Another slight issue today - very long

[jonjeffryes]

oh my goodness...today this bloody car nearly gave me a heart attack. It was still showing the Air suspension issue and orange light this am...so I ignored it, especially as you could see and feel the suspension adjust once the engine was started......however I did remove everything from the boot including spare wheel and polystyrene cover so I could check the vacuum tank connectors were all in place; I also unplugged the two electrical connectors and gave them a spray of electrical connector cleaner for good measure to no avail.

Apart from the above and the brake judder, the car has been running really well coping with Autobahn, N roads, Cities and mountain passes....until now that is. On the autobahn today, I had been running at between 90 - 110 mph for around 1/2 hour...usual for the 2 lane autobahn section; the high speed runs were regularly punctuated with hard breaking back to 65 as lorries pulled out to perform overtaking manoeuvres; followed by brisk acceleration using the superchargers grunt up to and holding 100 - 110 mph.

I'd performed this on about 7 - 8 occasions when accelerating (not full throttle but sufficient to make the supercharger whine) there was a massive juddering from the engine - really violent jolting the whole car - I immediately backed off and because of the traffic conditions, had to accelerate again to avoid the following car driving over the top of me! This time, the car accelerated as per normal???

As soon as I could I pulled into the (relatively) slow lane at 70 per - everything operating fine - car smooth, no smoke or bangs - temperature normal. I stopped as soon as I could (within a couple of miles) pulled into services and let the car idle...no issues, smooth & quiet. I revved blipping the throttle gradually increasing the revs - no issues???

So shut things down, let everything settle and then checked the levels - around the engine bay for anything out of place - no funny smells, noises or anything unexpected.

Back on to the autobahn, gradually building speed all OK for about 5-10 miles then the same again - it is like the fuel or the ignition being cut momentarily. this time i slowed down and pulled off the autobahn onto the back roads. This time the EML illuminated. I have my Carsoft reader with me so I connected it, but it would not read the engine module but it did cancel the EML. Again everything checked with nothing obvious???

For the rest of the day and about 70 miles, we have stuck to the back-roads which included mountain climbs and descents, 50mph cruises and 20mph trundles though towns. No problems whatsoever???

The only difference I can place is that I filled the tank at ARAL this am before the trip with Super 95RON that has 5%bio.....about 3/4 of a tankful was needed to fill the tank - I don't know if this has anything to do with it.

Finally, we parked up after the trip. Left the car for an hour and when we came back - no EML and no suspension issues...covered another 20 miles without issue????

What the hell is going on?

[J44EAG]

The bio fuel may have a detergent effect and disturbed some fuel system nasties. Have you changed the fuel filter since owning the car, Jon?

You might try some Cataclean or equivalent. An ideal time to use the chemical with all the high speed driving currently being undertaken.

Your comments about the air suspension are interesting. Since owning my car, I`ve only seen mine rise on start up a couple of times and that was in early days of my ownership. Otherwise little if any suspension inflation occurs that I can detect. I suspect you may have a leak somewhere on the system.

Your trip is certainly finding the gremlins. Thats what happens when a machine is put under a high rate of gunfire!

Mike

[jonjeffryes]

The bio fuel may have a detergent effect and disturbed some fuel system nasties. Have you changed the fuel filter since owning the car, Jon?

You might try some Cataclean or equivalent. An ideal time to use the chemical with all the high speed driving currently being undertaken.

Your comments about the air suspension are interesting. Since owning my car, I`ve only seen mine rise on start up a couple of times and that was in early days of my ownership. Otherwise little if any suspension inflation occurs that I can detect. I suspect you may have a leak somewhere on the system.

Your trip is certainly finding the gremlins. Thats what happens when a machine is put under a high rate of gunfire!

Mike

Thanks for the reply Mike....I have run Cataclean through the car when first purchased but not changed the filter (I knew there was something I would forget )

The cut out was massive...I thought the engine had come off the mounts on the first...or the gearbox had detached...it was that 'hard'. Thankfully, all seems ok...we'll see in the morning what other issues are thrown up, if any

[robv12]

Air Suspension light is an easy fix, or just live with it, it occurs when the piston ring in the compressor becomes worn, the pump fails to reach pressure in a given time, throwing the warning, the suspension works as normal, the one you don't want to see is "vehicle too low"

the fix is , bumper off, compressor off (three bolts, one air line, two leccy plugs), head off the compressor (two bolts), old seal out , new one in, and reassemble, I did one yesterday in less than two hours start to finish, Seal kits are £15 on ebay, loads for sale

problem you will encounter, bumper lower fixings can be a pain to shift, head bolts can snap, so I keep a spare pump ready done to bolt on, other wise its dead easy

some pictures attached of one I did this morning, in reverse order due to the way the website loads them!!, so start at the bottom and work up

[robv12]

on your other issue, it sound like the car is dropping into limp home, it won't rev past 2.5/3K rpm??

there is a vacumn pipe at the rear of the s/charger, this falls off and gives the symptom you describe, a pig to find the first time, but easy when you know where it is, both Mike K and I have had this issue on various cars. Also low battery voltage or a failing battery will drop a 350 into limp home, I have one here that throws knock sensor bank1 bank 2 low input voltage of the battery is not 100%

[jonjeffryes]

Thanks Rob,

I have the kit ready to fit at home (bought when I first purchased the car as an inevitable 'one-day' rebuild. I'll fit that when I return.

The EML can be cancelled and fault code light only comes back on when the engine is under load - not difficult around here as there are a few mountains...and then some more.

I packed a basic tool kit...but forgot the socket drive and spark plug removal gear....nobody around here sells anything that will fit anything less than a John Deere....or German equivalent so I'm a little stuck with regards to anything other than basic work.

The biggest worry is the problems I had on the autobahn. The car is running but seems to have underlining misfire felt mainly c 50mph in 6th gear - low revs and medium load - feels like a vibration through the transmission/engine rather than wheels. I can drive through it and at higher revs it isn't as pronounced but I seem to have an unhappy Jag at the moment

[jonjeffryes]

Thanks Rob,

I have the kit ready to fit at home (bought when I first purchased the car as an inevitable 'one-day' rebuild. I'll fit that when I return.

The EML can be cancelled and fault code light only comes back on when the engine is under load - not difficult around here as there are a few mountains...and then some more.

I packed a basic tool kit...but forgot the socket drive and spark plug removal gear....nobody around here sells anything that will fit anything less than a John Deere....or German equivalent so I'm a little stuck with regards to anything other than basic work.

The biggest worry is the problems I had on the autobahn. The car is running but seems to have underlining misfire felt mainly c 50mph in 6th gear - low revs and medium load - feels like a vibration through the transmission/engine rather than wheels. I can drive through it and at higher revs it isn't as pronounced but I seem to have an unhappy Jag at the moment

[J44EAG]

I suspect you night have a coil or two gone down, Jon.

Symptoms were misfires on my S-types at around 1500 and 2300 which could be driven through as you describe. Old plugs tend to wreck coils. I know you fitted new plugs recently and would guess your old plugs took the best out of the coils. Your recent high speed thrashes just finished one or two off. Perhaps you could find a Main Dealer and get new parts. Maybe the data stream facility on your iCarsoft could pick out the duff coils.

Mike

[jonjeffryes]

I suspect you night have a coil or two gone down, Jon.

Symptoms were misfires on my S-types at around 1500 and 2300 which could be driven through as you describe. Old plugs tend to wreck coils. I know you fitted new plugs recently and would guess your old plugs took the best out of the coils. Your recent high speed thrashes just finished one or two off. Perhaps you could find a Main Dealer and get new parts. Maybe the data stream facility on your iCarsoft could pick out the duff coils.

Mike

Thanks Mike,

I was guessing a duff coil may be the case as it needs the engine to get warm before the problem presents itself - had the same on my S type so i guess I will change the full set of coils when I return.

Can you read the engine module from your iCarsoft? my unit will read every other module but keeps saying it is not compatible with the engine module - I have to read it via ODB2

[J44EAG]

Just tried it on my car, Jon. The same with my car as a result. I wonder if the Carsoft has an issue with our cars which are both around the same age.

I`ve not yet attempted interrogation via my ELM327 Bluetooth OBD and Android/Torque app.

These units whilst being useful do appear to lack the abilities of full blown SDD professional kit. Rather annoying but we have to accept that the more we pay for a tool, the greater number of applications it will serve. The Carsoft unit appears to be lacking in some areas.

My own intermittent engine check and MIL fault persists with the Carsoft just saying there is a comms error but no other enlightening info. I`m currently running with the Carsoft permanently plugged to the car to clear the fault whenever it occurs. This is often about 30 seconds after start up or about 1 min 45 secs into the journey. Once the fault is cleared it never returns in the same journey. I suspect a plug and socket connection issue at the engine management ECU which I`m hoping is just a high resistance point on one of the socket pins. My other suspect is a leaking pressure pipe from the cowhorn charger plenum to the bi-pass actuator. As Rob describes, that pipe can and does go rotten. I had to take an inch off it at the plenum end but the throttle body has to come off to get to the other. A new pipe is on my desk here awaiting my attention.

Mike

[jonjeffryes]

Thanks Mike,

I have a supply of appropriate silicone tubing at home. Is there a diagram anywhere showing all of the vacuum pipes for the 4.2sc unit? I may as well replace all of them if there are more than one.

I would say i definitely have the symptoms of a dodgy coil pack so again, belts and braces and I will replace all 8

To add to my ill's I now have a fluid leak under the car (just about under the drivers side B post) It is sitting there dripping at the moment and looks, smells and feels like plain water?? Do you know where the drain for the air-conditioning system exits?? I wondered if it could be from the condenser maybe as the climate control is running permanently...not noticed before the holiday and I cannot see any topside leaks of reduction of fluid levels in the engine bay

[J44EAG]

That pesky pressure pipe from the cow horn outlet stub pipe to the actuator disappears under the NS edge of the throttle body and wends its way to the actuator on the OS. I`ve not yet replaced my tired pipe as it appears trapped under part of the throttle. Four Torx bolts secure the throttle body to the elbow which bolts to the back end of the charger. Gaining access in that area is extremely difficult due to the over hanging edge of the top of the bulk head. I`ve elected to just tough the issue out until I have the yacht refeb finished and I have the time to put the car out of action for a few days.

The amount of gubbins in the area of the throttle body makes work on the actuator, pipes and EGR valve something which I think is best tackled on the bench. The electrical plugs and sockets also present add to the nause. Worth noting that the third bolt which holds the charger to the plate atop the V of the engine can be removed once the throttle body and elbow have been removed. Tow more accessible bolts at the front of the charger also secure the charger to the top plate. With all removed, the charger lifts off to reveal the coolant hose runs that are easily seen and worked on at the front of the engine. With the charger out of the picture, all these pipes can be inspeccted and changed as required. There is apparently one coolant pipe in the mass that are present which is quite notorious for failing. Like me, Jon, I suspect you would do well to bite the bullet upon return home! Off with the charger for complete peace of mind. The fun will start when you try to identify these hoses with the Main Dealer parts guys. There are a fair quantity of them!

No doubt Rob will have had the top off the 4.2 SC lump and can maybe enlighten us further.

Does your car have a sun roof, Jon? Maybe partially plenum drains if it is. Otherwise the aircon must discharge its condensate somewhere if worked hard. Regret I don`t know where that is.

Hot tip. Buy a cheap M5 whilst you are in Germany!

Mike

[jonjeffryes]

Thanks again Mike,

No sunroof, but I cleared the bulkhead drains in front of the firewall before we left, so maybe it's the drain from there?? I pressure washed the car yesterday as we were attending a wedding today, so there would be a larger amount of water in that area to disperse, plus we had very heavy storms overnight....I'll just keep an eye for now.

Today the car behaved itself (kiss of death for tomorrow now) without the usual dash warnings. Tomorrow is our last full day here so we will cover c.100 miles touring and then pack the car up ready for the return journey.

All in all; apart from the couple of sessions of truculent behaviour; the XJR has proved itself a brilliant long distance touring car. It is so relaxing and so comfortable, we will do it again as soon as we can .....well after we've made it back to blighty and fixed it.