Surging @ HWY Speeds
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Surging @ HWY Speeds
Hey everyone. Need some help with 1995 3.0L 6 Cylinder Aero, aka the Green Goblin.
I've recently noticed that when I'm running between 50-65MPH the GG can't seem to decide whether it wants to stay in D or OD, I think. It's hard to tell whether or not the transmission is shifting or if it's just the engine revving. I don't have a tachometer but it's almost like the engine is revving /surges and then falls back, sometimes repeatedly. Could this be due to a vac line leak?
History- GG has 167K on it. I recently changed the oil, plugs, wires, distributor and air filter. Cleaned the MAF. Due to a failed AC compressor and low funds, had it removed and a bypass pulley installed. Needs a new pipe & muffler which is on the agenda.
I've recently noticed that when I'm running between 50-65MPH the GG can't seem to decide whether it wants to stay in D or OD, I think. It's hard to tell whether or not the transmission is shifting or if it's just the engine revving. I don't have a tachometer but it's almost like the engine is revving /surges and then falls back, sometimes repeatedly. Could this be due to a vac line leak?
History- GG has 167K on it. I recently changed the oil, plugs, wires, distributor and air filter. Cleaned the MAF. Due to a failed AC compressor and low funds, had it removed and a bypass pulley installed. Needs a new pipe & muffler which is on the agenda.
Lead Driver
Joined: Sep 2003
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From: SoCal
A vacuum leak is possible; so you could look for hoses disconnected or caps fallen from the vacuum tree.
Did you check the transmission fluid? When was it last changed?
If you think it's going in and out of OD, try keeping in D for a while and see how it behaves. On a transmission with that many miles, it's very likely that some parts are simply worn out.
Did you check the transmission fluid? When was it last changed?
If you think it's going in and out of OD, try keeping in D for a while and see how it behaves. On a transmission with that many miles, it's very likely that some parts are simply worn out.
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On a related note
Was wondering if some of the experts might weigh in with some confirmations and help.
If I'm correct, I'm looking at the cause of my stuck-in-defrost enviro controls- a melted/severed vacuum line, correct?
And if I'm correct, once I purchase a new line, where do I attach the other end? Thanks in advance.
If I'm correct, I'm looking at the cause of my stuck-in-defrost enviro controls- a melted/severed vacuum line, correct?
And if I'm correct, once I purchase a new line, where do I attach the other end? Thanks in advance.
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I was also checking another thread about ECVP issues and rough running. Is this, the silver cylinder with the sparkplug-like boot on the top, the ECPV?
Also, what are these two things over the canister itself?
Also, what are these two things over the canister itself?
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From: Florida
Your first picture. That line is what provides vacuum to operate the heater A/C controls. With no vacuum the system defaults to defrost position. That line being disconnected also creates a vacuum leak and can be the cause of your surging. On my 87 you can see it goes over the top of the intake manifold and connects somewhere in the back. I've never had any trouble with mine so I don't know exactly where. I assume the best access would be through the access door inside the cab.
Note: on my 97 it takes a different route along the side of the valve cover. Can't see it to take picture.
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Lead Driver
Joined: Sep 2003
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From: SoCal
There is a vacuum tree at the rear of the intake manifold on the driver's side. The vacuum line going to the AC control needs to be connected to that tree. While you're there, look for other openings, as there should not be any. There should be either a cap or a hose on every outlet on the tree. Every hose connected to it should be connected to something.
The evaporation trap canister has different control solenoid configurations depending on the year. But in general, there is a hose that goes from the canister to the intake manifold, and somewhere in between is the solenoid installed in the line. On mine it's under the intake manifold on the driver's side.
The silver cylinder in the first picture of your second post looks like a hot water control valve; it's a vacuum motor, while the ECVP is an electrical solenoid.
The evaporation trap canister has different control solenoid configurations depending on the year. But in general, there is a hose that goes from the canister to the intake manifold, and somewhere in between is the solenoid installed in the line. On mine it's under the intake manifold on the driver's side.
The silver cylinder in the first picture of your second post looks like a hot water control valve; it's a vacuum motor, while the ECVP is an electrical solenoid.
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Thanks XLT4WD90! I'm a visual/pic kinda guy so I looked on google and found this- http://http://www.explorerforum.com/...acuum_tree.jpg
I'm looking for something similar, correct?
I'm looking for something similar, correct?
Lead Driver
Joined: Sep 2003
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From: SoCal
Yes, that's a vacuum tree, at about the same place that yours should be. Yours may be pointed in a different direction. You should be able to get to it by pulling the doghouse cover, and searching with a flashlight.
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After removing the in-cabin "doghouse" cover, I found my vacuum tree. There is a piece of line/tubing that loops between the two lowest posts. Would I be correct in assuming that the line in my first two pictures needs to be attached to one of those inlets and the other one needs to be capped, since I no longer have an A/C compressor? If so, any idea which one?
Lead Driver
Joined: Sep 2003
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From: SoCal
Even though you don't have an AC compressor anymore, the vacuum motors still control where the air goes. So if you can, you should replace the vacuum lines that power those. The stock lines are plastic, and get brittle and crack with long exposure to the heat under the hood. Then plug up any loose vacuum lines that remain.
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Ok. So I've reconfigured the lines several times, including running a new line from the fitting in the first picture to several of the ports on the vac tree, including one that was capped. Currently I have defrost, floor and mix but still don't have vent- after putting everything back the way I found it...
The only lines I didn't mess with were this line with the fitting, which is cut off a little farther down the line and I believe comes off the freon reservoir (?) and ran to the a/c compressor, which is no longer there.
And this one which runs from the vac tree to the front driver side into a disc-shaped unit sitting behind the battery and has another line running from it into the firewall:
Any further suggestions?
The only lines I didn't mess with were this line with the fitting, which is cut off a little farther down the line and I believe comes off the freon reservoir (?) and ran to the a/c compressor, which is no longer there.
And this one which runs from the vac tree to the front driver side into a disc-shaped unit sitting behind the battery and has another line running from it into the firewall:
Any further suggestions?
Lead Driver
Joined: Sep 2003
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From: SoCal
Sounds like you've gotten most of the connections. When you change the settings of your ac/heater controls, does the air come out of the different registers as indicated by the controls?
Do you have a vacuum gauge? If so, you can connect it to one of the lines to see what kind of idle vacuum you're getting. It should be at least 16" Hg, but if it's much lower, you may still have a leak.
The first picture is (was) indeed a high pressure AC line. So that has no effect on the vacuum system.
The second picture may show the vacuum line to the cruise control motor; it's pretty thick. If you leave it connected, it should hold vacuum.
Do you have a vacuum gauge? If so, you can connect it to one of the lines to see what kind of idle vacuum you're getting. It should be at least 16" Hg, but if it's much lower, you may still have a leak.
The first picture is (was) indeed a high pressure AC line. So that has no effect on the vacuum system.
The second picture may show the vacuum line to the cruise control motor; it's pretty thick. If you leave it connected, it should hold vacuum.
Fleet Mechanic
Joined: Apr 2003
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From: Florida
I have marked two of your photos to show the components you asked about:
the first is the Heater Valve, it allows hot coolant to circulate into the heater core based
on the Temperature Selector **** next to the Air Selector ****. The "L" shaped rubber
connector is the vacuum line.
the second picture shows the two vent caps for the Charcoal Canister:
these are just caps that are "open-to-atmosphere", you can pull them off and push them back on.
the first is the Heater Valve, it allows hot coolant to circulate into the heater core based
on the Temperature Selector **** next to the Air Selector ****. The "L" shaped rubber
connector is the vacuum line.
the second picture shows the two vent caps for the Charcoal Canister:
these are just caps that are "open-to-atmosphere", you can pull them off and push them back on.