Symptoms of bad compression

What are the symptoms of bad compression?

Low/inconsistent PSI readings when performing a compression check.

AA wrote:

Low/inconsistent PSI readings when performing a compression check.

Haha!

Low compression in one or more cylinders kinda feels like running around with one or more dead spark plugs.Not the end of the world but will f**k up yer day if ya like to run on all six or eight or ten or twelve or whatever.

So here are my issues:

When driving around flat surface very little to no issue.

When driving up a hill or incline she will hesitate, or kind of stutter right at about 2500 or 1500 rpm

I have no hard shifts anytime. Car has hard time starting unless pressing the gas when starting it the first time. If I shut it down and try starting it up again she starts better.

My personal suggestion based on how the symptoms sound would actually be the maf sensor. Our lesabre has twice now in it's life developed a bad maf and it will be fine until driving on a grade. At first it just acts like it's choking/starving for air a bit and over time it develops into the point where it will literally act as though you're driving with mixed up plugs and then died. Swapping out the maf and it runs good as new. Took my dad and I to fix that after the dealership spent $1800 being useless... Same issue again on our 88 reatta and sane results from replacing maf. Just my suggestion

Although will say, never required fuel feed to start car although maybe to hold idle on cold start occasionally.

Ignition wires and/or plugs, imo.

Fuel delivery is my guess, either a pump or regulator.

New fuel pump, new fuel injectors and new fuel filter

Engines lose compression over time when you click certain miles.Turbo is the answer....u don't feel it that much.....hahaha

nebstewart07 wrote:

What are the symptoms of bad compression?

How would it manifest itself?  Probably a misfire, but that could be caused by lots of other things.  When you have a symptom, you don't go right to the most unlikely cause, you check the more likely causes first, which would also be the simpler things.  You can lose compression from a bad valve seal, or bad ring seal, both very unlikely.  Very simple to check cylinder pressure with a screw in gauge, which you can rent.  You can also do a leak down test, but that is a bit more complicated.  Compression can actually increase a bit over the life of an engine due to combustion chamber and piston deposit build up.

The hard start could be the CTS. They can get globbed with coatings of dex-cool if the car had it's antifreeze not changed for too long. Have you ever done the LIM gaskets? If so, do you recall if the 'free' coolant ports on the heads were plugged with mud?

I'm with everybody else though, the MAF sounds suspect. Do you have the factory airbox or a cone?

I talked to my dad and before he shipped the car he put a new mass air flow sensor on.

Potential it could be bad though as well. First maf replacement on our Lesabre was a reman delco unit done at the dealership and the frickin thing did not work at all.

stan wrote:

Engines lose compression over time when you click certain miles.Turbo is the answer....u don't feel it that much.....hahaha

hahahahahahaha exactly!!