Volkswagen Eos Forum banner
1 - 6 of 6 Posts

·
Registered
Joined
·
129 Posts
Discussion Starter · #1 ·
The last several weeks I have had a bit of a rough idle. The car runs fines, just the idle is rough. I have had a random CEL code to replace the cat (according to the dealer). Any idea why the idle would be a bit rough?
 

·
Registered
Joined
·
8,639 Posts
Could be anything, but closed loop emissions components, exhaust sensors, hoses and engine breathing are a good start.

You can do a lot more learning how to use decent diagnostics to make measurements, rather than just expect a binary fault code result? The CAT is more than a box cleaning up emissions. It has sensors fitted that feed back corrections to ECU mapping.
 

·
Registered
Joined
·
129 Posts
Discussion Starter · #3 ·
Could be anything, but closed loop emissions components, exhaust sensors, hoses and engine breathing are a good start.

You can do a lot more learning how to use decent diagnostics to make measurements, rather than just expect a binary fault code result? The CAT is more than a box cleaning up emissions. It has sensors fitted that feed back corrections to ECU mapping.
The diagnosis of a faulty cat came from the dealer.
 

·
Registered
Joined
·
8,639 Posts
The diagnosis of a faulty cat came from the dealer.
They probably have more expert knowledge than you do so why not get it put right?
Just because the car appears to drive o.k and not idle well doesn't mean your problem isn't CAT related? In U.K as part of the annual emissions test, they stick a test probe up the exhaust. If measured emissions are outside legal limits, it fails and can't be driven on the road.
 

·
Registered
Joined
·
129 Posts
Discussion Starter · #5 ·
They probably have more expert knowledge than you do so why not get it put right?
Just because the car appears to drive o.k and not idle well doesn't mean your problem isn't CAT related? In U.K as part of the annual emissions test, they stick a test probe up the exhaust. If measured emissions are outside legal limits, it fails and can't be driven on the road.
It may very well be the cat that is causing the rough idle. My cat has been throwing random codes for 3 years and this could be the progression of the cat getting worse. I was just wondering if it could be something else. I have limited money to put in this car. The car has 116K miles and has never had the timing chain and tensioner changed. It's just which repair takes priority.
 

·
Registered
Joined
·
8,639 Posts
Priorities are what you decide, often based on risk and there is no linear formula. In U.K a bad CAT is a car off the road and unsaleable. A bad tensioner could a grenaded engine and a scrapped car, even when you think your car runs great. If you car was being regularly serviced and repaired based on good advice from your garage, you would have spread the ownership cost over time. But you already made past decisions not to do things. If your CAT was throwing bad codes for 3 years as you say, there could be other reasons and the CAT could be o.k. But an engine with a CAT running great in a fault condition for a long time, could accelerate poisoning of the CAT and shorten its life?
 
1 - 6 of 6 Posts
Top