997 C4S hesitation at 2200rpm
Discussion
Hi all,
My gen 1 (2008) C4S sometimes (only 3-4 times in the last 1000 miles) hesitates at approx 2200 rpm. It definitely happens in 3rd gear and possibly 4th as well. It doesn't do it if my foot is to the floor and I'm accelerating hard, but does it if I keep it at the affected revs. It's difficult to describe but almost feels as if it misses a beat, a hesitation, or misfire. Many many years ago (in a different car) I ran out of fuel and the hesitation as it ran on fumes was very similar.
Can anyone advise?
My gen 1 (2008) C4S sometimes (only 3-4 times in the last 1000 miles) hesitates at approx 2200 rpm. It definitely happens in 3rd gear and possibly 4th as well. It doesn't do it if my foot is to the floor and I'm accelerating hard, but does it if I keep it at the affected revs. It's difficult to describe but almost feels as if it misses a beat, a hesitation, or misfire. Many many years ago (in a different car) I ran out of fuel and the hesitation as it ran on fumes was very similar.
Can anyone advise?
Unless the behavior is pronounced probably normal. In the higher gears the DME can adjust the intake valve timing perhaps even switch to low valve lift and could be driving the car at the RPMs in the right way -- low load -- to trigger this. It is more noticeable when this occurs in the higher gears whereas in the lower gears it is not.
While 2200 RPMs is not that low, I generally avoid low RPM usage in the higher gears, although my Boxster is pretty good down around 1000 in 4th. But its VarioCam system is of an older style than the one in your car's engine.
I take the fuel filter is not too terribly old, and the plugs are not past due and you run a good quality gasoline and buy from a busy station to ensure you get the freshest gasoline?
Do you ever just take the car out for a nice 30+ mile highway drive? These engines can perk up some after a 30+ mile highway drive.
Absent any CEL, active (or pending) codes, going to be a bit of an expensive hunt to find the "cause".
While 2200 RPMs is not that low, I generally avoid low RPM usage in the higher gears, although my Boxster is pretty good down around 1000 in 4th. But its VarioCam system is of an older style than the one in your car's engine.
I take the fuel filter is not too terribly old, and the plugs are not past due and you run a good quality gasoline and buy from a busy station to ensure you get the freshest gasoline?
Do you ever just take the car out for a nice 30+ mile highway drive? These engines can perk up some after a 30+ mile highway drive.
Absent any CEL, active (or pending) codes, going to be a bit of an expensive hunt to find the "cause".
Thanks for all the replies. To answer your questions;
I've had the car 3 months and only done 1200 miles.
It's not used any oil and neither side of the exhaust appears sootier than the other.
It's a weekend car so I've not, and probably won't, drive it in the wet.
Rockster the behaviour is definitely not pronounced, it took me a while to be sure that it was actually there at all. Always run on Shell V Power (99 Ron) since I've had it, it's had 4-5 tanks of this now.
As for fuel filter, plugs and coil packs; it was serviced by the garage that I bought it from so assume everything is in order. Can never be too sure though.
The hesitation is barely perceptible to be honest and I only really posted on here to make sure it wasn't something serious such as a sign of bore scoring or IMS failure. If it's unlikely to be this then I would feel much better.
In terms of plugging into diagnostics for a check up; do you think it's worth it?
Rob
I've had the car 3 months and only done 1200 miles.
It's not used any oil and neither side of the exhaust appears sootier than the other.
It's a weekend car so I've not, and probably won't, drive it in the wet.
Rockster the behaviour is definitely not pronounced, it took me a while to be sure that it was actually there at all. Always run on Shell V Power (99 Ron) since I've had it, it's had 4-5 tanks of this now.
As for fuel filter, plugs and coil packs; it was serviced by the garage that I bought it from so assume everything is in order. Can never be too sure though.
The hesitation is barely perceptible to be honest and I only really posted on here to make sure it wasn't something serious such as a sign of bore scoring or IMS failure. If it's unlikely to be this then I would feel much better.
In terms of plugging into diagnostics for a check up; do you think it's worth it?
Rob
JapanRed said:
Thanks for all the replies. To answer your questions;
I've had the car 3 months and only done 1200 miles.
It's not used any oil and neither side of the exhaust appears sootier than the other.
It's a weekend car so I've not, and probably won't, drive it in the wet.
Rockster the behaviour is definitely not pronounced, it took me a while to be sure that it was actually there at all. Always run on Shell V Power (99 Ron) since I've had it, it's had 4-5 tanks of this now.
As for fuel filter, plugs and coil packs; it was serviced by the garage that I bought it from so assume everything is in order. Can never be too sure though.
The hesitation is barely perceptible to be honest and I only really posted on here to make sure it wasn't something serious such as a sign of bore scoring or IMS failure. If it's unlikely to be this then I would feel much better.
In terms of plugging into diagnostics for a check up; do you think it's worth it?
Rob
????I've had the car 3 months and only done 1200 miles.
It's not used any oil and neither side of the exhaust appears sootier than the other.
It's a weekend car so I've not, and probably won't, drive it in the wet.
Rockster the behaviour is definitely not pronounced, it took me a while to be sure that it was actually there at all. Always run on Shell V Power (99 Ron) since I've had it, it's had 4-5 tanks of this now.
As for fuel filter, plugs and coil packs; it was serviced by the garage that I bought it from so assume everything is in order. Can never be too sure though.
The hesitation is barely perceptible to be honest and I only really posted on here to make sure it wasn't something serious such as a sign of bore scoring or IMS failure. If it's unlikely to be this then I would feel much better.
In terms of plugging into diagnostics for a check up; do you think it's worth it?
Rob
It's the perfect 911 for wet conditions!
Three options for you:
Plugs. (They have more effect than you might think)
Pre-cat lambda sensors. (They fail more then you might think)
Mass Air Flow Sensor. (Although they're actually more reliable than people make-out)
Plugs are relatively cheap and easily replaced (if you go to a decent indy). You should get them done as a matter of course. My instinct is the pre-cat lambdas are not doing their job properly. They can cause issues long before throwing a CEL. Again, a relatively easy item to replace, but more expensive.
As already said above, a full diagnostic check is really a prerequisite - it's never a good idea to just start throwing parts at a problem. Experiences have taught me, however, that a diagnostics check doesn't always find problems with the M97 engine (especially if the operator doesn't really know what the information means and is just looking for fault codes). It will however, normally show-up MAF faults, air leaks and coil-pack problems as well as more complex issues such as variocam and sensor faults and failures.
Plugs. (They have more effect than you might think)
Pre-cat lambda sensors. (They fail more then you might think)
Mass Air Flow Sensor. (Although they're actually more reliable than people make-out)
Plugs are relatively cheap and easily replaced (if you go to a decent indy). You should get them done as a matter of course. My instinct is the pre-cat lambdas are not doing their job properly. They can cause issues long before throwing a CEL. Again, a relatively easy item to replace, but more expensive.
As already said above, a full diagnostic check is really a prerequisite - it's never a good idea to just start throwing parts at a problem. Experiences have taught me, however, that a diagnostics check doesn't always find problems with the M97 engine (especially if the operator doesn't really know what the information means and is just looking for fault codes). It will however, normally show-up MAF faults, air leaks and coil-pack problems as well as more complex issues such as variocam and sensor faults and failures.
I have a vaguely similar issue on my 996, but the hesitation is only felt under full throttle at around 5500-6000 rpm. Mike at Sports & Classic checked it when it was serviced recently and noted that the MAF was working at the very limit of its window of tolerance, so was likely the issue. I spoke to the previous owner at the March RS day and he confirmed that the symptoms were the same just before the MAF was last changed (about 6-7 years ago) and a new one resolved it. I tried to get one on the day (Jonny from Unit 11 was coming down so tried to get one for me, but they only had one of 2 types in stock and mine was the other one, Sod's Law) as clearly I'd have lapped even faster with more ooommphh. I've bought one since but not got around to fitting it yet but I'm quite confident it'll sort it (it's a very minor issue that virtually no-one else would notice) and it can't do any harm.
I had a slight low rev hesitation in recent months but only during the first 5 mins of the journey and only a handful of times. Then, one day after a really through wash of the car, it started running on fewer cylinders than it should have been. Turns out some coil packs had failed so I had them all changed and since then, touch wood, all has been perfect with no hesitations.
I would suggest the OP takes a look at condition of the coil pack cases to see if they're cracking badly. If so then that could well be the cause and the symptom of what will be a bigger failure.
I would suggest the OP takes a look at condition of the coil pack cases to see if they're cracking badly. If so then that could well be the cause and the symptom of what will be a bigger failure.
My turbo has been doing this - only at light throttle / constant speed, and it feels like it occasionally doesn't fire for a split second.
Mine seems to be pre-cat O2 sensor on bank 1. It's logged a couple of fault codes there, and - more conclusively - it seems to sit at 1v constantly whereas bank 2 varies with throttle!
Mine is currently at the mechanics having that - and a dodgy sunroof - fixed.
Mine seems to be pre-cat O2 sensor on bank 1. It's logged a couple of fault codes there, and - more conclusively - it seems to sit at 1v constantly whereas bank 2 varies with throttle!
Mine is currently at the mechanics having that - and a dodgy sunroof - fixed.
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