Replace MAP sensor vacum line

[stinkydogfilms]

Hi everyone.
Is it possible to replace the vacuum line to the MAP sensor without removing the intake? The line from the intake is dry rotted and collapses. It’s probably the original line. It’s a 1990 Colony Park that is all stock.

[VicCrownVic]

I don't remember if that one goes all the way under the intake. If it does, there's not much chance of replacing it with out at least lifting the upper intake. May not have to disconnect everything, just lift enough to get under the upper intake, but then you run the risk of breaking the brittle plastic (1/8"?) vac lines.

[stinkydogfilms]

Thank you VCV. I’m looking into using medical clamps, the old roach clip kind and a mirror to see what I’m doing coming in from the firewall side. The clamps I have are too large and need to get a medium size. I just now thought about using a flexible tool grabber cable that may work to get it off.

[bgreywolf]

If the MAP sensor line is cracked, there are likely other cracked lines.
In fact, the MAP sensor line might be fine and the lines from the same vacuum tee might be leaking enough to skew the vacuum reading.

Since so many of the vacuum lines are under the intake, and hard to see (but easy to disturb); and since the upper intake usually comes off pretty easily (especially if you're just moving it slightly to get the vacuum lines, and not removing it from the car, so you can leave the throttle body stuff in place); why not replace all the vacuum lines and then not have to worry about it for another decade or more?

I bet the time and cost of the work won't be a whole lot more than you were planning on already, and it's much, much easier to use your hands and eyes without mirrors and medical clamps.

[VicCrownVic]

Also, if I'm not mistaken, the vac line at the intake connects to a much larger barb than at the MAP. If you got a line to fit the MAP it will be way too small for the intake end.

[bgreywolf]

It's been a little while but I think the vacuum tree under the intake has a small line for the MAP, a larger line to the splitter on the firewall (which feeds cruise, HVAC, etc) and a line or two to the evap and egr?
Again, once they start cracking and coming apart I figure I'm going to end up doing them all eventually, I'd rather do it once and be done.

[stinkydogfilms]

Thanks again VCV and BGW.
So far the plastic hoses look ok.
The line coming from the intake is rubber and connects into an adapter fitting that adapts to a smaller hose to the MAP sensor. THANKS AGAIN and I will update.

[VicCrownVic]

They may look ok, and functionally be fine, but one wrong move and they snap easy (which may be part of your concern of not wanting to remove the upper intake). Don't even sneeze on those tiny plastic lines, LOL.

My fix in that case is to insert both ends of broken plastic line into a piece of vac hose with 1/8" ID. If it doesn't break into a million pieces or too close to the end.

[DerekTheGreat]

You will never get the old hoses off unless you remove the upper. I had one upper off and it was still a pain in the ass to get the hoses off, ended up cutting them with a razor blade. Your back will thank you. Like others said, it'll give you a chance to replace all the other lines which need to be replaced.

[gadget73]

for the effort involved in trying to not remove 6 bolts, I would say its not worth it. You can get the upper intake off these cars in like 10 minutes.

[stinkydogfilms]

Guess I'll replace the fuel injectors then.
I didn't want to deal with an intake gasket.

[VicCrownVic]

I've reused the upper to lower intake gasket, you'll be fine there.

[gadget73]

no need to replace the injectors.

and +1 on recycling the gasket. I've re-used them several times. Just be careful and try to not damage it. If it does rip its not very expensive.

[stinkydogfilms]

I have a set of new rebuilt injectors on the shelf.
The car has at least 82,000 miles and thought I might as well do it at the same time.

[gadget73]

well in that case, may as well. No better time to do valve cover gaskets either if they have any leaks
before long we'll have you replacing the engine because its only a little bit more work