Rough Idle and misfire
#1
Rough Idle and misfire
Hi All,
Quick head scratcher to see what you guys think. My 2010 xkr 5.0 s/c randomly started rough idling as soon as I started it up one morning after being stationary for 5 days. Thought might just need to be run for a bit so started my journey but nope: limp mode after 2mins driving at low revs. Whipped it back home and turned off. Left for rest of the day until I got back from work and started up again but no engine light and rough idle remained. Checked for codes and nothing current or stored. Took it to the garage a week later and engine light came on on the way there. When checking with their reader it showed a cylinder 2 misfire and misfire on startup below 1k revs. The garage put it down to either coil or injector. They replaced the coil but still rough idles and misfire still there. I cut my losses and avoided the Injector replacement (heavily priced quote too). Went to collect the car a week or so later and low and behold, no rough idle or misfire...permanent codes remain stored and can't delete these with my reader bit symptomatically - no rough idling! Any ideas why the problem has suddenly resolved on its own accord???
Thanks in advance :-)
Quick head scratcher to see what you guys think. My 2010 xkr 5.0 s/c randomly started rough idling as soon as I started it up one morning after being stationary for 5 days. Thought might just need to be run for a bit so started my journey but nope: limp mode after 2mins driving at low revs. Whipped it back home and turned off. Left for rest of the day until I got back from work and started up again but no engine light and rough idle remained. Checked for codes and nothing current or stored. Took it to the garage a week later and engine light came on on the way there. When checking with their reader it showed a cylinder 2 misfire and misfire on startup below 1k revs. The garage put it down to either coil or injector. They replaced the coil but still rough idles and misfire still there. I cut my losses and avoided the Injector replacement (heavily priced quote too). Went to collect the car a week or so later and low and behold, no rough idle or misfire...permanent codes remain stored and can't delete these with my reader bit symptomatically - no rough idling! Any ideas why the problem has suddenly resolved on its own accord???
Thanks in advance :-)
#2
Join Date: Jan 2012
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#3
Hey thanks for getting back. There is just short of 120k miles on the clock. I only ever use 99 octane shell v power. The engine light comes on whenever it wants to be honest! Like I said it went off after it came on initially. Then came on again when I took it to the garage. Now taken it back from the garage today and no light and no rough idle at all!
#4
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If the injector is partially blocked, it can result in erratic performance.
In my experience, it's best to replace all four injectors on the same cylinder bank if one is beginning to fail due to the labour involved. If one is beginning to fail, the others are not far behind.
If the MIL begins to flash, shut off the engine as soon as possible because catalyst damage is occurring.
In my experience, it's best to replace all four injectors on the same cylinder bank if one is beginning to fail due to the labour involved. If one is beginning to fail, the others are not far behind.
If the MIL begins to flash, shut off the engine as soon as possible because catalyst damage is occurring.
#5
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#7
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While the coil units and injectors are removed, it's also a good idea to replace the cam cover gasket and spark plug boss seals along with the spark plugs themselves.
If you haven't done so already, replace the heater pipe between the cylinder heads at the back of the engine as it's a known failure point. If either the water outlet under the front of the supercharger, or the heater pipe fail, catastrophic engine damage is the likely result.
If you haven't done so already, replace the heater pipe between the cylinder heads at the back of the engine as it's a known failure point. If either the water outlet under the front of the supercharger, or the heater pipe fail, catastrophic engine damage is the likely result.
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jahummer (11-16-2022)
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#8
After taking it to the mechanic, he has checked all live data and faults which shows there's nothing to suggest an injector fault. Instead he thinks it's an air fuel mix issue and there is a distinct rattling from the inlet manifold and he thinks the flap from this has come off and is giving this intermittent rough idle. Any thoughts on this?
#10
After taking it to the mechanic, he has checked all live data and faults which shows there's nothing to suggest an injector fault. Instead he thinks it's an air fuel mix issue and there is a distinct rattling from the inlet manifold and he thinks the flap from this has come off and is giving this intermittent rough idle. Any thoughts on this?
Open your oil filler cap and smell.... do you smell gasoline?
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guy (11-23-2022)
#11
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#12
Nothing too strong. Obviously doesnt smell of fresh oil its been in there for 9 months but I don't smell any strong stench of petrol.
#13
What usually happens with the direct injectors is that one on either the right or left bank gets stuck open and pumps raw fuel 100% of the time, which douses that cylinder and also reduces the fuel pressure for the other three injectors on that side.
The feel is sort of like a V-8 trying to run on only one bank of cylinders, especially obvious when throttle is applied.
The feel is sort of like a V-8 trying to run on only one bank of cylinders, especially obvious when throttle is applied.
#15
#16
of course! That's understandable. You can only go on what I'm saying subjectively. I guess the general consensus based on what I've described is that the injectors are a strong possibility as culprit for the issue.
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guy (11-23-2022)
#17
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guy (11-23-2022)
#19
Yes the stored codes in this case was misfire cylinder 2 or 3 (cant recall which one) and then a p0316 code.