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Could bad EVAP lines going from the throttle body to the canister cause this problem? They look old and brittle and might have some hairline cracks. I will replace all those for sure. All the other vacuum lines look real good.
You cannot trust a visual check of those vinyl vacuum tubes. They are 20 years old and well known to not age gracefully. The fact the vents cycle from vent to defrost under load is telling you have there is a vacuum leak. Replace all of them.
Originally Posted by LCconvert
Also, I just noticed the rubber hose from the oil tube to the air intake housing was kinked real bad.
And finally, there is something like an air diverter or something (between the throttle body and the coil) that has an air outlet that does not have a hose going to it. Is there supposed to be a hose? Does it go to the air intake houseing? I don't have the stock housing, the PO put a K&N system on. I was thinking about tee-ing that in with the hose coming from the oil tube to the air intake housing.
The piece you are referring to is part of the air injection system, it's supposed to be open to the atmosphere. Do not try teeing it into the PCV vent hose.
<p>If the thing thinks it's lean, it's going to richen up the mix as far as it can.</p><p>That brings us back the the MAP sensor setup, which I believe uses throttle position and the MAP sensor to figure this out? Help me out here guys, it's been a while since I even opened the hood on a MAP-equipped vehicle <img alt="Evil Grin" src="https://www.ford-trucks.com/forums/images/smilies2/evilgrin0007.gif" style="height:19px; width:21px" title="Evil Grin" /></p>
<p>If there was a vacuum leak causing it to actually run lean, it wouldn't have such high HC and CO numbers.</p><p>It can't be both running rich (HC and CO) AND report lean condition from the O2 sensor at the same time.</p><p>Are there two O2 sensors and one bank is dumping gas, and the other side is running lean?</p><p> </p>
Since we already know the vents are cycling when accelerating that implies there is a vacuum leak in the intake system. Unmetered air is translated as a lean condition by the O2 sensor so the computer keeps dumping in fuel.
Since we already know the vents are cycling when accelerating that implies there is a vacuum leak in the intake system. Unmetered air is translated as a lean condition by the O2 sensor so the computer keeps dumping in fuel.
Well that may depend on a few things.
I may of missed this but what engine and size?
My 1995 F250 with a 351 had 2 or 3 O2 sensors. It would test out as a bad sensor and replacing
then did nothing to solve that problem. Sadly I never fixed it do to totaling it shortly after that.
I Just measured the vacuum at the manifold at 19-20 during idle and a little higher at 2000 RPM. Does this mean I can assume my vacuum lines are good?
I pulled off the hose from the throttle body to the EVAP canister purge solenoid (this was brittle and cracked) and the vacuum dropped. Like I stated before, I will replace all the EVAP hoses but it didn't seem to affect the vacuum while it was connected.
So I was just looking at the white line and noticed a rough texture...rubbed at it a little and it started to crumble. Looks like I will replace a section of this line!
I Just measured the vacuum at the manifold at 19-20 during idle and a little higher at 2000 RPM. Does this mean I can assume my vacuum lines are good?
No
Originally Posted by LCconvert
I pulled off the hose from the throttle body to the EVAP canister purge solenoid (this was brittle and cracked) and the vacuum dropped. Like I stated before, I will replace all the EVAP hoses but it didn't seem to affect the vacuum while it was connected.
What next?
If the EVAP lines are cracked I can guarantee the other vacuum lines are cracked. Replace all of them.
