Tail pipe -- rusty brown, where the black?

[oceanair]

My 1.9 runs very smoothly except at idle where it almmost has a slight miss, just isn't smooth. But driving, though all RPM she is sweet. The tail pipe has all the signs from my carb days of running lean. Should the pipe have some black in it, or the rusty brown a good sign.

Haven't been able to smooth out hte idle no matter what I have tried. I have yet to get a stethoscope in there to listen for leaks. Smooth running at all other times. Thoughts on the tail pipe? Lean running?

Thanks --
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84 Vanagon Pop Top Conversion from Tin Top, 1970 Ghia - all sweet rides! Love em!
Previous: Green 72 Tin Top, White 72 Westy, Blue 64 Beetle, Yellow 71 Squareback, 2014 Jetta TDI Wagon - wish I could have them all back!

[Howesight]

The colour you describe indicates a proper mixture. The WBX engine uses an early-generation lambda control system which is what determines the Air Fuel Ratio at 14.7:1 by mass.

Your miss at idle is very common on WBX engines, both 1.9 and 2.1. There are several possible causes of a miss at idle, but the most common cause is a vacuum leak or leaks. There are a number of places, including ones you would not expect, where vacuum leaks typically occur on these engines.

The other main source of lean miss at idle is injectors that need to be ultrasonically cleaned. The WBX has no ability to trim the fuel to individual cylinders as modern engines do. For this reason, the WBX is very sensitive to injector spray quantity and spray patterns. Over time, it is inevitable that injectors accumulate deposits that affect both injection quantity and spray pattern.

Here are links to earlier posts I made on the idle lean miss, the reasons it happens, and the cures:

http://www.thesamba.com/vw/forum/viewtopic.php?p=7790584&highlight=#7790584

http://www.thesamba.com/vw/forum/viewtopic.php?p=7725810&highlight=#7725810
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'86 Syncro Westy SVX

[oceanair]

So, best to spray for leaks or listen for them through a tube? Could very well be injectors. I dipped them in cleaner when I did the fuel lines. Is it worth pouring in a pour in the fuel cleaner?

Ever come over to the Island? I'm in Vic --
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84 Vanagon Pop Top Conversion from Tin Top, 1970 Ghia - all sweet rides! Love em!
Previous: Green 72 Tin Top, White 72 Westy, Blue 64 Beetle, Yellow 71 Squareback, 2014 Jetta TDI Wagon - wish I could have them all back!

[Wildthings]

There are two things you can do to improve the idle over a stock engine. You can add the orifice to the crankcase ventilation hose as per the 2.1L engine which will lessen the pulsations getting into the intake from the intake and you can add the "Vanagon Syndrome" capacitor to the AFM which will help damp out the electrical signal to the ECU. Yes check for vacuum leaks as well.

[VWinVT]

come take a look at my tail pipe...It has the 'black' you are looking for!! But I have an aircooled westy and lean=overheat....soooo, she is set to run a bit rich.
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1981 Westfalia with a 2001 Cabrio ABA

Small wheel turns by the firing rod,
Big wheel turns by the grace of God.
Every time that wheel turns 'round,
You're bound to cover just a little more ground.

[Wildthings]

Tailpipe color hasn't been a good indicator of mixture since they removed lead from the fuel decades ago. Add a cat and O2 sensor and it becomes pretty meaningless.