I need a favor. I need someone with a properly operating 4 cylinder to tell me vacuum pressure at..
05-23-2004, 01:43 PM
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I need a favor. I need someone with a properly operating 4 cylinder to tell me vacuum pressure at..
idle. My car has been running incorrectly for over 3.5 years now and the dealer is clueless. I am testing vacuum a vacuum gauge and I get an unsteady reading of about 10 inches of vacuum.
So if you could do me a favor and tell me what the engine should have at idle I would very much apprectiate it.
Dave
1990 Audi 80
So if you could do me a favor and tell me what the engine should have at idle I would very much apprectiate it.
Dave
1990 Audi 80
05-23-2004, 06:38 PM
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Perform engine vacuum tests; determine necessary action.
Task 6
A vacuum test can be used to help pinpoint the cause of an engine problem. The vacuum gauge should be connected directly to the intake manifold.
On an engine that is performing correctly, the vacuum gauge reading should be between 17 and 22 in. Hg (45 and 28 kPa absolute) and steady with the engine idling.
Some abnormal vacuum gauge readings and typical problems associated with them are listed below:
* A slightly low but steady reading indicates late ignition timing.
* A very low but steady reading indicates that the intake manifold has a significant leak.
<b>
* When the vacuum gauge pointer drifts back and forth between approximately 11 and 16 in. Hg (67 and 48 kPa absolute) on an idling carbureted engine, the idle mixture screws should be adjusted. On a fuel - injected engine, the injectors require cleaning or replacing.
* Burned or leaking valves cause the vacuum gauge to fluctuate between 12 and 18 in. Hg (62 and 41 kPa absolute).
* Weak valve springs result in a vacuum gauge fluctuation between 10 and 25 in. Hg (69 and 17 kPa absolute).
* A leaking head gasket may cause a vacuum gauge fluctuation between 7 and 20 in. Hg (79 and 35 kPa absolute).
* If the valves are sticking, the vacuum gauge fluctuates between 14 and 18 in. Hg (55 and 41 kPa absolute).</b>
* If, when the engine is accelerated and held steady at a higher speed, the vacuum gauge pointer gradually rises, the catalytic converter or other exhaust system components are restricted.
FROM:<ul><li><a href="http://www.fopinion.com/automotive/ase/keycodes/a1_demo/deeper/addionalq1.htm">Engine Diagnosis</a></li></ul>
A vacuum test can be used to help pinpoint the cause of an engine problem. The vacuum gauge should be connected directly to the intake manifold.
On an engine that is performing correctly, the vacuum gauge reading should be between 17 and 22 in. Hg (45 and 28 kPa absolute) and steady with the engine idling.
Some abnormal vacuum gauge readings and typical problems associated with them are listed below:
* A slightly low but steady reading indicates late ignition timing.
* A very low but steady reading indicates that the intake manifold has a significant leak.
<b>
* When the vacuum gauge pointer drifts back and forth between approximately 11 and 16 in. Hg (67 and 48 kPa absolute) on an idling carbureted engine, the idle mixture screws should be adjusted. On a fuel - injected engine, the injectors require cleaning or replacing.
* Burned or leaking valves cause the vacuum gauge to fluctuate between 12 and 18 in. Hg (62 and 41 kPa absolute).
* Weak valve springs result in a vacuum gauge fluctuation between 10 and 25 in. Hg (69 and 17 kPa absolute).
* A leaking head gasket may cause a vacuum gauge fluctuation between 7 and 20 in. Hg (79 and 35 kPa absolute).
* If the valves are sticking, the vacuum gauge fluctuates between 14 and 18 in. Hg (55 and 41 kPa absolute).</b>
* If, when the engine is accelerated and held steady at a higher speed, the vacuum gauge pointer gradually rises, the catalytic converter or other exhaust system components are restricted.
FROM:<ul><li><a href="http://www.fopinion.com/automotive/ase/keycodes/a1_demo/deeper/addionalq1.htm">Engine Diagnosis</a></li></ul>
05-24-2004, 11:10 AM
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If you have a gauge and a 4 cylinder it will take only a few seconds to check.
Running incorectly means my car is a beater. The car goes putt-putt rather loudly at idle, the exhaust bangs and pulses at idle, and the crank case has a positive pressure in it at idle.
The one dealer said there is nothing wrong with my car, so this means Audi's are suppose to sound like garbage or he is incompetent.
The one dealer said there is nothing wrong with my car, so this means Audi's are suppose to sound like garbage or he is incompetent.
05-24-2004, 11:43 AM
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Positive pressure in the crankcase usually means blowby - rings or valve seals are bad.
My Audi's - both 5cyl - idle smoothly. So did my 4cyl 4000CS when I had it.
Sounds like you may need an engine rebuild. Why not track down a competent independent mechanic for a diagnosis?
If not, then the data below tells what you need to know. 10psi and unsteady at idle is no good.
Sounds like you may need an engine rebuild. Why not track down a competent independent mechanic for a diagnosis?
If not, then the data below tells what you need to know. 10psi and unsteady at idle is no good.
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