Engine Rough @ 1500rpm only

[dannyboy201062]

My `03 passat sport 130 TDI has gradually over a year or so developed a rough spot at 1500rpm. During driving or stopped it is sweet at 1000 rpm and at 2000 rpm upwards. As the rev`s increase to 1500 rpm the engine starts to vibrate/ sizzle and you get minor vibration noises. The vibes die off as you approach 1800 rpm. I was convinced it the exhaust had a loose bracket but found nothing external. A good general look around reveals nothing. The engine performs well and returns good fuel consumption. The problem has gradually gotten worse and it tends to make you select a different gear to shut it up when driving in traffic as it feels rough. Any ideas ?

[Crasher]

Possibly cat monolith failure.

[dannyboy201062]

MMMM..........it did feel like something loose relating to the exhaust. I wondered could it be internal. I suppose feeling the exhaust at the cat before it get`s hot might confirm that . The only fix there would be a replacement CAT. tks for reply.

[PeteK]

I had a similiar issue to this where I had a loud vibrating noise coming from the engine bay at similiar rpm to yours. This turned out to be the air intake pipe vibrating against the box it attaches to, this is located in the o/s/f area of the engine bay and is only a push on fit. I packed some foam around it which cured the problem. The 130 TDi engine does seem to emit more vibration at 1500rpm and then smooths off at 2000 rpm plus.

[Adz99]

Hi Danny
I had a "rumbley/vibrating/chattering" kind of noise a few months ago - only on tickover or VERY low speed, which i couldnt pin point. Luckily I found the answer on here - alternator pulley! Sounds crazy but £200 later (the part was about £70, then 1 1/2 hours labour) and it was swwweeeeeeeeeeet again.

Just check to see if the fan belt looks a bit slappy when the engine is running.

Good luck.
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(BIG fan of this site!)

[dannyboy201062]

Tks peteK, I`ll have a look, I had a vibrating air filter intake to grille snag a year ago or so which i solved with foam............I`ll have another look............danny boy.

[dannyboy201062]

Tks Adz99...............but I had this problem a few months back and the forum saved me going off on the wrong expensive route.....The replacement pulley sorted the rough idle with squeeky power steer belt. ...It`s in the forum there somewhere as a reply to somebody else.....tks all the same. ..............danny Boy.

[PeteK]

Tks peteK, I`ll have a look, I had a vibrating air filter intake to grille snag a year ago or so which i solved with foam............I`ll have another look............danny boy.

That sounds like the part I was trying to describe! I located mine by getting someone to hold the revs at 1500, when pressure was applied to the offending item the noise stopped. Some foam placed around the pipe cured the vibration.

[dannyboy201062]

Tks peteK........will follow up and let you know how i got on.............dannyboy