2007 2.5T poor throttle response

[zanzabar]

I've been chasing this for awhile. Starting out in first gear it's very noticeable, second gear a little, seems fine in all higher gears. When starting from a stop it feels as if the engine rpms rise without a proportional increase in power. There is also a noticeable delay from hitting the gas pedal at full stop or low speed to when the engine rpms ramp up and acceleration ensues. Plenty of power at anything over 50-75% throttle, just 5-50% in first or second seems a little bit off. It also starts slowly, and occasionally I notice the rpms bounce up to 3k and then back down again before the engine catches.

What I have tried:
new plugs
flushed transmission (Mobil 3309)
replaced fuel filter
cleaned and balanced injectors
cleaned throttle body
looked for vacuum leaks (found none)
no codes
installed remanned Cardone MAF (no change from old one, put old one back in), also cleaned old one a couple times
in-tank fuel lift pump makes noise and appears to be functional, have not verified
brakes are good, not dragging

Some ideas I may look at next:
measure fuel pressure at startup, idle, and after engine shutdown
monitor long term and short term fuel trim
02 sensor?
update transmission software?
...what else should I check?

[nsjames]

you need to hook it up to vida and look at the throttle blade numbers.

[zanzabar]

Starting the engine when it's warm outside or when the engine has been warmed up and then sits for an hour or so is also getting pretty bad. Real slow to start and doesn't want to catch and run right away.

[JRL]

Perhaps it was not cleaned right or you need a new throttle body

[zanzabar]

What's the failure rate on these later ones? I see lots written about the early P2's (2000-2001?) having lots of issues but not the later ones.

Would it be smart to try a used Ebay version or off brand for a little under $100 or should I really go all the way and get the $350 Bosch unit?

For less than $100 I would lean towards throwing a part at it and see if the problem gets fixed. For $350 I think I'd rather verify by looking at some numbers through Vida. Don't have a Vida though so I'm going to have to figure that out.

Do bad throttle bodies eventually throw codes or what? A code would sure help here.

[nsjames]

they have potentiometers in them to report back actual throttle blade angle.
They get dirty, or fail. Or the stepper motor is herky jerky.

You need someone that can get at the commanded/actual throttle blade numbers to see what it's doing in response to the pedal. It could be throttle body, pedal sensor or any manner of wiring issue in between.
I think vida says if the angle sensors are off more than 10* the throttle body needs replaced.

[abscate]

What's the failure rate on these later ones? I see lots written about the early P2's (2000-2001?) having lots of issues but not the later ones.

Would it be smart to try a used Ebay version or off brand for a little under $100 or should I really go all the way and get the $350 Bosch unit?

For less than $100 I would lean towards throwing a part at it and see if the problem gets fixed. For $350 I think I'd rather verify by looking at some numbers through Vida. Don't have a Vida though so I'm going to have to figure that out.

Do bad throttle bodies eventually throw codes or what? A code would sure help here.

Definitely worth a PnP replacement try.

The 1999-2001 ETB were the nasty Magnetti Marellis that had Italian class but puked out between 100-200k miles

[zanzabar]

I threw a new $102 Ebay throttle body unit at it and it is much better now. Less throttle delay and startup is better too. I could hear something rattling around inside the original Volvo stamped Bosch unit that I removed.

[abscate]

Can you share vendor and part number for reference please?

[zanzabar]

Sure:
http://www.ebay.com/itm/331311501726

Brand: OE Replacement
Manufacturer Part Number: AWTB28075O131
Interchange Part Number: O280750131