Complex issue

[Evamonster]

I have a 2003 ls v6. It's a great car and I've thoroughly enjoyed it. Recently the check engine light came on. The car was running fine but I went to check the code. The eurozone guy ran the code and it had quite a few to do with electronics and misfire in cylinder 6. The symptoms of the problem are odd, the car runs perfectly fine, normal idle etc most of the time, the one problem I have noticed is around 2k rpm the engine shudders and sometimes the CEL flashes. If the rpms go over 2k it seems to go away. I have had one issue a few months back where I cranked the car and it wouldn't stay on but ensured a good connection on the hose that runs on top of the engine on the left side and around the back, and things went back to normal. If a list of the codes would help I can get it. Help would be greatly appreciated. I dont have any mechanic nearby I really trust here, and I know how things can go with "electrical" issues.
Thanks

 

[joegr]

Yes, a list of the codes would likely help.
That said, you are probably like almost everyone else. If so, the answer is:
Replace all six coils with new Motorcraft (not from ebay) coils.
Replace all six spark plug with new, NGK recommended. Verify the gaps are all set correctly.
You will probably also want to replace the upper half manifold gasket and the PCV valve and any questionable vacuum hoses/tubes while you are in there.
The issue is probably not as complex as you think.

 

[Evamonster]

How complex is it to change the coils and manifold gasket on a ls v6?

The main reason it seems so odd is the sporadic nature of the symptoms. I'll get a list posted asap.

 

[joegr]

I don't have a V6, so I can't answer specifically. There are several threads on here by people who do and who have done this. Some may respond here, but in the meanwhile, you might search out a few.
I think that what is confusing you is that the LS PCM is subject to EMI/RFI from marginal coils, and that can cause it to do really weird stuff and cause false error codes, particularly about the ETC (Electronic Throttle Control). The coil most likely to cause this is #4 on the V8s, and #3 on the V6s, since those are the closest to the PCM. Since you have a #6 misfire, it seems likely that this is your problem.

Edit: corrected coil numbers

 

[Evamonster]

The codes i got from o rielly are P0306,P0108,P1000,P1406

Any advice greatly appreciated!

 

[joegr]

The codes i got from o rielly are P0306,P0108,P1000,P1406

Any advice greatly appreciated!

P0306 - misfire on #6 - need to replace coils and plugs

P0108 - Manifold Absolute Pressure/Barometric Pressure Circuit High - Could be a bad vacuum tube/hose to the EGR valve, but it is usually the EGR valve assembly itself. The LS is not very tolerate of aftermarket EGR valves, get the Motorcraft one.

P1000 - OBD Systems Readiness Test Not Complete - You've disconnected the battery recently. This code will resolve itself after a while. It's not a problem.

P1406 - Differential Pressure Feedback Sensor Downstream Hose Off Or Plugged - This is just a result of the bad EGR valve from the P0108 code.

 

[Evamonster]

Thank you, is the cool plug change straight forward?
I've done it on modular mustang's, f 150s, and a 03 celica, similar?

 

[Evamonster]

Looking for instructions on replacing egr valve any ideas?

 

[joegr]

Looking for instructions on replacing egr valve any ideas?

Two vacuum tubes, two bolts, one pipe compression nut.

Coil and plug changes are easy enough. The catch is that the top half of the intake manifold has to be removed to get to three of the six.

 

[Evamonster]

Two vacuum tubes, two bolts, one pipe compression nut.

Coil and plug changes are easy enough. The catch is that the top half of the intake manifold has to be removed to get to three of the six.

Is there instructions on these forums?
A cylinder diagram?
Wondering if the egr problem could be creating the single inconsistent misfire code on cylinder 6?

 

[Evamonster]

Anyone know the size on the compression nut on the egr 2003 ls v6?

 

[joegr]

Cylinder numbering
V6
Radiator
Driver - Passenger
4 - 1
5 - 2
6 - 3
Firewall

 

[Evamonster]

Cylinder numbering
V6
Radiator
Driver - Passenger
4 - 1
5 - 2
6 - 3
Firewall

That's great thanx I should be able to get to cylinder 6 rarely easily.

 

[LunaEros]

P1000 - OBD Systems Readiness Test Not Complete - You've disconnected the battery recently. This code will resolve itself after a while. It's not a problem.

Hey Joe, how long does it usually take for the P1000 code to resolve itself and go away?
Mine is still showing up after I stupidly cleared ALL the codes with FORScan before I knew what I was doing. That was almost 2 weeks ago (12 days)

Stephen

 

[joegr]

It depends on how much you drive and how you drive. For example you have to drive enough at different speeds and different levels of gasoline in the tank.