Question about 2001 Chevrolet Cavalier

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I have an oil senor that is moving all over the place. It always used to read 40 (on a scale of 0 to 80, not sure if it is pressure or quantity), but now it has started to go back and forth from 40 to 0 and in between constantly. It just oscillates back and forth.

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It is pressure and either your sender is bad, or the pump is going out. If you have a bazillon miles on it you may need a new pump, but unlikely. The sender unit is cheap and fairly easy to replace so start with it. These can be had at parts stores, you find the thing which looks just like your new one but screwed into the side of your engine and replace it with the new one.

Posted on Apr 01, 2011

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No power after 4000 rpms


This sounds like a fuel pump or fuel filter problem.
The 1988 Jetta has two fuel pumps. The "main" one under the car directly in front of the gas tank on the right hand side. The other fuel pum is in the tank. You can access that fuel pum by removing the round access panel in the trunk towards the back seat.

You'll need a fuel pressure gauge. You can usually borrow one from a large auto parts chain store.

FUEL DELIVERY & SYSTEM PRESSURES
System Pressure
Connect Pressure Gauge (VW 1318) between line from fuel distributor to cold start valve and
test port connection on lower chamber of fuel distributor, using Adapter Fittings (VW 1318/5).
Test port is sealed by a threaded plug. Bridge fuel pump relay with Jumper Switch (US 4480/3).
1.
Disconnect wiring from Differential Pressure Regulator (DPR). Open valve on pressure gauge
(points at cold start valve line when open) and activate fuel pump. System pressure must be 75-
82 psi (5.3-5.8 kg/cm2 ). If pressure reading is low and fuel pump delivery quantity is good,
replace pressure regulator.
2.
If pressure reading is high, disconnect fuel tank return line from DPR. Repeat test. If reading is
correct, check for plugged return line. If reading is incorrect with line open, replace DPR.
3.
Differential Control Pressure
Close valve on pressure gauge. Activate fuel pump with jumper switch. Leave DPR
disconnected. DPR reading should be 2.9-7.0 psi (.2-.5 kg/cm2 ) less than system pressure. If
pressure is incorrect, disconnect lower chamber return line and measure volume.
1.
Close open port to diaphragm pressure regulator. Activate fuel pump with jumper switch. Fuel
volume should be .14-.16 qts. (.13-.15L) for period of one minute. If volume is correct, replace
DPR. If volume is incorrect, replace fuel distributor.
2.
Close valve on pressure gauge. Install Test Harness (1315A/1) between DPR and vehicle
harness. Set multimeter to DCA 200 mA scale. Connect multimeter to test harness. Disconnect
wiring to coolant temperature sensor. Connect 15 k/ohm side of Test Resistor (VW 1490) to
sensor wiring.
3.
Turn on ignition and fuel pump. Differential pressure should be 10-17.5 psi (.7-1.2 kg/cm2 )
less than system pressure. DPR current should be 50-80 mA. If pressure is incorrect and current
is correct, replace DPR.
4.
If both pressure and current readings are incorrect, remove test harness from DPR. Ensure
resistance of DPR is 17.5-21.5 ohms. If reading is incorrect, replace DPR.
5.
If reading is correct, check ground from temperature sensor to cold start valve. If ground is
good, check power supply fuse. If fuse is okay, check terminals on ECU connector. If connector
is okay, replace ECU.
6.
Residual Pressure & Internal Leak Testing
Open valve on pressure gauge. Operate fuel pump for 30 seconds. Pressure can drop to a
minimum of 38 psi (2.7 kg/cm2 ) after 10 minutes. If pressure drops below specification, inspect
fuel pump check valve and all fuel fittings for leakage.
1.
NOTE: Pressure and leak testing does not include checking cold start
valve.
FUEL INJECTION SYSTEM - BOSCH CIS-E -1988 Volkswagen Jetta Page 1 of 3
http://www.ondemand5.com/mric/common/asp/printart.aspx 11/25/2011
If there are no leaks, check airflow sensor plate clearance. If plate clearance is correct, replace
diaphragm pressure regulator and repeat leak test. If pressure drop is not within specification,
replace fuel distributor "O" rings.
2.
Transfer Pump Delivery Volume
Check voltage supply to pumps. Connect Jumper Switch (US 4480/3) in place of fuel pump
relay, on relay panel. Remove fuel filler cap. Disconnect and plug off Black fuel line from
sending unit.
1.
Connect hose to sender port and place in measuring container. Turn on fuel pumps. Minimum
transfer pump delivery volume should be .42 qts. (.4L) in 10 seconds. Reconnect fuel line to
sender.
2.
Main Pump Delivery Volume
Check transfer pump (if equipped) and fuel filter. Disconnect fuel return line and place in
measuring container. Switch on fuel pump with jumper switch. Check fuel pump delivery
volume for 30 second period. Delivery rates are given with voltage reading at pump as volume
will change with different voltages.
1.
Minimum delivery volume for Fox, Quantum and Quantum Syncro models is .71 qts. (.68L) for
30 seconds with reading of 11.4 volts at fuel pump. Minimum delivery volume for other models
is .62 qts. (.59L) with 11.4 volts at fuel pump.
2.
Fuel Distributor
Check sensor plate adjusting lever and fuel distributor control piston for smooth operation.
Disconnect fuel injector lines at fuel injectors.
1.
Remove fuel pump relay and bridge fuel pump circuit. Use Jumper Switch (US 4480/3) in place
of fuel pump relay. When pressure has built up, turn off fuel pump. Move sensor plate from rest
position to end of travel.
2.
Uniform resistance should be felt during entire movement. No resistance should be felt on
quick return to rest position. Connect injector lines. Install fuel pump relay.
3.
Injector Quantity Comparison
Remove fuel pump relay, from relay panel, and install Jumper Switch (US 4480/3) in off
position in place of relay. Attach Fuel Quantity Analyzer (US 4480) to bumper and secure in
place. Remove injectors from cylinder head with fuel lines attached. Check and replace fuel
injector "O" rings as necessary.
1.
Check tightness of injector insert (2-piece inserts). If inserts are loose, remove and clean
threads. Use sealing compound when installing upper insert. Replace sealing washer that goes
against cylinder head below lower portion of insert. Lubricate injector "O" rings with gasoline
and install injectors, with fuel lines connected, into fuel quantity analyzer tubes.
2.
Ensure lines are not kinked or bent. Loosen fittings to align fuel lines and retighten. Remove
rubber boot from airflow sensor housing above sensor plate. Turn and lift setting screw and
adjusting slide of Sensor Plate Adjustable Holder (VW 1348/1) into upper position. This
simulates full throttle operation. See Fig. 11 .
3.
FUEL INJECTION SYSTEM - BOSCH CIS-E -1988 Volkswagen Jetta Page 2 of 3
http://www.ondemand5.com/mric/common/asp/printart.aspx 11/25/2011
Fig. 11: Sensor Plate Adjustable Holder (VW 1348/1)
Courtesy of AUDI OF AMERICA, INC.
Place sensor plate adjustable holder on airflow sensor housing with holder centered over plate.
Pointer on edge of holder base must point toward center of fuel distributor. Push adjusting slide
of holder down onto stop.
4.
Turn adjusting screw clockwise until magnetic end touches sensor plate retaining bolt. Activate
fuel pump with jumper switch. Turn adjusting screw of holder counterclockwise until any one
injector starts to deliver fuel. Turn off jumper switch and empty fuel quantity analyzer after
taking sample.
5.
Idle injection quantity is measured first. Lifting adjusting slide of holder to first stop simulates
idle position of sensor plate. Activate fuel pump until fuel level reaches 20 ml on scale of any
tube.
6.
Check that all injectors have identical spray patterns that are even and cone-shaped. If not, raise
sensor plate up quickly to full lift position and release. Repeat idle quantity test. Compare
amounts of fuel delivered by all injectors with analyzer held level. Maximum difference in
delivery quantity between injectors is 3.0 ml of fuel.
7.
If fuel delivery quantity differs between high and low levels by more than 3.0 ml, interchange
injectors and repeat test. If difference of delivery quantity changes with injectors, replace
injectors. If difference of delivery quantity does not change with movement of injectors, either
fuel lines are pinched or fuel distributor is defective.
8.
Measure full throttle injection quantity. Empty analyzer into fuel tank and reinstall injectors in
analyzer. Lift adjusting slide of holder to last stop to simulate full throttle position of sensor
plate. Activate fuel pump with jumper switch until fuel level reaches 80 ml on scale of any tube
of analyzer.
9.
Check that all injectors have identical spray patterns that are even and cone-shaped. If not, raise
sensor plate up quickly to full lift position and release. Repeat full throttle quantity test.
Compare amounts of fuel delivered by all injectors with analyzer held level. Maximum
difference in delivery quantity between injectors is 8.0 ml of fuel.
10.
If fuel delivery quantity differs between high and low levels by more than 8.0 ml, interchange
injectors and repeat test. If difference of delivery quantity changes with injectors, replace
injectors. If difference of delivery quantity does not change with movement of injectors, either
fuel lines are pinched or fuel distributor is defective.
11.
Check fuel injectors for leakage immediately after delivery quantity test is complete. Set sensor
plate in rest position. Activate fuel pump with jumper switch for 2 minutes. Injectors should not
drip. Replace injectors that drip.
See image. Fuel filter is probably located on the frame between the engine and fuel tank.
8_24_2012_11_36_10_pm.jpg8_24_2012_11_36_30_pm.jpg

Jul 03, 2012 | 1988 Volkswagen Jetta

1 Answer

2001 jeep cheokee limited, straight v6, 4.0 liter engnie - oil pressure is droping to 20 when stopping and rising to 40-50 when accelerating. No check engine light is coming on when this occurs. Any idea...


A low reading of 20psi is not dangerous. As an engine wears, clearances increase and allow some oil to escape out the sides of the bearings. Even at 15 psi you would still be OK.
There are several other causes for a low reading. Make sure the oil is not contaminated with fuel (smell the oil on the dipstick). If the oil has been in service too long, pressure can also drop...Oil has a VI rating (viscosity index). Especially in inexpensive oils this index is maintained by additive packages added to the oil base. Those additives break down from heat and shearing forces inside the engine.
If you are using any 5w oil (except synthetic) discontinue using it. Even in colder climates, most engines don't need anything that thin. Most synthetic oils are thinner than conventional lubricants and will give low readings...in that case, it's not a problem because they are so far superior that there is no sacrifice in protection.
As far as the difference between at idle pressure and at speed pressure, that is normal. Your oil pump is driven off the camshaft. As the engine rpm's increase the pump spins faster, giving you higher pressure as needed. When I build any engine, I always use a high pressure high volume pump. Even with those, idle pressure is lower than driving pressure and pressure always becomes slightly lower as the oil heats up.
So, the pressures you see are good, providing you hear no noises. Use a good quality oil 10w or 20w (better) as a first # and no less than 30 as the second number. If you want to add your own additive package, Use Lucas oil stabilizer or a small amount of marvel oil. Lucas will increase the VI number and marvel is a good cleaner as well as the fact that it seeks out hot spots where other oils run from them. Change your oil at 3,000 to 4,000 miles (depends on how hard you drive), Always use a good quality oil filter and you should not have a problem

Oct 26, 2010 | Jeep Cherokee Cars & Trucks

1 Answer

How do I check and possibly replace the engine oil pressure sensor in a 2006 GMC Envoy Denali?


Oil Pressure Test Check for proper oil pressure at the sending unit passage with an externally mounted mechanical oil pressure gauge. A tachometer may also be needed, as some specifications may require running the engine at a specific RPM.
  1. While the engine is cold, locate and remove the oil pressure sending unit.
  2. Following the manufacturer's instructions, connect a mechanical oil pressure gauge and, if necessary, a tachometer to the engine.
  3. Start the engine and allow it to idle.
  4. Note and record the oil pressure reading when the engine is cold. The engine may need to run at a specified RPM, if so check the vehicle's specification.
  5. Run the engine until normal operating temperature is reached.
  6. Check the oil pressure reading again with the engine hot and record the value. Turn off the engine.
Compare the hot oil pressure reading to the specification. If the reading is low, check the cold pressure reading against the specification. If the cold pressure is well above the specification, and the hot reading was lower than the specification, the engine may have the wrong viscosity oil. Change the oil, making sure to use the proper grade and quantity, and then repeat the test.
Low oil pressure readings could be attributed to internal component wear, pump related problems, a low oil level, or oil viscosity that is too low. High oil pressure readings could be caused by an overfilled crankcase, too high of an oil viscosity or a faulty pressure relief valve.

Oct 09, 2010 | 2006 GMC Envoy Denali

1 Answer

Where is the oil pressure sensor located on a 1996 murcury cougar


Look for the oil pressure sending unit on the block or the cylinder head on the V-6 or V-8 models. --- OIL PRESSURE TEST Check for proper oil pressure at the sending unit passage with an externally mounted mechanical oil pressure gauge (as opposed to relying on a factory installed dash-mounted gauge). A tachometer may also be needed, as some specifications may require running the engine at a specific rpm.
  1. With the engine cold, locate and remove the oil pressure sending unit.
  2. Following the manufacturer's instructions, connect a mechanical oil pressure gauge and, if necessary, a tachometer to the engine.
  3. Start the engine and allow it to idle.
  4. Check the oil pressure reading when cold and record the number. You may need to run the engine at a specified rpm, so check the specifications.
  5. Run the engine until normal operating temperature is reached (upper radiator hose will feel warm).
  6. Check the oil pressure reading again with the engine hot and record the number. Turn the engine OFF.
  7. Compare your hot oil pressure reading to specification. If the reading is low, check the cold pressure reading against the chart. If the cold pressure is well above the specification, and the hot reading was lower than the specification, you may have the wrong viscosity oil in the engine. Change the oil, making sure to use the proper grade and quantity, then repeat the test. Low oil pressure readings could be attributed to internal component wear, pump related problems, a low oil level, or oil viscosity that is too low. High oil pressure readings could be caused by an overfilled crankcase, too high of an oil viscosity or a faulty pressure relief valve.

Sep 09, 2010 | 1996 Mercury Cougar XR7

1 Answer

What should oil pressure be at idle.Does the read out on your dash always right.


my 4.0 reads 18 PSI at idle, but on the 3.5 versions I have a lot of bad oil pressure sensors. They end up reading very high or go off scale at the top. Replacing the sensor fixes it only for a short time. I finally gave up on it.
Should probably read 40 -60 PSI driving.

Jul 08, 2010 | 2003 Oldsmobile Aurora

1 Answer

Engine started knocking. put in some oil detergent to try to quiet. ran about 40 miles. oil pressure pushed filter gasket out and lost oil. shut down quick. replaced oil, filter, and put in engine fix. as...


Everytime the system is over-filled, it would always find a way to escape.
When you replace your engine oil, it is best to park the car on a level ground, and tried to get as much old oil as possible from the engine.
My guess is that your engine might have been abused or subject to a long/hardous use, causing the engine to knock in the first place. But, what if only one or two cylinders are causing the knock? So in this case some discreation is necessary.
Detergent based oils always foam, and when this happens on a large scale, the result could be surprising.
It might be worth it to get a used engine from a reliable wrecking yard, and adhere to engine oil specifications.

Dec 19, 2009 | 1998 Suzuki X-90

2 Answers

2002 Jeep Grand Cherokee 4.0L oil pressure gauge reading too high


if the gauge starts a 0 - goes to 1/2 , than full - sounds like gauge is OK - seems to me like the sending unit is bad - you could try removing the sender and trying to clean out the port with "brake clean", letting it dry than re-installing it. the pressure switch is still the least expensive place to start

Oct 27, 2009 | 2002 Jeep Grand Cherokee

2 Answers

When car is cold oil pressuer is at 75 lbs when car is warmed uped it drops to 40 lbs (v6 3800) when warmed uped and give it gas it goes up to 60 lbs but when i stop it dropes to 45 lbs why is this please...


When the oil is cold it is thinner or watery and the pump moves more oil as it turns making the pressure go up. As the oil warms up it thickens and the pump moves less oil letting the pressure go down. Increasing the engine speed makes the pump turn faster, therefore it moves more oil and the pressure goes up. Changing oil grades will change the numbers somewhat, for example 10W40 will give you different readings than 5W30. I don't see any problem with the readings you put in your posting. I wouldn't be concerned until the warm idle pressure gets down to about 30 or a little lower. Hope this helps.

Oct 27, 2009 | 2001 Chevrolet Camaro

1 Answer

1992 jeep wrangler oil pressure goes off scale while accelerating


try replacing the oil filter and oil make sure u use the right grade oil for it if it still does it u need yo go to mechanic or if u have one connect a external oil pressure gauge to the engine to check if the car gauge is reading correctly if it is reading right then the oil pressure releif vale is stikking

if the car gauge is reading wrong change oil pressure sender

Dec 20, 2008 | 2002 Jeep Grand Cherokee

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