TheSamba.com :: View topic - Sigh

Thu May 17, 2012 5:11 pm

I have a 1982 Vanagon which is suppose to be driving up to Kern River tomorrow evening for a weekend of fishing and relaxation. Of course, I'm having a hard time not worrying that the trip won't be as relaxing as I need it to be.

I took the van into the shop for my exhaust leak, start up issues and horrific fuel mileage. My battery tests perfect. Temp 2, cold start, and starter test right. Fuel injectors aren't leaking and the fuel pressure was on spot.

I had the exhaust leak fixed and he tested my Airflow meter and said it was to far worn and completely out of whack. So I had it replaced.

He also set my idle a little low to help with the mpg.

At start up I need to deliver gas or it will stall out, which I expected because of the low idle, but while I'm driving there is a lag.
I can press the accelerator and I can get a response at first, but then there is no response...And still no response... Then a little jolt and I accelerate again.
He has set the idle low for me before and this has never happened. Is this an idle issue? Or something wrong with my new AFM?

Thanks for any help.

Thu May 17, 2012 7:35 pm

How high or low you set the idle has nothing to do with fuel economy. Unless, the idle dropped because he retarded the timing. Which, by the way, would decrease fuel economy. My first suspect for the fuel econ would be the O2 sensor. Hard starts could be the cold start injector(fifth injecctor).

Maybe there is some miscommunication between you about what is wrong and how it is fixed. Maybe your mechanic is not well experienced with vanagons. Maybe you should get a second opinion.

Hans

Thu May 17, 2012 8:53 pm

You can test the AFM pretty easily with a multimeter. I think the usual failure is a 'drop out' in the voltage as the arm sweeps but really I doubt that is the problem with a 'new' AFM.

Also easy to test the O2 sensor which I agree is what comes to mind when mileage goes south in a hurry. Be sure to verify the shielding on the cable is grounded and that the center wire (to the O2) is not.

Thu May 17, 2012 9:28 pm

A new AFM just means you now have a cleaned up used one that passed minimal testing. Sometimes nothing is done to them at all, just a quick external clean and a new box. Sadly when buying an AFM you are often just buying someone else's problem. Your original could probably have been easily fixed with information found here on The Samba. When replacing an AFM, it is imperative that function be tested carefully and the wiper and spring set using an exhaust gas analyzer.

Have you checked and rechecked your throttle position switch?

I agree with hdenter, the idle setting has zero to do with gas mileage. All it can do it cause the engine to stall more readily.

Thu May 17, 2012 9:41 pm

Symptoms sound like the CO mix didn't get adjusted, which is part of the AFM on later Vanagons.. (not sure if this holds true on earlier ones)

Thu May 17, 2012 9:57 pm

Eh. What a mess. I will check the O2 sensor and the throttle position switch. AND find a second opinion.

What is more amazing about how little I know about cars is how much less I knew three years ago prior to owning this van.

Fri May 18, 2012 7:11 am

I trust you have been here.....

http://www.thesamba.com/vw/forum/viewtopic.php?t=369815

Fri May 18, 2012 2:08 pm

No I have not seen that link. Thank you!
So this morning I dropped the van back off to the mechanic to look at it since I did pay him all that money. Now he says he thinks it is the catalytic converter. Is there a way to test this?

I will also say last night I fueled up after posting. While I still have four gallons at least in the tank a few of the problems went away. The van is still sluggish. Almost as though it is unresponsive to me pressing on the gas pedal. I also am having issues accelerating to freeway speeds and the slightest incline causes me to slow down.

Fri May 18, 2012 2:28 pm

A clogged converter typically will make the exhaust sound funny. Any throatiness from the individual exhaust valves opening will be lost and replaced by a hissing like sound.

Fri May 18, 2012 2:42 pm

Hmm. When I pick it up I will take a listen. And I guess the next question is has anyone ever purchased the cat from bus boys. The California version seems a bit cheaper than bus depot.

Fri May 18, 2012 3:18 pm

In the past I have removed the O2 sensor and used a pressure gauge in that opening to see if there was excesive back pressure in the exhuast (blocked cat). Don't know if this is SOP but it led me to rule out the cat as a cause of a running problem.

When you're experiencing the poor running try switching the engine off & on (no need to even take it out of gear, just off & on) and see whether the problem gets better for a minute or two before recurring as before.