1985 Vanagon 1.9 idle fluctuation

[ryancr500]

I have been trying to diagnose an idle issue with my vanagon. I consulted the Bentley manual since the idle seemed high. First, made sure the timing was correct. Adjusted throttle cable to proper specs. Then adjusted idle screw... But engine then seemed to stutter when throttle pressed.
After further investigation, I noticed that idle switch by throttle body was needing adjustment. It only 'clicked' at full throttle and not at idle. So I adjusted the switch so it clicked she. Throttle depressed off idle and clicked at full throttle..... Unfortunately, not the idle fluctuates between 1000-1400 rpm, going up and down. There were no fluctuations prior to adjusting the idle switch.
Does anyone know what may be causing the idle variation??

An help would be greatly appreciated.

Ryan

[Terry Kay]

You didn't set the primary throttle adjustment screw properly prior to adjusting the switch.

What is the vacuum at the throttle body at idle?

I am assuming that you have the later model single TPS from your description.
_________________
T.K.

[ryancr500]

I have the 1985 model with the tps sensor on the under side of throttle body. I don't really know what it does, but ever since I adjusted it, the idle is fluctuating. I referred to the manual when Making the adjustments. I did adjust the throttle adjustment screw, but maybe I'll double check that. I don't have any vacuum testing equipment so I don't know what the vacuum levels would be.

[Terry Kay]

You MUSt set the preliminary throttle stop screw First, prior to adjusting anything on the TPS.

You have the later model TPS--

You must have a vacuum gauge to verify the adjustment--

I thought you said you read the Bentley & adjusted accordingly from the info there.--

I think you missed some stuff--the stop screw must be adjusted first prior to touching anything--
_________________
T.K.

[ryancr500]

I have the official factory repair manual and it said not to adjust since it's set from factory. I thought I would double check the adjustment from the manual and it was a little off, but not by much.
I will double check my adjustments in the morning. Manual says preliminary throttle stop screw adjustment. "turn adjusting screw out u til gap exists. Turn screw in until it touches stop. Turn screw clockwise additional 1/2 turn"

[Terry Kay]

run in the screw with a piece of paper between the screw & the stop.
you didn't read the entire instruction.
Stop as soon as you can slide the paper out--do not turn the screw anymore.
then adjust the tps.


get a vacuum gauge--

You are supposed to see 0 at the throttle body vacuum port if the switch is set right--your isn't.

Do not be in a hurry here--it'll never run right if you are-
_________________
T.K.

[ryancr500]

I am picking up the vacuum gauge today. I will start the adjustments over beginning with throttle stop screw. Will let you know results.
Thanks for your assistance

[ryancr500]

I've run into a bit of a problem trying to fix my idle fluctuation. I started by setting the throttle stop screw to the correct position. I then started the van to see how it was running, it ran for a few minutes and then died. I haven't had a chance to use the vacuum gauge because I haven't been able to get it running again. I can't imagine what part I moved in order For it to fail to start. Frustrating!!

[Terry Kay]

I'd be frustrated too.

You need;
Fuel,
Air,
Spark,
Timing.

Which one are you missing?

You had th TB off to set the adjustment on the switch propery--right?
It can be done on the engine if you know what to expect, it's a bunch easier to bench adjust it for a first timer.
_________________
T.K.

[ryancr500]

I'm trying to figure that out but I had to call in the absentee father to assist. I started by checking fuel pump but it's hard with one person, I'm just about to check for spark. There's power at the coil. Just waiting for my helper!!!

[ryancr500]

I did remove the throttle body to adjust the idle switch.

[ryancr500]

I checked spark and there is none! There is power to the coil and I can generate a spark if I turn the key on and off while touching the coil wire to the ground. Does this sound like a distributor issue?. What a coincidence it would be. Any help would be greatly appreciated.

[Terry Kay]

Pull a plug, lay the plug on the block to ground it,hooked to its plug wire, and crank the engine over.
Got spark?
_________________
T.K.

[ryancr500]

No Spark!

[Terry Kay]

Wires to the hall sensor broken, hall sensor failed, it's dead, cap, or rotor are all done.
Take your pick, it's one of the above.
_________________
T.K.

[ryancr500]

Ok... going to find a new hall sensor, distributor cap and rotor. I'll let you know when I've sourced them.
Ryan

[Terry Kay]

Prior to "sourcing" anything, are the wires broken, pinched, going into the side of the distributor?
Is the cap; cracked, have carbon tracks, a broken carbon contact, eaten up brass contacts?
Is the center of the rotor corroded, broken, the end of it burnt or green?

Going from a running engine with a crummy idle, you remove the TB to adjust
the switch, and then the engine doesn't run at all, no spark is pretty remote, super coincidental, unless you are really an animal and were ripping & throwing stuff at the engine.

Really wild bottom line.
_________________
T.K.

[ryancr500]

I can't believe it's just a coincidence but it seems unlikely making throttle body adjustments would cause a loss of spark. The rotor and cap look fine. Wires to distributor are a little brittle but not broken. Coil could be an issue... Just did a quick test on it and spark seemed really yellow. Was able to hold it. What are the chances of a coil going bad???
Ryan.

[ryancr500]

In my search for a reason why I dont have spark. I noticed something suspicious...but not sure if it's the cause. The 3 wires that go into the distributor are loose and the plastic plug is slightly disintegrated. The plug was held firm by some zip ties. I noticed when checking the coil with the distributor lead close to a ground point, I would hear the injectors firing, just by moving wires. Seems the 3 wires that go into the distributor were grounding out on the distributor metal body.
I don't know if the result of this 'grounding' would damage the hall generator or if it would cause damage to something else.
Either way, it still doesn't run, even if I make sure the wires are protected from grounding on the distributor.
In the meantime, I removed, sanded and cleaned most of the grounds in the engine bay, transaxle and battery. I've ordered a hall generator as well as a coil, distributor cap/rotor and spark plug wires.
Hoping for the best!! Ryan

[morymob]

Most just repair the broken wire (s), a wire is a wire, not spec made 4 a hall, small stranded not a single solid wire, as usual no warranty offered at this time. Did u plug the cable back in to the afm?