Fast idle continues
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Elrick
Fast idle continues
Put your thinking caps on....I have a yellow '77 Westy. Bus continues to refuse to idle correctly once warmed up. After the beast is warmed up the idle stays at 2000 rpm even after restarting. No vacuum leaks, good timing and tune up parameters are good. I followed the Bentley's troubleshooting steps but can't pin the problem down. I suspect the decelleration valve and it seems to act as it should but it's difficult to tell. Does anyone know where to purchase a replacement deceleration valve or have any thoughts on this maddening problem. Volt-ohm checks on the temp sensors seemed OK but Bentley seems to be a little general when describing correct resistance. Oh, obviously the idle adjusting screw is turned all the way in. Thanks for your ideas.
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Dave_Darling
- Posts: 2534
- Joined: Thu Apr 27, 2000 12:01 am
Fast idle continues
Take a pair of vise-grips and squeeze the hose from the manifold to the Decel Valve shut. If the idle RPM drops, you have found a bad DV. Repeat this test on the hose from the manifold to the Auxiliary Air Regulator. If the warm idle (engine running for ~10 minutes or more) drops, you have found a faulty AAR.
Some AARs can be repaired reasonably easily, some cannot.
If the AAR is found to not be closing, make sure it's getting power and that the case is grounded to the engine or other good ground point.
--DD
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1974 VW-Porsche 914 2.0 (Type IV powered!)
Pelican Parts' 914 Tech Geek http://www.pelicanparts.com
Some AARs can be repaired reasonably easily, some cannot.
If the AAR is found to not be closing, make sure it's getting power and that the case is grounded to the engine or other good ground point.
--DD
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1974 VW-Porsche 914 2.0 (Type IV powered!)
Pelican Parts' 914 Tech Geek http://www.pelicanparts.com
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rich2481
- Posts: 1539
- Joined: Tue Dec 18, 2001 12:01 am
Fast idle continues
Do you have a aux. air regulator?? it is located on the right hand side of engine and is easy to locate, if that is not working you will have a fast idle because it is bypassing the throttle body, it is supposed to have a heater in it that spins a wheel to shut the vavle, the coil measures 30 Ohms whne good, allow van to warm up ( 15 minutes ) unplug regulator from boot ( behind air flow valve) and see if it is pulling vacuum, if it is then it is bad.
of course if you have vacuum line pliers, the kind toi squeeze a hose shut then you can use them instead
Rich
of course if you have vacuum line pliers, the kind toi squeeze a hose shut then you can use them instead
Rich
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regis101
- Posts: 1070
- Joined: Wed Oct 10, 2001 1:01 am
Fast idle continues
Greetings. This is a long shot ,but maybe the EGR is not adjusted properly. Mine ( 78 westy ) is mechanical and ...disconnected. However, if I ever so slightly accuate the lever, I can increase the idle speed. Opening it too far and it stumbles. ?????
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pbanders
- Posts: 103
- Joined: Wed Jul 11, 2001 12:01 am
Fast idle continues
I know you say you have no vacuum leaks, but the symptoms you describe sure sound like a leak. If your timing is right (adv. timing can also cause high idle), then you need to go through the entire system to find the vacuum leak source. Some areas include (some of these may not apply to your motor):
1. All vacuum hoses. Pull them and verify that there aren't cracks that extend under the cloth covering.
2. As DD mentioned, the aux air regulator. Remove the supply line from the air box and hold your thumb over it. If the idle drops, the AAR is stuck open.
3. Decel valve. Test it the same way as the AAR. Check the control line, too.
4. Manifold pressure sensor. Usually, if you have a severe vac leak due to a cracked full-load diaphragm, you'll have other problems, so this is unlikely. But check it anyway. Pull the hose to the MPS off of the plenum and suck on the line. If it doesn't hold vac, the MPS is defective.
5. Distributor vacuum adv/ret cells. Best way to test these is to use a hand vac pump with a gauge (about $30 from Kragen/Checker). Pull a vac on each line (if present) and verify they hold vacuum. The retard line is the one that is likely to affect the idle.
6. Throttle Body-to-Plenum gasket. Check it by squirting a bit of carb cleaner around this area, if the idle changes, it's leaking.
7. Cold start valve-to-Plenum gasket. Check as in 6.
8. Intake runner boots. Very common vac leak on older motors. Check as in 6.
9. Injector O-ring seals. Again, a common leak area that's overlooked.
Brad Anders
1. All vacuum hoses. Pull them and verify that there aren't cracks that extend under the cloth covering.
2. As DD mentioned, the aux air regulator. Remove the supply line from the air box and hold your thumb over it. If the idle drops, the AAR is stuck open.
3. Decel valve. Test it the same way as the AAR. Check the control line, too.
4. Manifold pressure sensor. Usually, if you have a severe vac leak due to a cracked full-load diaphragm, you'll have other problems, so this is unlikely. But check it anyway. Pull the hose to the MPS off of the plenum and suck on the line. If it doesn't hold vac, the MPS is defective.
5. Distributor vacuum adv/ret cells. Best way to test these is to use a hand vac pump with a gauge (about $30 from Kragen/Checker). Pull a vac on each line (if present) and verify they hold vacuum. The retard line is the one that is likely to affect the idle.
6. Throttle Body-to-Plenum gasket. Check it by squirting a bit of carb cleaner around this area, if the idle changes, it's leaking.
7. Cold start valve-to-Plenum gasket. Check as in 6.
8. Intake runner boots. Very common vac leak on older motors. Check as in 6.
9. Injector O-ring seals. Again, a common leak area that's overlooked.
Brad Anders
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Dave_Darling
- Posts: 2534
- Joined: Thu Apr 27, 2000 12:01 am
Fast idle continues
Brad, I think the 77 Westy would be L-jet, not D-jet. That would mean no MPS, and also that opening up the intake to atmospheric pressure (e.g., removing a hose from the intake pipe) would result in a very lean mixture. That would tend to mess up the diagnostic...
--DD
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1974 VW-Porsche 914 2.0 (Type IV powered!)
Pelican Parts' 914 Tech Geek http://www.pelicanparts.com
--DD
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1974 VW-Porsche 914 2.0 (Type IV powered!)
Pelican Parts' 914 Tech Geek http://www.pelicanparts.com
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pbanders
- Posts: 103
- Joined: Wed Jul 11, 2001 12:01 am
Fast idle continues
DD, yes, duh, you're right 
Brad Anders
(myoptic about D-Jet....)
Brad Anders
(myoptic about D-Jet....)