Passat (B5) :: 2001 VW - Rough Idle / Loss Of Power And Poor Gas Mileage

I have a 2001 VW Passat Wagon 1.8t AUG. A couple of months ago, I took it into my shop for a check engine light. The did the following work on the vehicle:

Replaced MAF sensor
Replaced broken oil level sensor
Replaced outer CV boots
Resealed my transmission pan (it was leaking)
Replaced bad vacuum hoses

When I got the car back, it was idling really rough, and one time it even stalled. Just after starting it, when I hit the gas it wouldn't respond immediately and sputtered for a little while. Once I got going it was usually OK, unless I was going uphill...where it wouldn't perform as well and the engine noise kinda wavered. I also noticed that my gas mileage wasn't nearly as good as it used to be. (I never experienced any problems like this before they did this work) So I took it back to the shop and they replaced both the front and rear 02 sensors. I still had the same problem, so I took it back, and they replaced the fuel filter. Still has the same problem.

The light came on after a month, so I took it back and it was the random cylinder misfire code...and they said that didn't really know what to do about it. So I decided to take matters into my own hands. I cleaned the MAF sensor they installed (took it out and sprayed it with cleaner) nothing. I replaced the spark plugs and while doing so found that one of my ignition coils was bad, and I replaced that as well. Turns out the AutoLite plugs that a local parts store sold me are crap for this engine (actually caused misfires) so I went and got Denso double platinum plugs the next day and put those in. And finally I changed my air filter. Still having problems.

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Ford 7.3L Power Stroke (1999-2003) :: 2001 - Rough Idle - Poor Fuel Mileage?

My7.3 is idling rough till I pull the fuse for the fuel pump them it will smoothen out I ran a by pass switch to us my truck but the fuel mileage is bad why

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Golf IV / Jetta IV :: 2000 - Won't Start At Cold / Poor Fuel Mileage

I own a 2000 Jetta VR6 5 speed. Car has over 300,xxxkm on it, with documented maintenance including chains within the past 12k. Car has intake, 2.5" resonated exhaust, stock software.

I have recently noticed that the car has a cold start issue. Its winter here in Canada, so in the morning when i go to start the car and let it warm up for a couple minutes, the idle is choppy at first and then evens out at around 900-1k rpm. If i try to blip the throttle, or even hold it (half way or WOT) the car just wants to bog out, EXTREMELY rough idle. It will eventually, after about 2 mins of idling, go away and i can drive.

I have absolutely no issue with allowing the car to idle for a few mins to warm up, but i know for a fact that whether a car is cold or not, it should be able to rev freely.

I also have horrible fuel milage. I use 91 octane, and average about 250-300km per tank. 70% city 30% hwy driving.

The following parts have been replaced in the past 1200 to try and resolve the issue

OE Mass air flow sensor

OE spark plugs

BREMI wires

OE Bosch front O2 sensor

I have scanned the car several times, which led me to change the parts i did. Only had a CEL once and it was for the front O2 sensor which i just replaced. Any other codes were for random multiple and a cat efficiency fault. Again those were fault found off a GFF test done at VW, they were not enough to trigger a CEL, but i still changed the parts.

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Sierra :: 1996 SL V6 - Rough Idle After Tune Up / Skipping When Accelerate

1996 GMC Sierra SL V6. Owned since new. 100,000 miles, never tuned up. I decided to get a tune up in hopes of increasing mpg, and it was overdue really. New plugs, wires, cap, rotor. Got truck back and it runs rough, knocking, skipping, hesitating, bogging down when trying to accelerate, rough idle. Went from 15.5 mpg, down to about 14 mpg. They said they put in all AC Delco parts. Brought it back to them twice now and they cannot figure out the problem. It ran PERFECTLY before I send it in for a tune up. No problems whatsoever.

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Ford F-150 - 1997-2003 :: Skipping / Rough Idle And Loss Of Power - Misfire On Cylinder 4

Replaced the spark plugs and wires a couple months ago. Started skipping yesterday throwing the #4 misfire code so I replaced the coil pack, reset the check engine light but it's since came back on and has a rough idle and loss of power. By the way, it's a 97 F150 4.6L 4x4 with 200,000 miles.

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Accent MC (2006-11) :: 2008 GS - Misfire On 3 Cylinders / Rough Idle And Poor Acceleration

After scouring through hundreds of threads on this forum (which is Awesome, BTW), it seems as if this misfire / rough idle thing is fairly common (which is scary!!). CEL is on steady. Had the codes pulled; P0301, P0302, P0303. At the recommendation of the mechanic, I had the plugs replaced...no improvement. He then replaced the ignition coils...no improvement. Just finished replacing the MAP sensor. This actually had a VERY temporary positive effect. However, after about 5 miles of driving, the misfiring returned. Took the car to the Hyundai dealership, and they acted as if they didn't want to fool with it. They referred me to a couple of local repair shops...????

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Ford F-150 - 1997-2003 :: Rough Idle And Poor Performance - Code P0401

97 4.6.. So it would appear that I have the wild goose chase of codes. The major symptoms are rough idle and very poor performance. I started off by cleaning the egr valve and ports. Then I checked the egr valve itself and watched the valve open and close under a vacuum. I was suspecting the DPFE sensor but I wanted to trying something else first. I was under the Impression that if at idle you apply a vacuum to the egr valve it would cause the engine to "stumble and stall". I did this and there was no change in the way the engine was running. So now I'm lost as to where to go from here.

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Elantra HD (2006-10) :: 2008 - Bad Gas Mileage And Skipping Gears

I have a 2008 Elantra with 50,000 miles. I know I was overdue on the tranny fluid change and the car was getting bad gas mileage and skipping gears. I brought it in and had the tranny flushed and refilled and now its running good. I thought it would be good to get a price on spark plugs because the book said replace at 60,000. I called the dealer and he basically told me he has not sold many of the plugs and they should last 100,000.

I seem to be getting conflicting info on what should and should not be done at the maintenance books written schedule. I looked for a price on Fuel Filter air filter which is in the maintenance to replace but again conflicting info stating that should not be changed unless there is a problem. Anyway, what should and should not be replaced at specified intervals? I know the tranny fluid change should have been done at 30,000 because it was very dirty and causing issues for me.

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Nissan - Maxima :: 1993 - Rough Idle / Horrible Gas Mileage

My daughter has a 1993 maxima SE (3.0 DOHC) that ran ok until one day when she left work and started the car it was running very rough (missing and sputtering). She had the car towed here and I looked it over,it had a lot of visible problems which I have fixed (cracked coil packs,leaking valve cover gaskets, filthy fuel filter,clogged pcv valve, oil saturated air filter,spark plugs burned down to nubs etc, I replaced all those obviously defective parts) but the car still idles very rough, idles too low RPMs (400-500 rpms), exhaust smells like raw fuel and it only gets 5 miles to the gallon on my last test drive.

I removed the intake manifold to get to the rear fuel injectors to see if they might be stuck open and leaking.The car had been sitting for about 5 days with the battery disconnected and when I removed the first injector there was no fuel in the injector or the rail and no pressure in the rail.I left the injector out overnight and the next morning there was fuel all over the top of the engine and in the fuel rail.I put the injector back in and unbolted the rail,I reconnected the battery and turned the key to start the fuel pump.I waited for about 3-4 minutes and did not see any fuel leaking from the injectors.I turned the key off and removed it from the ignition,disconnected the battery and bolted the fuel rail back down.I again removed one of the injectors and there was no fuel in the injector or the rail and no pressure in the rail.After about 2 minutes, with the key out of the ignition and the battery disconnected,I saw fuel start filling the rail and the injector port, so I quickly put the injector back in.

I`m thinking the next step would be to replace the fuel pressure regulator and recheck the injectors for leaks.Am I on the right track here with the pressure regulator? What could be causing the car to suddenly start acting this way, my daughter said the car ran fine on her way to work ( although I hardly think it could have been running "fine" with cracked coil packs,clogged air filter,worn plugs etc)...

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Ford :: 2007 - Poor Gas Mileage?

I have a 07 Ford F150, 4.2 liter V-6, that the city gas mileage has fallen from 17 to 12.5, highway from 22 to 16.5, in that last year or so. Two garages have ran a test on the computer and can find nothing wrong.

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Tiguan :: 2012 - Poor Fuel Mileage?

My wife and I just purchased a 2012 SEL front-wheel drive. Our first tank (mixed use) was 19 MPG. We took the vehicle on a roadtrip this weekend that was 95% highway driving on mostly flat Texas roads using cruise control as much as possible. Our best tank was 23.3 which was achieved driving 70-75 MPH on I-20. Is this consistent with what others are seeing? My mileage figures are at the link below. Note, all values are calculated by me, not the MFD that reads about 1 MPG high.

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BMW - 325 :: Getting O2 Sensor / Code P2231 - Poor Gas Mileage

Having O2 sensor bank 1 heater circuit short on a 03 BMW 325i. Changed O2 sensor, reprogram DME - no solution!

Symptoms: check engine light - code p2231 Engine surge upgrade Poor gas mileage

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Honda - Accord :: 2011 - Poor Gas Mileage?

I have a 2011 honda accord with 15,000 miles on it that Has only gotten 20mpg since it was new. It is supposed to get 23mpg city and 34mpg highway. I figured I was the tires but since fixing the leaking valve stems it is still only 20mpg. I asked the dealer about it several times during oil changes after I first bought it and they claimed to look into it and find nothing wrong. Is there anything I can do to fix this or would it be covered under new yorks lemon laws?

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Passat (B6) :: Rough Idle When In Drive / Slight Loss Of Power With Horrible Gas Mileage

My 07 2.0T (101k mi.) Passat idles roughly when in the drive position (at a stop light, or sign, etc.), the engine sounds "gruffy", and suffers from a slight loss of power with horrible gas milage. I've had spark plugs and the coil pack replaced two weeks ago, and still can't seem to find the source. There are no misfire codes or any others showing up. From reading many posts here, I've found that a common issue is carbon build up for similar symptoms of my car. Do I need fuel injector cleaner, and or valve stem cleaner, etc? As far as the possibility of cleaning out the intake valve, I only open the hood to add oil, washer fluid, check my oil, and wipe down the engine.

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Ford F-150 (2004-2008) :: Rough Idle / Bad Gas Mileage / Stalls Out / RPMs Jumps Around

I bought an 04 f150 super crew cab with the 5.4L triton in it 3 years ago with 50k on it from my great uncle who was the original owner. It's had a tick to it since he had it but the dealership told him they couldn't find anything wrong with it and to get use to the noise. It's ran pretty good up until last couple months where it's been running really rough and not doing the best. It's still hasn't been all the time but more intermittent and comes and goes, but when it's running bad the rpm drops down to about 200 and my motor sounds blown.

When that's happening I could put in neutral and rev it up and it would go back to normal for a bit, but now it's all the time and stalls out even at 70 on the hwy. The codes it throws are, p1000- monitor checks not complete-more driving required, p0345- camshaft pos sens circ error(bank 2), p0022- A camshaft pos timing-over retarded bank 2. Things I have tried-changed all 8 plugs, added K&N air intake, replaced both cam sensors, replaced fuel pump driver module (due to corrosion). Tonight I'm going to clean the throttle body, mas air flow sensor, change fuel filter.

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Prius (Gen 2) :: Poor Gas Mileage And Transmission Not Going To High Gear?

My 08 has been getting poor mileage for the past 3 weeks or so ..... I tried a "push the power button and trip reset shift to reverse to eliminate the backup beep" mod and it did not work. However I find now that I cannot get my MPG average above 42. When I tried the mod the odometer went immediately to all bars and then the bar indicators went out one by one until the regular odometer reading came on .... I'm wondering if doing that also set the car into another "mode" where the tranny will not shift to a higher gear???? So symptoms are constant engine running when cruising to a stop and after 20-30 seconds the motor will shut off .... and while driving on the highway the engine will pick up at least 1000 - 1500 rpms just by adjusting the accelerator a smudge .....

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GTI 337/20th Anniversary :: Poor Gas Mileage - Got CEL For Coolant System

What these codes mean and what I need to do to fix this?

Codes:

P0141 o2 sensor heater circuit bank 1 sensor 2

P0138 o2 sensor circuit high voltage bank 1 sensor 2

P0036 H02S heater control circuit bank 1 sensor 2

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Ford F-150 (2009-2014) :: 2012 - Got Poor Mileage - 11.4 Mpg?

I have a 2012 f150 stx 5.0 and I drive mostly city with a few highway miles. Why get this bad of gas mileage?

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Honda - Accord :: 1998 - Vapor Leak And Poor Gas Mileage

I have a 1998 Honda Accord, automatic with 179,000 miles. The malfunction indicator light came on so I had the car smoked and found that it needed a purge valve. I replaced the purge valve and smoked the car again which indicated the car still has a vapor leak and the malfunction light stayed on. The only place visible smoke is coming from is from the fuel filler neck (place where fuel or gas is put into the car) when the gas cap is off. Where the leak may be? My car is also getting horrible gas mileage. I was going to replace the fuel filter but I heard it was in the gas tank, is this right and is it replaceable? Would replacing the gas cap work for either the vapor leak or gas mileage?

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