I've noticed lately as the temps drop here in Canada, that my engine, if I get in fire it up and go, it's rough acceleration, and rough idle at all times, even when the engine temp has reached 80*C.

If I start it up, and let it idle till it warms up to 80*C it'll run smooth with lots of power. Also, in the first instance, with the rough idle, if I turn it off hot and go into the store or something and come back out it runs smooth with power as though I had let it warm up when just 5 minutes ago it was feeling like 7 cylinders...what gives?? WUR? AAV? or some ignition thing? I have new plugs, new cap/rotor but old wires.

Oh yeah, RPM in D drop to ~510-520RPM REGARDLESS of N idle speed. For me to achieve a loaded (in D) idle speed of 650, translates to a free idle of roughly 1200-1500 RPM. 2000RPM cold start up.

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RIP: 80 300SD
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2002 E430 4matic (212,000km)
2002 ML500 'sport'

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CIS fuel injection is ALL about fuel pressures.

That car uses the old mechanical warm-up regulator to control the control pressure.
Most likely you have an issue with the calibration of the warm-up regulator.

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Yup! I know I've done my reading on CIS and compared it to the D-jet, and I admire CIS' simplicity,. I suspected the WUR to be faulty, but wasn't sure as there are a few other items that could be culprits.

so when a WUR fails, or goes into a failure mode, is it the heater that burns out? (resistance test?) or is it the bimetallic spring that weakens?

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RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

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FACEBOOK: PANZER450

I'd take a 3mm long allen wrench and try 1/4 turn CCW on the fuel injection adjustment through the air cleaner.

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K-jet has no access thru air cleaner, the KE does, but I know what you're talking about except that the screw plug is seized in the housing and the slot is chamfered in the CW direction. I'm going to try to drill and re-tap the access port. I just unplugged the PCV circuit and cleaned the idle air distributor and I've already seen a marked improvement in acceleration and idle. I'll see how dead cold idle is tomorrow morning..

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RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

____________________________
FACEBOOK: PANZER450