Vacuum loss going up hills

[[email protected]]

I have a '95 Town car that has great a/c, except for when going up hills it shuts down. As soon as I take my foot off the gas, it comes roaring back.

I've checked the vacuum storage canister (black plastic box) on the left fender well, and it's o.k.
I've checked all the red, blue, green, yellow vacuum lines @ the heater control and the various bellows that they control for scrapes/ kinks and they all hold vacuum/pressure.
I've checked the main vacuum line coming out of the elbow behind the throttle body and it is new and o.k.

I occasionally get the infamous "low flow egr" code, but I think this is due to loss of vacuum that is required to hold it open. The egr is brand new, as is the pipe to the right bank exhaust pipe and we have 4 new o2 sensors installed too. Also the horse shoe shaped passage under the intake manifold elbow is squeaky clean.

Any other ideas would be welcome.........

Thanks,
Mike in Colorado

[olopezm]

I would inspect the remaining vacuum hoses at the firewall as well as the pcv valve hose, all these can cause a loss of vacuum.

For the EGR seems like you've checked everything other than the DPFE sensor and the EVR.

The dpfe is attached to the intake elbow and has two black hoses running to the exhaust pipe of the egr valve. Make sure all these hoses are ok and correctly attached.

The evr is also attached to the elbow at the passenger side and has a red and a green hose. Remove the upper cap being careful not to break it to reveal the filter. Clean this one with mild soap and water, let it dry and finally clean the evr case with a wet cloth.

Oscar.

[danielsatur]

A smoke test will pinpoint any vacuum leaks.

Insufficient flow to egr, is probably because of blocked egr gas passages on your Intake.

[Moppie]

I wonder if there is some moisture sitting in one of the lines, and the change in angle as you go up a hill is enough for it run together and cause a problem?

[[email protected]]

Originally Posted by olopezm

I would inspect the remaining vacuum hoses at the firewall as well as the pcv valve hose, all these can cause a loss of vacuum.

For the EGR seems like you've checked everything other than the DPFE sensor and the EVR.

The dpfe is attached to the intake elbow and has two black hoses running to the exhaust pipe of the egr valve. Make sure all these hoses are ok and correctly attached.

The evr is also attached to the elbow at the passenger side and has a red and a green hose. Remove the upper cap being careful not to break it to reveal the filter. Clean this one with mild soap and water, let it dry and finally clean the evr case with a wet cloth.

Oscar.

Oscar,
Thanks for the leads.
I cleaned the foam filter @ the top of the EVR this a.m.
Yes, the two black hoses that run from the DPFE to the EGR feed pipe are in good shape and hooked up properly The ones w/ the orange centers.

Question, There are 2 vacuum lines that run thru the firewall. the small black one seems to "power" all the a/c, vent/ heater controls on the dash.
The larger white one runs someplace up the steering column and then a smaller white one comes back down and goes to a bellows on the emergency brake.
They appear to be separate systems coming from a "distribution block" mounted on the firewall behind the EVR.
What stumps me is the power brake system, which relies on vacuum, seems to be unaffected by all this.
Mike

[Moppie]

Originally Posted by [email protected]

Oscar,
What stumps me is the power brake system, which relies on vacuum, seems to be unaffected by all this.
Mike

The brake booster should be feed from a separate, and dedicated line off the manifold.

[olopezm]

You're welcome!

The brake system is unaffected because it also has a small reserve in the booster and a check valve on it; it is the big plug that attaches to the booster unit.

The 2 vacuum lines are the AC control vacuum and the emergency brake automatic release lines (you know the e-brake is released when you put the car on D).

Since you mention you have checked the remaining components and they are OK I would think the check valve on top of the vacuum "distribution block" (also called vacuum distribution tree) has gone bad, it should be easily available at most autoparts stores.

To check it remove the two parallel lines at the top of it (one at a time) with the engine running and check for vacuum. If you are getting vacuum on both lines the next step will be to connect a 'T' fitting to both lines and pump 15 inches (maximum) of vacuum. If the vacuum loss is bigger than 1 inch per minute the check valve is bad.

Good luck,

Oscar.

[[email protected]]

Oscar,
Thanks for the "lead" about the check valve. I'll do your test this afternoon.
Can you tell me how to remove the check valve from the "tree" without breaking the tree. If I break it, it's going to be a nightmare reconnecting the vacuum lines to the new one.
Mike

[danielsatur]

Thant's why a smoke test is better!

[olopezm]

Originally Posted by [email protected]

Oscar,
Thanks for the "lead" about the check valve. I'll do your test this afternoon.
Can you tell me how to remove the check valve from the "tree" without breaking the tree. If I break it, it's going to be a nightmare reconnecting the vacuum lines to the new one.
Mike

To be honest I don't know if the check valve can be removed alone in our model, I knowsome models had it integrated to the tree and some others didn't. If you have problems with available space you can always remove the cowl under the wipers, it will take about 15 minutes but you'll have LOTS of space.

Originally Posted by danielsatur

Thant's why a smoke test is better!

The smoke test is a great idea, but will only show leaking points and no defective components like the check valve.

Oscar.

[[email protected]]

oscar,
The check valve @ the top of the distribution tree just plugs in w/ a rubber tube that fits into the body of the tree.
I found a generic replacement @ NAPA for $6.50 and pluged it in.
Now I get a/c thru the floor and defroster vents, but not thru the dash vents.
Got to go back in and check all the tubes under the dash.
I knew I should not have put it all back together before I tried it.
Mike

[olopezm]

If that's the only thing you disconnected then your problem lies there, one of the lines either is not properly seated/disconnected or got cracked during the process.

When there is no vacuum to the dahsboard the system defaults back to defrost mode to prevent your windshield to become foggy should you have a vacuum delivery problem.

Oscar.

[[email protected]]

Originally Posted by olopezm

If that's the only thing you disconnected then your problem lies there, one of the lines either is not properly seated/disconnected or got cracked during the process.

When there is no vacuum to the dahsboard the system defaults back to defrost mode to prevent your windshield to become foggy should you have a vacuum delivery problem.

Oscar.

Oscar,
The NAPA generic replacement did not work, as the 2 barbs for the vacuum tank and the feed to the htr/ac controls were not big enough to seal on the lines.
I ordered a ford part from my local dealer today. $ 8.00 total cost.
I'll put it in on Friday. For now the old part is back in. It has a short piece of rubber tube on the bottom barb and just pops into the top of the tree.
Will let you know how the new one works next week, after a road trip to Denver and back.
Mike

[[email protected]]

Originally Posted by [email protected]

Oscar,
The NAPA generic replacement did not work, as the 2 barbs for the vacuum tank and the feed to the htr/ac controls were not big enough to seal on the lines.
I ordered a ford part from my local dealer today. $ 8.00 total cost.
I'll put it in on Friday. For now the old part is back in. It has a short piece of rubber tube on the bottom barb and just pops into the top of the tree.
Will let you know how the new one works next week, after a road trip to Denver and back.
Mike

New info,
I replaced the one way valve @ the top of the "tree" this p.m. w/ the official ford part.
Started her up, and here's what happened.

With the htr/ac system off, and the car idling, I turned the system on by pushung the "vent" button , and got air from the 4 dash vents.

Then I pushed the "floor" button and got air from the floor and defroster.

Then I pushed the "vent" button again and the system WOULD NOT go back to blowing air out the vents.

However when I turned the system off, I could get air from the vents again by hitting the "vent" button.

I have not tested her on any hills yet to see if it still defaults to floor/defrost on a long pull. But I have a hunch it will.

Very perplexing ???????????
Mike

[olopezm]

Hi Mike,

Hmmm that sounds weird. I would think maybe something is causing the deflectors not to properly return to their positions, perhaps low vacuum coming from the engine??

I would try the guide in the following link and see if anything comes up:

http://www.lincolnsonline.com/tech/00128.html

Oscar.