budedm

So will a smoke test find it? Should I tell them to test it cold?

RLXXI

Never smoke tested them, we knew what the problem was because we had so many come thru our shop doing it, it was like second nature to us. Labor time is something like 4 hrs, we did so many all of us could do the entire job in 45 mins.

That common of a problem.

budedm

So, I watched a you tube for replacing the intake gaskets. Looks pretty straight forward. Just a long job. Lots to remove. I can do it if you think that is the problem. Do you think I can run it like this for a few weeks? When I clear the code, it takes about 150 miles for it to appear again so I'm thinking the leak isn't terrible.

RLXXI

It's like I said, right after you start the engine it's running in open loop, the pcm will ignore the O2 sensors and read from others until the sensors heat up, when they do the system goes into closed loop, think maybe 10-15 secs after engine start then the system goes into closed loop and the pcm will now ignore most other sensors and sample the readings from the O2 sensors and it's still cold enough to allow air to be sucked in, after maybe 30secs to 1 min running the plastic and engine have heated up sufficiently to seal the leak that the shrunken manifold O-rings cause.

All of which can be seen with a live data stream from a scan tool, that's how we figured it out.

All I can do is offer my experience in dealing with a very common problem of the system in question, I can't say with 100% certainty that is your problem without actually hooking up a scan tool and monitoring my self.

Best I can tell you is there is a 99% chance this is your issue.

budedm

Lots of good info. So let me ask this. The SEL light comes on after it's warm and running on the highway. Does that make sense? Maybe I should forget the smoke test ($90) and just replace the gasket if it's a 99% chance. I have gone over everything else so I can't imagine what else it could be. But why didn't I get a rev up when I sprayed it? I sprayed it cold once, then the next day I tried it warm. Nothing either way.

RLXXI

Very small leak only picked up by a very sensitive sensor. We could never find it using carb spray or anything else either, it was the live data feed as well as many other pinpoint tests ran to the point of nothing else it could be.

Process of elimination.

budedm

Not sure my garage can do a live data feed. But it seems I have eliminated everything else.

Z7What

Yes because that's when it would go into Closed Loop like RNLComp said. Just change the intake gaskets its a simple job and is cheaper than the $60 smoke test.

Wayne

budedm

Simple, but long. I'll prolly do plugs at the same time. And maybe coil packs.

RLXXI

While you have the manifold off, clean out the egr ports to prevent a future SEL, they are notorious for clogging up with carbon, mainly directly between the throttle body and manifold. The gasket kit will come with a new gasket for that.


P.S. Make sure you use Motorcraft parts if you can or you might just create more headaches down the road.