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jdgomez69
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 Posted: Sun Jul 01, 2007 2:45 pm Post subject: HELP...Strange Idle...May have found the problem! Could it b |
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Okay so, I have been I've been fighting a very high idle as some of you know. I've got an 84 1.9l. As fas as I know everything is stock. When I first start up it idles around 900rpm. Once the engine is warm is idles at 1500 and cuts in and out. So, I just checked and have been checking variuos things. So far I know the throtle switches are working correctly, I have a new Temp II and I checked it, seems to be working properly, I have replaced all the vacuum lines, and rechecked seems good, AFM seems ok...Haven't put on a meter...How do I check it? Could a leaking injector cause this idle problem? A cloged charcoal canister? Aux. air control? I'm lost at what else to check. So, I checked the timing, it's correct. If I lower the timing the idle goes down acordingly. So I though "ok maybe I'm timing it incorrectly" So, I change the timing to where the idle is at around 850rpm. I go around the block...Backfire, lack of power, etc. So, I put it back. I'm thinking this might have something to do with it but, I'm not sure. Someone please give me an idea here! Anyone in Colorado Springs thats more knowledge in VW's than me wanna come help me look at this problem? I have beer if someone is willing to come by look around at things and give me some ideas....
Last edited by jdgomez69 on Tue Jul 03, 2007 2:22 pm; edited 1 time in total |
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Wildthings
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| Posted: Sun Jul 01, 2007 3:00 pm Post subject: |
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To have an overly high idle speed you have to be getting more air than you want. The air has to be either passing through the throttle body or finding a way around it. The cutting in and out indicates a lean condition and that the excess air is probably not passing through the AFM.
The list seems endless as to places a WBX can leak air.
Brake booster
intake manifold gaskets
intake manifold boots
Throttle shaft
Throttle body gasket
injector gaskets
cold start injector
stuck open aux air valve
dozens of vacuum lines, boots, and seals
Not much help I know, you just have to keep looking and looking |
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wbx
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Joined: April 11, 2005
Posts: 1254
Location: Monterey, CA
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| Posted: Sun Jul 01, 2007 5:14 pm Post subject: |
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Just out of curiosity, how are you timing the engine? Are you bypassing the idle stabilizer? That is a very important and sometimes overlooked step on these engines.
-Damon
_________________
'84 Westy (first owner).......but my daily driver has pedals
My "perspective" mantra:
A Volkswagen Vanagon is just a material thing,
As such, it is of the earth,
And if i need to, I can let my Van go. |
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jdgomez69
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Joined: February 08, 2006
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| Posted: Sun Jul 01, 2007 11:58 pm Post subject: |
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| I tried checking the timing acording to the Bently I got from the Library... Yes idle stab. is bypassed...I don't think I have any air leaks. I've changed all the Vacuum hoses. You mention the brake booster. What type of signs would I be looking for? The brakes work fine! Well, it's hitting 1500rpm's and according to the bently if the Throttle switch is working it will shut off fuel..Maybe that is causeing it to surge but, what could be causing the high idle is the problem.... |
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Terry Kay
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Joined: June 22, 2003
Posts: 13331
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| Posted: Mon Jul 02, 2007 3:34 am Post subject: |
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It sounds to me that the low speed switch is either out of adjustment, or it isn't working.
It signals the ECU what position the throttle plate is in, and it sure looks like it isn't functioning properly.
A saturated charcoal cannister will make the idle wander too---
This is a hit or miss situation with the cannister though---how do you see if it's saturated?
Put a hand vacuum tester/ pump on it and see if it holds a vacuum--it shouldn't.
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T.K. |
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tencentlife
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Joined: May 02, 2006
Posts: 10078
Location: Abiquiu, NM, USA
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| Posted: Mon Jul 02, 2007 7:30 am Post subject: |
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Auxiliary Air Regulator. You already know the problem, you even mentioned it. Your rising idle with warmup points strongly to that as the problem, and it is a component very prone to failure with age. Make sure the AAR is completely closed when warmed up.
Good luck finding a new one, too. Salvage yards may be your best bet.
Retarding timing can cause backfiring, no mixture changes needed. Put it back to its previous setting, it was probably already correct. It should be set with the DIS bypassed. |
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jdgomez69
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| Posted: Mon Jul 02, 2007 8:17 am Post subject: |
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| The low speed switch is working properly. I checked it with an ohm meter. It tested correctly accordign to the Bently. How do I test the AAR? I did notice some oil around it when I took the hose off of it. Could that mean anything? |
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tencentlife
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Location: Abiquiu, NM, USA
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| Posted: Mon Jul 02, 2007 9:30 am Post subject: |
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| Quote: |
Make sure the AAR is completely closed when warmed up.
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jdgomez69
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| Posted: Mon Jul 02, 2007 10:20 am Post subject: |
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| What's the best way to test it? The Bently wasn't too helpful. It just said to clamp the hose and RPM's should not change. Pinch when cold RPM would go down....ANy other way to test it? |
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Wildthings
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| Posted: Mon Jul 02, 2007 10:45 am Post subject: |
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With the engine warm pull the 90° boot off and plug both the AAR and the hose. If the AAR is leaking the idle will drop when you plug it.
You can also remove the valve and look through it. Warm it should be closed to the point you can see no light through it.
If the AAR is not closing you should be getting a high, but steady idle.
Last edited by Wildthings on Mon Jul 02, 2007 10:48 am; edited 1 time in total |
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jdgomez69
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| Posted: Mon Jul 02, 2007 10:46 am Post subject: |
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| Okay, I will check that out here in a bit. |
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jdgomez69
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| Posted: Mon Jul 02, 2007 2:42 pm Post subject: |
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| Okay, just got testing that and if course again the temp II....Both are working fine! No air leaks at the AAR. I also rechecked all the Vacuum lines. NO leaks. So, I pulled the vacuum hose from the fuel pressure regulator....NOTHING changed. I figured the engine would either die or start racing. No change that I could here. Well maybe 100rpm or so from pulling the vac line before I could get my fingure on it. But in all actuallity no real change. So, could this cause a high idle? I did clean the AAR with carb cleaner. A lot of crap came out....I also sprayed some into the Charcoal Canister. It flowed right through so, I'm thinking that means that is okay. I cleaned the throttle body and checked it and it looked good. So, Some how it's either getting too much air or too much fuel... I'm lossing my mind here. I'd like to get this figured out before the end of next week. I'm going on Vacation the last week of July! |
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tencentlife
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Location: Abiquiu, NM, USA
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| Posted: Mon Jul 02, 2007 4:48 pm Post subject: |
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Sorry my response was so short earlier; I had to hurry out just then.
Pinching off the hose either side of the AAR while idling should have been a conclusive test.
Pulling the vacuum control line at the pressure regulator while idle is at 1500 may not cause any audible change in idle speed when the fuel pressure increases. You are already aware of the slight change due to the open line, but it goes back down when you plug it. At that speed, vacuum on that line may not be as high as it would be at a normal idle, and the slight increase in speed from more fuel pressure may be masked by the already high idle speed.
Make sure the Temp2 sensor connector is in good shape, no frayed wires, and it is clean and firmly connected. Use an ohmmeter to test between the body of the switch and the block. There should be zero resistance. Resistance between the wire pole and the block should correspond with the present engine temp on the table in Bentley.
How is idle when the DIS is bypassed and ignition timing is set correctly?
Does idle speed slow when you remove the diz vacuum advance line (the one facing away from the diz)? When you remove the retard line, the idle speed should increase. Either mechanical timing function in the diz could be stuck or malfunctioning.
Does your van have the PS and/or AC idle speed boost valves on the forward engine bay wall on the right? If you pinch off the large hose coming off the rubber intake bellows, you will rule out air leaks thru these and the AAR in one test. If that lowers idle speed, pinch the lines to or from both valves in turn to tell which one is open.
Last edited by tencentlife on Tue Jul 03, 2007 8:55 am; edited 1 time in total |
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jdgomez69
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| Posted: Mon Jul 02, 2007 10:56 pm Post subject: |
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| When I pinch the line going into the intake (AAR line) there is no change in idle speed. I do have one controller for A/C but, no power steering. I messed around with that and everything seems to be just fine. There is no air coming from there or vacuum when A/C is off. Okay so, to the vac lines at the Distributor (the dizzy right?)...When I pull the vac line nearest to the back of the Van the idle goes up. When I pull the van line nearest the front nothing happens. The is no vac on this line unless I rev the engine. Should something change here when I pull that line? There being no vac untill engine reved is correct right? Of course there is vac at idle on the other line that makes the idle go up and it goes down when engine speed increases. So, the temp II. It's new, I got 1683 Ohms before I started the engine this morning and I than ran it as I was checking other things. I than got 200 Ohms after it ran for about 30 minutes. Where would I test to make sure the correct reading is getting to the ECU so I can make sure the wires are in good order?!? When the green box is bypassed and idle is set correctly the idle is realy not much of a difference than after I shut it down replug it in and than start back up. ABout 1500 once warm connected or bypassed. I'm woundering on to check this but am a little confussed about what the Bently says. I set timing according to the bently. Used the notch it states, marked it with chalk. Timing seems to be very correct. Just only way so far I've found to lower the idle is to turn the timing way down. It doesn't miss when I do this but, it has NO power so of course I set it back at 5 degress as is recomended in the Bently. I am at 6000 ft so, I don't know if I need to make any adjustments for my altitude but, I'm not thinking I do? I will check the wires from the temp II in the morning. I also just re-read your post. How can I check to see if the Diz advance is stuck? is there a way to clean this or fix it? I thank you to all that have helped me so far! If someone is near Colorado Springs that might like to take a look a cold one is one me! |
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jdgomez69
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| Posted: Mon Jul 02, 2007 11:52 pm Post subject: |
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| I forgot one thing....Then I'm going to bed....When I turn the CO screw on the AFM, out the idle did come down a slight amount.... maybe about 75 to 100 rpm....That would almost tell me that somehow it's not getting enough air...However, I'm not expert. |
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Wildthings
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| Posted: Tue Jul 03, 2007 7:39 am Post subject: |
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| Have you actually turned in the idle adjusting screw on the throttle body? This is how you are supposed to set you idle speed. It is not unusual to fix an old nagging problem on your engine and find that it now idles faster. A PO or mechanic may have compensated for some past problem by screwing out the idle screw. When you fix the problem you must also undo the compensation. |
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jdgomez69
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| Posted: Tue Jul 03, 2007 8:45 am Post subject: |
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| The idle screw on the T.B. is turned all the way in. |
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tencentlife
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Location: Abiquiu, NM, USA
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| Posted: Tue Jul 03, 2007 9:54 am Post subject: |
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OK, seems like you've covered a lot of ground. The vacuum line checks at the diz seem consistent with proper operation of the vacuum advance and retard functions. What you saw there is what you'd expect to see, so it sounds like the diz isn't responsible for your high idle as long as your basic setting is correct.
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| How can I check to see if the Diz advance is stuck? |
You can use your timing strobe light to watch spark advance at the pulley wheel. It helps a lot to have a degreed wheel, but of course none of us do. There are strobes available that allow the user to dial in advance on the strobe, but they are much more expensive than the basic static strobe. What you can do is take chalk or grease pencil and make a series of marks to the right of the TDC mark on the pulley, say every 5 or 10 degrees, then watch with the strobe while you rev the engine. This involves a little math to be at all accurate, but timing isn't such a critical setting that you can't be off one or two degrees. That's pretty much the book tolerance, +/- 2 degrees. You would measure the diameter of your pulley wheel, multiply by pi (3.1416), and divide that by 36 to get the distance on the circumference of the wheel that represents 10 degrees. Divide by 72 to get 5 degrees. Use a cloth tape measure to mark off to the right of the TDC mark up to about 40 degreees advance, and you can then watch the wheel under the strobe light as you rev the engine, remove the vac retard line, and rev with the vacuum advance line removed to see how much avance is being added by the centrifugal mechanism inside the diz. None of this is pertinent to your problem at present; I'm just addressing your question above so you can entertain yourself. No, honestly, this is good stuff to know for general diagnosis and especially for tuning.
At your altitude you should add 2 degrees additional advance (1 deg. per every 1000' that is over 4000'). Of course that will probably increase the idle speed a bit further, so hold off on altitude tuning until you get your high idle problem solved.
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| I got 1683 Ohms before I started the engine this morning and I than ran it as I was checking other things. I than got 200 Ohms after it ran for about 30 minutes. Where would I test to make sure the correct reading is getting to the ECU so I can make sure the wires are in good order?!? |
Those readings appear to be fine according to the table (p.24.32). You may want to also check the intake air temp sensor, which is part of the AFM. See p.24.28 for the pins to check (1 and 4). The resistance according to temp is the same table as the Temp2 uses. Confirm the other resistance values of the AFM that are also on that page.
You can also backtrack to the ECU connector to verify that all the relevant signals are reaching it. All the pins and values are listed in the tables on pp.24.20 and 24.21.
Normally when idle is high it is suspected that too much air is being allowed into the intake tract somehow, and that is the first variable to eliminate, but too much fuel will do the same thing. If you want proof, observe the speed increase from raising fuel pressure by pulling the vac line from the fuel pressure regulator, and if you really want proof, warm up the motor and remove the wire from the Temp2 sender. On a Digifant that will send idle straight to 2000 rpm, no additional air needed. I haven't tried it on a Digijet but I don't doubt that the result would be about the same. The extra enrichment is enough to do the trick, partly because these FI's run so lean. Of course, over-advancing timing can do the same thing.
In light of that, you should do a basic fuel pressure test, to make sure yours isn't too high. This value is one of the foundations of the FI's normal functioning; if it is off, the ECU has no way of knowing. All the injection duration values are based on the assumption that delivery pressure is correct.
You should also put your voltneter between the O2 sensor signal wire and ground with the engine warm and running. You should see a varying voltage between 0.2 and 1.0 volt. If there is no voltage present, your sensor has failed and the engine will run rich, which could be part of your high idle.
So, you've ruled out most of the usual suspects that allow extra air to raise idle. One that hasn't been dealt with is the throttle body itself. Problem is, all of these cars are so old, and the TB was such a faulty design that made for extreme wear, that they are almost universally leaky. The fact that you have turned your idle bypass screw on the TB all the way in is an indication of this; that is practically normal with these old TB's. So much air is leaking around the throttle plate that you can't lower idle speed.
A secondary problem due to air leakage wthin the TB is that the EEC (charcoal canister) control valve can be receiving a vacuum signal when the throttle is fully closed, which it shouldn't. I don't think you are experiencing this because the response when you pulled the vac advance line at the diz sounded normal. That is the same vac signal that goes to the EEC valve. If you want to verify, there are two ways you can test. One is to remove the vac advance signal hose from the diz, and put a vacuum gauge on it. There should be less than 1"Hg. of vacuum on this line at idle (this test is buried in Bentley somewhere, but damned if I can find it). If you don't have a vac gauge, you can find where the canister vent line comes into the engine bay, and follow it to the wye-connector before the intake plenum. Remove the line and plug the port on the wye. If idle speed decreases, you need to get the EEC system working so that that line is only open above idle.
Had enough? I have. |
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jdgomez69
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| Posted: Tue Jul 03, 2007 10:06 am Post subject: |
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| Yeah I've had enough... LOL ... It's driving me crazy. Yes I've checked the O2. It's working just fine. Well, ok try this. I know this seems wierd but, I though I had the vac hoses that go to the EEC mixed up so I revesed them. Guess what, Idle went down. Then after checking the Bently I realized that they were wrong. So, I put them back and the Idle raised agian. So, could that mean anything? I'm not sure. Time to go do some more looking. Yes, I checked the TB and it seemed okay but of course I didn't remove it a investigate that much. Temp I on the AFM is the first thing I'm going to check... |
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tencentlife
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Location: Abiquiu, NM, USA
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| Posted: Tue Jul 03, 2007 10:19 am Post subject: |
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Even the worst TB's "seem OK" with a quick look. You have to have the ting cleaned up and in your hand and take a really close look inside. If you don't have a tight one to compare it to, they'll all "seem OK", but they're really nearly all of them crap at this point, except the ones wit really low miles. Well, you know how rare those vans are.
Switching the EEC lines making idle lower says something is up with that. If you take off the white line, the one attached to the bottom of the control valve, and try to pull vacuum on it, it should be totally blocked when the engine is idling. As soon as you tip the throttle, the vac signal on the advance line should open the control valve and then you should be able to draw air thru that line. The EEC system is totally off-line at idle. Basically, at idle, no air should be able to be drawn thru either line. If switching them caused your idle to fall, then I think that's the tree you oughta go over and bark up. Maybe a cat will fall out and you'll have lunch. |
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