switch and relief solonoids. plus strange idle
02-07-13, 08:54 PM
#1
switch and relief solonoids. plus strange idle
I have a 90 gxl. Just wondering what exactly the relief and switch solonoids do.
I swapped the engine not long ago so I could have some vacuum lines and solonoids switched around. The car seems like it has 2 idle speeds. The main speed is at around 1700 RPM and the second is at 800 RPM.After it's warmed up the car will idle at 1700 RPM rock solid for a few minutes or until I put load on it like slowly loading the clutch to lower the engine speed and then it will automatically drop to 800 RPM. It will stay steady at 800 RPM with only a slight miss until I blip the throttle again or turn on the A/C, then it will bounce back up to 1700 RPM. It will actually shoot up to 2400 RPM with the A/C running.
If I adjust the idle screw on the TB while its at 1700 RPM down to 750 RPM It will idle solid for a minute until it switches into its 2nd idle speed, then it dips between 100 RPM and 400 RPM for a few seconds until it stalls. I don't get why there are two idles, and I dont get why it doesn't stall while its idling at 800 RPM, but it stalls when I adjust the idle screw inward to the proper 750 RPM. This car has always had a weird idle, but it has never been to the point of stalling.
-Checked timing...solid
-Tried a back up set of plugs
-Replaced all vacuum hoses, fuel injector O rings and grommets, UIM and BAC gaskets during swap
-Spayed starter fluid to locate vacuum leaks...none found
-Inspected TB. plate clearance, fast idle, thermowax clearance and all is well.
I tried to follow the FSM vacuum diagram to, but it's a bit confusing how they criss cross over each other in the picture so I'm still not positive it's correct. I'm thinking about just throwing in the towel and doing a full emission delete...
I swapped the engine not long ago so I could have some vacuum lines and solonoids switched around. The car seems like it has 2 idle speeds. The main speed is at around 1700 RPM and the second is at 800 RPM.After it's warmed up the car will idle at 1700 RPM rock solid for a few minutes or until I put load on it like slowly loading the clutch to lower the engine speed and then it will automatically drop to 800 RPM. It will stay steady at 800 RPM with only a slight miss until I blip the throttle again or turn on the A/C, then it will bounce back up to 1700 RPM. It will actually shoot up to 2400 RPM with the A/C running.
If I adjust the idle screw on the TB while its at 1700 RPM down to 750 RPM It will idle solid for a minute until it switches into its 2nd idle speed, then it dips between 100 RPM and 400 RPM for a few seconds until it stalls. I don't get why there are two idles, and I dont get why it doesn't stall while its idling at 800 RPM, but it stalls when I adjust the idle screw inward to the proper 750 RPM. This car has always had a weird idle, but it has never been to the point of stalling.
-Checked timing...solid
-Tried a back up set of plugs
-Replaced all vacuum hoses, fuel injector O rings and grommets, UIM and BAC gaskets during swap
-Spayed starter fluid to locate vacuum leaks...none found
-Inspected TB. plate clearance, fast idle, thermowax clearance and all is well.
I tried to follow the FSM vacuum diagram to, but it's a bit confusing how they criss cross over each other in the picture so I'm still not positive it's correct. I'm thinking about just throwing in the towel and doing a full emission delete...
02-08-13, 10:28 AM
#2
The switching solenoid controls switches between air pump air going to the port air or split air paths in the ACV. The relief solenoid opens/closes the relief port on the ACV; this happens above 3500 RPM and/or moderate-to-high load conditions. Both are purely part of the secondary air injection system and not idle-related.
Have you tried disconnecting the AWS valve or BAC to see how it behaves? It sounds like the ECU is dumping extra air in for a short time, but then cutting it when it sees a signal from the neutral switch (gear change).
Have you tried disconnecting the AWS valve or BAC to see how it behaves? It sounds like the ECU is dumping extra air in for a short time, but then cutting it when it sees a signal from the neutral switch (gear change).
02-08-13, 10:36 AM
#3
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just to add to RR88's explanation, the switching and relief valves are inline with each other, so the relief chooses, relief or the switching, and switching chooses port air, or split air.
i do agree the diagram in the manual isn't good enough, i pull the hose off the solenoid and the ACV and blow thru it, to make sure they are going to the right place.
for your fast idle thing, i would look at the thermowax, i've had two cars in a row where the water hoses to the thermowax were just full of crud, and i had to clean em all out, and then pull of the tb and clean out the thermowax as well.
i do agree the diagram in the manual isn't good enough, i pull the hose off the solenoid and the ACV and blow thru it, to make sure they are going to the right place.
for your fast idle thing, i would look at the thermowax, i've had two cars in a row where the water hoses to the thermowax were just full of crud, and i had to clean em all out, and then pull of the tb and clean out the thermowax as well.
02-08-13, 11:57 AM
#4
When it's idling at 1700 RPM I can push down on the little thermowax cam to separate it from the pellet and it makes no difference so it's not a sticky thermowax. In all honesty I think it's electronic because it switches back and forth between 1700 and 800 RPM on it's own with no physical influence from me. It's not a bouncy bad TPS kind of idle switch, its a full either 1700 or 800 idle. No hunting.
I was thinking perhaps the switch and relief may have been crossed into another line or something. Or the ACV is bad causing port air to circulate back into the intake manifold or something. The ACV is the only system I have not had off the car for inspection.
AWS solonoid is installed, but I shoved large rubber plugs in both the inlet and outlet hoses and reconnected them to the engine. Basically it's there, but completely disabled. I thought this was the problem so I took the plugs out and reconnected it, but it's the same.
The only things not stock (engine related) are the exhaust, which is a full Racing Beat, and charcoal canister removal. The bottom nipple on the middle iron is vented as well as the small vacuum line coming from the gas tank (near the oil filter).
The car has been throwing code 17 for 3 years too btw.
I was thinking perhaps the switch and relief may have been crossed into another line or something. Or the ACV is bad causing port air to circulate back into the intake manifold or something. The ACV is the only system I have not had off the car for inspection.
AWS solonoid is installed, but I shoved large rubber plugs in both the inlet and outlet hoses and reconnected them to the engine. Basically it's there, but completely disabled. I thought this was the problem so I took the plugs out and reconnected it, but it's the same.
The only things not stock (engine related) are the exhaust, which is a full Racing Beat, and charcoal canister removal. The bottom nipple on the middle iron is vented as well as the small vacuum line coming from the gas tank (near the oil filter).
The car has been throwing code 17 for 3 years too btw.
02-08-13, 12:28 PM
#5
The BAC is suspicious. If you jumper the initial set coupler, does the rpm still rise when you turn on the AC? It shouldn't
Also, the diaphragm behind the ACV could be acting up. Sometimes seating correctly (low idle) and sometimes not (causing vac leak->high idle).
Lastly, have you checked your TPS for dead spots when warm? If you move the plunger while it's idling high, will it drop down to 800?
And there was a thread here recently about an s5 that had an erratic idle because the wiring to the mixture resistor wasn't plugged into the ecu.
Also, the diaphragm behind the ACV could be acting up. Sometimes seating correctly (low idle) and sometimes not (causing vac leak->high idle).
Lastly, have you checked your TPS for dead spots when warm? If you move the plunger while it's idling high, will it drop down to 800?
And there was a thread here recently about an s5 that had an erratic idle because the wiring to the mixture resistor wasn't plugged into the ecu.
02-09-13, 12:30 PM
#11
I will add this to the puzzle... It has an automatic transmission throttle body. I was not aware of any differences as far as vacuum porting is concerned. There is one extra nipple on the underside that appears to be used for the slow opening butterfly delays, but it is capped off. Plate clearance is a tad higher on an AT, maybe 0.2 mm?
02-10-13, 01:19 AM
#14
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Buddy of mine had a s5 vert that was real weird.
it sounds like your scenario too.
it turned out to be a Check valve on one of the Hoses..(don't ask me about the S5.sorry man)
it sounds like your scenario too.
it turned out to be a Check valve on one of the Hoses..(don't ask me about the S5.sorry man)
02-10-13, 01:39 AM
#15
I'm beginning to think it's the ACV. I've noticed a strange noise coming from under the car near the header while driving for awile. It normally does it while decelerating or down shifting. It kind of sounds like a bearing whirling around and a bit of a pssst sound. I thought it was the pilot bearing, but I replaced it and the throw out bearing when I did my clutch replacement a year ago.
02-10-13, 11:27 AM
#16
I'm beginning to think it's the ACV. I've noticed a strange noise coming from under the car near the header while driving for awile. It normally does it while decelerating or down shifting. It kind of sounds like a bearing whirling around and a bit of a pssst sound. I thought it was the pilot bearing, but I replaced it and the throw out bearing when I did my clutch replacement a year ago.
Last edited by satch; 02-10-13 at 11:31 AM.
02-10-13, 12:37 PM
#17
I removed the ACV today for the first time in the 3 1/2 years I've owned this car and yep... The gasket was installed at a 45 degree angle by a previous owner kind of swiveling freely on the top stud and the exposed gasket had crumbled apart so I never saw the problem from the outside. So in short 2 or 3 of the vacuum ports were exposed to unmetered air. When I blow through the vacuum line on the front of it (probably for the aux. ports and VDEI) air comes out of the 2 ports that were exposed, so it has had a direct vacuum leak for the entire time I've had it. On top of that I'm sure the aux. and VDEI have been either barely or non functional.
The anti-afterburn valve was installed straight and appears functional so maybe it was just a vacuum leak while decelerating that made all those weird noises I hear. So this explains why it would stall when I rev it or come to a stop from in gear (stop light).
I ordered a new ACV gasket from Atkins so well see in a few days if its all true.
The anti-afterburn valve was installed straight and appears functional so maybe it was just a vacuum leak while decelerating that made all those weird noises I hear. So this explains why it would stall when I rev it or come to a stop from in gear (stop light).
I ordered a new ACV gasket from Atkins so well see in a few days if its all true.
02-16-13, 07:26 PM
#18
I figure out the problem. It was mainly the TPS. Probed it at warm idle and it read 1.57 volts. I slowly pushed the plunger in by hand until it read 1 volt and the idle smoothed out and dropped to 1000 rpm from the 1700 rpm idle. After setting the TPS at 1 volt and playing with the idle set screw and the secondary throttle plate stop screw a bit I got it to idle steady at 900 rpm. Anything less and it will stumble, but doesn't stall.
So I'm thinking it could just need new plugs and wires to hopefully smooth it out to a steady 800 rpm idle.
The ACV gasket got rid of my 3 year code 17 plague. It runs much better both from the TPS adjustment and ACV gasket. I can actually feel the ports and vdei come on now! Hopefully MPG will go up as well. It averages 18 highway which sucks for a NA.
Is it normal to idle better under 1 volt? If I lower the idle to 800 rpm and lower the TPS to 0.85 volts it seem to idle smoother.
So I'm thinking it could just need new plugs and wires to hopefully smooth it out to a steady 800 rpm idle.
The ACV gasket got rid of my 3 year code 17 plague. It runs much better both from the TPS adjustment and ACV gasket. I can actually feel the ports and vdei come on now! Hopefully MPG will go up as well. It averages 18 highway which sucks for a NA.
Is it normal to idle better under 1 volt? If I lower the idle to 800 rpm and lower the TPS to 0.85 volts it seem to idle smoother.
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