92 oldsmobile 88 stalling when cold fine when warmed up
03-09-2006, 03:16 AM
#52
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Originally Posted by 92olds88royale
i checked around the throttle body and around the intake manifold , and nothing. But it does sound like air is leaking neer the pcv even though its all sealed up. It might just be the belt though im not sure. i will go out in do a compression test in a few minutes and see what turns up.
Long shots: If the sound is not from the PCV , but in the neighborhood, you might have a leaking o-ring seal on a nearby injector. Try squirting with WD-40 while idling. Could be a cracked plastic housing around the PCV valve; squirt that too.
CAUTION: Be careful spraying any flammable liquid around the engine. Have a fire extinguisher nearby.
03-09-2006, 04:29 PM
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as soon as my dad gets home im back to looking for a vaccum guage. also i will try the wd-40 and let you guys know what happens. btw the pcv is the correct one for this car and ive changed it since the problem started happening.
03-15-2006, 10:45 AM
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after about 6 cans for carb cleaner spraying around looking for the air leak ive still gotten no where. i ordered a vaccum guage from autozone and it should be here tomarow. so ill let you guys know the vaccum readings when i get it.
03-16-2006, 02:39 PM
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First off it sounds like your starting to get it sorted out...something i have found in my past work has been a weak magnet for the cam sensor located in the cam gear of the timing chain...i have had these cause me cold idle issues and not trigger any codes (you will need a digital graphing scope to look at the signal) it should be a nice clear waveform.
check manifold vacum and post up i am curious myself whether it is low or not as this will determine what direction your diagnostics takes.
Good luck,
also i saw the posts on the PCV valve and would like to clear up some misconceptions...
there are three flow positions in a PCV valve system, closed, small orifice (spring fully compressed) and large orifice.
this is a section from one of my IM240 emissions tech manuals (on DVD
):
PCV System:
When the engine is running, intake manifold vacuum is supplied to the PCV valve. This vacuum moves air through the clean air hose into the rocker arm cover. From this location, air flows through cylinder head openings into the crankcase where it mixes with blow-by gases that escape from the combustion chamber past the piston rings. The mixture of blow-by gases and air flows up through cylinder head openings to the rocker arm cover and PCV valve.
Intake manifold vacuum moves the blow-by gas mixture through the PCV valve into the intake manifold. The blow-by gases are then moved through the intake valves into the combustion chambers where they are burned. Since blow-by gases contain hydrocarbons and other pollutants, these gases must not be allowed to escape to the atmosphere.
The PCV system prevents the escape of blow-by gases to the atmosphere. On many engines, the PCV system delivers blow-by gases to one location in the intake manifold. This type of system may not deliver these gases equally to all the cylinders.
This action may result in an air-fuel ratio variation between the cylinders, which results in rougher idle operation. Some engines, such as the Ford 4.6 L V8, have passages from the PCV valve system through the intake manifold and gaskets that supply blow-by gases equally to each cylinder, resulting in smoother idle operation. PCV Valve Position with the Engine Not Running The PCV valve contains a tapered valve. When the engine is not running, a spring keeps the tapered valve seated against the valve housing.
PCV Valve Position During Idle or Deceleration
During idle or deceleration, the high intake manifold vacuum moves the tapered valve upward against the spring tension. Under this condition, there is a small opening between the tapered valve and the PCV valve housing. Since the engine is not under heavy load during idle or deceleration operation, blow-by gases are minimal and the small PCV valve opening is adequate to move the blow-by gases out of the crankcase.
PCV Valve Position at Part Throttle
The intake manifold vacuum is lower during part-throttle operation than during idle operation. Under this condition, the spring moves the tapered valve downward to increase the opening between this valve and the PCV valve housing. Since engine load is higher at part-throttle operation than at idle operation, blow-by gases are increased. The larger opening between the tapered valve and the PCV valve housing allows all the blow-by gases to be drawn into the intake manifold.
PCV Valve Position During High Engine Load and Engine Backfire
When the engine is operating under heavy load conditions with a wide throttle opening, the decrease in intake manifold vacuum allows the spring to move the tapered valve further downward in the PCV valve.
This action provides a larger opening between the tapered valve and the PCV valve housing. Since higher engine load results in more blow-by gases, the larger PCV valve opening is necessary to allow these gases to flow through the valve into the intake manifold. When worn rings or scored cylinders allow excessive blow-by gases into the crankcase, the PCV valve opening may not be large enough to allow these gases to flow into the intake manifold. Under this condition, the blow-by gases create a pressure in the crankcase, and some of these gases are forced through the clean air hose and filter into the air cleaner. When this action occurs, there is oil in the PCV filter and air cleaner. This same action occurs if the PCV valve is restricted or plugged.
If the PCV valve sticks in the wide-open position, excessive air flow through the valve causes rough idle operation. If a backfire occurs in the intake manifold, the tapered valve is seated in the PCV valve as it is when the engine is not running. This action prevents the backfire from entering the engine where it could cause an explosion.
James
check manifold vacum and post up i am curious myself whether it is low or not as this will determine what direction your diagnostics takes.
Good luck,
also i saw the posts on the PCV valve and would like to clear up some misconceptions...
there are three flow positions in a PCV valve system, closed, small orifice (spring fully compressed) and large orifice.
this is a section from one of my IM240 emissions tech manuals (on DVD
):PCV System:
When the engine is running, intake manifold vacuum is supplied to the PCV valve. This vacuum moves air through the clean air hose into the rocker arm cover. From this location, air flows through cylinder head openings into the crankcase where it mixes with blow-by gases that escape from the combustion chamber past the piston rings. The mixture of blow-by gases and air flows up through cylinder head openings to the rocker arm cover and PCV valve.
Intake manifold vacuum moves the blow-by gas mixture through the PCV valve into the intake manifold. The blow-by gases are then moved through the intake valves into the combustion chambers where they are burned. Since blow-by gases contain hydrocarbons and other pollutants, these gases must not be allowed to escape to the atmosphere.
The PCV system prevents the escape of blow-by gases to the atmosphere. On many engines, the PCV system delivers blow-by gases to one location in the intake manifold. This type of system may not deliver these gases equally to all the cylinders.
This action may result in an air-fuel ratio variation between the cylinders, which results in rougher idle operation. Some engines, such as the Ford 4.6 L V8, have passages from the PCV valve system through the intake manifold and gaskets that supply blow-by gases equally to each cylinder, resulting in smoother idle operation. PCV Valve Position with the Engine Not Running The PCV valve contains a tapered valve. When the engine is not running, a spring keeps the tapered valve seated against the valve housing.
PCV Valve Position During Idle or Deceleration
During idle or deceleration, the high intake manifold vacuum moves the tapered valve upward against the spring tension. Under this condition, there is a small opening between the tapered valve and the PCV valve housing. Since the engine is not under heavy load during idle or deceleration operation, blow-by gases are minimal and the small PCV valve opening is adequate to move the blow-by gases out of the crankcase.
PCV Valve Position at Part Throttle
The intake manifold vacuum is lower during part-throttle operation than during idle operation. Under this condition, the spring moves the tapered valve downward to increase the opening between this valve and the PCV valve housing. Since engine load is higher at part-throttle operation than at idle operation, blow-by gases are increased. The larger opening between the tapered valve and the PCV valve housing allows all the blow-by gases to be drawn into the intake manifold.
PCV Valve Position During High Engine Load and Engine Backfire
When the engine is operating under heavy load conditions with a wide throttle opening, the decrease in intake manifold vacuum allows the spring to move the tapered valve further downward in the PCV valve.
This action provides a larger opening between the tapered valve and the PCV valve housing. Since higher engine load results in more blow-by gases, the larger PCV valve opening is necessary to allow these gases to flow through the valve into the intake manifold. When worn rings or scored cylinders allow excessive blow-by gases into the crankcase, the PCV valve opening may not be large enough to allow these gases to flow into the intake manifold. Under this condition, the blow-by gases create a pressure in the crankcase, and some of these gases are forced through the clean air hose and filter into the air cleaner. When this action occurs, there is oil in the PCV filter and air cleaner. This same action occurs if the PCV valve is restricted or plugged.
If the PCV valve sticks in the wide-open position, excessive air flow through the valve causes rough idle operation. If a backfire occurs in the intake manifold, the tapered valve is seated in the PCV valve as it is when the engine is not running. This action prevents the backfire from entering the engine where it could cause an explosion.
James
03-16-2006, 08:07 PM
#57
Senior Member
True Car Nut
Originally Posted by Turbocharged400sbc
First off it sounds like your starting to get it sorted out...something i have found in my past work has been a weak magnet for the cam sensor located in the cam gear of the timing chain...i have had these cause me cold idle issues and not trigger any codes (you will need a digital graphing scope to look at the signal) it should be a nice clear waveform.
check manifold vacum and post up i am curious myself whether it is low or not as this will determine what direction your diagnostics takes.
Good luck,
also i saw the posts on the PCV valve and would like to clear up some misconceptions...
there are three flow positions in a PCV valve system, closed, small orifice (spring fully compressed) and large orifice.
this is a section from one of my IM240 emissions tech manuals (on DVD ):
PCV System:
When the engine is running, intake manifold vacuum is supplied to the PCV valve. This vacuum moves air through the clean air hose into the rocker arm cover. From this location, air flows through cylinder head openings into the crankcase where it mixes with blow-by gases that escape from the combustion chamber past the piston rings. The mixture of blow-by gases and air flows up through cylinder head openings to the rocker arm cover and PCV valve.
Intake manifold vacuum moves the blow-by gas mixture through the PCV valve into the intake manifold. The blow-by gases are then moved through the intake valves into the combustion chambers where they are burned. Since blow-by gases contain hydrocarbons and other pollutants, these gases must not be allowed to escape to the atmosphere.
The PCV system prevents the escape of blow-by gases to the atmosphere. On many engines, the PCV system delivers blow-by gases to one location in the intake manifold. This type of system may not deliver these gases equally to all the cylinders.
This action may result in an air-fuel ratio variation between the cylinders, which results in rougher idle operation. Some engines, such as the Ford 4.6 L V8, have passages from the PCV valve system through the intake manifold and gaskets that supply blow-by gases equally to each cylinder, resulting in smoother idle operation. PCV Valve Position with the Engine Not Running The PCV valve contains a tapered valve. When the engine is not running, a spring keeps the tapered valve seated against the valve housing.
PCV Valve Position During Idle or Deceleration
During idle or deceleration, the high intake manifold vacuum moves the tapered valve upward against the spring tension. Under this condition, there is a small opening between the tapered valve and the PCV valve housing. Since the engine is not under heavy load during idle or deceleration operation, blow-by gases are minimal and the small PCV valve opening is adequate to move the blow-by gases out of the crankcase.
PCV Valve Position at Part Throttle
The intake manifold vacuum is lower during part-throttle operation than during idle operation. Under this condition, the spring moves the tapered valve downward to increase the opening between this valve and the PCV valve housing. Since engine load is higher at part-throttle operation than at idle operation, blow-by gases are increased. The larger opening between the tapered valve and the PCV valve housing allows all the blow-by gases to be drawn into the intake manifold.
PCV Valve Position During High Engine Load and Engine Backfire
When the engine is operating under heavy load conditions with a wide throttle opening, the decrease in intake manifold vacuum allows the spring to move the tapered valve further downward in the PCV valve.
This action provides a larger opening between the tapered valve and the PCV valve housing. Since higher engine load results in more blow-by gases, the larger PCV valve opening is necessary to allow these gases to flow through the valve into the intake manifold. When worn rings or scored cylinders allow excessive blow-by gases into the crankcase, the PCV valve opening may not be large enough to allow these gases to flow into the intake manifold. Under this condition, the blow-by gases create a pressure in the crankcase, and some of these gases are forced through the clean air hose and filter into the air cleaner. When this action occurs, there is oil in the PCV filter and air cleaner. This same action occurs if the PCV valve is restricted or plugged.
If the PCV valve sticks in the wide-open position, excessive air flow through the valve causes rough idle operation. If a backfire occurs in the intake manifold, the tapered valve is seated in the PCV valve as it is when the engine is not running. This action prevents the backfire from entering the engine where it could cause an explosion.
James
check manifold vacum and post up i am curious myself whether it is low or not as this will determine what direction your diagnostics takes.
Good luck,
also i saw the posts on the PCV valve and would like to clear up some misconceptions...
there are three flow positions in a PCV valve system, closed, small orifice (spring fully compressed) and large orifice.
this is a section from one of my IM240 emissions tech manuals (on DVD
):PCV System:
When the engine is running, intake manifold vacuum is supplied to the PCV valve. This vacuum moves air through the clean air hose into the rocker arm cover. From this location, air flows through cylinder head openings into the crankcase where it mixes with blow-by gases that escape from the combustion chamber past the piston rings. The mixture of blow-by gases and air flows up through cylinder head openings to the rocker arm cover and PCV valve.
Intake manifold vacuum moves the blow-by gas mixture through the PCV valve into the intake manifold. The blow-by gases are then moved through the intake valves into the combustion chambers where they are burned. Since blow-by gases contain hydrocarbons and other pollutants, these gases must not be allowed to escape to the atmosphere.
The PCV system prevents the escape of blow-by gases to the atmosphere. On many engines, the PCV system delivers blow-by gases to one location in the intake manifold. This type of system may not deliver these gases equally to all the cylinders.
This action may result in an air-fuel ratio variation between the cylinders, which results in rougher idle operation. Some engines, such as the Ford 4.6 L V8, have passages from the PCV valve system through the intake manifold and gaskets that supply blow-by gases equally to each cylinder, resulting in smoother idle operation. PCV Valve Position with the Engine Not Running The PCV valve contains a tapered valve. When the engine is not running, a spring keeps the tapered valve seated against the valve housing.
PCV Valve Position During Idle or Deceleration
During idle or deceleration, the high intake manifold vacuum moves the tapered valve upward against the spring tension. Under this condition, there is a small opening between the tapered valve and the PCV valve housing. Since the engine is not under heavy load during idle or deceleration operation, blow-by gases are minimal and the small PCV valve opening is adequate to move the blow-by gases out of the crankcase.
PCV Valve Position at Part Throttle
The intake manifold vacuum is lower during part-throttle operation than during idle operation. Under this condition, the spring moves the tapered valve downward to increase the opening between this valve and the PCV valve housing. Since engine load is higher at part-throttle operation than at idle operation, blow-by gases are increased. The larger opening between the tapered valve and the PCV valve housing allows all the blow-by gases to be drawn into the intake manifold.
PCV Valve Position During High Engine Load and Engine Backfire
When the engine is operating under heavy load conditions with a wide throttle opening, the decrease in intake manifold vacuum allows the spring to move the tapered valve further downward in the PCV valve.
This action provides a larger opening between the tapered valve and the PCV valve housing. Since higher engine load results in more blow-by gases, the larger PCV valve opening is necessary to allow these gases to flow through the valve into the intake manifold. When worn rings or scored cylinders allow excessive blow-by gases into the crankcase, the PCV valve opening may not be large enough to allow these gases to flow into the intake manifold. Under this condition, the blow-by gases create a pressure in the crankcase, and some of these gases are forced through the clean air hose and filter into the air cleaner. When this action occurs, there is oil in the PCV filter and air cleaner. This same action occurs if the PCV valve is restricted or plugged.
If the PCV valve sticks in the wide-open position, excessive air flow through the valve causes rough idle operation. If a backfire occurs in the intake manifold, the tapered valve is seated in the PCV valve as it is when the engine is not running. This action prevents the backfire from entering the engine where it could cause an explosion.
James
03-23-2006, 02:46 PM
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You might want to check your EGR valve and passage.
I haven't had any problems with my 3800 engines, but I've cleaned and/or replaced my 94 4.3 Chevy several times.
Just a thought.
I haven't had any problems with my 3800 engines, but I've cleaned and/or replaced my 94 4.3 Chevy several times.
Just a thought.
03-23-2006, 05:00 PM
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sorry i dont have an egr valve. also ive been trying to get the vaccum guage still ordered one and it was **** it was missing the needle so i couldnt use it. i think im going to have to order it off the internet somewhere. Also for the oil breather what kind of car do i tell autozone its for? or do i get one of the ones i just cut a hole in my oil filler cap to use?
thanks
jay
thanks
jay
03-24-2006, 04:09 AM
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Hello everyone,
To simplify James (Turbocharged400sbc) above post:
"Open" PCV is a simple device with only two jobs.
1) to draw air from the crankcase thru a controlled vacuum leak
2) In case of backfire, to close the valve to prevent an explosion.
"Closed" PCV system adds filtered air and a sealed filler cap. By coincidence, the original "open" systems drew outside air thru a vented oil filler cap.
When the filler cap is removed, it'* changed from a "closed" to an "open" system. If it'* functioning properly, there should be no difference in idle quality.
The statement is incorrect. At idle, vacuum holds the PCV open, not closed. Willwren is right in thinking the comp is compensating for an improper mixture, but it'* actually leaning a rich one.
Someone mentioned not feeling any vacuum at the filler. In this case, it'* there, just not enough to feel with the bare hand, as it'* source is a pretty small orifice.
If there was an obsruction at the fresh air inlet, it would cause the symptoms "92olds88royale" discribes. All my filters are in the air cleaners. Don't know where his is.
Regards, Norm
To simplify James (Turbocharged400sbc) above post:
"Open" PCV is a simple device with only two jobs.
1) to draw air from the crankcase thru a controlled vacuum leak
2) In case of backfire, to close the valve to prevent an explosion.
"Closed" PCV system adds filtered air and a sealed filler cap. By coincidence, the original "open" systems drew outside air thru a vented oil filler cap.
Originally Posted by 92olds88royale
........ When i take the oil cap off it throws the car into the rough idle ........
Originally Posted by bill buttermore
........ if I remember how PCV valves work, they are calibrated to be pretty much closed at high vacuum, then open up as load increases and vacuum falls ........ the leak (wherever it is) is dropping the vacuum in the manifold and allowing the PCV valve to open up, putting the crankase under a light vacuum, which sucks in air and throws off the idle when you open the cap ........
Someone mentioned not feeling any vacuum at the filler. In this case, it'* there, just not enough to feel with the bare hand, as it'* source is a pretty small orifice.
If there was an obsruction at the fresh air inlet, it would cause the symptoms "92olds88royale" discribes. All my filters are in the air cleaners. Don't know where his is.
Regards, Norm