Blinking engine light.

[Antony]

2003 LS 3.0 v6 198,000 mi.... two weeks ago installed new injectors, plugs ( correctly gapped at spec), coils/w new boots. ran fine until 3 days ago, when engine light started flashing( signaling a misfire/emission issue) and continues until 3 or 4 miles down road and engine temp is up to normal. runs rough and shifts erratic somewhat. has anyone had this issue or experienced this and what is the solution ? I am thinking 02 sensors. Thanks for your time.

 

[DaleGrib]

2003 LS 3.0 v6 198,000 mi.... two weeks ago installed new injectors, plugs ( correctly gapped at spec), coils/w new boots. ran fine until 3 days ago, when engine light started flashing( signaling a misfire/emission issue) and continues until 3 or 4 miles down road and engine temp is up to normal. runs rough and shifts erratic somewhat. has anyone had this issue or experienced this and what is the solution ? I am thinking 02 sensors. Thanks for your time.

What brand coils did you use?

 

[04_Sport_LS]

Instead of guessing... why not go to you local auto parts store... and have them hook up a scanner to see what codes are being stored.

They do it for free.... and that will give you an idea what is going on and where to start.

 

[Antony]

Instead of guessing... why not go to you local auto parts store... and have them hook up a scanner to see what codes are being stored.

They do it for free.... and that will give you an idea what is going on and where to start.

Getting ready to do just that. lol It would be quicker.

 

[04_Sport_LS]

As an afterthought... maybe you should go back and check your work (if you haven't already).

An electrical connector may not have seated fully... and popped back apart... or the locking tab may have broke.

 

[milehighmikey]

As part of the V6 spark plug/cop access, you have to pull the intake manifold upper plenum, which is highly disruptive to the top end of the engine with the amount of hoses and cables to disconnect. There is a PCV line that runs from the back end of the engine, driver's side, across the upper plenum, and it connects to the throttle body. The hose is about 5/16" or 8mm and stiff plastic, but the ends are rubber boots that accept the 5/16" hose on one end of the boot and and convert it to 5/8" to make the connections to the PCV system under the intake and the throttle body. On my V6, that hose adapter at the back end of the engine was significantly cracked and caused a very rough idle once the engine got to closed loop operation. It would sit there and shake like a top fuel dragster engine at idle, making the ugliest popping noises and nearly stalling. Ran like a champ for driving and power, but could not idle down while coasting until the car reached a full stop. (std trans) Well after I found this problem, the car now behaves properly at idle and running/coasting. I would imagine that many of the V6s have this problem.

 

[04_Sport_LS]

Mikey has a good point for something to check into.

The pvc system is a known issue on the V6. Not just on the LS... but on other Ford vehicles, because the design is similar... and a bit of a pain to access and work on.

It can be done without pulling the intake... but is in a tight area.

 

[milehighmikey]

Mikey has a good point for something to check into.

The pvc system is a known issue on the V6. Not just on the LS... but on other Ford vehicles, because the design is similar... and a bit of a pain to access and work on.

It can be done without pulling the intake... but is in a tight area.

I don't think you can get at the rear of the engine where the hose comes from without pulling the cowl and brace though. Stuff is balls deep back there.

 

[milehighmikey]

But you can easily rule this out on a temporary (very temporary) basis by removing that hose from the throttle body and plugging the fitting in the throttle body with a piece of a plastic bag, for example, and reinstalling the hose to see if the problem still exists, perhaps even trying this as you've pulled over from it just starting to occur, since you don't want your crankcase to build pressure too much. The problem could also be in the nether regions of the intake, underneath the lower intake where the PCV valve is. There is another weak link in the system where the PCV connects to that 5/8" metal tube that brings the flow to the rear to front hose that we are talking about. It's a small 90 degree elbow of 5/8" rubber that tended to dissolve into soft rubber and leak badly.

 

[SultanGris]

Check the codes for sure, mine did that but it was something to do with the EGR valve and the blinking meant it was damaging the catalytic converter or something I believe but I forget the exact code, scan it and find out. Mines a V8,2003

 

[04_Sport_LS]

I don't think you can get at the rear of the engine where the hose comes from without pulling the cowl and brace though. Stuff is balls deep back there.

It's tight... but not as bad as the V6 in an Escape. I invented new cuss words working on an Escape... but with the right tools it was possible to do without pulling the intake.

I have pics somewhere.

 

[Antony]

As an afterthought... maybe you should go back and check your work (if you haven't already).

An electrical connector may not have seated fully... and popped back apart... or the locking tab may have broke.

double checked that before reinstalling intake, just because it is a pain in the ass to remove everything to access plug and coils. had codes pulled. showing O2 sensors are not functioning properly. will be replacing those Tuesday.

 

[Antony]

As part of the V6 spark plug/cop access, you have to pull the intake manifold upper plenum, which is highly disruptive to the top end of the engine with the amount of hoses and cables to disconnect. There is a PCV line that runs from the back end of the engine, driver's side, across the upper plenum, and it connects to the throttle body. The hose is about 5/16" or 8mm and stiff plastic, but the ends are rubber boots that accept the 5/16" hose on one end of the boot and and convert it to 5/8" to make the connections to the PCV system under the intake and the throttle body. On my V6, that hose adapter at the back end of the engine was significantly cracked and caused a very rough idle once the engine got to closed loop operation. It would sit there and shake like a top fuel dragster engine at idle, making the ugliest popping noises and nearly stalling. Ran like a champ for driving and power, but could not idle down while coasting until the car reached a full stop. (std trans) Well after I found this problem, the car now behaves properly at idle and running/coasting. I would imagine that many of the V6s have this problem.

View attachment 828576366

Thanks for your info, have replaced all of this with motorcraft parts. not much that I have not replaced on this. will double check though as this stuff is subjected to a lot of engine heat due to everything being crammed together tight on these engines and engine bay.

 

[Antony]

But you can easily rule this out on a temporary (very temporary) basis by removing that hose from the throttle body and plugging the fitting in the throttle body with a piece of a plastic bag, for example, and reinstalling the hose to see if the problem still exists, perhaps even trying this as you've pulled over from it just starting to occur, since you don't want your crankcase to build pressure too much. The problem could also be in the nether regions of the intake, underneath the lower intake where the PCV valve is. There is another weak link in the system where the PCV connects to that 5/8" metal tube that brings the flow to the rear to front hose that we are talking about. It's a small 90 degree elbow of 5/8" rubber that tended to dissolve into soft rubber and leak badly.

I have not pulled the lower intake, that will suck if I have to go back and do that. will check the elbow you are talking about though.

 

[04_Sport_LS]

Do the following... at your own risk. I assume no liability.

If you really think you might be chasing a vacuum leak... you could use a spray can of some sort of flammable liquid... such as brake parts cleaner or carb cleaner.

Use the straw that comes with the can... and lightly spray around the engine while it's running. If there is a vacuum leak... the engine idle will change slightly.

Keep a fire extinguisher handy... just in case.

Obviously... don't spray around the exhaust manifolds.

Some people recommend a smoke test kit... which is safer... but if it's windy and/or the engine fan kicks on... it may be hard to pinpoint the leak.

Plus... if the leak is small or in a tight spot... you may not find it with a smoke test.

Looks like Harbor Fright has a smoke test kit pretty cheap... but I don't know how well it works.