Mysterious "hesitation/hiccup" at 2,000 RPM

'03 TDI, 140K miles, 5-speed
Just started in the last 2K miles. Engine experiences a brief hiccup at 2,000 RPM in 5th (less obvious in 4th) gear. Does not occur (or is not noticeable) in gears 1-3. More pronounced when accelerating up a long gradual incline. Once past the 1,900 to 2,100 RPM zone, there is absolutely no hiccup all the way up to top end. Some other details:
new fuel filter
almost new air filter
no check engine light
otherwise engine starts fine and has normal power

Any suggestions on where to focus would be greatly appreciated. Thanks guys.

I have a similar problem but at much higher rpm's (~3200). I believe it is the mass air flow sensor (MAF). Do the quick and easy test, unplug the MAF, drive it under similar conditions that exhibit the problem. If the problem goes away it is the MAF. Replace it. TDIparts.com has them and can get them to you quick. All you'll need is a phillips and a plier to do the job.

barley said:

I have a similar problem but at much higher rpm's (~3200). I believe it is the mass air flow sensor (MAF). Do the quick and easy test, unplug the MAF, drive it under similar conditions that exhibit the problem. If the problem goes away it is the MAF. Replace it. TDIparts.com has them and can get them to you quick. All you'll need is a phillips and a plier to do the job.

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Thanks. Did you replace the MAF? If so, did it solve the problem?

richmondvatdi said:

'03 TDI, 140K miles, 5-speed
Just started in the last 2K miles. Engine experiences a brief hiccup at 2,000 RPM in 5th (less obvious in 4th) gear. Does not occur (or is not noticeable) in gears 1-3. More pronounced when accelerating up a long gradual incline. Once past the 1,900 to 2,100 RPM zone, there is absolutely no hiccup all the way up to top end. Some other details:
new fuel filter
almost new air filter
no check engine light
otherwise engine starts fine and has normal power

Any suggestions on where to focus would be greatly appreciated. Thanks guys.

Click to expand...

My car did similar things when I first bought it. What I did was listen to folks here and drove it like I stoled it and have every since and the problem went away. Driving these things like an old lady will clog them up. The harder you drive them the more they like it.

richmondvatdi said:

Thanks. Did you replace the MAF? If so, did it solve the problem?

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I haven't yet, but probably will. I did do the unplug test and the problem seemed to go away.

Lefty said:

My car did similar things when I first bought it. What I did was listen to folks here and drove it like I stoled it and have every since and the problem went away. Driving these things like an old lady will clog them up. The harder you drive them the more they like it.

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I do not baby the engine. Never have. I've driven it hard since just after break-in.

If it is a MAF sensor, wouldn't it be throwing a fault code?

One more note: I have been battling an intermittent glow plug fault for the past few months. Glow plugs are fine (exactly the same resistance) and voltage to the plugs is fine (11.94V). Based on "Glow Plugs 101", the next step is probably replacing the harness as soon as I have time. Is there any way this could be related to a hiccup at 2,000 PRPM's?

Bad MAFs seldom throw codes - occasionally but not when they're just a tad bad.

Glow Plug issues - did you clean the connections from the harness to the gps? A good cleaning often fixes the cel issue. Very unlikely it could cause anything with respect to the operations of your engine, if you are in the northern hemisphere and the weather is normal.

If you haven't cleaned your snow screen of late you may want to do that. Then unplug and reinsert your MAF electrical connector. Just to clean the pins. With older style MAF you can use a suitable spray cleaner on the MAF element in an attempt to remedy certain problems.

On some model years there is an extended warranty on MAF to 70,000 miles. Dates of manufacture covered are somewhat broken up around 2000 – 2002 in three sets (if I recollect) and their abouts. You'll have to check VW web site for your coverage. I just know my 2004 BEW is not covered as the service writer at O'Briens VW in Urbana , IL politely showed me the book today. My car has 51,800 miles so I'm 1,800 past warranty. That seems the “story of my life”. However: Thanks to this fraternal club I am assured I'm not the only person in the world whom comes up on the “short end of the stick.” lol

So now at 51,800 miles my total out of pocket unscheduled repair expense is $125 plus shipping and handling. Needless to say that's not enough to drive me to drinking. Regardless of how my day went my martini is chilled just right. And I love my TDI. 5 o'clock on a Friday. Life is sweet.

Long_Range said:

If you haven't cleaned your snow screen of late you may want to do that. Then unplug and reinsert your MAF electrical connector. Just to clean the pins. With older style MAF you can use a suitable spray cleaner on the MAF element in an attempt to remedy certain problems...Needless to say that's not enough to drive me to drinking. Regardless of how my day went my martini is chilled just right. And I love my TDI. 5 o'clock on a Friday. Life is sweet.

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It's probably been 30K miles since the snow screen was cleaned. I just ordered a can of Deoxit D5 to try to clean oxidation between the harness and the GP's. Does anyone know if the Deoxit can be used to clean the MAF?

I have no problem spending $125 on a new MAF (at 142,000 miles). I just want to be fairly sure that the MAF is really the problem.

It's 3:41 on a Monday afternoon and that martini is sounding awfully good.

One ghetto method of diagnosing TDI MAF is to unplug it for a test drive to see if the issue goes away with the ECU on default. That will throw a CEL that won't go away after you re connect your MAF.
Without a VAG COM it's hard to get a definitive diagnosis.

At my dealer two technicians took the car out with their laptop connected. One drove while the other watched the graph. Other test done in shop. Service writer told me it's usually a one hour labor charge to diagnose and replace a MAF. He only charged me half hour since they were out of MAFs after replacing two the day before. Their price on a new MAF for a BEW was $165 any way so I was a bit happy they were out.


With your 2003 model with ALH engine you are lucky to be able to replace your MAF with a Pierburg unit. Tdiparts dot com has them for $90. They are a much more durable unit and cost less too.

UPDATE on 2,000 RPM Hiccup

Disconnected the MAF sensor and the hiccup went away. Just cleaned the MAF contacts with a Q-Tip and the Deoxit that arrived in the mail. Once it's nice and dry I'll put it back together and take it for a spin.

It hasn't thrown a CEL yet, but I've got VAG-COM so I will just reset it if it does.

With the Vag Com you can watch the grafts to see if the MAF is bad. However it's a fairly complex exercise. It could be you just had a bad connection at the plug. Count yourself very lucky if that's the case.

Also count yourself lucky you don't have to change spark plugs in a 2003 Ford E-250 VAN like I do tomorrow. COP (coil over plug) Any one know what size cap screw head for the coil retaining bolt? I can't even see any of that stuff. It's all reach your arm up and feel for the parts. Three hours book to change spark plugs. And I'm sure #3 coil is bad since that's the miss fire code. So I'll have to purchase ten dollars worth of batteries for my ohm meter to test the $80 ignition coil. How I love my simple TDI.

Then the fuel filter needs changing out. System is under high pressure even at rest. Their's a procedure to bleed off the fuel pressure but come on. I'll just crack it open and let a few quarts of high flammable gas spew out on my drive.

Point of my rant is: Don't ever think working on a TDI is hard.