rough idle and cel codes

[hstephenson]

I recently replaced the heater control valve and OAS while i was in there. The car ran fine for about a week. now throwing 300, 302, 304, 306 misfire codes. can anyone give me an idea what to look for. cannot find any vacuum hoses loose.

2003 Boxster S

[Starter986]

Originally Posted by hstephenson

I recently replaced the heater control valve and OAS while i was in there. The car ran fine for about a week. now throwing 300, 302, 304, 306 misfire codes. can anyone give me an idea what to look for. cannot find any vacuum hoses loose.

2003 Boxster S

Cherck ALL the AOS connections ensuring they're snug. ALL connections... not just the ones you can see. There's a snap-in tube on the AOS that snakes into the hidden world... and, when you're disconnecting it from the AOS... it could become loosened or dislodged on the other end (hidden world).

My money is on the AOS connections, not that I have any money.

[hstephenson]

Thanks for the response

[BYprodriver]

Originally Posted by hstephenson

I recently replaced the heater control valve and OAS while i was in there. The car ran fine for about a week. now throwing 300, 302, 304, 306 misfire codes. can anyone give me an idea what to look for. cannot find any vacuum hoses loose.

2003 Boxster S

Misfire is usually caused by ignition related parts, Ignition coil, spark plug oil fouled from failed AOS ?? I believe the code numbers indicate which cylinder is misfiring so check cyl.# 2, 4,& 6 for oily spark plugs

[blue62]

Originally Posted by BYprodriver

Misfire is usually caused by ignition related parts, Ignition coil, spark plug oil fouled from failed AOS ?? I believe the code numbers indicate which cylinder is misfiring so check cyl.# 2, 4,& 6 for oily spark plugs

I agree mostly

But misfire on 2,4,&6 are all on the same bank.
So oil intake from the AOS should affect both banks equally.
But the OP just has the misfires on one bank.

I would look for something that would affect that 2,4,6 bank only.
First thing I would do is a very good visual inspection of all the wiring leading to that bank.

Something could have been disturbed by the previous work.
Some connection could be loose.
wiring could have gotten pinched.
Something could be grounding or shorting out.

Something I never see mentioned on this forum is.....
When one has a problem.
Before you even touch anything.
Get a flashlight and do a very intensive visual inspection

[jcp]

Originally Posted by blue62

I agree mostly

Before you even touch anything.
Get a flashlight and do a very intensive visual inspection

This ^^^^^^^^^^

[Boxtar]

Originally Posted by blue62

I agree mostly

But misfire on 2,4,&6 are all on the same bank.

I believe cylinders 1, 2 and 3 are on the right side (bank 1); 4, 5 and 6 are on the left (bank 2)...

[blue62]

Originally Posted by Boxtar

I believe cylinders 1, 2 and 3 are on the right side (bank 1); 4, 5 and 6 are on the left (bank 2)...

Thanks for the correction.
I just assumed that the layout was alternate count from side to side.

Soooo oil from the AOS could be an issue.
But I think I would still start with a good look at the previous work done.

[hstephenson]

sorry it took so long to update. you nailed it I had cracked the oil dipstick tube. replace it along with some of the vacuum lines nearby and she runs fine. thanks