2001 Jetta TDI
Originally it was a problem with the EGR Valve being clogged with carbon deposits and the codes said there was not enough airflow through the EGR Valve. Now that it has been cleaned out by a mechanic, the codes say there is too much airflow. The mechanics here are baffled, any ideas?
Could you give us the DTC code that the mechanic found originally and the code being found now.
This is possible if the cleaning action damaged the EGR valve seat or dislodged something that is holding the valve slightly open. Does the engine seem to idle rougher or at a higher RPM?
So, I don’t have the codes right now, but I can post them later. As for the question on high rpm’s, no it doesn’t. It works perfect at high speeds and low, the only problem I have is when I travel over the pass between home and the college I’m going to next year. On flat highway, I can get it up to 70+ no problem, but as soon as I start climbing the mountain pass, it drops from 75mph to 55mph unless I have enough momentum to keep me going for a while. This is dangerous especially on I90 because there are semis that move enve slower than that that I have to try and pass without getting hit by the rest of traffic that is still moving 75. This problem first started when it was still clogged with carbon, but I have only seen minimal improvement since it has been cleaned. The only reason I want to fix this is because I don’t want to try to drive over the pass in the winter with this problem as well.
The clogged EGR is a symptom, not the cause. There is something else wrong with the engine. Have a compression test done to see if the engine is worn out. The EGR should not affect high-speed power like that. It is normal for the EGR to open while at speed.
the loss of power while going uphill sounds like a MAF (mass air flow) sensor problem. It would cause you to have a decreased acceleration, although this would’ve been a gradual problem, and you wouldnt have noticed. best way to check if it is the maf is to unplug it and try going uphill with it unplugged. it will cause a fault code, but the code will go away once the maf is plugged back in. I was having the same problem last year, where i would be going uphill and drop from 120km/h to 80km/h. A faulty MAF would give you bad fuel economy i would get about 500km to a tank with a bad maf and 800km when i replaced it. ebay is a good place to buy them, although do buy it from an ebayer who is selling many mafs. i bought one for a better price from an individual and it didn’t work and he would accept a return because i had discarded the box it came in. to locate the maf just look at the picture i’m including of the engine bay. it is number 4 on the diagram