15% Compression Cylinder 2
Gentleman's Relish
Joined: Feb 2005
Posts: 13,189
From: AZ
So, in reading this thread I see there are TWO OBDII codes but only one of them for the KAM is given.
What is the exact misfire code?
See there are two code types ('x' would be replaced by the cylinder number it's pointing to.)
P035x means it's ignition/electronids related like a bad PCM driver, bad coil, or bad plug, etc.
P030x is usually more relevant for mechanical failure like the valve train.
Mustang08 is correct, a loss of 15% in one or more cylinders overnight means a mechanical issue so, lets assume it's a P030x type code. Anyways, the only way to really see where the fault is, is to run a leakdown test. A leakdown goes a step further and will tell you what is failing mechanically. Given by the way it runs ok sometimes and other times it doesn't, I'm going with the valve train, specifically, you have a burnt exhaust valve or a valve with a warped seat.
What is the exact misfire code?
See there are two code types ('x' would be replaced by the cylinder number it's pointing to.)
P035x means it's ignition/electronids related like a bad PCM driver, bad coil, or bad plug, etc.
P030x is usually more relevant for mechanical failure like the valve train.
Mustang08 is correct, a loss of 15% in one or more cylinders overnight means a mechanical issue so, lets assume it's a P030x type code. Anyways, the only way to really see where the fault is, is to run a leakdown test. A leakdown goes a step further and will tell you what is failing mechanically. Given by the way it runs ok sometimes and other times it doesn't, I'm going with the valve train, specifically, you have a burnt exhaust valve or a valve with a warped seat.
Last edited by Derf00; May 14, 2018 at 02:23 PM.
Thread Starter
Joined: Apr 2018
Posts: 17
From: Alabama
It was a specific code to cylinder 2. I replaced the fuel injector and it has been fine since.. maybe a week now. I wanted to be sure before posting the status of it. Havent done a running cylinder compression test yet. But no codes... i still get the unusual exhaust muffle now and then. But after i put long tube headers and a offroad x pype. By deleting the cats im hoping to eliminate that problem.
Banned
Joined: Jan 2018
Posts: 2,327
From: Pennsylvania
If you put a gauge on Cylinder #2, then no, there is no other way. You can't
test it hot, and it won't get hot without the plug in it. SO, if it looses compression
once the motor is run, then it's a mechanical issue. Or, if it runs good, then bad,
then good again, and it is actual loss of compression, still a mechanical
issue.
Did you do the leak down test? That's pressurizing the coolant system, and see if it
holds pressure, but then again, if you're not losing coolant, that probably wouldn't be it....
Physical loss of compression means the compressed air us getting passed a valve,
or rings...
test it hot, and it won't get hot without the plug in it. SO, if it looses compression
once the motor is run, then it's a mechanical issue. Or, if it runs good, then bad,
then good again, and it is actual loss of compression, still a mechanical
issue.
Did you do the leak down test? That's pressurizing the coolant system, and see if it
holds pressure, but then again, if you're not losing coolant, that probably wouldn't be it....
Physical loss of compression means the compressed air us getting passed a valve,
or rings...
Banned
Joined: Jan 2018
Posts: 2,327
From: Pennsylvania
Then you need to do a pressure test. You pressurize the coolant system.
A tool attaches to the reservoir, and you pump it up to pressurize it, and there
will be a gauge on it. Pump it up to 15lbs, and see if it holds. If you see the gauge
go down, you need a head gasket, it's leaking into the cylinder. The loss of
compression can either be due to the less air in the chamber when the coolant
is pulled in (displaced air), or the air is going passed the head gasket.
Sample:
A tool attaches to the reservoir, and you pump it up to pressurize it, and there
will be a gauge on it. Pump it up to 15lbs, and see if it holds. If you see the gauge
go down, you need a head gasket, it's leaking into the cylinder. The loss of
compression can either be due to the less air in the chamber when the coolant
is pulled in (displaced air), or the air is going passed the head gasket.
Sample:
Gentleman's Relish
Joined: Feb 2005
Posts: 13,189
From: AZ
I feel like we're going in circles here....
OP, we've given you a couple of things to check but instead, you replaced an injector and now mention you're losing coolant in addition to loss of compression. Are there any other symptoms that you haven't mentioned, things that you've replaced, work done on the car recently, or any type of event (like a big bang/pop/whatever) that happened before the problem started?
Anyways, @Mustang08 there's also a check that can be done for exhaust entering the coolant.
OP, we've given you a couple of things to check but instead, you replaced an injector and now mention you're losing coolant in addition to loss of compression. Are there any other symptoms that you haven't mentioned, things that you've replaced, work done on the car recently, or any type of event (like a big bang/pop/whatever) that happened before the problem started?
Anyways, @Mustang08 there's also a check that can be done for exhaust entering the coolant.