, might it be the case that a blocked breather hose could be causing a crank/ no start situation?

 

ya, I am at a loss too. With the ECU water ingress, it literally runs down the wires as droplets and into the connectors. But that typically causes drivability issues and not starting issues, so I think we should discount that. What about the connector to the round sensor right above the compressor? I forget the name of that sensor. It’s round and it’s got a tiny window in it .

also, if you have the old blue relays, their imminent demise was probably hastened by water.

On a hunch, I just really feel like this one is going to be a situation where cranking and the gas pedal are what’s going to get her up again. Idk what else to look for.

 

I would pull out the coils and blow everything out with a compressor. Let everything dry and it should start. And make sure intake hose is on properly.

 

The round thing above the compressor is the camshaft sensor, I cycled and cleaned the connector, also the car could start without it, would just take about 30 seconds of cranking for thr crankshaft sensor to figure out the timing order.

I've been going through the Hella relays as that's normally what causes issues for me with the AJ16 XJS.

I took three coils out to inspect them, under the coil cover it was dusty and bone dry as i covered the main block when washing the engine but it wouldn't hurt to leave them out and sit for the day! I'm open to trying anything.

I've left the battery disconnected over night in an attempt to reset the computer incase that might do anything.

 

It won’t.

Might as well take the other three coils off. It only takes one….

 

I didn't think it would, just wishful thinking! Coils are off today and hopefully the sun will dry anything out that needs drying out. Taking the time to strip and polish the wheels on my '95 as it's long overdue!

 

It started for a moment!

I went to go and recconenct the batteries and uplug the coils and I thought I would just quickly try and start it before pulling the coils and it started straight up! It revved at about 1500rpm for about 30 seconds and then as it dropped down to 600 it cut out and I'm back to a crank and no start situation.

Does it ellude to an intermittent sensor, or perhaps it is just drying out? Either way it's great to hear it going again for a brief moment!

Also quick tip, over cleaner will do a brilliant job to get all of that pesky brake dust off the rear of your rims!

 

Shouldve let it run and it wouldve smoothed out. Instead youre back to where you were. Next time let it run. It needs to recalibrate itself. Not sure if anyone hasnt gone through the trouble to tell you, but Please dont ever wash your engine again.

 

I tried to let it run. I know it would have smoothed out, whenever I clean the throttle body the same thing happens and it smooths out fairly quickly. It cut itself out once the revs dropped to the normal idle speed.

Of course, I think it goes without saying, I will not be washing my engine bay in the same manner again!

​​​

 

Remove and clean your MAF, clean the harness too