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Old 10-04-2009, 10:40 PM
PanzerSD's Avatar
Join Date: Jan 2006
Location: Saskatchewan Canada
Posts: 2,351
Question Engine Symptoms

I'd appreciate anyone's thoughts on this please!

1978 450 SEL M117.986 EGR disconnected

What symptoms could arise from having one or more faulty components?

I am currently experiencing the following:

An occasional miss at idle

When taking off from a dead stop, it hesitates really bad an misses a few times and misses till It's up around 1500RPM. Makes merging and taking off long and arduous. No backfiring, no smoke. Just a miss and no power.
Once I get thru that i have all the power I need till I come to a stop again.

Starts in 1st gear, (goes thru it's stumble)
Shifts to 2nd, and hold's 2nd till, on my speedo is about 43KmH but in reality I'm moving at about 50Kmh at that point
Flares into third.

In my city the major speed limit is 50kmh so driving around town in second gear doesn't cut it for me. Surely to god it should be in third gear closer to 45kmh.

Disconnect Modulator, and same shift gap but no flare. Bad Modulator? I have bypassed the vacuum source to my own known good vac source.
I used plastic airline that is used in air springs (cuz it was what I had on hand)

The inside diameter is at least twice if not three times larger than the hard line that originally fed the modulator, could this allow TOO much vacuum to get to the modulator?

Thanks guys!

RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)

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Old 10-05-2009, 08:18 AM
Posts: n/a
You have a vacuum leak of some description. It is possible that the EGR valve is the source of the leak, not the vacuum line to the valve, but the pintle portion of the valve that allows exhaust gas into the intake.

Connect a vacuum gauge to confirm that there is a vacuum leak, and if so, find it.

My $0.02,

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