jaguar x350 xj8 2005 Have about 80K miles but the car have been park still for almost 3 years. Got new battery, fuel pump and filter replaced. All Fuel injector cleaned and tested. Fuel pressure is 50 psi plus at the rail. After a long attempt maybe few hours it starts right up. Took it for a spin with no problem but next day same issue no spark. No fault code reading. Any ideas would be greatly appreciated.

 

Did you resolve this?

 

Hi wforslund3, problem have not been resolve. Still lost....wonder how come it starts right up sometime. If it does start up then usually does not have any problem the rest of the day. Usually does not start up during morning time at 1st start when engine is cold.

 

Is there any evidence a criiter was nesting or dining under the hood? Check to make sure new battery is at full voltage. Do you have an OBD2 code reader you can plug in and record live data?

Bil

 

Thanks Bil. Yes, there was rat nesting under the hood when bought this car few month back. I have IDS program which can read live data. What should I look for when engine running?

 

Other members please chime in also as I am no mechanic!!

If its running it probably won't show anything unless you get a code, but battery voltage should be able to be seen. If I remember correct you need to have no less then 12.5v while running for things to work. Nut if its not starting thete is another issue. Sounds more likely critters chewed some wires. Check as many wire looms as you can closely with a bright flashlight. Some plugs may have gotten corroded too, if you can disconnect, inspect and reconnect them it might help. I put a little "bulb grease' in the socket part before connecting. I've also been wiping the looms and connectors with Armoral cleaner wipes and protectant wipes to make sure the stuff doesn't get any more brittle. Makes underhood look nice too.

 

IDS is great but not the easiest to use for some rather ordinary live data. It'll do it, though, and a million other things as well.

Check as many sensor readings as you can for plausibility. Lots you won't know or figure, just skip them, but think and do what you can.

E.g. if ECT is wrong or IAT then fuelling will be wrong. It may or may not run depending. And so on.

Look at fuel trims. Maybe something is out and will have affected them.

You're after info i.e. clues.

 

Pete,

If the battery voltage while cranking drops below something like 10.5 volts, the engine control module (ECM) will not trigger the ignition to fire. Even with a new battery it is possible the ECM is not seeing sufficient voltage while cranking due to corrosion on battery power connections and/or ground points in the starting/charging/engine management circuits. If I recall correctly, IDS will show you battery voltage as sensed by the ECM. By the way, for an X350, SDD would be the better diagnostic program to use if you have it.

JagV8's suggestions are good regarding possible problems with the engine coolant temperature sensor (ECTS) or intake air temperature sensor (IATS) are good possibilities too - if their readings are off, the ECM may fail to apply cold-start fuel enrichment, leading to long crank times and possible no-starts.

Other components that can cause starting problems when they begin to fail are the crankshaft position sensor (CKP) and camshaft position sensors (CMP) (there is one on each bank).

By the way, how are you confirming there is no spark?

Cheers,

Don

 

Thanks Don, I pull one of the coil out and stick new spark plug and pointed toward front strut bolt and crank the engine. Most of the time there is no spark mostly during morning hours but if wait around for maybe few hour and crank again then it starts right away running with only seven cylinder. But sometime it doesn't start at all whole day no matter how much I try. I will check voltage on IDS while cranking next time probably next week. Oh I also did replace CKP which cost me around £90.

 

First let me apologize for jumping on this thread but I'm I'm having exactly the same problem with my 05 XJ8L. I have no spark on crank. It will start one time then run fine but if you switch it off it will not restart until it has sat for a day or so and then starts right up. I have checked the crank sensor it was good but I put a new one in anyway. this all started about a year ago with extremely long cranking but would always start eventually but now it will not start even with prolonged cranking except for the one time deal after having sat for a while. Am I right in thinking that if a cam sensor or both were to fail it would still start but run like crap?
I have removed the ECM (pain in the ****!) and checked for corrosion on terminals and the board but found none. I have voltage at the coils with Ign on and during crank, it seems that they are not receiving a trigger signal but what other sensors would cause a no signal situation? I'm a 60 year old professional motor technician but this has me tearing my hair out! glad it's my car and not a customers I'd have lost my shirt a long time ago......

 

Hi minimans,

I think your instincts about the crank position sensor were good (in Jag terminology its abbreviated CKPS or CKP). I haven't studied this aspect of the X350 engine management system (EMS), but in earlier models they work as you suspect: at startup the engine control module (ECM) refers to the camshaft position sensors (CMPs) to determine cylinder 1 TDC within less than one full revolution of the engine. Once the engine starts, the ECM refers to the CKPS for ignition timing. I think that in vehicles with variable valve timing (VVT) the ECM must also continue to reference the CMPs. The normally aspirated V8s have VVT but the supercharged engines do not.

I have to run to work, but I'll try to post links to relevant Jaguar Engine Management System manuals - in the meantime you could check the X350 'HOW TO' quick links thread on the home page of this X350 forum, as well as the jagrepair.com website hosted by our member Gus.

Cheers,

Don

 

One thing I usually ask people to try is this:

While attempting to start the car, try to jab (and release quickly) the gas/ throttle pedal. Does it help the car start every time? Does it have any effect?
Holding the pedal all the way down should cut fuel.
It might or might not change anything, but gives you some data points while trying to figure out if something in the intake air logic isn't right.


Also, not much experience with the X350 cam and crankshaft sensors, but in the Nissan world they could manifest in many different ways. Sometimes the car just won't start, or it takes longer to turn over at startup, or dies on the highway... then sometimes it's intermittent. Most times they throw codes, but sometimes not at all.

 

I forgot to mention that the only code it throws is the crank position sensor fault and only then intermittently after extended cranking, I checked continuity between the ground and also the signal/voltage wire back to the ECM and all seems OK. I think tonight I'll check the cam sensors and wiring, at almost $150 a piece I'm not changing them unless they show as bad!
Thinking more about it I am sure it must be a sensor or wiring fault as it will start, albeit one time so not a hard fault and once it's running it continues to run OK until switched off, it would appear to be a signal it needs to find position but once running uses the Crank sensor as the main signal. Oh and yes it it a Nat aspirated with VVT
I restore 50's 60's cars for a living so this is a different experience for me. I just wish my T4 rover computer was able to talk to the car............

 

Well both Cam position sensors checked out fine, so now I'm stumped! I think it's time to start changing parts, something I always advocate against as a poor substitute for a proper diagnosis, so I have an ECM coming, used with the same part number and designator and I'm led to believe this will be a plug and play swap from another thread on this forum?

 

Hi minimans,

Will your scan code read only the P (Powertrain) DTCs, or will it also read the proprietary C (Chassis), B (Body) and U (Undefined, but mostly Network) codes? With your symptoms I would be surprised if no U codes have been flagged.

If you have an oscilloscope, you can view the crank sensor (CKP) output signal.

Here are some documents that may be helpful:

Jaguar Engine Management Systems & Advanced EMS Diagnostics - Book A

Jaguar Engine Management Systems & Advanced EMS Diagnostics - Book B

Jaguar X350 Technical Guide 2004-2005

Jaguar X350 Electrical Guide 2005

Jaguar X350 DTC Summaries Guide

Cheers,

Don

 

Sounds more likely a sensor than the PCM. With some CKP codes has it been replaced / connectors & wiring checked?

Next suspect - an air leak.

 

Crank and Cam sensors have been checked for continuity and output at the ECM plug and all is good. I cannot see anything else that would effect spark output? But I don't know, that's the problem. As I said the coils are getting 12V at the plugs but no trigger to fire them. Fuel pressure is good and they are firing, so what else in the system would cause a no spark? Possibly the anti theft system? but I don't think so..............

My code reader will only show P codes but will show real time data logging ie fuel pressure, engine temps and such.

 

The most common cause of no spark is low battery voltage while cranking. If the voltage falls to below a certain threshold (around 10.5 volts, I think), the ECM/PCM will not trigger the ignition to fire (see my post #8 in this thread). Many digital volt/ohmmeters cannot react quickly enough to measure actual voltage sag, so try an analog meter or a quality battery/charging/starting system tester (I use a Midtronics EXP-800).

The ECM/PCM may also fail to trigger the ignition if the engine speed remains below a calibrated threshold for longer than a calibrated period while cranking.

I'm not certain about your market but problems with the security system, key transponder, etc. can inhibit spark (maybe cranking too).

Book B of the EMS manual that I linked to earlier contains a detailed explanation of system operation and a section on Advanced EMS Diagnostics toward the end of the book.

Cheers,

Don

 

Thanks I'll take a look at that EMS Manual, I hadn't thought about cranking speed I always work with a battery charger attached when checking the electrical systems. but I havn't checked cranking voltage, I'll give it a go.

 

Well I got the replacement ECM, same part number and codes but the car won't crank over. I suspect the alarm ECU is not letting it crank? I was told it was a plug and play for this ECM but apparently not. Oh well back to the drawing board I suppose....................