Evening folks. I am in a bit of a pickle. Today I decided to renew my spark plugs and give the car an oil change.

Now the car hardly starts. If it does idle it dies after a few seconds. If I coax it into life and then hit the throttle it dies immediately. If I very very gently apply the throttle it will rise in revs and at higher revs I can hold the revs fine but any further movement on the throttle it chokes out and dies. I have no idea what have done, so I will explain below in detail exactly what I did and what I have since checked:

SPARK PLUGS: removed the cover and unplugged the coils. Removed old plugs. Installed new ones - 0.9mm gap. Refitted coils, connectors and cover. I have since removed the cover and checked again - everything secure and in the right order.

OIL CHANGE: I vacuumed the oil out through the dipstick tube. I did it this way since I recently bought a compressor-fed tank to use on my XKR. Since I was working from above and not below I removed the MAF and intake boot. Unclipped the MAF at the airbox. Undid jubilee clips, remove its plug and pulled it out. Then unplugged some kind of sensor just before the breather pipe that goes to the manifold. Then remove the breather pipe from the intake boot. Loosened the big jubilee clip on the throttle body and removed the little 10mm retaining nut and removed the intake boot. This gave me access to get my hand on the oil filter. Swapped that out. Bit of gunk in the intake boot so I have that a wipe out and a blast of brake cleaner. Gave the throttle body a quick blast of brake cleaner but didn't move the throttle plate or anything. Gave the MAF a bit of a spray. Refitted everything and thats it - now won't run properly. Checked all connectors properly secure. Removed intake boot again to check it had no splits or tears - perfect condition. Refitted it being very careful to check it was properly seated onto the throttle body opening. Refitted everything - same. Then I borrowed a MAF from a friend with the same car thinking maybe it didn't like being sprayed to clean it. Same. Tried running it with MAF connector off. Same. Cannot understand what is going on. Now the car is basically immobile and blocking the driveway - can't even move it a few metres since obviously I can't put it into drive at high RPM.

Any ideas? I have tried using my Autel 906 Pro scanner on it but won't connect unless I pretend it is a Lincoln Towncar (!!) - and then it only gives me limited information. A cheaper scanner using OBDII did show one code but that was to do with immobiliser which I deleted and hasn't come back so I assume stored previously. As the engine dies the check engine light flickers on - same when I hit the throttle and it starts to stall. The higher the revs the easier it is to rev up if that makes sense - and it does rev right up to the limiter if I just very gently increase the throttle but even at high RPM if I then stab the throttle it dies.

 

The spark gap seems huge , by that I mean huge

The aft 2 coil wires can easily be swapped

Light Green / Orange # X

Light Green / Purple # Y

Following up in a bit , wifi issues

 

If you remove the battery do not put back in backwards , positive post car fwd

The aft most coil is # 6



And this may not be the final change on spark plugs , no exotics like iridium or platinum , just plain cheap copper

05.1-07 Amended

 

Just had one of those "thoughts" - the plug I connected to the MAF comes straight up from below it. I was looking at this thinking thats odd, looks too tight to me but given almost all my mechanical experience is BMW where only one plug fits in one place I thought I must be wrong. Now looking at photos of AJ-16 3.2 engines the MAF cable seems to be coming from towards the bulk-head/body of the car not straight up from below and has plenty of slack on it. Have I plugged the wrong plug in? When I removed the intake boot I was trying to get my hands on the oil filter so perhaps I saw another plug and removed it. Been going crazy trying to find photos of engines out of the car but they are junk engines with the harness removed!

Is there a plug below the throttle body that is the same as the plug for the MAF?

 

The MAF is 3 pins

TPS is 2 as well as the inlet air temp sensor ( IAT ) downstream of the MAF

IAC valve is 4

 

Looking at photos of the bottom of the throttle body on X300 - 3 pins and the shape of the connector looks the same as the 3 pin MAF connector. Well, its academic now since its pitch dark and midnight here so I'll check in the morning. Be great to remove the intake boot and find the MAF cable hanging down below it!! Its got to be something I have done wrong because it drove into my garage and when I finished an oil change its broken. I'll be pretty embarrassed if I have connected the wrong plug to the MAF but lets see.

 

Okay so I checked the wiring connections and everything is plugged in where it should be. Put a better battery on it but its exactly the same. It almost "locks up" when trying to start it - like the engine physically won't turn. Very worrying. Coil packs connected correctly by the way and battery was not removed from the car yesterday so its not that.

 

To spin through the crankshaft is a 34 mm , you can easily remove the fans shroud as it lifts straight up , do not unlock the fans motor connectors lock tab too aggressively , can be brittle

Recommend removing plug to get a better feel as you spin through

Your starter pulls it through full rotations, and you had it slightly running

In the starting sequence the fuel pump will run for 3 seconds only on key rotation

It will come back on when the crankshaft position sensor ( very front and not the hockey puck with the round plastic window ) sees engine rotation , safety design

A good CKPS will read 1300 ohms and is a common part , not Jaguar specific

You can command the fuel pump to stay on at all times by jumper Ing the power sockets between 3 and 5 of the fuel pump relay , this will drain your battery with your keys in your pocket

Recommend blade type connectors and medium size wire the auto parts store can make for you from a toy box behind the counter

There is a fuse for the fuel pump relay closing control power ( not muscle power ) # 10 right heelboard fuse box that requires the relay in the corner of the fuse box to close , this relay can be swapped with the left engine bay fuse box same relay

 

Thanks fir this and trying to help me - much appreciated. Reviewing your last reply, the fuel pump thing I understand and I can make #1 relay bypass no problem.

What I want to clarify is the reference to the crank sensor. I am assuming you think this is to blame? I watched a YouTube video of an English guy driving an XJ and the sensor failed whilst he was driving - revs up and down all over the place and broke down. The next day when he was trying to start it, it did sound kind of similar to mine starting. He replaced it and after a few difficult starts it ran okay.

What gets me though is that I drove it into my garage and it started fine. Soon as I finish what I am doing it then doesn't work. So is it a extraordinary coincidence that the crank sensor failed at the same time rather than it being something I have touched? You can see why I would be sceptical.

So I want to understand your logic in the turning of the engine with a 34mm on the crank. I did actually do that slightly when I changed the plugs just to put it at TDC to check the circle in the little window on the hockey puck which lined up fine. It was difficult getting a socket on it on the end of a breaker bar. Perhaps I knocked the sensor or something but given where it is that seems unlikely. So you suggest turning it over by hand - how many times? What will this do though? I mean several times I did get it to run and gradually increased the revs very very gently up to 4-5,000 RPM - it only died when I actually pressed the throttle more firmly or if I let it drop to idle. One it actually started at idle and idled for a second before dying again. Would that happen with a bad crank sensor?

Thank you again I really want to fix the car - it is still in the way on the driveway and I would hate to have to get it towed away.

 

1. Please doublecheck your MAF connection. Go to JagRepair.com - Jaguar Repair Information Resource and make sure the wire colors line up with yours. You may want to invest in a OBD2 reader. The ones they make that work with your phone work well in tee,a of helping to diagnose. I’d love to see what the ECU thinks it’s seeing from the MAF.

2. Pull the little hose off of your fuel pressure regulator. Is it wet? Does it smell of fuel? If yes, you may have a problem there.

3. Coolant Temp Sensor could be toast. Cheap and easy to replace.

4. Going back to the OBD2 reader. Would love to know what the ECU sees at your TPS.

5. Lastly, check the connections at the tubes between the MAF and the intake manifold. Sometimes the rubber boots get torn or tucked the wrong way and create a massive vacuum leak,

0.9mm or 0.035” is the correct gap. These wires tend to get crunchy over time. Please be absolutely sure you replugged the coils all back correctly. Only the two farthest from the front of the car, or closest to the firewall, can possibly be mixed up, but it happens.

Also a blocked fuel filter?

only sensors that are being used for fueling at cold startup is 1. TPS, 2. Coolant Temp Sensor and 3. MAF. O2 sensors are just being checked for temp at this stage.

What about the Idle Air Control Valve? I’ve not heard of a failure causing this kind of a problem, usually it’s a high idle, but it’s plausible. There’s a procedure to do a manual reset of this sensor. It’s temporary, but if it makes any difference, it may be the culprit?

 

You would have to rotate the crankshaft 2 circles to verify no mechanical interference

Short cut is to jumper the fuel pump relay , again this will keep the fuel pump running as you put your keys in pocket

The crankshaft position sensor once it reads a certain unknown to me engine RPM is a enable to the ECU to provide a ground ( by the ECU ) to close the fuel pump relay for the duration of your drive

The CKPS is one signal used in many parts of the ECU and tach gauge , any of these aspects can fail to decern a not so perfect CKPS signal ( square wave on a scope )

Any of these aspects can fail and others be OK and rarely gives a P0335 CEL code

Do you see starter rotation speed of 300 RPMs

The CKPS can be cleaned of grime on the face of the sensor other than a connector clean , this interferers with the inductor pickup , 1300 ohms , as a basic meter reading is a good CKPS

The middle wire on the MAF connector will read1.2 volts DC at the proper idle speed and go toward but not on 5 with throttle up , you can stab the backside of the MAF connector as it must stay installed for this return signal

The CKPS is 1 mount position and no adjustment

CKPS about 95 dollars US and is a generic part at the local parts store , not Jaguar specific , some keep a spare in their trunk

Least cost option is Vee's coolant temp sensor but this only supposed to come into play long after start to command ECU closed loop engine regulation which is only when the O2 sensors are used as a return signal to the ECU

Most likely milage and timewise for a main fuel filter change , bad job but why it's skipped , there should be O - rings down inside the filter fittings , flow arrow points outboard

TPS will read about 11 - 13 % as a full closed butterfly so don't be alarmed if you see that . On paper 0.60 + or - 0.02 volts DC on the middle wire of a closed butterfly on the connector wire color X as it comes over the fuel rail ( nick insulation )

There is a common meter test of the TPS through it's full travel / sweep as is a wiper arm variable resistor that can have a bad " spot "

You can do it an alternate way on that middle TPS connector or at the ECU connector sockets Y and Z

Your releasing the throttle pedal points to the IAC valve not scheduling down to near closed

The fast acieration stalling points away from IAC

Wifi problems

 

Good afternoon. My good friend visited today and we had a bit of a tinker with the XJ6.

We changed the crank sensor for a new one but this made no difference at all. Then he questioned me why are you ignoring the plugs since this is one of the things that I changed between it driving into my garage and working okay, to not running. A few searches showed that others had problems with using non-spec plugs. The ones I used were from Autodoc and made by Stark. For today, he suggested we remove these, clean the soot off the (since even though brand new they are soot black already with the unburnt fuel) and re-gap them from 0.9mm to 0.75mm which we did. At the same time we set TDC and checked the camshaft position sensor was aligned correctly - miles off so we adjusted that so that at TDC the indent lines up with the circle in the window. Went to start it - noticeably easier to start and now idles for perhaps 10 seconds and then dies. With light throttle the revs rise and you can hold whatever revs you want but any stabbing at the throttle it bogs out and dies. At one point we thought it was fixed since we let the revs gradually drop to idle and it was happy to idle and then ..... died. The strange thing is that it doesn't splutter to a stop, it is almost as if someone just turns the key off.

We then did the fuel relay bypass suggested to see if something was commanding the pump to stop - no difference.

So his suggestion is get the correct plugs - he believes Champion but i need to check that - and see if this is the issue. Any thoughts on that?

Separately we broke out the Autel scanner and this time managed to connect - it doesn't support the X300 in the Jaguar cars menu but does have "other" option which then let you choose by VIN range. This showed one engine fault code - P1621: Engine control module engine immobilization input circuit malfunction. This is a similar to the code I saw on the cheapy OBD reader I used last week and that I deleted. So I deleted it again and when we re-scanned it again after trying to start it a few times and it was back again. Any ideas? Just for info, the key fob for the central locking stopped working years ago and when I changed the battery it still didn't work. So I always open the car on the key with the beep beep beep etc. before I put the key into the ignition and turn it. On locking the central locking cycles several times before a single BEEEP and its locked. This has been the same for years and is still the same now. Thats just background info.

Anyway I hope something in the above might jog someones memory of a similar issue?

Thanks

 

There is an inertia / crash switch that can be fickle

If you take apart the switch internals parts will fly everywhere , ask me how I know

This switch will drop out the fuel pump ( but then your jumperd the relay ) and a few other things drop out , it's these few other things as the intent is to stop the engine

It does not always reset , and you can jumper on the inertia switch socket between the 2 white wires of the switch connector , paperclip fine

This switch will always be on the car's right , fwd of the engine ECU

Someone made a pic

 

See page 40 for inertia / crash switch that can be fickle , does not always reset

The switches intent is to stop the engine

Your 7 stopsign double hash point is the right engine bay fuse box ( referred to as ignition positive ) relay opening back up , ECU 1st power as fuse # 12 right engine bay fuse box , this requires the relay be closed for fuse to be hot

Somewhere along the way stopsign 6 and circle 6 do not correlate

It also drops out your fuel pump but you have that jumperd , this is point 6 circle double hash

You can jumper between the 2 white wires , paperclip fine

If you take apart the switch spring loaded parts will fly everywhere , ask me how I know

It will always be on the car's right and I have someone's pic on a right hand steering model

jagrepair.com/images/AutoRepairPhotos/jagxj1996.pdf

 

Thanks but if the fuel pump relay is bypassed it is on all the time even with keys out of the ignition so how would this inertia switch be able to cut the fuel? When the engine dies its literally like someone turning off the key. So if the pump is running then it must be something that either stops the injectors or the coils/spark?

I have to keep going back to one key point: this car was a daily driver, for years. Just lately not so much but still never had any issue in starting and running. I changed the sparks plugs and in changing the oil filter I removed the intake boot (including the MAF sensor). So within 1-2 hours it went from working to not working. Surely it must be connected with this work?

 

There is a 2nd large relay as 2nd ECU power ( used at all times ) , fuel injectors , 1/2 your engine sensors and returns back to ECU as the high current half of the ECU

This relay if dropped out will defiantly kill the engine

There are some relay swapping options

small left # 7 for the right # 9 engine bay fuse box , 1st power

Large headlight , fog , AC clutch of the same 6707 part # for the large # 5 right ECU " Controlled " relay , 2nd power

As to a relationship to the messing around the MAF as there is a splice in the power ( Black / Light Green color wire ) to the MAF , This can be seen on the wiring guide above with the finger pointed to the circuit , if the MAF drops out would kill the engine but I'm not so sure about that

This power wire to the MAF is battery B+ volts Dc

This splice should be close to the MAF connector ( ? )

The EVAP valve is right there under the air filter box with the 2 vac hoses on it

 

Can you not try putting the old plugs back?

 

Sounds interesting that - I will check it - thanks!

 

Sadly no! I threw them into a bucket that is half full of water and half full of oil and old oil filters!! We did fish one out just to take the plug gap which was less than 0.9mm which is what led us to reduce the gap to 0.75mm.

 

Added some info on your MAF messing around in above post