Failed Engine/Cyl Compression Test??, Unplugged Fuses & Impala.... :(
03-11-2016, 05:39 PM
#21
Senior Member
Posts like a 4 Banger
Thread Starter
I Need Help Badly.
and........"WHY" were you doing a compression test in the first place?
Have you checked fuel pressure with a gage, checked for spark, checked for injector pulse, like Mike asked?
Have you scanned for codes?
Tried starting vehicle with MAF disconnected?
Check for fuel in vac line to fuel pressure regulator?
Have you checked fuel pressure with a gage, checked for spark, checked for injector pulse, like Mike asked?
Have you scanned for codes?
Tried starting vehicle with MAF disconnected?
Check for fuel in vac line to fuel pressure regulator?
If You read the last thread I started You'll get the whole story.
But, I was trying do the Comp. test to find out why I had a misfire in Cyl #5. (Which didn't work out well either)
Only thing was it had a Mild Persistent Misfire in Cyl #5. I posted a Vid of it in One of My Posts.
03-11-2016, 05:47 PM
#22
Retired
Certified Car Nut
Misfires are commonly caused by faulty ignition components.
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03-11-2016, 10:04 PM
#24
Senior Member
True Car Nut
You can buy a fuel pressure tester from a lot of places, Amazon has them for kind of cheap, or you can see if your local auto-parts store rents them.
Here is a guide for testing your Fuel Pressure.
https://www.gmforum.com/trouble-shoo...4/#post1392202
And something on testing injector pulse.
Part 1 -How to Do a Fuel Injector Noid Light Test (GM 3.8L)
And in case you want to test the injectors..
Part 1 -How to Test the Fuel Injectors (GM 3.8L)
Here is a guide for testing your Fuel Pressure.
https://www.gmforum.com/trouble-shoo...4/#post1392202
And something on testing injector pulse.
Part 1 -How to Do a Fuel Injector Noid Light Test (GM 3.8L)
And in case you want to test the injectors..
Part 1 -How to Test the Fuel Injectors (GM 3.8L)
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Soft Ride (03-12-2016)
03-12-2016, 03:35 PM
#25
Artist
True Car Nut
Engines need 3 things to run.
1. Air
2. Fuel
3. Spark
We already know the engine is getting air, maybe getting fuel, but you do hear the pump prime, but are you getting spark and fuel into the cylinders?
One way to test the fuel/spark is to remove the intake duct off the throttle body and squirt a tad bit of carb cleaner into the intake while the engine is being cranked over. If it attempts to run, you now know you have spark. Now you need to find out why you are not getting fuel into the cylinders.
1. Air
2. Fuel
3. Spark
We already know the engine is getting air, maybe getting fuel, but you do hear the pump prime, but are you getting spark and fuel into the cylinders?
One way to test the fuel/spark is to remove the intake duct off the throttle body and squirt a tad bit of carb cleaner into the intake while the engine is being cranked over. If it attempts to run, you now know you have spark. Now you need to find out why you are not getting fuel into the cylinders.
4. Compression
03-12-2016, 03:47 PM
#26
Senior Member
Posts like a Turbo
Excellent post by WilliamE
Auto Zone has the testing tools for rent well free.
Deposit then you get your money back
They even have the circuit tester Noid lights for the injectors
Auto Zone has the testing tools for rent well free.
Deposit then you get your money back
They even have the circuit tester Noid lights for the injectors
03-12-2016, 04:23 PM
#27
Senior Member
True Car Nut
Brian has a point, engines are technically glorified compressors, if there is no compression then nothing else matters.
Thanks Karl, Auto Zone was the place I had in mind, cannot remember if AdvanceAuto has them for rent as well or not..
Thanks Karl, Auto Zone was the place I had in mind, cannot remember if AdvanceAuto has them for rent as well or not..
03-12-2016, 05:46 PM
#28
Retired
Certified Car Nut
Compression only aids in the ignition of the fuel/air mixture. Otherwise, its difficult to start it.
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2002 *-10 5.7 V8
2023 Jeep Rubicon Diesel
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WilliamE (03-12-2016)
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