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Old 01-13-2003, 03:32 PM
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gsxr gsxr is offline
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smartin,

From what you describe, the "flare" could be a transmission or torque converter problem. It's hard to troubleshoot without more information. There should be no "overrev" as you describe. First thing to do is change the fluid & filter though.

The power loss is very likely due to a blockage SOMEWHERE between the banjo bolt on the intake manifold and the ALDA. It's also possible the ALDA is leaking, which also reduces power, but requires a MityVac to test with pressure. Check all the lines, you can bypass the overboost protection switchover valve (temporarily) and see if that helps. (I left mine permanently bypassed on my '84 as it was plugged and the max boost I measured was ~12.5psi with the wastegate hose blocked, and the circuit doesn't trigger until 16-18psi!)

About the EGR. I politely disagree with Ken. Most, if not all, Mercedes diesels will run significantly better - AND get better MPG - with the EGR disabled. If not, something is wrong. You can plug the line, but that only works if the valve physically seals inside. A more permanent method is to insert a piece of sheet metal between two gaskets at the intake manifold side. This will kill the EGR regardless of the valve condition. Dumping sooty exhaust back into the intake never helps, even on CA cars. I have the valve removed totally on my one CA model 1987, it runs GREAT, and it's disabled on both of my other cars.

Also disconnect and plug the vacuum line to the ARV (air recirculation valve) on the turbo. This is a big power & MPG killer as well. It existed to help the trap oxidizer, which is gone, so you sure don't need the ARV bleeding off boost and hurting part-throttle power. It's disconnected on all my cars, works great.

FYI, 15mpg is REALLY REALLY bad. I've never seen one worse than 18mpg, and 20-22 is the typical bottom end for W123 diesels. I'd check for a fuel leak somewhere - seriously. Also, the factory spec for acceleration is 15.2 (?) seconds from 0-100kmh (0-62.4mph), with two occupants, +/- 7%. Yours should be in the 15-17 second range, on flat roads, near sea level. MPG can be affected significantly by the ALDA adjustment, try messing with it like Ken said (turn CW until power drops, then back 1/2 turn or so). Ignore any smoke seen at night in headlights - please! That's normal even on good running cars, like my 30-32mpg 87's! Look for smoke in bright sunlight under full throttle, high RPM, should be just a wisp - any black clouds and either it's too rich OR you have carbon being burned out. Drive it like you stole it and this should improve in a few weeks or months.

It would also be a very good idea to check timing chain stretch, do a valve adjustment (required every 15kmi), and if possible check the injection pump timing (easy with a $30 tool from the dealer).

Good luck,
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Last edited by gsxr; 01-13-2003 at 03:37 PM.
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