[Guest (MBNZ)]

Lately, my 1985 300d has been... err... a tad sluggish. Moreso than usual, its normal 0-60 time of 14 seconds has been increased to well above 20 seconds.<br> <br> Here are possible factors, but they don't really answer my question. Any suggestions would be VERY much appreciated, for I'm fearing a bigger problem than just one of the following.<br> <br> >I have 205/70/14 snow tires on the back, which will come off soon. These, I'm told, COULD give the car a slower 0-60 time.<br> >It is also winter, but the car even drags a bit during 50-degree days.<br> >There is NO power at ALL above 3,000rpm. It seems that just after the turbo kicks in, the car slows down. This evening, I floored it from a dead stop on a level road. The car pulled alright through 1st, okay through 2nd, but when it got above 3,000rpm in third gear it just stopped pulling. With the pedal FLOORED, the car barely had the power to get up to 4500rpm and shift to 4th. When I got the car last August, its power zone was past 3500rpm, and now barely WILL go past that.<br> <br> I hope to hear that it's just the cold, or the tires, but I fear a bigger problem.

 

[Guest (MBNZ)]

I'd put a large wager that overboost sensor is kicking in. When boost pressure exceeds the rating of the switch (which is screwed into the intake manifold), it energizes a switchover valve (located on the firewall near the master cylinder). This cuts the signal to the ALDA. The ALDA (anneroid compensator, located on the injection pump) is what adds extra fuel when boost pressure increases. If it thinks there's no boost, it won't provide fuel enrichment, therfore no power. You describe a classic case of this.<br> <br> As to what the problem is, make sure the tube from the intake to the switchover valve is clean, and make sure you can blow through the s/o valve. If all that checks out then you need to test the sensor and/or boost pressure. If your wastegate is faulty, providing too much boost - the sensor is then doing its job and saving your engine from meltdown. Spec for your engine is, I think, 0.85-0.95 bar. Plumb a gauge in with a 'T' and see what it is. If it's over 1.0-1.1 bar your wastegate is probably stuck closed. If not the sensor may be bad. It has the rating stamped on it, check it with a MityVac and an ohmmeter to see if it's within spec.<br> <br> This has NOTHING to do with your tires, btw! <br> <br> <br> <br> Good luck,<br> <br> Dave M.

 

[Guest (MBNZ)]

Solved!<br> <br> Fuel filter was clogged.<br> Replaced it for eleven bucks at Pep Boys.<br> <br> Now my 0-60 time is a little under 14 seconds, and my car hauls ass uphill, which as far as I'm concerned is spectacular!<br> <br> -an ecstatic (and relieved) Jerrold<br> 232,000 miles (actually more, but my odometer just stopped spinning. Any ideas?) Speedo works.