93LX5.0L5SpdConv

And I mean tap or feather the throttle, not wide open.

It's also throwing strange and inconsistent codes, mostly sensors out of range, and it doesn't finish the KEOR cycle, it loops around usually showing the same codes in the same order.

mjr46

vac leaks will affect idle expecially if they are large enough reving motor up will drop manifold vaccum/opening throttle plate, unless you have a gauge for testing fp, you can't verify it/assume

93LX5.0L5SpdConv

OK, got a vac gauge. Gonna read up on where best to test and test it.

93LX5.0L5SpdConv

Here's the vac test. That's me revving, it's not doing it on its own.

What's that hollow little-drum sound? A backfire?

mjr46

where did you hook the gauge to?? vac reading at idle is way to low!! you should have at least 15-18 inch at idle for a stock cam in that car. did you look under the intake......front and rear at the hidden trees and make sure none of the vac lines and or caps have decayed/come off?? check the pcv as well......popping in the intake can be a few things, misfire due to valve issue, huge vac leak = had very such issue on friday last week with a customers 68 bronco with a 90 5.0 efi swap, big vac line under intake was left off

93LX5.0L5SpdConv

Tested vac again plugged directly to upper intake manifold, reaching past the distributor - same results.

Then I hooked tester up to A/C outlet on the vacuum tree, different results:

93LX5.0L5SpdConv

Looks like big vac leak doesn't it? Which explains the wacky sensor out of range codes also, with no vac they can't perform/report properly, correct?

mjr46

with inability to idle well and lean as crap if that's what it is, the ole garbage in/out theroy applies........anyway, if the intake has been off recently check torque on all plenuim bolts, if not look for all lines leading to the intake and check all vaccum lines under intake and make sure no air leaks between throttle body and maf exist and make sure the egr valve pintle is seated = easily verified by removing......but first check for a vac line off and a large one at that...............a smoke machine is waht I use to find vac leaks quick or my ear for a whistle, but you must have a trained ear for that.

93LX5.0L5SpdConv

I've had it for 10 years and more than 100K of its 195k miles, intake has not been off, no reason to think it was off before. No smoke machine here either, I suppose it's cans of carb cleaner - although I'm open to other suggestions of course...

Now to pull the EGR.

mjr46

visual inspection when it's running that bad, if it's not a blown upper plenuim gasket then when the car is running that bad it 'll often be a major vac line, get a mirror and look at the tree under the intake at the back and at the front, also make sure the evap vent selonoid that goes from carbon canister to the intake is not stuck open, that'll simulate a huge vac leaK IF it is....it should be normally closed