2.0L Engine stumbles...

[JessicasDad]

Sometimes the engine will stumble (maintaining or increasing throttle position has no effect and RPM's start dropping as if it's starving of fuel). It usually happens about five to fifteen minutes after starting and most often when traveling at highway speeds. Removing your foot from the accelerator pedal, allowing the engine to return to idle and waiting a moment allows the engine to return to normal operation. I don't think it is electrical because the engine idles OK and doesn't idle roughly. After a moment the engine has normal operation. The MIL (malfunction indicator light) does not come on. Recently replaced Fuel Pump, Forward O2 sensor and MAF sensor with no improvement. Added a can of fuel system cleaner with no effect. Any thoughts?

[mbrown3039]

Does it happen while CC is engaged? Only with CC? Never with CC? Or, CC doesn't seem to matter?

Have you checked for vacuum leaks? Checked the airbox and snorkel (the pipe that goes from the airbox to the headlight housing) for blockages? You can take the snorkel out, btw.

Have you Seafoam'ed the engine? Mike

[ApexerVR6]

Sometimes the engine will stumble (maintaining or increasing throttle position has no effect and RPM's start dropping as if it's starving of fuel). It usually happens about five to fifteen minutes after starting and most often when traveling at highway speeds. Removing your foot from the accelerator pedal, allowing the engine to return to idle and waiting a moment allows the engine to return to normal operation. I don't think it is electrical because the engine idles OK and doesn't idle roughly. After a moment the engine has normal operation. The MIL (malfunction indicator light) does not come on. Recently replaced Fuel Pump, Forward O2 sensor and MAF sensor with no improvement. Added a can of fuel system cleaner with no effect. Any thoughts?

Sounds like coilpacks to me.

[JessicasDad]

Hi there MBrown3309 and Apexer VR6. Thank you both for responding. First I appologize for my ignorance. What is meant by the acronym "cc"? I will definitely check for blockages in the tubing between the air cleaner box and the fender. I haven't tried Seafoam, but did just finish running a bottle of Chevron Fuel system cleaner in the last tank with no noticeable difference. The problem spirratic. It will not happen every time the car is driven, but my daughter has told me that she thinks that it only happens when the tank has less than 1/2 of a tank of fuel in it. So I told her to just keep her tank more than 1/2 full! (Actually it's not a bad idea...that way when it does happen I can discount her theory! jk! Love Ya Jessica!

Now onto the coil pack theory. I have been thinking about that as a possible cause. My daughter tells me that it usually happens within 5 - 15 minutes after driving it and I was thinking that it could be a scenario where something starts to warm up and during the transition period from outdoor temperature to normal operating temperature under the hood could cause something to open circuit momentarily. I read somewhere that there was a recall on this part for a 2001. Does that recall apply to the 2004 model?

Thanks again to all my friends on Jetta Junkie! What a great group of people.

[mbrown3039]

CC = Cruise Control.

Also, I'd recommend you tell Jessica to not let the tank get PAST 1/2 full...in other words, never more than half full -- you need this to happen a bit more often to be able to diagnose it (assuming that's a relatively safe thing to suggest). Mike

[JessicasDad]

Hey Mike,

Jessica has only used the cruise control once (trip to Las Vegas) and when it happened to me once te CC was not on - so I think we can discount the CC. I have come around to your thinking and am going to switch vehicles when her when the fuel level drops below a 1/2 tank. When it does happen I plan on pumping the accelerator pedal to see if it has any effect. If not, then it would indicate a fuel delivery problem. Once the low fuel light comes on I will pull the cover off the fuel tank and inspect my work I did with the fuel pump. When I replaced the fuel pump many months ago, they assured me it was the correct one, even though I thought it looked a little different, I took their word for it. Well it wasn't (do you see a theme developing here? re: MAF sensor!). Anyways the differences were the nylon case which contains the actual pump itself (a metallic cylinder that had the same construction as the failed pump). I therefore swapped the pumps and used the old nylon case. I know your thinking why not just return it to the place I bought it? Because everywhere else I looked for the fuel pump said it would be a couple of hundred dollars more and we needed to get her car running fast. So I cannibalized the new/old system to get it going again. While I'm in there I plan on also replacing the fuel filter.

All of this probably won't happen till mid/late next week. I'm keeping my fingers crossed that I catch it when it happens.

FYI - Watching your Steelers this morning on TV - that Temp quarterback sure can scramble!

[mbrown3039]

...Watching your Steelers this morning on TV - that Temp quarterback sure can scramble!

You, sir, have me confused with someone who admires the rather pedestrian colors of black and yellow...I root for the BURGUNDY AND GOLD of my beloved Redskins...on Sundays, anyway. Saturdays are for the Longhorns!

I live in Vegas -- and no worries about car-side surgery: I once drove a Volvo that had rear brake calipers that were a homolgation of parts from several different model years! Brakes worked fine for 2+ years... Mike

[JessicasDad]

Your so right! BillH1012 from a recent post is the Steeler fan.

Later this week my daughter and I will be switching vehicles. Then I'll have some more data.

[ThePain321]

I have a 2.0 with a similar problem. It comes and goes, this night it is bad enough I thought I'd check here.

When I cruise everything is fine. When I accelerate in any gear it will drop RPM to the point it will kill the car if I was stopped at a light. The only way to keep it going when this happens is to rev it up a little bit and burn rubber! Then once I hit 2nd it has enough momentum not to kill the car. I Don't understand...
This has been going on for 2 years now, off and on with out any persistant pattern. I've noticed something getting worse, I hear a slight fluttering noise beneath the sound of the choking revs of the engine when I'm accelerating. It worried me tonight. Shifting feels nice and smooth. It doesn't pop out of gear or struggle to go in gear. I just have this random acceleration problem with a new symptom of a fluttering noise. Best described as a sounding like a pigeon?
Usually once it drops rpms the acceleration is much slower then it should be and it's a very jerky while accelerating.
One time the corrosion on the battery caused this loss of steady power/acceleration it seemed like. Another time I just changed an old Spark Plug Wire. This time I Am Lost. Everytime the symptoms are identical.

OH YA! forgot to mention, it turns my check engine light on. The CEL will flash, I hear some dinging and the oil light will come on too!


AFTER SCAN- This morning I scanned it to see the error. Cylinder 4 misfire Again! It has new plugs and wires yet cylinder 4 is the reason I changed all the plugs and wires 2 months ago. This sounds bad, couldn't it be a bad rod or bearing that's messing up the piston's movement? My only indepth motor experience is with my 2 stroke dirtbike...

[mbrown3039]

^^^ Have you changed your coil yet? How many miles on it (I'm assuming it's the original one)?


Jessica'sDad: Any update? Mike

[JessicasDad]

It can't be anything as serious as a bad rod or bearing - you would have severe problems and it would be constant not intermittent. Because your problem occurrs when you accellerate indicates to me that it is a fuel delivery problem. Additionally the slower than normal acceleration and jerkiness suggests to me either a clog in your fuel system or possibly a fuel pump that is intermittent due to an electrical connection. You too have a problem whereas the condition is not constant and that can be difficult to trace. my recommendation is to buy yourself a cheap notepad. Draw some columns in it. Each time it happens record everthing you can think of about the situation. Date of occurrance, Fuel guage level, # of passengers, Radio On/Off, Outside temperature, time of day, How long you were driving, I'm sure you can think of a few others. You might find a pattern and then you can work from there. I've heard it mentioned before that the Coil pack has a problem, but don't know if applys to your/my year ('04) vehicles. I switched vehicles with my Daughter starting this morning so I should start collecting data first hand soon. She gave me the car with an 1/8 of a tank and I gave her mine with 3/4 full. Such is the life of a father...

[JessicasDad]

Hi Mike,

As indicated in my post to ThePain321, I'm just taking over driving her car starting this morning. I hope to have some "results" within the next couple of days. I'll keep everyone posted. Thanks for asking. I say again, what a great source this is for Jetta owners. This morning on the drive in I was thinking that Japan has this reputation of very reliable cars and Volkswagen has reliaibility problems. Is it that VW's tolerances are too tight causing alarms (MIL triggers) or is it their suppliers are cutting corners. I can't figure it out, it just seems that if you own a Volkswagen your in for problems.

I love the way a German car "feels" when your driving it, but I'm not wild about their reliability. I've heard it said that they "last for ever", but I'm now of the opinion that they "last for ever (as long as they are well taken care of)". When I bought this car for my daughter I did it because I had so much fun in my GTI when I was her age. I just didn't think that I would be spending as much time under the hood as I did when I had my GTI. I try to think of it as it get's me more face time with my daughter, but I'd rather be spending it doing something else like taking in a movie or going out for a meal together. OK, I'm done complaining now. Sorry! : - )

[mbrown3039]

^^^ No worries, I know how you feel. I've owned several Japanese cars and -- in my experience -- they're mostly bulletproof with large amounts of "just set it and forget it" reliability. But they have no soul, no character -- so I traded reliability for grins.

If you get too depressed about it, go out and rent any Quattro Audi (I like the 2.0T, myself) and then spend 2-3 hours driving it like you stole it. It's great therapy! Mike

[JessicasDad]

Mike your right, four wheel drive cars handle amazingly great.

Last night I was driving the car for about 30 minutes when I was simply cruising down the highway at 70 MPH when the engine just cut out. I engaged the clutch pedal, pumped the accelerator pedal with no success. I watched as the RPM needle fell to zero and the red seat belt light came on. I then tried to restart and the engine came back to life on the second or third try and behaved like nothing was wrong! It settled at around 800 RPM (idle) and I immediately punched the throttle and released the clutch and the car accelerated from 50MPH back to 70 with no problems. The tank's low fuel warning light had come on a few minutes before hand so when I got home I pulled the cover off the tank and inspected the hoses and found no problems (hoses were routed properly, no visible cracks or splits that I could see and the electrical connector was connected properly.

Does anyone know what the "suction Jet Pump" is and what is it's function? The service manual barely even mentions it but I see it inside the fuel tank. It appears to be construction of nylon and I don't know if I could get it out of the tank. I just happened to notice that the location where it narrows seems dark. I can't tell if it's a O-ring or an accumulation of dirt but wondered if this could be responsible for the periodic stumble at less than 1/2 tank. When I replaced the fuel pump last winter, I made sure the screen at the bottom of the pump was clean. The tank itself seems amazingly clean so I don't know what could be causing this problem, but I did order a replacement fuel filter from VW-Golf-parts.com (love their prices). However they don't stock everything.

Also, If anyone knows where I can pick up a new/used coil pack I'd be interested. Autozone want's close to $200 for one and I'm not paying that much for something that might be responsible. It's got to be "for sure" before I pay that kind of money for that part. Also if someone knows where I can pick up a fuel pressure gauge for less than 119.99 I'm listening!!! (http://www.partsplaceinc.com/product...aspx?sku=15577).

Thanks Friends! Chris

[mbrown3039]

I looked in both Chilton and Bentley and found no reference to a "suction Jet Pump" anywhere....have you got any more info on it? Maybe a pic?

Also, for a fuel pressure gauge -- maybe your FLAPS has a loaner program? I know Autozone and O'Reilly/Checkers/Kragen/Schucks do...mike

[JessicasDad]

Hi Mike,

The Bently manual refers to the Suction Jet Pump on p. 20-15, Illustration #M20-0142 Item #2. As I said before, not really sure what it's function is, but I figured as long as I was in there I would check it for possible blockage - anything that might explain why there could be a fuel starvation problem when the fuel level get's low (besides the obvious). Thanks for the tip about the loaner programs. I will check with them. I know that O'Rielly wanted to sell me one! Actually they told me that they don't have one for BOSCH systems and that they would give me the number for a MAC tools guy. Greaaaaaat. Chris

[mbrown3039]

Oh, I see it -- in the BBW section. For some reason I thought you had an AEG. Sorry, no clue what it is/does....but it sounds like you're on the right track.

Is there any way to clean it out or is it a sealed unit? Mike

[JessicasDad]

I get a little nervous working around fuel (personal experiences have taught be to be very respectful of gasoline and how dangerous it is) and since there's no details on what it actually does, I'm sort of nervous about taking it apart (same feeling I had when I changed by clutch and the heater core in my Dakota). Usually it all comes out OK, but I just get worried that I might not be able to put humpty dumpty back together again. I believe it is some sort of gravity fed fuel compression - sort of like a funnel - but I wont really know till I get it out and take a look. I just don't like taking things apart when I can't really see what it looks like. Part of me thinks I should drop the fuel tank so that I can get a better look at it, but then the efficiency side of me says just do it while accessing through the back seat. I have ordered the fuel filter and that should get here by the weekend.

[mbrown3039]

NO worries, I understand -- but, for what it's worth, it's the fumes you need to worry about. I've actually seen a lit match repeatedly thrown into a cup of gas and nothing happened...the match just kept going out PLEASE -- NO ONE TRY THIS AT HOME! Keep a fan blowing on your work area and you should be OK. Mike

[JessicasDad]

Replaced the fuel filter and no appreciable difference. Then Yesterday Daughter was driving the car down the freeway with 1/4 tank of fuel and the car just quit. I brought a couple of gallons of fuel and added it to the tank and no effect. Car will not start. Had it towed home and checked for spark from #4 cyl and it seemed to spark OK. Then pulled out the code reader and it read P0354 Ignition coil Primary... OK so where can I get a used or new Coil pack? Anybody have any good recommendations on where to shop for this?

[billh1012]

here is a link to germanautoparts.com http://www.germanautoparts.com/Volks...ectrical/57/12

does your coil look cracked or anything?

[mbrown3039]

If it were me I would check out GAP, autohausaz, ECS, and carpartsdiscount.com. Maybe rockauto, also.

Sicne it's a pretty common part, I would also take a quick peek at the websites for any/all of my FLAPSs. M

[Marc1987]

pffft go to a junkyard lol, or find a mk3 getting parted out on vwvortex.com

[JessicasDad]

OK, well, being a cheap skate, I decided to take my diagnostics a little further. First thing I tried doing was starting it again. pumped the pedal furiously and it had no effect at all. No indication at all that it was even trying to start. Next I checked for spark in Spark plug #1 and 4 (again). Both wires gave a good spark to Ground. Next I pulled the spark plugs. Bone Dry. No evidence of wetness at all. This brings me back to a fuel delivery problem. Guess I need to get my hands on a fuel pressure gauge kit.

[JessicasDad]

Hey, how about the fuel pump relay? That could be intermittently making contact and then once the contacts are sufficiently burnt may cause an open circuit. I checked the fuse to the relay and it looked fine. I think I will pull the relay and test at work tomorrow.

[mbrown3039]

Update? Mike

[Franc]

I have a 2004 Jetta with the infamous BBW with the variable valve timing. I blew a timing belt at 100,000 and needed some valves. Slapped it together and went on my merry way. I started getting a noise on two lifters at idle. 10,000 MILES later I had to pull the cam at a whopping 1200 dollars us from the dealer. 1500 miles later i still had a little clack. I bought new lifters and still had a clack. I checked oil pressure at the front of the head next to the thermostat and had 25psi at idle and 70 at 2500rpm. Pulled the cam again and opened both sides of the oil gally on the head and blew out the oil. Then I pushed a wooden 5/16 dowel from the driver side to the passenger side to push the screen out and check it. Clean. The oil comes up through the head via the second foreward head bolt hole driver side and enters the main galley. Then it goes foreward to the veriable valve timing solenoid , oiling the lifters and cam along the way. The solenoid valve has the oil enter the front and three oil holes at different depths and angles . the coil part of this solenoid is alighned by a flange and screw. But the valve part can be rotated by hand and missalighn the oil holes. Thease fools at vw diddnt set a lock on the valve or mention something in the book about this and my valve was rotated to a position where all my oil went into the sump. 1600 dollars later and lots of bloody nuckles and I'm back on the road. The only way to truly alighn this stupid thing is to pull the cam and take a toothpick and push it in the oil passage of the foreward cam bearing . Then rotate the valve untill the oil hole alighns with the barrel of the valve. Then take a pair of pliers and hold the barrel while alighning the coil flange screw hole. So much for german engineering

[Marc1987]

Thread is 2 years old bro

Sent from my SGH-I997 using Xparent Blue Tapatalk 2

[JessicasDad]

Regretfully, It appears this mystery will not be solved. My Daughter threw in the towel on her Jetta and bought herself a new Civic. I am now trying to sell her '04 Jetta for her. It has 137K Miles. I'm asking $5600. It's in good shape as it's a So Cal native (no snow). Am I asking too much? I listed it last weekend on Autotrader and didn't get a single call. I also noticed a lot of postings for used Jettas - both of these are not good signs.

[DJ Kingpin]

i dont mean to hi-jack..

but i have similar issues. i went to autozone to get my codes read. i replaced upstream and downstream o2 sensor... fuel filter, and i went to a junk yard and got a fuel purge valve too. my jetta is rough to start after getting gas, and sometimes gives accelleration issues like jessicasdad stated earlier.

one thing i notice about this 2.0... when i start it, i hear this loud whine... it comes from this canister-pump lookin thing infront of the engine... hoses connected to the air box and looks like it goes to the back of the cyl head. it kinda looks like some type of crankcase vent pump, or EGR.. but it looks like a pump. it whines for like 2 mins and then stops.

does that happen to any of you 2.0 peeps?


MPG's is also pretty sh*tty... its probably about 15mpg right now.