PeachParts Mercedes-Benz Forum - View Single Post

m1tch · #11 04-18-2015, 12:45 PM

I have been doing a bit of trouble shooting today, the car had issues where it would sometimes lack power when kicking down, eg stuck in gear at say 4,300 and not then change gear.

I also had an issue where I had some screaming/squeeking coming from around the EGR area. After unplugging various vac lines I noticed that the noise went away when the EGR was meant to be actuated.

I then thought of other things to unplug to pin it down, in the end I actually unplugged the MAF which resulted in an immediate power increase with the gearbox working correctly and shifting as it should.

It seems that the MAF has never been cleaned and the engine hasn't really been under much load over most of its life. I cleaned a huge amount of muck and dirt out of it yesterday evening. I think that the sensor was so completely blocked that the engine simply ignored it and just run on a base map with slow shifting via the adaptive shift tech.

Now that I have reset the gearbox and cleared the MAF out it must have been giving a signal but that signal was incorrect so therefore not fueling correctly at all - eg too much air and not enough fuel. Unplugging the MAF returns it to a fixed base map but this time with the transmission reset.

I think I will replace the MAF, although will try and clean it up more using MAF/contact cleaner tomorrow to see if that works any better. Happy currently running on the base map though as its giving some good power and it shifts well.

Next week or maybe the week after I will be removing the inlet manifold, I can see its looking rather horrific around the EGR so I am guessing perhaps a small boost leak somewhere plus I am guessing a very clogged inlet manifold.

Need to work out how to get the manifold off, I can see the bolts on top, I can just about see the jubaliee clip from the stock intercooler to the inlet manifold but I know that there will be a connector to the EGR pipe somewhere as well.

I will be cleaning the inlet manifold but keeping the EGR at this time - need to get a baseline of how the car performs with it connected. I can easily disable it by removing the vac line but it shouldn't be actuating when accelerating anyway. I will be simply blocking it off and adding in a tube instead to remove any restriction. I did unplug the EGR earlier today and drove it around a bit and there wasn't a code at all.

I will also be getting an engine bay code reader - the engine doesn't have the usual OBD2 port inside the car owing to the age, it just has the plate where it should be but no plug. Won't be an issue though as I will just get an adapter for the engine bay so I can pull codes and also perhaps do some logging when doing a run.

Next things to buy would be a boost gauge to see how much its boosting on stock - won't be touching any of the stock setup yet but will look to add a manual boost controller to ensure that its getting the correct boost levels.