Yes, the Merc will be moving on later this week. It's been fun but just wasn't the car I was looking for...just don't think one that's tidy enough for me is in my budget any more. Still glad to have had it though.Dick wrote: ↑Mon Jan 17, 2022 5:30 amWill we be saying goodbye to the Mercedes ?short lived visitor but very welcome do you have any news of the jag? Im missing it...
I was due my 3rd jab later this week but tested positive last week ... ive never taken the egr? Valve apart ... while im on unplanned "holiday" for a week i might have a look for the one on the shran... (im nicking the turbo)
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This surging behaviour seriously has me intrigued. Managed to catch it doing it again today and got a better video properly catching it.
https://youtu.be/JT0X3XLBsCw
This clearly shows how it's essentially a regular "blip" approximately once a second that happens irrespective of the engine speed - and that during this behaviour she chucks out a shedload of smoke.
You can always *smell* that something is off when it's doing this, the smell from the exhaust lingers for ages. If you're in a car following it, it makes your eyes water apparently.
Physically disabling the EGR valve by removing and plugging the vacuum line to the actuator has no effect. I know the valve is moving as you can clearly hear it snap open or closed - and it sealed well enough that carb cleaner wasn't even seeping through the orifice while I was cleaning it yesterday. So I think the valve itself is innocent.
However if I unplug the *electrical* connection to the solenoid valve which controls said valve, the problem completely goes away. Idle immediately smooths out perfectly (it sounds to me like the injection timing or duration also changes as the engine note itself does change too), you hear the throttle valve in the intake snap fully open, and the throttle response becomes perfectly smooth through the whole rev range - and we see absolutely zero smoke aside from the expected tiny initial puff of black if you absolutely boot it, and that's not enough to be visible in the headlights of a following car. Also notable that any noticeable smell completely vanishes too...it just smells like an early 00s diesel VW.
Now I'm sure unplugging that would trigger an engine management light if I had one and I'm sure will have logged a fault code, and disabling an emission control device like this is illegal, so it's not a permanent fix...however it provides me with useful data to add to my diagnostic process and *definitely* puts the van in a less polluting state while I get to the bottom of the root cause. You've seen the cloud if you've watched the video above!
I need to make my reading today working out exactly what the sequence of operation is for the various bits of the emission control system on this engine and how the various parts interact with each other. I get the impression that understanding how that lot works will shed some light on what might be happening.
Decided that the Caddy could have a day off as errand running workhorse today.
Which went absolutely fine until I heard a suspicious "ding" at one point and saw something small and round disappearing into oblivion behind me.
When I eventually found somewhere safe to pull over, the cause didn't take long to find.
Ah. That's sub optimal. The air filter element was still present, wedged between the chassis and suspension arm thankfully (as they're surprisingly expensive), however the cover plate and wing nut are long gone. Even if I could spot it, as with so much of MK there's nowhere safe to pull over to retrieve it safely as it's on a 70mph dual carriageway with no pedestrian provision even vaguely nearby. So I'll need to find a replacement. Thankfully it's a bit of standard Steyr-Puch engine rather than a bespoke bit of Invacar so shouldn't be difficult to track one down, even if it may mean getting a whole new air cleaner assembly.
Guess we need to add "check air filter element retaining wing nut is tight" to the weekly checklist!