Replacing lifters to address a misfire, some questions.
07-26-2019, 04:42 PM
#62
Great write up. Since you have done so much to address your issue, figure reaching out for an advice. I have been dealing with intermittent random misfire for over 6 months now. It is a 2001 3.4L C4 with 100,000k miles. I have checked the following:
-Fuel pressure
-New MAF
-New crank sensor
-New fuel injecters,
-New plugs+coils
-New DME and Injector relays
-Check vacuum and fule trims
-Oxygen sensor response looks normal
-cam deviation at -3, and +4
-new fuel filter
-cold compression test all around 138 psi
-leak down test on all less then 8%
The misfire is very intermittent and random from cylinder to cylinder, all 6 of them. I do notice there is tapping noise some time, but not all the time. When I hear the tapping, it will clear when I light increase the RPM. No misfire when doing spirited run. It always happen when cruising around 1800 rpm to 2800 rpm. The faults codes are always the P0300 plus a couple P0301 to 6 randomly. There is no other codes that come with the misfires. Question 1. Do you think it is the Variocam got anything to do with this, since this always happen at the time advancement range(Variocam, not the plus), though no other code? Question 2. What is chance do you think that all lifters are failing? 3. Another thing I am thinking is a faulty DME.
As you described in your first post" So after plenty of reading and the above facts I am sure I have sticking lifters, it also makes sense when you look at the symptoms, then the car is hot and you run at high RPM when the liter is activated, it sticks and then as the revs drop it is over filling the cylinder and triggering a CEL. It cools, the lifter retracts and then it runs fine. " Can you explain a little bit or point me to other reading on why you were so sure it was the lifters?
Any feedback would be great to help me in solving this dreaded random misfire. Thanks.
-Fuel pressure
-New MAF
-New crank sensor
-New fuel injecters,
-New plugs+coils
-New DME and Injector relays
-Check vacuum and fule trims
-Oxygen sensor response looks normal
-cam deviation at -3, and +4
-new fuel filter
-cold compression test all around 138 psi
-leak down test on all less then 8%
The misfire is very intermittent and random from cylinder to cylinder, all 6 of them. I do notice there is tapping noise some time, but not all the time. When I hear the tapping, it will clear when I light increase the RPM. No misfire when doing spirited run. It always happen when cruising around 1800 rpm to 2800 rpm. The faults codes are always the P0300 plus a couple P0301 to 6 randomly. There is no other codes that come with the misfires. Question 1. Do you think it is the Variocam got anything to do with this, since this always happen at the time advancement range(Variocam, not the plus), though no other code? Question 2. What is chance do you think that all lifters are failing? 3. Another thing I am thinking is a faulty DME.
As you described in your first post" So after plenty of reading and the above facts I am sure I have sticking lifters, it also makes sense when you look at the symptoms, then the car is hot and you run at high RPM when the liter is activated, it sticks and then as the revs drop it is over filling the cylinder and triggering a CEL. It cools, the lifter retracts and then it runs fine. " Can you explain a little bit or point me to other reading on why you were so sure it was the lifters?
Any feedback would be great to help me in solving this dreaded random misfire. Thanks.
07-26-2019, 05:12 PM
#63
Rennlist Member
i'm sure you will get feedback from others more knowledgeable than me, but there's been lots of discussions lately about the "tapping sound" you are describing. look at a recent post "tap, tap, tap". best of luck.
07-26-2019, 05:36 PM
#64
Just a car guy
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Great thread!
It would be nice to get an update on the status of the car after all of this work. Hope everything is still on the positive.
I have to admit, I had apprehension as to whether there would be a less than desirable outcome after being driven for a while. Certainly hope those fears are unfounded.
...tagged for future reference...
It would be nice to get an update on the status of the car after all of this work. Hope everything is still on the positive.
I have to admit, I had apprehension as to whether there would be a less than desirable outcome after being driven for a while. Certainly hope those fears are unfounded.
...tagged for future reference...
07-27-2019, 04:45 PM
#65
Originally Posted by Di Zhao
Great write up. Since you have done so much to address your issue, figure reaching out for an advice. I have been dealing with intermittent random misfire for over 6 months now. It is a 2001 3.4L C4 with 100,000k miles. I have checked the following:
-Fuel pressure
-New MAF
-New crank sensor
-New fuel injecters,
-New plugs+coils
-New DME and Injector relays
-Check vacuum and fule trims
-Oxygen sensor response looks normal
-cam deviation at -3, and +4
-new fuel filter
-cold compression test all around 138 psi
-leak down test on all less then 8%
The misfire is very intermittent and random from cylinder to cylinder, all 6 of them. I do notice there is tapping noise some time, but not all the time. When I hear the tapping, it will clear when I light increase the RPM. No misfire when doing spirited run. It always happen when cruising around 1800 rpm to 2800 rpm. The faults codes are always the P0300 plus a couple P0301 to 6 randomly. There is no other codes that come with the misfires. Question 1. Do you think it is the Variocam got anything to do with this, since this always happen at the time advancement range(Variocam, not the plus), though no other code? Question 2. What is chance do you think that all lifters are failing? 3. Another thing I am thinking is a faulty DME.
As you described in your first post" So after plenty of reading and the above facts I am sure I have sticking lifters, it also makes sense when you look at the symptoms, then the car is hot and you run at high RPM when the liter is activated, it sticks and then as the revs drop it is over filling the cylinder and triggering a CEL. It cools, the lifter retracts and then it runs fine. " Can you explain a little bit or point me to other reading on why you were so sure it was the lifters?
Any feedback would be great to help me in solving this dreaded random misfire. Thanks.
-Fuel pressure
-New MAF
-New crank sensor
-New fuel injecters,
-New plugs+coils
-New DME and Injector relays
-Check vacuum and fule trims
-Oxygen sensor response looks normal
-cam deviation at -3, and +4
-new fuel filter
-cold compression test all around 138 psi
-leak down test on all less then 8%
The misfire is very intermittent and random from cylinder to cylinder, all 6 of them. I do notice there is tapping noise some time, but not all the time. When I hear the tapping, it will clear when I light increase the RPM. No misfire when doing spirited run. It always happen when cruising around 1800 rpm to 2800 rpm. The faults codes are always the P0300 plus a couple P0301 to 6 randomly. There is no other codes that come with the misfires. Question 1. Do you think it is the Variocam got anything to do with this, since this always happen at the time advancement range(Variocam, not the plus), though no other code? Question 2. What is chance do you think that all lifters are failing? 3. Another thing I am thinking is a faulty DME.
As you described in your first post" So after plenty of reading and the above facts I am sure I have sticking lifters, it also makes sense when you look at the symptoms, then the car is hot and you run at high RPM when the liter is activated, it sticks and then as the revs drop it is over filling the cylinder and triggering a CEL. It cools, the lifter retracts and then it runs fine. " Can you explain a little bit or point me to other reading on why you were so sure it was the lifters?
Any feedback would be great to help me in solving this dreaded random misfire. Thanks.
07-27-2019, 05:00 PM
#66
Great write up. Since you have done so much to address your issue, figure reaching out for an advice. I have been dealing with intermittent random misfire for over 6 months now. It is a 2001 3.4L C4 with 100,000k miles. I have checked the following:
-Fuel pressure
-New MAF
-New crank sensor
-New fuel injecters,
-New plugs+coils
-New DME and Injector relays
-Check vacuum and fule trims
-Oxygen sensor response looks normal
-cam deviation at -3, and +4
-new fuel filter
-cold compression test all around 138 psi
-leak down test on all less then 8%
The misfire is very intermittent and random from cylinder to cylinder, all 6 of them. I do notice there is tapping noise some time, but not all the time. When I hear the tapping, it will clear when I light increase the RPM. No misfire when doing spirited run. It always happen when cruising around 1800 rpm to 2800 rpm. The faults codes are always the P0300 plus a couple P0301 to 6 randomly. There is no other codes that come with the misfires. Question 1. Do you think it is the Variocam got anything to do with this, since this always happen at the time advancement range(Variocam, not the plus), though no other code? Question 2. What is chance do you think that all lifters are failing? 3. Another thing I am thinking is a faulty DME.
As you described in your first post" So after plenty of reading and the above facts I am sure I have sticking lifters, it also makes sense when you look at the symptoms, then the car is hot and you run at high RPM when the liter is activated, it sticks and then as the revs drop it is over filling the cylinder and triggering a CEL. It cools, the lifter retracts and then it runs fine. " Can you explain a little bit or point me to other reading on why you were so sure it was the lifters?
Any feedback would be great to help me in solving this dreaded random misfire. Thanks.
-Fuel pressure
-New MAF
-New crank sensor
-New fuel injecters,
-New plugs+coils
-New DME and Injector relays
-Check vacuum and fule trims
-Oxygen sensor response looks normal
-cam deviation at -3, and +4
-new fuel filter
-cold compression test all around 138 psi
-leak down test on all less then 8%
The misfire is very intermittent and random from cylinder to cylinder, all 6 of them. I do notice there is tapping noise some time, but not all the time. When I hear the tapping, it will clear when I light increase the RPM. No misfire when doing spirited run. It always happen when cruising around 1800 rpm to 2800 rpm. The faults codes are always the P0300 plus a couple P0301 to 6 randomly. There is no other codes that come with the misfires. Question 1. Do you think it is the Variocam got anything to do with this, since this always happen at the time advancement range(Variocam, not the plus), though no other code? Question 2. What is chance do you think that all lifters are failing? 3. Another thing I am thinking is a faulty DME.
As you described in your first post" So after plenty of reading and the above facts I am sure I have sticking lifters, it also makes sense when you look at the symptoms, then the car is hot and you run at high RPM when the liter is activated, it sticks and then as the revs drop it is over filling the cylinder and triggering a CEL. It cools, the lifter retracts and then it runs fine. " Can you explain a little bit or point me to other reading on why you were so sure it was the lifters?
Any feedback would be great to help me in solving this dreaded random misfire. Thanks.
07-28-2019, 05:30 PM
#68
Rennlist Member
Great write up. Since you have done so much to address your issue, figure reaching out for an advice. I have been dealing with intermittent random misfire for over 6 months now. It is a 2001 3.4L C4 with 100,000k miles. I have checked the following:
-Fuel pressure
-New MAF
-New crank sensor
-New fuel injecters,
-New plugs+coils
-New DME and Injector relays
-Check vacuum and fule trims
-Oxygen sensor response looks normal
-cam deviation at -3, and +4
-new fuel filter
-cold compression test all around 138 psi
-leak down test on all less then 8%
The misfire is very intermittent and random from cylinder to cylinder, all 6 of them. I do notice there is tapping noise some time, but not all the time. When I hear the tapping, it will clear when I light increase the RPM. No misfire when doing spirited run. It always happen when cruising around 1800 rpm to 2800 rpm. The faults codes are always the P0300 plus a couple P0301 to 6 randomly. There is no other codes that come with the misfires. Question 1. Do you think it is the Variocam got anything to do with this, since this always happen at the time advancement range(Variocam, not the plus), though no other code? Question 2. What is chance do you think that all lifters are failing? 3. Another thing I am thinking is a faulty DME.
As you described in your first post" So after plenty of reading and the above facts I am sure I have sticking lifters, it also makes sense when you look at the symptoms, then the car is hot and you run at high RPM when the liter is activated, it sticks and then as the revs drop it is over filling the cylinder and triggering a CEL. It cools, the lifter retracts and then it runs fine. " Can you explain a little bit or point me to other reading on why you were so sure it was the lifters?
Any feedback would be great to help me in solving this dreaded random misfire. Thanks.
-Fuel pressure
-New MAF
-New crank sensor
-New fuel injecters,
-New plugs+coils
-New DME and Injector relays
-Check vacuum and fule trims
-Oxygen sensor response looks normal
-cam deviation at -3, and +4
-new fuel filter
-cold compression test all around 138 psi
-leak down test on all less then 8%
The misfire is very intermittent and random from cylinder to cylinder, all 6 of them. I do notice there is tapping noise some time, but not all the time. When I hear the tapping, it will clear when I light increase the RPM. No misfire when doing spirited run. It always happen when cruising around 1800 rpm to 2800 rpm. The faults codes are always the P0300 plus a couple P0301 to 6 randomly. There is no other codes that come with the misfires. Question 1. Do you think it is the Variocam got anything to do with this, since this always happen at the time advancement range(Variocam, not the plus), though no other code? Question 2. What is chance do you think that all lifters are failing? 3. Another thing I am thinking is a faulty DME.
As you described in your first post" So after plenty of reading and the above facts I am sure I have sticking lifters, it also makes sense when you look at the symptoms, then the car is hot and you run at high RPM when the liter is activated, it sticks and then as the revs drop it is over filling the cylinder and triggering a CEL. It cools, the lifter retracts and then it runs fine. " Can you explain a little bit or point me to other reading on why you were so sure it was the lifters?
Any feedback would be great to help me in solving this dreaded random misfire. Thanks.
06-24-2020, 12:51 PM
#69
Great thread!
It would be nice to get an update on the status of the car after all of this work. Hope everything is still on the positive.
I have to admit, I had apprehension as to whether there would be a less than desirable outcome after being driven for a while. Certainly hope those fears are unfounded.
...tagged for future reference...
It would be nice to get an update on the status of the car after all of this work. Hope everything is still on the positive.
I have to admit, I had apprehension as to whether there would be a less than desirable outcome after being driven for a while. Certainly hope those fears are unfounded.
...tagged for future reference...
The sticking lifter was definitely what was causing my problems.
06-24-2020, 02:07 PM
#71
I just fancy something different, I'm pretty sure I'll sell it, but something else and then hanker for another 996. If there was a serial car buyers anonymous I would be going to the meetings every week!, I think I'm up to 54 cars over the last 24 yrs.
06-24-2020, 03:51 PM
#73
Rennlist Member
I’m all the trying out different cars, and I’ve had 10 in 25 years, but then now, my 996 has been the car that I cannot easily replace with something better in this price range.
06-24-2020, 05:43 PM
#74
I have only purchased the exact same car once.......the 996 40th!, the car I have kept the longest and still have is a BMW E90 328, nothing particularly special about it but it just works. The 2 that stand out would be the BMW E39 M5 I had and sold to move house about 8 yrs ago, and the Audi S8 with the V10 engine that got totaled a few years ago in the snow.
09-18-2020, 09:30 AM
#75
Good luck with the sale of your 40th. I enjoyed reading through your posts and learning so much about our cars. I really like your suspension set up and will likely do the same for mine. Was there significant issues with the car being lower- I realize you need to be more careful but closing in that gap on those wheel wells and the car driving experience has got to be worth it
Thanks
TG
Thanks
TG