Rough idle on startup..please Help
#21
06-09-2014, 11:46 AM
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.
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.
I wouldn't be concerned about loss of compression and other more serious problems since as you say, the other symptoms don't fit.
just read the post about leaking injectors, that does seem to fit with the fuel smell which I had somehow missed earlier.
Good luck!
Last edited by kreyszig; 06-09-2014 at 11:49 AM.
#22
06-15-2014, 07:41 AM
Veteran Member
#23
06-16-2014, 04:07 AM
Thanks JagV8, but the problem is rough idle on startup, it clears after 5 mins of so and is down on a few cyls initially.
If it was air leak surely it the problem would persist.
I have found oil in one sparkplug well where it weeped out of valve cover. Ive tightenened the bolts holding the valve cover and im awaiting delivery of new plugs.
Last time I started it the Torque app gave misfire faults x 8... ie all cylinders.
Ill put in the new plugs and take it from there, ie leakdown test after that.
Mike
If it was air leak surely it the problem would persist.
I have found oil in one sparkplug well where it weeped out of valve cover. Ive tightenened the bolts holding the valve cover and im awaiting delivery of new plugs.
Last time I started it the Torque app gave misfire faults x 8... ie all cylinders.
Ill put in the new plugs and take it from there, ie leakdown test after that.
Mike
#24
06-16-2014, 12:08 PM
Veteran Member
#25
06-17-2014, 07:18 AM
as is yours that changing the plugs is unlikely to help! it's a good place to start and the last thing you want to find out after changing 8 coils is that the plugs were the problem... just my 2 penneth
#26
06-17-2014, 10:18 AM
Veteran Member
Sort of, except I've seen a lot of people post that they've changed the plugs and got no improvement, and I've also seen that coils are usually to blame. You don't have to be in the same situation but if I were a betting man...
I'd definitely check LTFT as I first posted, no matter what. By far the cheapest.
I'd definitely check LTFT as I first posted, no matter what. By far the cheapest.
#27
06-18-2014, 03:48 AM
Thanks JagV8, some more questions for you...
What values am I looking for on the LTFT's idle and above 2500 that would indicate intake/vac leak?
As regards coils, is the only way to diagnose just to buy 2 coils and swap them around to see which ones are dodgy?
Why do I get misfires on all 8 cyls on the scanner yet only one plug well has oil?
If its coils why does it sort itself out after 5 mins of starting the engine?
I got plugs today,so Ill fit them over the next day or two, seal the oil leak temporarity whilst I order a valve cover gasket and plug orings from the uk.
What values am I looking for on the LTFT's idle and above 2500 that would indicate intake/vac leak?
As regards coils, is the only way to diagnose just to buy 2 coils and swap them around to see which ones are dodgy?
Why do I get misfires on all 8 cyls on the scanner yet only one plug well has oil?
If its coils why does it sort itself out after 5 mins of starting the engine?
I got plugs today,so Ill fit them over the next day or two, seal the oil leak temporarity whilst I order a valve cover gasket and plug orings from the uk.
#28
06-18-2014, 09:42 AM
This is a classic case for a leaking fuel injector. When they leak down overnight, that cylinder misfires and smokes until the excess fuel gets dispersed as the piston throws it out. A little rarer would be a boo-boo EGR valve that is sticking when cold. When it gets old and gummed up, it can stick open and cause a vacuum leak. Pull it and clean off the valve area to be sure.
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BurgXK8 (07-12-2014)
#29
06-18-2014, 04:06 PM
Veteran Member
#30
06-19-2014, 03:47 AM
#31
07-16-2014, 06:26 PM
Me too....
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.
.
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.
.
1) Returned from 800 mile road trip, parked car (2003 XKR) overnight in garage.
2) Started her up the next morning and got a rough idle. Based on what you described above, I could have a clogged or leaking injector. Codes showed p0305, meaning the #5 injector is misfiring, according to the book.
3) Dumped some Lucas injector cleaner into a full tank the following day, hoping I could clear up the problem with a ten dollar Hail Mary. Ha. Not a chance (why can't I just get flat tires anymore??)
4) Car now starts and idles ok, but once warmed up runs like it is on 4 cylinders. page 6 of the OBD guide here
describes my situation almost exactly. I am now getting p0305, p1313, p1316 and p1000 codes.
5) half way home from this short test drive i stopped to push the injector plugs in just a bit as much as I thought they would move - in the hopes one or two of them was just a bit loose. No dice - had no effect on the rest of the drive home.
Is there anything I may have missed? I read something about IMT o-rings which confused me but I do not think that is related.
#32
07-17-2014, 03:44 AM
This sounds very similar to a problem I've just discovered:
1) Returned from 800 mile road trip, parked car (2003 XKR) overnight in garage.
2) Started her up the next morning and got a rough idle. Based on what you described above, I could have a clogged or leaking injector. Codes showed p0305, meaning the #5 injector is misfiring, according to the book.
3) Dumped some Lucas injector cleaner into a full tank the following day, hoping I could clear up the problem with a ten dollar Hail Mary. Ha. Not a chance (why can't I just get flat tires anymore??)
4) Car now starts and idles ok, but once warmed up runs like it is on 4 cylinders. page 6 of the OBD guide here
describes my situation almost exactly. I am now getting p0305, p1313, p1316 and p1000 codes.
5) half way home from this short test drive i stopped to push the injector plugs in just a bit as much as I thought they would move - in the hopes one or two of them was just a bit loose. No dice - had no effect on the rest of the drive home.
Is there anything I may have missed? I read something about IMT o-rings which confused me but I do not think that is related.
1) Returned from 800 mile road trip, parked car (2003 XKR) overnight in garage.
2) Started her up the next morning and got a rough idle. Based on what you described above, I could have a clogged or leaking injector. Codes showed p0305, meaning the #5 injector is misfiring, according to the book.
3) Dumped some Lucas injector cleaner into a full tank the following day, hoping I could clear up the problem with a ten dollar Hail Mary. Ha. Not a chance (why can't I just get flat tires anymore??)
4) Car now starts and idles ok, but once warmed up runs like it is on 4 cylinders. page 6 of the OBD guide here
describes my situation almost exactly. I am now getting p0305, p1313, p1316 and p1000 codes.
5) half way home from this short test drive i stopped to push the injector plugs in just a bit as much as I thought they would move - in the hopes one or two of them was just a bit loose. No dice - had no effect on the rest of the drive home.
Is there anything I may have missed? I read something about IMT o-rings which confused me but I do not think that is related.
If it's as rough as you saw when warm then I would expect a few more codes?
edit: my cylinder numbering (2000) is different to yours, I think. by 8 I meant a coil on the same bank, and I would use one as far away as possible, probably makes near as no difference
Last edited by kreyszig; 07-17-2014 at 03:49 AM.
#33
07-17-2014, 03:46 AM
Veteran member
Burg, swap that #5 coil to an adjoining plug. I've gone thru a coil myself. You don't have any IMT o-rings to worry about on your 4.2.
If its not the coil, it might be the connector (cracked/brittle)...and you can always pull #5 spark plug while you're swapping the coil...just to get a visual on it too.
If its not the coil, it might be the connector (cracked/brittle)...and you can always pull #5 spark plug while you're swapping the coil...just to get a visual on it too.
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BurgXK8 (07-17-2014)
#36
07-17-2014, 09:43 AM
Pulled a few of the plugs and found the one closest to the firewall on the driver side (not sure if that is number 5 or not) to be soaked in gasoline. It makes no difference whether I connect or disconnect the lead to that coil pack, so I presume this is what is causing the rough running.
Is it best to replace all coil packs at once or can I get away with a cheapie and do just the problematic one - assuming that is the only problem?
Thanks!
EDIT: The one closest to the firewall on the driver side is the #8 plug, according to the diagram I found for my car. The #5 cylinder is on the passenger side of the engine, second from front. So... could have more than one bad coil or a combination of coil/injector problems. We shall see...
Is it best to replace all coil packs at once or can I get away with a cheapie and do just the problematic one - assuming that is the only problem?
Thanks!
EDIT: The one closest to the firewall on the driver side is the #8 plug, according to the diagram I found for my car. The #5 cylinder is on the passenger side of the engine, second from front. So... could have more than one bad coil or a combination of coil/injector problems. We shall see...
Last edited by BurgXK8; 07-17-2014 at 10:41 AM.
#37
07-17-2014, 11:41 AM
Pulled a few of the plugs and found the one closest to the firewall on the driver side (not sure if that is number 5 or not) to be soaked in gasoline. It makes no difference whether I connect or disconnect the lead to that coil pack, so I presume this is what is causing the rough running.
Is it best to replace all coil packs at once or can I get away with a cheapie and do just the problematic one - assuming that is the only problem?
Thanks!
EDIT: The one closest to the firewall on the driver side is the #8 plug, according to the diagram I found for my car. The #5 cylinder is on the passenger side of the engine, second from front. So... could have more than one bad coil or a combination of coil/injector problems. We shall see...
Is it best to replace all coil packs at once or can I get away with a cheapie and do just the problematic one - assuming that is the only problem?
Thanks!
EDIT: The one closest to the firewall on the driver side is the #8 plug, according to the diagram I found for my car. The #5 cylinder is on the passenger side of the engine, second from front. So... could have more than one bad coil or a combination of coil/injector problems. We shall see...
I'd swap 8 and 5 with another on their respective banks, after clearing codes. Then fire her up and see if there's any change. Sometimes you need a couple of drive cycles for a cylinder specific misfire code to stick (I think!) so bear that in mind.
#38
07-18-2014, 12:11 PM
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