I'm here looking for a favor from an E300 owner in the Washington, DC metro area (or surrounding suburbs).

I believe my throttle position sensor is bad. I have light hesitation & surging while cruising on the highway at a constant speed. City driving I have no issue. If I floor it, it accelerates nicely without issue. If I take my foot off the pedal, it slows down without issue. If I continually vary the amount of throttle, I have no issue. It only hesitates / surges when cruising on the highway at a steady constant speed.

I have a CEL with the throttle position sensor code. I understand this code can also be thrown by vacuum leaks, faulty intake manifold flaps, vacuum control valve, and other associated parts. The thing is - in trying to troubleshoot this, I've already replaced almost all of these parts, including all the vacuum hoses, cleaned / lubed the flaps, etc.

I can't find a used TPS *anywhere*, and a brand new one is nearly $500. It's specific to the E300 diesel (E320 gas tps has a different p/n). I think it's also specific to the '96-'97 diesel, so one from a '98-'99 turbodiesel probably is a different p/n.

Before plunking the cash on a new one, I'd like to swap in a known-good one and go for a 10 minute test drive. That will tell me immediately if this is indeed the source of my CEL. I really really REALLY don't want to drop $500 on one of these only to find out it doesn't fix my issue. Being an electrical component, it's non-returnable if I buy one from the dealer and find out it doesn't solve my problem.

The TPS is right there near the hinge when you open the hood, on the driver's side. Very simple 5 minute job to swap it out. If anyone here that's within an hour or two drive from DC would be willing to spare a few minutes of time to do this, I'd gladly show my appreciation by buying you a full tank of fuel.

Thanks in advance!

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'98 E300 turbodiesel

Check the Manifold Pressure vacuum line. Its the one that comes out of the top of the intake manifold and goes to the pressure switch on the firewall.

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Dennis
2006 E320 CDI Black/Black Leather. Nav, HTD Seats HK stereo 32000 miles.
2000 VW Passat 1.8t 300,000 miles as of Dec 09, 2009 original owner
1997 E300d Silver 300,000 miles As of Jan 05, 2010
3rd owner SOLD

The short (10cm) one? Yes, it's been replaced already.

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'98 E300 turbodiesel

Did you take a pipe cleaner and clean out the nipple??? I think I got the TPS code also when mine was surging on the freeway. Can you get yours up to 5000RPMS? Mine would stop short somewhere around 4000-45000RPMs

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Dennis
2006 E320 CDI Black/Black Leather. Nav, HTD Seats HK stereo 32000 miles.
2000 VW Passat 1.8t 300,000 miles as of Dec 09, 2009 original owner
1997 E300d Silver 300,000 miles As of Jan 05, 2010
3rd owner SOLD

I'll check the nipple, but I recently had the entire intake manifold hot-tanked at a machine shop. Inside and out, it was clean enough to eat off of, so I doubt the nipple is clogged.

Yes, If I "floor it", it will rev freely all the way to redline. Accelerates nice and quick, also makes a glorious OM606 noise in the process!

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'98 E300 turbodiesel

Love to help you out, I know how frustrating this can be. When I did my glow plugs I broke one of the wires to a transducer for the flaps. Drove me nuts, finally paid the DIAG fee at the dealer and had them fix it. Closest to you I will be is Fairfax on July 31 and Aug 1, then again on 2nd to 3rd for work.

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Dennis
2006 E320 CDI Black/Black Leather. Nav, HTD Seats HK stereo 32000 miles.
2000 VW Passat 1.8t 300,000 miles as of Dec 09, 2009 original owner
1997 E300d Silver 300,000 miles As of Jan 05, 2010
3rd owner SOLD