Discussion
I'm sorry to keep 'harking on' about this, but I'm really struggling with this one 
I've been looking at her again tonight and am still no further. I've taken her out for a bit as well, I'm going to go through what she feels like as my observations have changed a bit;
Idling
She doesn't sound totally right whilst idling. Not awful, just not right. The revs sound like they're falling and raising slightly, not by much perhaps 50/100 rpm - I honestly cannot say that it's not always done this, sometimes you only notice these things when you're actually looking for a problem.
Most noticeably when idling though is that she's popping a lot from one of the tail pipes - a couple of pops a second. Whereas the other doesn't pop at all. Somebody commented on either here or Yahoo that this is normal as their's does it, as above I honestly cannot say for definate that it didn't do it before, but I don't think it did. And to me it's the fact that it's only doing it from one that seems most signifigant.
Can anybody tell me how the silencer is plummed inside? is it pretty much a straight pipe going from one side where is connects to the cat accross the silencer to come out the other side with the tail pipe or something else?
Normal Driving
To drive normally she isn't too bad. It just feels rough. Light to medium throttle will result in a car that mostly accelerates normally, but surges a lot. Instead of being smooth the power is uneven as it accelerates - noticeable to the driver but not terribly noticeable to a passenger.
Most noticebly is that she is cracking a lot out of the exhaust. Where normally if I give the car plenty of stick I may oocasionaly get the odd crack out of the exhuast every now and then, whereas now you'll get at least one full blown crack as you accelerate through the rev range in each gear.
Full Throttle - Spirited Driving
This is pretty much a no go. You'll get a massive crack out of the rear, the car will just feel like you are driving into a 100mph head wind or somebody has stuck a hill in front of you. It's not as severe as fuel cut, ie it doesn't feel like somebody's stuck the brakes on, it just feels like it really doesn't want to accelerate.
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I'm just after suggestions for what to look at, no matter how crazy. Or even a rough suggestion as to what is likely to be going on based on my observations. I'm thinking the popping and cracking is unburnt fuel in the exhaust system, so she's either massively over fueling or one or more cylinders isn't firing.
How would it feel if one cylinder wasn't firing on a v8? I'd know for a 4 cylinder, but would it be noticeable on a v8?
o2 sensors, do these fail on these? I'm thinking about swapping post cat to pre cat sensors over to see what happens?
Somebody suggested that the cambelt could've jumped a tooth, is this likely, based on my observations? How would I be a able to tell? It was changed 3,000 miles ago, does this make this more or less likely?
If I could get this down to a bank then this would help me, which is why I'm eyeing the popping from one of the tail pipes, at least then I can set about swapping bits between banks and see if the fault moves.
Sorry for my ramblings, but any suggestions are very much appreciated and always looked into.
Col
I've been looking at her again tonight and am still no further. I've taken her out for a bit as well, I'm going to go through what she feels like as my observations have changed a bit;
Idling
She doesn't sound totally right whilst idling. Not awful, just not right. The revs sound like they're falling and raising slightly, not by much perhaps 50/100 rpm - I honestly cannot say that it's not always done this, sometimes you only notice these things when you're actually looking for a problem.
Most noticeably when idling though is that she's popping a lot from one of the tail pipes - a couple of pops a second. Whereas the other doesn't pop at all. Somebody commented on either here or Yahoo that this is normal as their's does it, as above I honestly cannot say for definate that it didn't do it before, but I don't think it did. And to me it's the fact that it's only doing it from one that seems most signifigant.
Can anybody tell me how the silencer is plummed inside? is it pretty much a straight pipe going from one side where is connects to the cat accross the silencer to come out the other side with the tail pipe or something else?
Normal Driving
To drive normally she isn't too bad. It just feels rough. Light to medium throttle will result in a car that mostly accelerates normally, but surges a lot. Instead of being smooth the power is uneven as it accelerates - noticeable to the driver but not terribly noticeable to a passenger.
Most noticebly is that she is cracking a lot out of the exhaust. Where normally if I give the car plenty of stick I may oocasionaly get the odd crack out of the exhuast every now and then, whereas now you'll get at least one full blown crack as you accelerate through the rev range in each gear.
Full Throttle - Spirited Driving
This is pretty much a no go. You'll get a massive crack out of the rear, the car will just feel like you are driving into a 100mph head wind or somebody has stuck a hill in front of you. It's not as severe as fuel cut, ie it doesn't feel like somebody's stuck the brakes on, it just feels like it really doesn't want to accelerate.
===================
I'm just after suggestions for what to look at, no matter how crazy. Or even a rough suggestion as to what is likely to be going on based on my observations. I'm thinking the popping and cracking is unburnt fuel in the exhaust system, so she's either massively over fueling or one or more cylinders isn't firing.
How would it feel if one cylinder wasn't firing on a v8? I'd know for a 4 cylinder, but would it be noticeable on a v8?
o2 sensors, do these fail on these? I'm thinking about swapping post cat to pre cat sensors over to see what happens?
Somebody suggested that the cambelt could've jumped a tooth, is this likely, based on my observations? How would I be a able to tell? It was changed 3,000 miles ago, does this make this more or less likely?
If I could get this down to a bank then this would help me, which is why I'm eyeing the popping from one of the tail pipes, at least then I can set about swapping bits between banks and see if the fault moves.
Sorry for my ramblings, but any suggestions are very much appreciated and always looked into.
Col
I've just had straight thru pipes fitted to my V8 and yesterday and today I've noticed that only one side is making a popping noise at idle. An S4s owner did suggest it was my ears ( cheeky git ) but he listened to it today and said the same thing. So the popping on one side might be a bit of a red herring.
Adrian said:
So the popping on one side might be a bit of a red herring.
I know
was it there before or not, that is the million dollar question The one thing is, it is very noticeable. One exhaust just sounds like an exhaust, whereas the other is giving very noticeable {though not loud cracks or bangs, just pops} pops at least every second, sometimes multiple pops a second.
I don't think it's anything as serious as a cambelt issue. Probably a coil pack/plug leads or possibly, like you mention, an O2 sensor.
You have a couple of choices - 1..start swapping parts for new ones (lowest costed part first!) and hope you stumble across the correct, er faulty, part early on in your experiment..
or 2..get the car plugged into a diagnostic tool to give you some idea as to what the ecu might have to complaining about.
I see you're on the IOW, well a short ferry ride and a 20 mins chug along the A36 will get you to the guys at Sportomotive in Salisbury. They know their stuff and won't charge you a million pounds, either. (Cos or Dave on 01722 410893)
I'm assuming you still have your cats in place, so remember that they don't like unburnt fuel chucked at them.
You have a couple of choices - 1..start swapping parts for new ones (lowest costed part first!) and hope you stumble across the correct, er faulty, part early on in your experiment..
or 2..get the car plugged into a diagnostic tool to give you some idea as to what the ecu might have to complaining about.
I see you're on the IOW, well a short ferry ride and a 20 mins chug along the A36 will get you to the guys at Sportomotive in Salisbury. They know their stuff and won't charge you a million pounds, either. (Cos or Dave on 01722 410893)
I'm assuming you still have your cats in place, so remember that they don't like unburnt fuel chucked at them.
If you want to pop along to the Castle Coombe action day on saturday, I can bring my Autoxray 4000 to plug in ... www.lotusespritworld.co.uk/EMaintenance/OBII_4000.html
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