Recently I had noticed when driving it felt like there was no power when pushing it from a stop or even on the highway. It almost felt like the timing was "retarding". Pair this with symptoms of a stuck duovalve in the a/c system I decided to spend some time under the hood doing some maintenance.
First off my friends code reader found no active or latent codes. I've checked the "W/S" switch because yes there have been times where I must have flicked it accidentally, I tried re-adapting the tranny but no luck. The fuel filter was changed about 10k miles ago.
It's been about 25k miles since I last cleaned and reoiled the K/N and looking it turned out the filters were absolutely crudded up with crap. One item fixed. I then notice the clip holding the MAF was not locked. I'm thinking there was a possibility of air leaking after the sensor causing a lean running condition. I reconnected the clip and everything was tight. Next I notice a tube is not connected to my drivers side valve cover. I'm not sure if this is part of the EGR system or what but now it's back on. Some power is back but it still feels like she is only running ~60 - 70% power.
Today I'm going to try cleaning the MAF and changing the plugs (much needed as I now have 85k miles and they are the original plugs). I also read that I should disconnect the battery for some time to clear the computer. We will see how things are after this work is done.
As for the duovalve: there is a grey fairly rigid tube running past the duovalve. It is broken at what looks like a union. Thing is the tubes aren't long enough to reach and directly connect. I can't find anywhere they would otherwise connect to. Does anyone know what this tube is? does it link to itself or is there something else between?
If you are running the original MAF sensor, cleaning it will not will not be as rewarding as replacing it. The difference would be phenomenal. Just my two cents.
This is the second MAF. The dealer replaced it under warranty just over a year ago.
I cleaned the Duovalve without problems but everything looked okay. When I checked the refrigerant pressure on the low side port it was good. Looks like I need to take her in for a/c work.
Will clean the MAF today and order the plugs from online. Still don't know what that grey tube is.
Vehicle: 99 E55 AMG, 2002 E430, 2002 Dodge Grand Caravan ES
Location: Falls Church, VA
Posts: 40
RE Grey tube
You should hear a hissing noise coming from it when engine is running. the missing part is a small valve. its a vacuum tube that operates door locks, gas filler door, trunk??? one of those. you may get a rubber vacuum you find in saki burners. you should be able to bridge that gap with a rubber vacuum hose.
regards
Cleaned the MAF and the car has a different personality. Still didn't get to the plugs but the performance is much improved.
Charged the A/C with about 24 oz R134 and the air is ice cold quick again. No problems, no hissing from the center vent. (thank goodness for this forum helping with A/C diagnostics)
As for the grey tube being the pneumatics system, all of my pneumatics work properly without any noise or leaking. It almost looks like some sort of drain tube, I saw a picture somewhere that shows a fitting in the middle that runs through to the wheel well (this is what led me to this conclusion. It hasn't been confirmed yet though), I'm not going to worry about it for now.
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