Help Requested: Test-driving TDI but low "oomph"

This forum is for TDI (Turbo Direct Injection) questions/posts. Non-TDI Motors (Including the 1.6, and 1.9 or other variant turbo diesel motors) should go in the VW Diesel General Forum

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Winnipeg Golf
Turbo Charger
Posts: 490
Joined: Thu Dec 18, 2003 3:20 pm
Location: Winnipeg, MB

Help Requested: Test-driving TDI but low "oomph"

Post by Winnipeg Golf »

Hi:

I haven't posted for a while and normally when I did post it was in other forums because I drive a '91 Golf 1.6 NA diesel.

Yesterday I test-drove an '02 Golf TDI on behalf of my in-laws. They live in a different city & province but found this car in Winnipeg (where I live) for a good price and asked me to test-drive it on their behalf.

The car is a lease buy-back from Montreal that was auctioned off by VW and picked up by a local independent used car dealer. Everything seems great with the car except for the lack of power. My in-laws and I are wondering about the car considering that it looks to be in great shape, has a great price, and really low mileage (78,000 km).

I timed it and it took ~35 seconds from stationary to 100 km/hr. This seems really long, especially considering that my old 1.6D Golf could probably do just as good. It also seemed like there was no grunt when flooring it ink 5th gear at 100 km/hr. That being said, I had no trouble keeping up with traffic but it was cold & slippery outside so people were driving more slowly.

Couple of questions:
1) How apparent is the turbo-whistle from inside the cab? I couldn't seem to hear it clearly.
2) Any ideas on the loss of power, how to fix it and probable cost? FYI: there were no check engine lights when I drove the car. Is this one of those dreaded MAF sensor problems? Weak turbo?
3) It was -20°C outside yesterday...would cold outside air temps play into the MAF calculations and cut-back power output?
4) I'm guessing the car has mostly city miles. Could this be a case of a gunked-up intake manifold and/or dirty injectors?

It's hard for me to objectively speak on the power output of the car because I have only driven a TDI a few times in the past and most of my experience is based on my old 1.6D. This one is peppier than my 1.6D but more sluggish than I expected out of a TDI.

Any feedback is appreciated. Respond here or send me a PM.

Thanks.

Derek
'91 VW Golf GL
1.6NA ME Engine, hydraulic lifters
337,000 km's as of 12/2006
RIP: WRITE-OFF thanks to kids in stolen car
v8volvo
Turbo Charger
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Joined: Tue Feb 03, 2004 9:56 pm
Location: Seattle WA

Post by v8volvo »

A TDI should be pretty peppy and very torquey, especially in top gear on the highway. Was the engine warm? I'd suspect problems either with intake sludging, MAF sensor, or turbo boost control.

Have someone run a VAG-COM code scan on it--just because the engine light is not on doesn't mean it hasn't stored any trouble codes. Log a boost map on it, to see if it's getting the requested turbo boost (or close to it) at all times. Pull the intake hose off the throttle body (yes, post-'99 TDIs do have throttle bodies) and see if there's any obvious sludge/gunk in there. Reach back to the turbo and check that the VNT mechanism is moving freely through its entire range. Look for disconnected/kinked/leaky vacuum hoses in the boost control circuit. Unplug the MAF sensor and see if it runs better/has more power. Any smoke at all, under any circumstances? Also, when you have the VAG-COM plugged in, check the injection timing--just like on our old 1.6D motors, the TDI needs to have its timing reset every time the t-belt is changed, and a lazy mechanic might not have done that, resulting in power loss.

Note that if the car has been basically well maintained and doesn't have too many short-distance city miles, all these problems are fixable and the car will probably turn out to be a great one anyway. The MAF would be the most expensive one, but, at least in the US, VW has an extended MAF warranty on those models. See if this car applies to something similar in Canada. TDIs seem complicated at first, but they're so beautifully engineered and built that most of the time they're actually just as easy to work on as an old all-mechanical diesel, if you know what you're doing.
'81 Rabbit 1.6D/5-speed, sold '09
'86 Volvo 740 TD wagon, 295k
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