Hi there folks,

I posted this a few weeks ago but didnt get any real feedback, I'll try again...


I guess there could be a lot of answers to this problem through the forum, but Im a newbie and I need some help pretty quick.
I bought a yr 2000 xk8 a few weeks back.

An issue has developed where occasionally upon starting (predominantly from cold) the car fires up but within 5 secs or so of running its starts to run very rough and stalls with warning lighe stating the obvious "stalled"
Seems to stall if regardless of feathering the throttle or not.
I manage to get it restarted pretty quickly with foot to floor to cut out the fuel, then upon catching I feather throttle, car runs very rough (incl white/grey smoke clouds and stink of fuel) and it then settles in under a minute and car is fine for journey.
Doesnt happen every time but maybe 1 in 10/15 times of starting when cold.
On the occasions where it doesnt happen, car starts fine with a perfect idle.


My background with cars is based on onld rwd fords etc so Im not too clued up on the high tech stuff. Im guessing that I need to look at the following...

- Clean maf (done ..no change)
- Clean throttle body & butterfly (done...no change)
- Intake duct check for holes, tears etc (done ... no holes/tears)
- Thinking crank sensor (but surely this would give problems through journey and not just from cold)
- Injector clean ( but car runs perfect when warm)
- Idle air control valve clean(where is it?)
- O2 sensor??

Need some experienced advice ...please..

Thanks
Mike

 

Their could be many opinions about where to start, this is how I would tackle this. First, I would check for any stored codes or pending codes, you need an OBD reader. Then check to see what your long term fuel trims are, this should be a good indicator if you have any vacuum leaks or bad injectors. I would check fuel pressure each time before starting and see if when you have the problem if your fuel pressure is low. It is possible that you have an intermittently leaking fuel injector which dumps fuel and results in pressure loss. Next, check for intake leaks. I know you said you checked the intake tube, but it can be extremely difficult to visually spot problems. I suggest the OBD reader set up to monitor live short term fuel trims and spray starting fluid all around the tube, MAF, TB, intake manifold, and watch for sudden drops in fuel trims. If you see any, you have found a leak. I would also watch live data for as many sensors as possible and jiggle connector and wire harnesses to see if there is a bad connection. I would also search the forum for throttle body electrical connection issues to see what others have experienced with some of the earlier model TB's. You don't mention spark plugs, but there have been problems with leaking valve cover gaskets and o rings allowing oil to fill spark plug wells, this could cause misfires. Pull the coils, check for oils etc, and if you don't know when the last time plugs were changed, consider replacing them. Bottom line, if you smell fuel, you either have too much fuel or not enough spark.

 

Thanks Steve. Ive just orfered an bluetooth obd reader, should get it mid next week.
Havent checked plugs, so Ill do that. Engine is missing when started but comes right when warm, so plugs could be oil contaminated and burn off as car gets warmer, so I'll check those plug wells.

Thanks again,
Mike

 

You are on the right track. My Jaguar had the same symptoms, turned out to be a dried and cracked O ring on the valve cover allowing a small amount of oil to pool in the plug well. Code reader is a must.

 

Regarding the bluetooth code reader, this will work if you have an Android phone, but not an iPhone. Apple has a proprietary BT stack and iPhones won't work with BT code readers, instead you would need a wifi OBD reader.

For what it is worth, I don't like the wifi reader paired with my iPhone because the iPhone makes the active wifi connection the primary path for all (non phone call and text) communications, i.e., Internet, email, etc. this causes me issues with Pandora, TuneIn Radio, and Motion X GPS, where they won't connect to the internet, as they try to go through wifi, which is only local connection to the OBD device, and the iPhone doesn't have enough sense to know there is no internet there and switch to my 4G for Internet. Therefore, if I want a connection to my OBD, I need to not use Pandora, TuneIn, and not search for locations on the GPS app. Now with that said, I plan to purchase a cheap second hand Android for use only with my bluetooth OBD reader.

 

Be aware that when an EFI car is cold the O2 sensors are also cold and will not be reporting to the ECU. This is known as 'open loop' and the engine is operating from pre-determined look-up tables. Once the O2 sensors warm up and begin reporting the engine begins operating in 'closed-loop' and the ECU adjusts injector dwell (on-time) in response to the O2 sensors' signals.

Reading what you posted re: the start-up issue, I'd probably first concern myself with the possibility that you have an injector or two that leaks down overnight. That would flood one cylinder (or more, one leaking injector per cylinder) with raw fuel and cause the misfiring and raw fuel smell until the excess fuel is cleared and enough oil splashes up to reseal the piston rings. One spoiled injector would probably cause a rough idle and slight smell but probably not enough to stall the engine.


There is also the possibility you have one or more injectors that have issues with build-up on their tips. Cold starts allow a lot more fuel than warm engines and nasty injector tips can cause dripping, etc. instead of nice, concentric, fully atomized spray patterns. This can also cause cold start issues. Using a can or two of Techron cleaner, as prescribed on the can, might clear up your problem, then again, maybe not. For a few bucks you may try it as a Hail Mary before delving deeper.


How to diagnose? Either have someone knowledgeable and equipped do an injector leak-down test or do it yourself. You'll need a fuel pressure tester to watch how much pressure is lost after engine shut-down. I wouldn't be too concerned over a 5-8 psi loss overnight but much more than that and I'd be looking for the cause.


One other thing comes to mind. As I recall (and we're talking the memory of an old guy with a failing memory and a wide-spread number of various vehicles on his plate) the earlier XK8s had some sort of air system employed with the injectors. You might acquaint yourself with how that system operates or at least find someone familiar with it if the simple things don't return any solid information.

 

Thanks Guys ,

All very valuable info. I'll post progress as sonn as I get some time to spend on the car.
Mike

 

Im in the same boat as you. got pretty much the exact same fault, its so random that im not sure of the cause either, i have cleaned the throttle body and maf sensor and it hasnt happened for 2 days but im sure its gonna happen again soon.

i have jsut bought a code reader that im going to use with my iphone or laptop to check everything out, like fuel trims spraying carb cleaner around the valve cover gaskets and air intakes and see if that affects anything.

i just thought it would idle rough all the time if there was an air leak not just from cold until the engine reaches temperature.

Keep us informed, cheers

 

Hi Steevo,

I'll let you know if I make any progress, please do likewise. Im not going to get much time to work on the car over the next few weeks (its not my daily driver either), but code reader due this week and when I get time Id like to do a leakdown test on the injectors, i think i could do this by pressurisning the rail, then turning off ign and have some plastic bottles taped to each injector and see if any leak over night.

Rgds,
Mike

 

Can you pressurize the rail by attaching a cycle pump to the valve on top and pump it till you reack say 30psi and look for leaks around the gaskets with leak detector spray or see if rhe pressure gauge drops over night?

 

It'll pressurise every ignition on, won't it?

 

Yes, I assumed turn on ign to pressurise, then turn off and see if any injectors leak into attached bottles overnight to identify if injectors leaking fuel into cylinders overnight could be the cause a rough idle and difficult start up from cold.
Rgds,
Mike

 

Easy to check fuel trims and proceed as in an earlier post. Cheap to do.

 

If you suspect they are leaking maybe its worth running some of that injector cleaner stuff through to see if that helps. Thats on my to do list

 

ck engine coolant temp sensor !

 

Ok hear where Im at....

Car continues to shudder on startup when cold ,eventually settles down after 5 mins or so.

- Ive checked intake side with carb cleaner, nothing found
- Maf cleaned
- Throttle body and butterfly cleaned
- Injector cleaner used
- plugs on left bank look clean and no oil in plug wells (didnt get time to do other bank)

Ive checked the codes and heres what I got...

P1316 and P0300 CODES : Left bank multiple misfires I think.
Fuel trims: LTFT=20.3 and STFT=0

Also had some message about "Fuel System Status : Open loop due to system failure" Whats this mean????

I noted some other data...

Air/fuel ratio = 14.7 (thats normal)
Intake = 21.2psi
Maf 8.5gs
Timing advance hovered between 4.5-6.5

Should I post a separate thread with thsi info to solicit a bit more help?

Thanks,
Mike

 

That's a very high LTFT value. the P1316 is misfire excess emissions, possible causes:

Cylinder compression low
Worn camshaft / broken valve spring(s)
Fuel delivery pressure (low / high)
Fuel injector(s) blocked / leaking
Fuel injector(s) continuously open
Fuel contamination
Fuel injector circuit fault(s) (Injector DTCs also flagged)
Spark plug failure / fouled / incorrect gap
ECM to ignition module primary circuit
fault(s) (Cylinder misfire detected DTC
also flagged)
Ignition module ground circuit open
circuit, high resistance
Ignition module / coil failure

Don't panic when you read that list; its likely to be something easy and fairly cheap to fix, rather than the top couple of items which are pretty major!

Take fuel trim readings at a range of revs. In particular if they drop at high revs you are looking at a vacuum leak. Since the STFT value is low, at first glance I'd guess that this isn't the problem.
How do the fuel trims compare left/right? You should have LTFT1 and 2 (Long term fuel trim on bank 1 and 2). If they are both high, I'd suspect the MAF or a leak before the throttle.
If one side is worse than the other, it could be 02 sensor on that side.
Again air/fuel ratio I would expect one value per side, I'm not sure I've seen this value on my iphone so don't know if you can rely on it to test the 02 sensors.
You can check for a faulty MAF (at least on aspect anyway) by taking the peak flow measurement; as I was advised in another thread, record MAF rate only to get a high resolution output, and get the car on the limiter in second (third if you have time/space). Post the peak flow value here, there should be a like-for-like measurement somewhere for the xk8; I'll have to see if I can find it.
I haven't had the misfortune of injector problems (touch wood); that's another avenue to go down that someone else will be able to help with. At least you're not going to have to take the blower off to work on the injectors!

You may find in the next couple of days you start getting individual misfire codes. If you do, try swapping plugs and then coils between cylinders to see if the misfires move.

The following threads may help you:
https://www.jaguarforums.com/forum/x...-fault-109766/
https://www.jaguarforums.com/forum/g...ed-quiz-49317/
https://www.jaguarforums.com/forum/x...-trims-109508/

 

Ill make this easy for you,as I see your confused.

Delete the codes, drive the car, see what codes return,.Then repair that specific code only.

Your looking at replacing coil packs and spark plugs.

 

Is there a list of what the average gauges should be, as i have got lots of information using dashcommand with live data logging but dont know what im meant to be looking for.

going to give bg-44k cleaner a go see if that helps.

what injector cleaner did you use dublinmike?

 

I cant get BG44K here. I used a redex one shot injector cleaner.

Kreyszig, thanks for the info, I nearly passed out when I looked at the first few as I wouldnt have the finds to fix those sort of problems. Given the problem always settles down after 5 mins running would that not rule out some of the possible causes such as poor compression etc.

Thanks Aode06, Plugs look fine and normal brown but I dont know how much miles they have done. I guess I just should replace them? Theyre max 88k but look ok.

Think I start by removing inj rail and see have I got leaky injectors. May take a few days to give some feedback as I dont get a lot of spare time to play with the xk.