XJ XJ8 / XJR ( X308 ) 1997 - 2003

Cylinder Wash vs. ECU Failure

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Old 10-24-2012, 07:05 PM
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Default Cylinder Wash vs. ECU Failure

Since symptoms seem quite similar (crank without start, no CEL, no DTCs set), what's the simplest way to discern? Car started the other morning, ran for about 5-6 seconds then chugged and shut down with an "engine stalled" error message on the dash. Key on gets all the proper fuel pump and throttle body motor noises but no injector ticking.

Car has 40 lbs of fuel at the rail. Battery is fully charged. Relay swapping has not caused the car to start with another system failing. All fuses checked in the car so far seem to be fine (two blocks underhood, one in trunk).

Check for spark? I can do that, have a tester, just need to get home early enough in the evening.

If a cylinder wash issue, is oiling the cylinders the only recourse? Is this something that a day or two of sitting will not help with... the cylinder would drain of gas, into the crankcase presumably, and not re-oil? If I've tried cranking (several times) would that push the fuel out or not likely? Would it eventually start or just score the cylinder walls to keep cranking?

The lack of injector tick leads me to thinking in the ECU direction, but there's no simple way to test apparently. My code scanner is only pulling a P1000 but if it's pulling even that, does it mean the ECU is communicating and thus should be fine?

I'm at a standstill.
 
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Old 10-24-2012, 07:25 PM
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If the car started and ran it had to have compression so for the question was it cylinder washing at this point I would say no, however, it is possible. If you do not have any codes then I would use this procedure to start with before you go to adding oil to the cylinders.

Link JagRepair.com - Jaguar Repair Information Resource
 
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Old 10-24-2012, 10:14 PM
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If the engine sounds like a V12 when it cranks (like there is no compression) then it might be cylinder wash. There should be a 'compression' sound when each cylinder is at TDC firing. If you get a steady 'whir' like you took the plugs out then it needs oil in the cylinders.

bob gauff
 
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Old 10-24-2012, 11:10 PM
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Originally Posted by motorcarman
If the engine sounds like a V12 when it cranks (like there is no compression) then it might be cylinder wash. There should be a 'compression' sound when each cylinder is at TDC firing. If you get a steady 'whir' like you took the plugs out then it needs oil in the cylinders.

bob gauff
It definitely has compression. It's not free spinning. I might have to bring the recessed plug compression tester adapter home from work to run a quick compression test on a cold engine... not even going to worry about doing a leakdown test until it's back running and I can get it on a lift.
 
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Old 10-25-2012, 02:20 AM
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You could use a noid light or a scope on an injector to look for a pulse.
When you've got the lead off check for 12V on one side - you can check JTIS for the colour coding for +12 for that injector or just test both wires.
The ECM grounds the 12V to open the injector.
Obviously no 12v = ignition fuse or similar, 12V and no pulse = (probably) bad ECM.
 
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Old 10-25-2012, 09:31 AM
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Originally Posted by steveinfrance
You could use a noid light or a scope on an injector to look for a pulse.
When you've got the lead off check for 12V on one side - you can check JTIS for the colour coding for +12 for that injector or just test both wires.
The ECM grounds the 12V to open the injector.
Obviously no 12v = ignition fuse or similar, 12V and no pulse = (probably) bad ECM.
Noid light is going home with me tonight.

I'd love to check JTIS but work has Win7 x64 and I'm a Mac user so it doesn't play nice in either place. I'm trying to get an older WinXP laptop for this sort of thing now.
 
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Old 10-26-2012, 04:34 AM
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Jimlombardi very kindly made the electrical diagram available as a pdf on an earlier post
https://www.jaguarforums.com/forum/x...05/#post374701

Be sure to press the thanks button for him.
 
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Old 10-26-2012, 05:33 AM
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Originally Posted by Highlander64
Noid light is going home with me tonight.

I'd love to check JTIS but work has Win7 x64 and I'm a Mac user so it doesn't play nice in either place. I'm trying to get an older WinXP laptop for this sort of thing now.
It is now also available in PDF format from links in a thread in this section, or it may already be in the stickies at the top of this section.
 
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Old 10-26-2012, 06:08 AM
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I had a good look but couldn't find it in the Stickies.
 
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Old 10-26-2012, 08:40 AM
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I picked up an ECM from a running salvage car for $75 - if it fires, I'm shipping my original out to be repaired instead of waiting for this one to let go as well.

If not, I'll do some more diag this weekend. With an impending large storm coming next week it came down to swap in a part hoping to save some time - not the usual procedure at all but $75 in time is not enough to do a full diag anyhow, and I have no way of bench testing the ECM.

If I hit 12v to the injector circuit I should theoretically be able to trigger them - what's the amperage? Don't want to fry anything.
 
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Old 10-26-2012, 09:20 AM
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^^ Replying to myself is tacky but... wondering if the stability/abs symptoms might be related to a failing ECM? Before I start swapping in modules, or pulling and testing them, obviously continuity and resistance need to be checked to each sensor, sensors need to be ohm'ed out, all the usual electrical diag.

But the question remains is the stab/abs issue by any chance related, or is it more likely to be in the sensors or ABS pump/control module?

Hoping to have some good news later today and get a "resolved" at the top of the thread!
 
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Old 10-26-2012, 12:46 PM
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The ABS problem may be a real problem but it would not cause the car not to start. It is at times related to a low battery voltage that could have taken place in your effort to start it.
 
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Old 10-26-2012, 01:43 PM
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Originally Posted by Gus
The ABS problem may be a real problem but it would not cause the car not to start. It is at times related to a low battery voltage that could have taken place in your effort to start it.
Got the car with the Stab/ABS faults. Battery tested good (despite 2007 date) and has been on charge while doing diag and cranking. My Harbor Freight OBD scanner is, unfortunately, one of those that can not read ABS codes.
 
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Old 10-26-2012, 07:45 PM
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No spark!

Coil relay is good (swapped with starter relay, known good). Ignition +V fuse is fine, delivering power to the fog lamp switch. Every circuit seems to test as it should, but no light from the plug tester.

If it was cam timing severe enough to not start, I'd expect to have spark and unpleasant noises.

So... is there a cam position sensor that would inhibit spark? Crank position sensor? A way to test either without surgery?
 
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Old 10-26-2012, 08:09 PM
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Look and see if your security light is flashing. You checked your relay but did you check the fuse feeding it?
 
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Old 10-26-2012, 11:18 PM
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Originally Posted by Gus
Look and see if your security light is flashing. You checked your relay but did you check the fuse feeding it?
Security light is not flashing. What would that indicate?
 
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Old 10-27-2012, 08:02 AM
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Thinking that the security system could have gotten confused and went into shutdown it has a direct link to the engine control module. Did you attempt to start the car with the shifter in “N” not “P”? In the past we have seen a few fuse boxes with connection issues. I would to be sure power is being delivered to the ignition coil relay.
 
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Old 10-27-2012, 11:49 AM
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Originally Posted by Gus
Thinking that the security system could have gotten confused and went into shutdown it has a direct link to the engine control module. Did you attempt to start the car with the shifter in “N” not “P”?
Yes. Security, from my understanding, prevents the car from even turning over when it fails.

Originally Posted by Gus
In the past we have seen a few fuse boxes with connection issues. I would to be sure power is being delivered to the ignition coil relay.
All relays are functioning, and each relay is getting power. Test light shows each circuit gets power as it should. Fluke shows correct voltage in the circuits. Don't have a scope at home.

Does anyone know the proper resistance for the crank position sensor? There are a few threads here, and posts elsewhere, talking about similar symptoms, mentioning the sensor, then... *poof* no follow up, no resolution, nothing. I'd like to think that's because it solved the problem but changing parts until something works is a poor way of going about car repair.
 
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Old 10-28-2012, 04:11 AM
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I only know for sure about the 4.2 engine but according to JTIS
Note: If CKP Sensor fault exists, engine will start after approximately 5 seconds of
cranking as the ECM will default to CMP Sensor 1 signal for synchronization.

and there will be a P0335 code.
I can't find exact figures for the CPS but the resistance should be a few hundred ohms and with the meter set to AC you should see a small voltage (>200 mV) when cranking.
 
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Old 10-28-2012, 08:32 AM
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Did you attempt to start the car with the shifter selector switch in the “N” position. The other area I would check would be the exciter ring.

It is located at the ignition switch and it has 2 wires. Ohm it and it should read 33.4.
 

Last edited by Gus; 10-28-2012 at 08:44 AM. Reason: Added Ohm Reading


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