hard time keeping idle when van sits for a day or two

[kshbaja]

If I let my 1986 vanagon sit for a few days, when it first starts it will barely hold idle and stall if I don't nurse it along by hitting the gas. After maybe a minute or two of this nursing, it holds its idle and will be fine. A couple days later, same thing. It seems to act a lot like carbureted cars I have owned. What are the usual suspects for this sort of a problem?

I am pursuing another issue where my idle lopes (800-1000) with the idle air valve connected, but purrs nicely when the valve is disconnected (checked vacuum hoses, replaced valve). I am wondering (hoping) there is a common culprit.

[khoyer01]

I have had a similar issue and I began replacing old sensors.
Typically your condition can be caused by a number of diffrent things i.e.
Bad temp 2 sensor(thermostat housing)(Common)
worn or broken throttle switch (underneath throtle body)there is a easy test for this.(common)
bad idle stabilizer(rare)
Bad idle control valve(rare)
Bad ECU (ouch)

there is a serries of test you can do and I believe dogpilot has some of the manuals online. that run you through the trouble shooting process.

What I ended up replacing was my temp 2 sensor, OX sensor, and now my throttle switch, which I have found to be the true culprit of the cutting out idle.

Hope this helps,
Kyle

[albiwan]

I have the same issue and I ordered the temp 2 sensor and will install it this weekend. Only about a 10 dollar part. One thing the vendor said, up front, is that oftentimes it isn't the part itself that is bad, but rather the contacts, terminals. They recommend cleaning them up (nice and honest of them.)

I went ahead and ordered the part 'cause it was cheap and if i'm in to my elbows, might as well replace the part.

[kshbaja]

I replaced the temp2 and o2 sensor (among many others) as part of the major overhaul I did when I first got this rig. The connector terminals on temp2 look clean, but I should probably clean them just to be sure.

My throttle switch appears to be functioning properly, but I may swap it out with another I recently found at a junkyard for the sake of comparison. I've got nothing else more exciting going on this afternoon!

I've tested with a known good idle air valve and tomorrow I will have access to a known good idle stabilizer to test against.

I am not used to having to give a fuel injected car gas when starting it. Not only do I have to give it gas right away to keep it running, if I don't hit the gas WHILE it is trying to start, it won't catch. It is acting very much like a carbureted car.

[khoyer01]

When did you replace the sensors? sometimes they can go bad right away. additionaly you should hear the throtle switch activate with the slightest of movement from the throttle on or off( I recomend off cause you can hear it better). it sounds like a "click", and you should hear it as the throttle opens and closes.

on another note your afm maybe shot as well, or you may have bad gaskets in the air intake or a cracked air intake which allows for fluctuating idle
or your injectors are clogged or not working.

There is alot of diffrent things that can cause your issue. you just have to go through each component and do the recomended checks. I'd also recomend checking with the multimeter as well because things can look clean and all right but it does not mean that they are working.

Best, Kyle

[kshbaja]

I just did the temp2 sensor a few weeks ago. It doesn't have more than 100 miles on it. I preemptively changed it while I was doing everything else, so maybe I will put the old one in and see if it makes a difference. Injectors were cleaned/tested by WitchHunter. I just ran through the TPS adjustment again and it all seems to check out. All the intake hoses/boots are solid. Maybe the intake runner gaskets? I tried testing them with propane, but I question if that diagnostic method even works as holding the propane right up to a detached vacuum hose made no difference to the engine operation.

I will look into debugging the AFM. Thanks for that tip.

Oh by the way, I noticed in your post you said you eventually changed out your TP switch to resolve your issue. How did you get that little pinch washer off the end of the throttle plate shaft? Just pry it off? It looks delicate.