New 2001 Boxster owner, P0300, P0303, P0306 at high rpms

[mongo747]

I am a new Boxster owner, I like the car, was kind of babying it at first.  Then read this forum about everyone running high rpms, so I pushed it and got a bunch of codes.

Car has 45K miles, had IMS and RMS done (hopefully), new plugs, new clutch.

 

I have a scanner, so I get that these are miss fires on cylinder 3 and 6.  Actually the first time I got these codes, I got an o2 sensor code (don't remember which one), and P030x on some other cylinders.

 

So I can reproduce this pretty easily, take it to 5K to 5500 in first or second, and they start coming up.  Total loss of power, thought it was a clutch slip at first, blinking CEL.

 

I really don't need to drive at this rpm's, but I would rather address an issue than ignore it or drive around it.

6K rpms is not really a big deal, my minivan can do that, just feels weird having your head a foot away from it happening!!!

 

I cleaned the Mass Air Flow for some reason, looked brand new.  The previous owner was a woman and I am really concerned that the repair shops took advantage of her based on the service history.

Called the shop before I bought it, (found a car in the owners manual before I bought it and called them with the VIN).  They were helpful, told me they serviced it, new clutch, LN, new top, new plugs.

 

Air filter is clean (paper not K&N).  I do have some oil on the outside of the air intakes, connections seemed tight, didn't seem any were lose or any leaking noise, (the black tubes in the middle on the top of the engine next to the plastic "PORSCHE" thing on top).  I just got this thing, I'm not up to speed on what's called what.

Took the oil cap off while running, their was vacuum, idle moved, not sure if it when up or down.

 

So I'm guessing I'll hear change plugs and coils, but I had misfires on other cylinders before. 

I ran a tank of gas through it, if I keep running at 4999 rpms, I can clear out another tank pretty quick.

 

Scanner also gave me a fault on fuel system 1 and 2, (OL FAULT), but that's probably from the misfires.

 

The car is fun, but doesn't really seem that fast, seems to rev ok, but I don't get the feeling its all there.  I have had a Merc AMG C32, and a BMW 550i, and they would blow this car away.  I would think being 4 inches off the ground even if this car is slower, it would feel faster (go cart experience).

 

Any help would be great.  Thanks

 

[JFP in PA]

I am a new Boxster owner, I like the car, was kind of babying it at first.  Then read this forum about everyone running high rpms, so I pushed it and got a bunch of codes.

Car has 45K miles, had IMS and RMS done (hopefully), new plugs, new clutch.

 

I have a scanner, so I get that these are miss fires on cylinder 3 and 6.  Actually the first time I got these codes, I got an o2 sensor code (don't remember which one), and P030x on some other cylinders.

 

So I can reproduce this pretty easily, take it to 5K to 5500 in first or second, and they start coming up.  Total loss of power, thought it was a clutch slip at first, blinking CEL.

 

I really don't need to drive at this rpm's, but I would rather address an issue than ignore it or drive around it.

6K rpms is not really a big deal, my minivan can do that, just feels weird having your head a foot away from it happening!!!

 

I cleaned the Mass Air Flow for some reason, looked brand new.  The previous owner was a woman and I am really concerned that the repair shops took advantage of her based on the service history.

Called the shop before I bought it, (found a car in the owners manual before I bought it and called them with the VIN).  They were helpful, told me they serviced it, new clutch, LN, new top, new plugs.

 

Air filter is clean (paper not K&N).  I do have some oil on the outside of the air intakes, connections seemed tight, didn't seem any were lose or any leaking noise, (the black tubes in the middle on the top of the engine next to the plastic "PORSCHE" thing on top).  I just got this thing, I'm not up to speed on what's called what.

Took the oil cap off while running, their was vacuum, idle moved, not sure if it when up or down.

 

So I'm guessing I'll hear change plugs and coils, but I had misfires on other cylinders before. 

I ran a tank of gas through it, if I keep running at 4999 rpms, I can clear out another tank pretty quick.

 

Scanner also gave me a fault on fuel system 1 and 2, (OL FAULT), but that's probably from the misfires.

 

The car is fun, but doesn't really seem that fast, seems to rev ok, but I don't get the feeling its all there.  I have had a Merc AMG C32, and a BMW 550i, and they would blow this car away.  I would think being 4 inches off the ground even if this car is slower, it would feel faster (go cart experience).

 

Any help would be great.  Thanks

 

It would be helpful to know the year of the car, and see a list of all the actual codes it is throwing.

[mongo747]

It was in the the topic title.  Its a 2001 Boxster Base, throwing P0300, P0303, P0306.  Thanks

[JFP in PA]

It was in the the topic title.  Its a 2001 Boxster Base, throwing P0300, P0303, P0306.  Thanks

 

OK, you have a misfire on cylinders 3 and 6; possibly plugs or coil packs.  What about the "fault on the fuel system" and O2 sensor codes you mentioned?

[mongo747]

I forgot the codes for the o2 sensor, for the fuel system I got an OL Fault (open loop fault) on the scanner for the fuel system.  I think that's just the response to the other fault.

I am checking the service history, I think the plugs and coils were done within 10K miles.

 

The reason I'm thinking its something else is, during the first failures I got P030x on other cylinders, like 2 and 3 and 4.  Seems to be on both sides of the engine.

I see so many posts where people change the plugs and coils and that's not the issue.

 

I'll change them if I need to, but I am more interested in understanding how the Porsche acts during situations so that I don't end up replacing every part on the car to fix something simple or give up!!!  Thanks

[JFP in PA]

You can test components by a process of elimination; try moving the suspect coils to other cylinders, and then see if the misfire goes with them or stays in the original locations.  You can also do the same thing with the plugs as a separate test.  Normally, if a plug is consistently misfiring, it should look pretty bad compared to a plug that is firing normally.