Why does my car feel quicker part throttle?

Noticed this since becoming the owner of my '03 Jetta back in December. While cruising and I tip in the throttle further for passing the car feels quite zippy and accelerates well. Dead stop and WOT through the gears vs part throttle through the gears, part throttle feels quicker.

Is this normal for you and your VE TDI's?

Hard to say what you're feeling through your pants...

Peak torque is around 1,900 rpm. When hitting in this area you're going to be getting a good dose of boost. Boost starts to be regulated down as RPMs increase (and load decreases). In lower gears things feel a lot more pronounced: things happen a lot faster; in taller gears things happen more slowly.

Clogged intake, however, will tend to result in slow RPM climb. My car was a dog in higher gears past about 2,400 rpm- it's intake was pretty well clogged up.

Only real way to measure this is to, well, measure it (VCDS)!

Not normal. I might guess your turbo vanes are stuck half open or something else is not allowing full boost. For me full throttle the tires will chirp 1st and 2nd.

Can you drive over 75mph? Sounds like limp mode to me.

UhOh said:

H
Clogged intake, however, will tend to result in slow RPM climb. My car was a dog in higher gears past about 2,400 rpm- it's intake was pretty well clogged up.

Only real way to measure this is to, well, measure it (VCDS)!

Click to expand...

I need to order one. For $199 for a 3 VIN, that's not a lot of $$. Intake is clean as when I took apart the turbo and cleaned the vanes I also installed a spare clean intake manifold. Filter and snow screen is clear too.

BobnOH said:

Not normal. I might guess your turbo vanes are stuck half open or something else is not allowing full boost. For me full throttle the tires will chirp 1st and 2nd.

Click to expand...

Boost comes on, then lessens, then comes on again but not to great. Almost like the control loop isn't tuned right in a PID controlled system which I don't think this is.

snakeye said:

Can you drive over 75mph? Sounds like limp mode to me.

Click to expand...

Oh yeah, no problems. I've only gone up to 90, maybe 95. Plenty of power, just inconsistent with the pedal floored vs not.

Run a log at wot from 1500 to 4500.
Drop into malone website and post a link.
Might be a maf, unplug and see if it changes.

eddieleephd said:

Run a log at wot from 1500 to 4500.
Drop into malone website and post a link.
Might be a maf, unplug and see if it changes.

Click to expand...

Will do once I buy a cable. I do remember when I was trying to diagnose a limp mode problem early on, the car wouldn't run with the MAF disconnected. Opposite what people posted would happen.

Now that's odd. With the MAF unplugged, it uses default values for fueling etc. If it won't run could those values be inaccessible?
Do you see any wiring mods or think maybe the ECU has aftermarket programming?

Yeah, an uplugged MAF is no more than an open to the ECU, in which case it triggers running a default map. This is basically a limp mode, whose purpose is to allow your engine to run despite some faulty sensor (or perhaps a problem with what the sensor is monitoring).

If there's surging then it's an issue of fueling and or turbo (vanes): N75, vacuum lines, actuator- all could also be at odds with you. With the turbo, just because you cleaned it that don't mean that it will operate correctly. The backing plate for the vanes is known to warp: its surface might be clean, but the vanes will still stick because of the warpage.

Pretty sure it's not a vane problem, and yeah the MAF unplugged it won't run. I have good fuel mileage (regularly 49-50MPG, all freeway, 75-80mph when it's not gridlocked traffic).
I do remember that when I did rent a VAG cable my IQ setting was really low:

03TDICommuter said:

When I rented a VCDS cable to check my car I saw on my bone stock '03 Jetta that the IQ value was really low and not knowing any better I thought that was a good value for fuel economy. (I think the value was 0.8). This vehicle I bought from someone that only ever had the dealer work on it.
Now I know better and it's the inverse for this setting but my car seems to run fine and I'm getting 50mpg all freeway. Do I mess with it?

Click to expand...

This car has been dealer maintained before I bought it (1" stack of receipts). Dealer did the timing belt/WP at 300K miles so I'm guessing they put the IQ setting where it's at today. Perhaps this is a clue?

Timing and iq go hand in hand.
You need a cable and I think that it's probably the timing.

No way the dealer adjusted the IQ.

Guessing ain't going to cut it. VCDS, log stuff and then report back.

eddieleephd said:

Timing and iq go hand in hand.
You need a cable and I think that it's probably the timing.

Click to expand...

Timing was spot on in the center. Yep, need a cable.

BobnOH said:

No way the dealer adjusted the IQ.

Click to expand...

Because they don't?

Followup. Replaced the MAF and that solved the flat spot during WOT acceleration.

Thank you!
So few threads with actual solutions.....