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Old 03-20-2019, 10:08 PM   #9
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Originally Posted by amc49 View Post
Consider too a vacuum leak showing up at the much higher vacuum of decel ONLY.

I mention it because the zetec has a crap super thin gasket section at the idle bypass port at the joint between TB and intake.

I've had that thin section pull out sideways to then reseat back in place before and it gave me fits finding it. The entire TB does not sit right on the intake surface flat, rather the bolt holes in the corners have slight 'stands' molded into them to hold up the TB assembly roughly .010" or so high on the intake. That airspace is what allows the gasket to pull out of place, it is not hard pinched to not move at all. The gasket as well with age loses a whopping amount of the physical 'body' stiffness the material has normally that would stop that, it becomes extremely flexible. I could see by the coloration of the silicone there that the gasket right there had been sucked out in the wind at least part of the time, it was twisting sideways out of place. Kooky, man.

My problems there were not the same as here but with a little imagination I could see the gasket moving at decel only to leak to help kill engine then falling back into normal place to run right. Far-fetched but not impossible.
I have had valve cover gaskets do exactly that.

Good call.
I will check that as well.

I never think about that seal because we aren't supposed to disturb it or whatever, but, I did pull the TB off of my other focus and put it back on with seemingly no issues.

A couple of ideas:

Since my car dies if trying to idle whilst rolling over 30mph, yet, is fine if I'm only going 5mph, could the MAF be wrong even though it is seemingly tracing perfectly on the graph?
Maybe it's not wrong about airflow, but, just not heating up to it's proper temp, then, sending a false intake temp to the ecu?

Another thought I had that I plan to check tonight is the timing belt could have stretched a little too much.
It's at 120k after all.

I read on here about someone who had their belt stretch just enough to retard their exhaust cam a couple of degrees and cause my dieing issue.

Thanks again for the ideas!

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