Ford Aerostar :: Engine Is Revving / Surging Then Falls Back At Highway Speeds
May 21, 2015
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.
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I've been noticing some weird, very subtle engine sound changes while driving at highway speeds lately. Something almost like surging, but not. I don't know how to describe it. I might try to make an audio recording next time I take it out so I can explain it.
Anyway, I don't know why but ICP popped into my head. Maybe, for some reason, the engine was varying ICP causing the surging sounds.
So I hooked up AE and did a test. I've attached a screen shot.
With my idle speed actuated as high as it will go, and ICP actuated as high as it can go, I can only get a pressure of about 1450 PSI. I always thought ICP should go higher than that. I seem to recall reading somewhere around 3600 PSI.
So am I misinformed, am I reading the data wrong or do I have a problem? How high should Injector Control Pressure go? I missed it in the screen shot, but ICP is actuated to 100%.
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The primary electric fuel pump in the fuel tank of my 2004 W12 failed last month, shortly after I had set out on a cross-Canada trip from Vancouver Island to Toronto. The whole process of diagnosing and identifying the cause of the problem, mitigating it so that I could continue the trip, and finally replacing the fuel pump was kind of complex, so, here's the write-up.
The problem presented itself as a surging of the engine - a momentary loss of power - at normal highway operating speeds. The onset was progressive, but it didn't take very long - only about 60 miles of driving - from the first little cough of the engine until total failure of the pump. The first indication was failure of the car to maintain speed (while on cruise control) when climbing hills. That progressed to failure to maintain speed on flat surfaces, and finally led to the car coasting to a stop, engine stalled, at the side of the road.
I soon learned that if I floored the accelerator pedal and held it against the floor, the car would cough and burp for a few seconds, then take off like a rocket. So, for the next 40 miles, I coaxed the car into the next city by flooring it, accelerating to about 80 MPH, then coasting until the speed dropped to 20 MPH, and flooring it once again and accelerating to 80 MPH. Fortunately, I was on a remote road with few other cars, and no police.
I checked the fuses for the two fuel pumps - fuses 34 and 35 in panel C (above the left battery), and they were both OK.
The next day, I visited a VW dealer in the Canadian Rocky Mountains, and together with the parts manager and one of the technicians, we looked at the Self-Study Guides (SSGs) for the Phaeton, and looked at wiring diagrams. Eventually, we came to a tentative conclusion that the primary electric fuel pump in the fuel tank had failed. The SSGs stated that the primary electric fuel pump (the pump on the right side of the car) operates all the time, and the secondary electric fuel pump (the pump on the left side of the car) only operates during starting and during 'periods of high demand'. That made sense to us - the car started fine, and worked OK when the accelerator pedal was held to the floor (high demand). It just didn't work worth a darn at any other time... the engine would stall, or, the car would not accelerate at all.
Here are two illustrations taken from the SSGs that describe how the fuel delivery system works. The first image is taken from the 'Phaeton Overview' SSG, which applies to all vehicles. The second image is taken from the W12 engine SSG. I kind of suspect that all the Phaetons operate in the same way, regardless of engine, because the fuel tank in all the Phaetons has the same shape - two lower lobes, which means two pumps are required.
Descriptions from the SSGs
I think that there may be an error in the description above. My experience suggests that the right hand pump (identified as G6, above) is the primary pump, and the left hand pump (identified as G23) is the one that switches on during starting and periods of high demand. Note also how the identification of G6 and G23 in the illustration above is reversed from what is shown in the illustration below. I believe that the text and illustration below is correct, and the text and illustration above is incorrect.
The 'effects of failure' in the description above would, I believe, make sense if it was the left-hand pump that failed. In my case, the right hand pump failed, and the effects of failure that I experienced were as I set them out in the beginning paragraphs of this post - quite different from the 'effects of failure' of the left hand pump that are described in the SSG above.
After coming to the tentative diagnosis that the primary electric fuel pump (the right hand pump) had failed, we checked the parts stock status in North America. There was one pump in stock, but it was in the United States, and being that it was a Thursday, the pump could not be delivered before the following Tuesday. I didn't want to spend that much time waiting for it, so, we started thinking about other possible solutions.
If we could somehow get the secondary electric fuel pump - the pump on the left side of the car that only operated during starting and heavy demand - to operate, that just might put me back on the road again. So, I removed the plastic cover from the small relay that operates the secondary pump, and wrapped a rubber band around the relay, thus keeping the relay in the closed position. A short test drive proved that this solution worked just fine, the car once again operated normally. The only "problem" was that the last 25% of the fuel in the tank would be unusable, because that fuel would be left behind in the right-hand lobe of the tank - the lobe with the defective primary fuel pump.
Electric Fuel Pump Relays
Here is an illustration from the Phaeton wiring diagrams identifying the various relays above the left battery.
Here you can see the two relays for the electric fuel pumps. They are identical part numbers.
Here you can see the relay for the secondary electric fuel pump, with a rubber band wrapped around it to keep it continually closed.
Aside from the loss of use of the last 25% of the fuel in the fuel tank, the car worked just fine with the secondary electric fuel pump running all the time. There were no problems noted even under heavy acceleration. It was, however, necessary to physically remove the rubber-banded relay from its position in the relay panel whenever the car was shut down for more than half a hour. The power to this relay comes from Terminal 30 (battery direct) - it is not switched on and off with the ignition as Terminal 15 power is. This meant that if the rubber-banded relay was left in position overnight, the left hand battery would totally discharge, because the fuel pump would operate continuously all night. I discovered this the morning after the first night...
So, for the next 8 days, I drove across Canada, removing the relay each night and replacing it each morning. I didn't bother to remove it when I stopped for meals or fuel. The rest of the 3,000 mile trip was uneventful - except once, when I let the fuel tank run down a bit too close to the 1/4 full mark, and the car began surging again because the left hand lobe of the fuel tank (with the functional secondary pump) had emptied out. That was a close call, but I managed to get to a gas station and refuel.
After arriving in Toronto, I called the parts staff at my home VW dealer and ordered a new primary electric fuel pump. I discovered that the left and right hand pumps are slightly different (the various hoses coming out of the pumps are different), and I also discovered that a pump costs about $400. The parts staff suggested I order two seals (one for each side of the tank), because I would have to remove both the right and left fuel tank covers to change the right pump. The seals were not expensive.
Here are two pictures that illustrate where the pumps sit in each lobe of the fuel tank. Note the fuel filler port on the left side of the pictures (as we know, it is on the right side of the car) for orientation.
Phaeton Fuel Tank, showing pumps
Fuel Pump Access Panels
Below is a picture that shows where the access panels to the two fuel pumps are. It's easy to get to these access panels, just remove the carpeted panel from the floor of the trunk.
Here's a close-up of the right side (primary) electric fuel pump access panel.
The instructions (from the VW Repair Manual, or the ELSA / ErWin system) for replacing the fuel pump are quite well written. The repair manual suggests that the fuel tank be drained before replacing a pump. I didn't want to drain the tank, so, I ran the fuel level down as low as I dared (remembering that 1/4 full is effectively 'empty' with a failed primary pump). That proved to be adequate.
There are a heck of a lot of steps involved in disconnecting all the hoses and loosening the various components before the pump can be removed. I strongly suggest that anyone attempting this task have a printed set of instructions before starting disassembly.
The fuel pump has quite a few hoses and connections on it, but fortunately, each connector is unique in design, thus it is not possible to hook things up the wrong way when installing the new pump. It is possible to 'lose' a hose inside the tank... for this reason, I attached a small piece of string to each hose I disconnected from the pump.
The process goes more or less like this:
1) Remove the two 404 relays, to ensure no power is sent to either fuel pump.
2) Lift the rubber cover, and remove the electrical connections from both pumps (left and right).
3) Using a special tool, lift up the three fasteners that hold the cap over top of the access panel (these are NOT threaded fasteners!)
Here is a side view of the three fasteners that hold the plastic cap in place - they are friction fit, not threaded.
4) Now you have a clear view of the access panel. It will probably be dusty and rusty, and should be vacuumed clean before proceeding, to prevent crap from falling into the fuel tank when the cap is removed. The rust is due to condensation forming on the cold metal part whenever the car is filled with cold fuel from an underground storage tank.
5) A special VW tool is used to remove the locking ring from the access panel.
6) After removing the locking ring, I buffed it up with a wire brush to remove surface corrosion.
7) The plastic access cap can now be lifted. There are two electrical connectors on each fuel pump, but three possible fittings on the plastic cap. Fortunately, the three fittings are keyed differently.
8) This is what you see inside the tank after removing the plastic cap.
9) After following all the detailed instructions for disconnecting and stowing hoses, disconnecting the fuel measurement probe from the pump housing, etc., it is possible to lift the pump out. It will be full of fuel.
10) The old and new pumps, side by side. I was very surprised at the amount of crap that was trapped in the filter screen at the bottom of the pump. The car only has 60,000 miles on it, and I have always used premium fuel in it.
11) I was also a bit surprised at the discolouration of the pump components. Below you can see the old and new pumps side by side.
12) It is necessary to get access to the opposite side (in this case, the left side) fuel pump, because hoses from each pump travel horizontally across the tank and connect to the other pump.
13) Here you can see a new hose from the right side pump connecting into a T fitting above the left side pump. It is easy to thread this hose across the top of the inside of the tank.
14) As mentioned earlier, there are three possible fittings on the base of each plastic cap, but only two connectors within the fuel tank. Everything is keyed, thus improper assembly is not possible.
Once the new pump has been installed, the hoses connected, and the fuel measuring probe reset into the side of the new pump, re-assembly of everything is quite straightforward. I replaced the rubber ring around the access panel opening on each side of the tank, and I also buffed up the locking rings using a wire brush (to remove corrosion) on each side.
It was not a pleasant job - your hands get covered in fuel, and there are some hazards associated with working on an open fuel tank with vapour escaping, but it is not a particularly difficult job. It is time-consuming, though.
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I have a 45 min drive to work every day, all highway. Lately on the way home in the afternoon I have been experiencing a surging noise that seems to just happen while I'm doing hwy speeds. It sounds to me like the fan is tuning on and off. Is that possible? It comes on for a few min. And then off again. I have new icp ipr cps. New oil and filter and fuel filter.
Also I'm still having a battery light on and off issue while I'm driving. Is possible the two issues are connected. I plane on doing extensive search for a bad wire this weekend. Batteries and alternator have checked out and are fairly new.
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My 1994 Aerostar, with 100,000 miles on it, started lurching at highway speeds. Weeks before this, the airbag light began blinking. The transmission man said it felt like it was shifting into overdrive, then out, then into overdrive, then out, etc.,etc. About this time, the cruise control quit being reliable. Dealership said codes didn't show a problem, "I must be mistaken". Then they said it sounded like a fuel filter.
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my 1990 Nissan 300zx with 136,000 miles often surges at highway speeds for several seconds then drops back down to normal. the surge is usually 1000 rpm. does not happen if not in overdrive, and will not happen unless having been driving for 15 minutes or so. also seems to occur more on hot days (80 degree +) than on cool days. mechanic has looked at this several times but not yet able to determine why.
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I have a 2011 Gen3. It's driving perfectly. Its charging when being driven by the ICE as normal. Its also charging by regen braking. However, when the car is 'stationary' with full EV battery- and when it looses its charge with lights, fans etc, it cuts out. When the battery indicator drops to the normal 2 bars, the engine falls back to 'ignition on' mode (i.e the dash lights illuminate and the steering goes heavy)
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I have been having to add 1-2 quarts of oil every 2-3 days. I have noticed the back of the engine wet, but have seen no visible leaks unless the engine runs then it drips. Does it sound like a valve cover gasket problem or a rear main seal?
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I have a 95 Mercury Villager that didn't pass inspection. I put SeaFoam in it before inspection to clean the engine. Now I have been told that it may have caused gunk to loosen up and that I need to run out all of the gas in it and then fill it up and run it at high speeds for a period of time on the highway before I try to get it re-inspected. Since it didn't pass inspection I couldn't get it registered and it is technically not street legal at this point. I'm letting it run in the driveway to burn up the gas. Should I fill it completely when I get gas or should I put just a bit in and run it out a couple of times before I try to get it inspected again? Also, if I put it in park and rev it for 20 mins or so would that be equivalent to driving it on the highway?
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I have an 04 Elantra GT and have been noticing a jerkiness when driving at a constant speed on the highway. I haven't noticed it around town or while accelerating. I also have noticed that when I disengage the clutch on the highway, the engine sometimes doesn't respond right away, or it even may surge. This has happened when exiting the highway when I disengage the clutch. The engine will slow, then speed up close to 3000 rpms.
I also had a check engine light come on and couple months ago. The code indicated that the upstream O2 sensor was bad. I took it out and cleaned it, but didn't replace it. Is this a likely culprit for this set of symptoms? If so, how can I test the sensor to be sure? I heard that I could disconnect it and run the car and see if the surging lessens, but wasn't sure if that was a good thing to do.
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Surging at idle computer check ( at Oreilys) says TPS is faulty. Also using water replaced water pump still leaking. We cannot see any obvious leaks.
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I drove our 95 3.0l aero to work today, I was going to a job 45 miles away. It sounded like it was revving awfully high for 65-70mph, but the gear selecter said od, so I figured I was just crazy. Got to the job and tried to back up and the shifter wouldn't go into reverse. Parked for the day after realizing the shifter would go N and down, but not into rev or park. Apparently it was revving high, as the gear indicator was now off and I was no doubt in drive, driving to work. I got it home, then had to drop my daughter at work, by staying in OD.
Then on the way home the van just DIES while going 35+- mph. Won't restart, smelled gas after many many attempts to start. Towed home. NO spark. I have 12+ volts at+coil. I tried my ignition module and a new one, neither sparked at the coil wire. I bought a new coil, then checked resistance at + &-, and - and coil output post. Basically same resistance new & old coil. Did my hall effects or cam, or crank sensor just go out or? Why both problems same day? I thought if it was the coil or ignition module, maybe it got too warm on drive revving high. Does a 95 3.0 coil get triggered by the distrib haal effects or does the crank sensor do it?
I can easily see one of those being bad as they are original, with 334,000+ miles. All the tune up, coil, wires, plugs, ign module, cap, rotor, were replaced 55,000 miles ago. ALSO does this distrib have a TFI module on it? My book says to pull the distrib and remove it, like my 5.0l Mustang, but I don't see one, I think thats the ignition module on the pass. inner fender. I'd like to see if I can get 400,000 miles out of it.
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I'm looking for directions on how to disassemble the sun roof to figure out which part is broken. It slides open and closed but will not tilt up. (It will tilt by pushing up on it from inside but won't stay open; it just falls back in place).
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2014 F250 SuperDuty 6.2L gasser, x-cab long bed work truck. 105k miles, original owner, 1 driver, mostly highway miles, well maintained and super clean truck.
First issue occurred at 83k miles, Aug 2016. Warm summer day climbing I-70 in CO, slightly loaded, and just entered the Eisenhower tunnel (11,150' altitude). Lost power, no RPMs - not running, I put it in N and rolled as far as I could. Hazards on and no-where to pull over, hugging the wall and blocking one lane. Power OK - will crank, no fire. 1/3 tank on the fuel gauge and >100 miles distance to empty on the trip computer. Tunnel rescue shut down traffic and pushed me out into the daylight.
After waiting an hour to fill our paper work for disabling the interstate tunnel I returned to the truck which quickly started. No symptoms, no lights, no codes. Topped off the fuel tank after a easy 15 mile drive downhill. Drove another 800 miles symptom free to my destination and checked it in at the dealer. At this time a check engine light had finally illuminated - PO420. I shared the story of stalling out at highway speeds with the Service Writer. Dealer replaced the cats, confirmed fuel pressure OK, computer condition OK, serviced the trans (at my request).
No symptoms reoccurred during the next 20k miles until last weekend. 105k on the OD now. Heading to Flagstaff, AZ on I-40 in similar conditions. Hot, AC running, climbing in elevation, slightly loaded, running on the bottom 1/3 of the fuel tank... Died while cruising at 79 mph. Well, at least this time I wasn't in a tunnel and had a shoulder to pull off on. Deja-Vu - full power, radio on, no engine lights, gauges normal, fuel reads over 1/4 tank, >100 miles till empty on the trip computer - won't start. Cranks, but no fire. Some sputtering during start attempts must have triggered the next trouble code.
Opened the hood, removed the gas cap, let it vent and cool for about 30-40 mins while I took a walk. Returned to the truck which easily started and let me drive to the next fuel station, 30 miles away. This time the check engine light stayed illuminated. It took 24 gals of fuel. Drove 3 more hours and almost 200 miles without symptoms - check engine light still illuminated keeping me curious and fully alert along the way.
Got the codes pulled at a parts store that was open on Sunday. PO300 & PO301. Random misfires and cylinder 1 misfires. Sounds consistent with poor fuel supply? Spent the rest of the day searching forums for any clue to this highway stalling. All I came up with was to clear the computer - disconnect battery, turn lights on, wait 15 mins, reconnect battery, start engine, apply brake, drive, etc. This and another full tank of gas gave me enough courage to set out on my trip home.
Next occurrence was just outside of Santa Fe, NM. Similar conditions again: Hot day, AC kicking, Interstate travelling about 80mph, slightly loaded, climbing in elevation, fuel tank just below half - stalled out. Repeat previous learned routine. Open hood, vent gas cap, walk it off for 30 mins, return to truck, start it up. Drive to next town and top off with fuel about 30 miles away - only took 16 gals! Made it home 4 hours later without stopping. No repeat symptoms, no check engine lights.
The next day a code - PO420. Catalytic efficiency below threshold.
Quick recap:
6.2L gas engine stalling at hwy speeds.
Cruising between 65-80mph
-Interstate travel - no stops between last fillup and stall.
-Warm weather, AC on
-Running on bottom ~1/2 tank
-climbing in elevation, slightly loaded
To clarify: slightly loaded - no trailer, maybe 1,500 lbs bed cargo, mostly wind drag. The most I have pumped into the fuel tank is 29-30 gals or so. I assume I have the 34 or 35 gal tank. Never seen the calculated "distance to empty" below 40 miles.
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I have a 1999 F350 200,000 miles. Now getting an intermittent engine light. Still runs well, although once or twice I felt a momentary surge at highway speeds. The light is on intermittently about 1/2 time. I read the codes and the following codes, as in the thread title, came up:
P0280 - ICP circuit out of range - low
P0113 - intake air temp sensor circuit - high input
P0470 - Exhaust back pressure sensor circuit malfunction
P0478 - Exhaust pressure control valve - high input
What would make these all code at the same time? Would these not make a noticeable problem driving? And how do I resolve these?
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I have a 2007 Santa Fe with the 2.7L engine and 62K miles. At 65-70 mph I have a very noticeable miss. The check engine light has not come on and a scan at a Parts House shows no trouble codes.
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96 Ranger x cab 4.0 ltr automatic... Starts fine, runs fine until I stop.
When I stop, the engine idles oddly - it slows and speeds back up, tachometer and the battery gauges both lower just a bit and immediately return to normal. When the headlights are on, they dim in rhythm when the gauges dip. It does not do this in park or neutral.
Sometimes it does it right away. Sometimes it doesn't do this at all. Of course it did not do this when I took it to the shop. The battery is nearly new. Cables are fine. Alternator checked out ok.
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I recently got a used 2000 silverado 1500 ext. cab with a short bed. Has a 5.3L engine. I noticed it has vibrations at highway speeds. I thought it was the crappy tires on it so I had all the tires replaced and balanced. Now it has all new tires and does the same thing. Runs really smooth all the way up to 40mph and then the vibrations begins. It is mostly felt in the steering/dash and pedals. A little more pronounced on accel. but vibrates if your on the gas on not.
Once your reach 65mph, the vibrations stop. I have also noticed that asphalt makes it vibrates more. When I go over concrete overpasses in the problem area of 40 to 65mph it smooths out. I took a look under the truck and saw nothing obvious. U joints feel tight and no play, seen it had weights which appeared welded onto the one piece drive shaft.
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I just got my new 2013 Persona Prius on Saturday. I haven't put too many miles on it (under 200) but I'm noticed that a feel a stuttering or hesitation when I reach highway speeds. Typically about 65 -70mph. I can't think of a better way to describe this but it feels like the when driving a manual transmission, when you need to shift to the high gear? That kind of stuttering feeling. I'm sure that it's not the same problem but it feels like that. Once I go faster, the feeling stops. Or slower. But going between 65 to 70, it's the same feeling.
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A few weeks ago i had a surging idle issue very intermittently, and it went away for a while so i stopped thinking about it. Just got back from a weekend in vermont, about 130 miles each way, and i noticed as soon as i got to vermont and came to a stop sign it was surging, and when i just got home it was surging again. Why would this have picked back up after long stretches of running for a while? Runs great as far as i know, just have this surging idle for some reason.
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A few months ago my car started whining at highway speeds. The noise has increased in pitch and volume, and is not dependent on engine speed--in fact, if I turn the engine off and coast, the whine persists, lowering in pitch (and getting quieter) when the car slows down. Recently the car has also started vibrating when I turn slightly to the right, as when I change lanes on the highway or bank right on a long turn (sharp right turns from a full stop don't elicit any noise). Do I have a problem with my alignment? I notice my tire wear looks a bit uneven.
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