DTC P3040

"cea1" <[email protected]> wrote in message
news:[email protected]
>I have a 1995 Toyota Avalon that has a persistent miss, that according to
> the Diagnostic Tool is P3040 (Misfire detected on cyclinder 4), I was
> supplied this code from my local Advance Auto Parts Store. After not being
> able to figure out, on my own, what was the problem with the cyclinder, I
> took it to the Toyota dealership, the mechanic at the dealership seems to
> think that the problem may be with the valve seal guides or a stick piston
> ring in cyclinder four. The compression check on this cyclinder is much
> lower than the other cyclinders. My guess is that the problem is the valve
> guide seal, and the reason I think so is because sometimes after letting
> the car set for a few hours and when it's started smoke comes from the
> exhaust.
>
> Anyone, what's your take on this issue?
>

The technician who looked at the car has a big advantage over everyone here
since he or she was able to examine the general condition of the car and
engine.

The tech should have been able to get a general idea about the condition of
the rings by seeing if the compression improves in a wet test.

Leaking valve stem seals will not in itself result in lower compression
although smoke out of the exhaust is a symptom.
--
Ray O
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"cea1" <[email protected]> wrote in message
news:[email protected]
> Hi Ray,
>
> Please explain the wet test.
>
> cea1
>

To take cylinder compression readings, the spark plug is removed, a
compression gauge is installed in the spark plug opening, the engine is
cranked, and the peak compression for the cylinder is recorded. This is
known as a "dry" compression reading. After recording the dry compression
reading, the compression gauge is removed and some engine oil is squirted
into the spark plug hole, the compression gauge is re-installed, the engine
is cranked, and the compression reading is recorded again. This is known as
a "wet" reading. If the compression reading increases when oil is squirted
into the cylinder, it indicates that the piston rings may be bad because the
oil acts to seal some of the leakage.

--
Ray O
correct the return address punctuation to reply

Interesting. Just like Ray pointed out, a worn valve guide seal has no
bearing on compression. The problem may very well be poor sealing at the
rings, but you can't make that determination from a dry compression test.
Like Ray said, you have to do a wet compression test also.
If I had this car in my bay and observed the condition you described, I
would recommend doing a cylinder leak-down test. They are MUCH more
effective in the information they provide compared to a simple compression
test, but also more involved. It involves finding TDC on the tested
cylinder and jamming air at about 90psi in through the spark plug hole. If
there is a compression loss, you will be able to see it on the gauge and
see it leaking from the engine. If there are bubbles pouring out of the
radiator cap, you have a bad head gasket. If there is air coming out of
the exhaust or intake, you have a valve problem, and air in the crankcase
would point to a bad ring or two.
The problem with compression tests is that they only measure a cylinders
sealing relative to the surrounding cylinders. There are a lot of variables
(cam lift, cranking speed, etc) that can affect readings. The leakdown test
is a pinpoint measurement and should be standard procedure before digging
in for a rebuild.

On Wed, 21 Dec 2005 12:53:08 -0600, "Ray O"
<[email protected]> wrote:
>"cea1" <[email protected]> wrote in message
>news:[email protected]

>> Hi Ray,
>> Please explain the wet test.
>
>To take cylinder compression readings, the spark plug is removed, a
>compression gauge is installed in the spark plug opening, the engine is
>cranked, and the peak compression for the cylinder is recorded. This is
>known as a "dry" compression reading. After recording the dry compression
>reading, the compression gauge is removed and some engine oil is squirted
>into the spark plug hole, the compression gauge is re-installed, the engine
>is cranked, and the compression reading is recorded again. This is known as
>a "wet" reading. If the compression reading increases when oil is squirted
>into the cylinder, it indicates that the piston rings may be bad because the
>oil acts to seal some of the leakage.

And if the compression on one cylinder is unusually low but the wet
test does not improve the readings, there is probably a bad valve or a
valve seat problem. Or it's a blown head gasket issue.

To narrow down the problem further, they put another adapter in the
spark plug hole called a "Leakdown Tester" that has an air chuck and a
pressure gauge.

You put the engine at top dead center for that cylinder and hold it
in place, then apply compressed shop air into the cylinder through the
adapter. If you hear hissing from the tailpipe, it's the exhaust
valve, from the intake manifold and it's the intake valve.

If the radiator starts bubbling it's not the valves... Head Gasket.
But this usually reveals itself in overheating issues.

--<< Bruce >>--

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

"cea1" <[email protected]> wrote in message
news:[email protected]
> Bruce,
>
> Thanks for the info. Can I purchase a Leakdown Tester from many parts
> store, or is this a tool that's generally only available at an auto repair
> shop?
>
> Oh by the way, do you know what DTC code P01300 means?
>
> cea1
>
I don't think there is such a thing as P01300 - there is one too many
digits.

You can check OBD II codes on this site: http://www.obdii.com/codes.html

P0130 means Bank 1 Sensor 1 O2 sensor malfunction.
--
Ray O
correct the return address punctuation to reply

"Ray O" <[email protected]> wrote in message
news:[email protected]
>
> "cea1" <[email protected]> wrote in message
> news:[email protected]
>> Bruce,
>>
>> Thanks for the info. Can I purchase a Leakdown Tester from many parts
>> store, or is this a tool that's generally only available at an auto
>> repair
>> shop?
>>
>> Oh by the way, do you know what DTC code P01300 means?
>>
>> cea1
>>
> I don't think there is such a thing as P01300 - there is one too many
> digits.
>
> You can check OBD II codes on this site: http://www.obdii.com/codes.html
>
> P0130 means Bank 1 Sensor 1 O2 sensor malfunction.
> --

Ray,
He said in his first post that he has a 1995. OBD II was not used until
1996, but I understand there was a "cut-in" period where earlier models
might get the OBD II. I guess that since we have OBD II Codes, we can be
sure the car is OBD II, nevermind.

As a Toyots mechanic, do you know with any certainty what the application
schedule is for OBD II as it relates to Toyotas? I assume that 1996 was the
drop-dead year, but some makers made the change earlier.

>
> You put the engine at top dead center for that cylinder and hold it
> in place, then apply compressed shop air into the cylinder through the
> adapter. If you hear hissing from the tailpipe, it's the exhaust
> valve, from the intake manifold and it's the intake valve.
>

BUT if you hear it from the exhaust and the intake; it could still be the
exhaust (Leaking into the manifold and finding it's way through another
cylinders open valve.

We just did one last week had a chipped exhaust valve; the first time I got
to use my leak down tester, and I've had it for 2 years.


--
Stephen W. Hansen
ASE Certified Master Automobile Technician
ASE Automobile Advanced Engine Performance
ASE Undercar Specialist

http://autorepair.about.com/cs/troubleshooting/l/bl_obd_main.htm
http://www.troublecodes.net/technical/

"Jeff Strickland" <[email protected]> wrote in message
news[email protected]
>
> "Ray O" <[email protected]> wrote in message
> news:[email protected]d.meganewsservers.com...
>>
>> "cea1" <[email protected]> wrote in message
>> news:[email protected]
>>> Bruce,
>>>
>>> Thanks for the info. Can I purchase a Leakdown Tester from many parts
>>> store, or is this a tool that's generally only available at an auto
>>> repair
>>> shop?
>>>
>>> Oh by the way, do you know what DTC code P01300 means?
>>>
>>> cea1
>>>
>> I don't think there is such a thing as P01300 - there is one too many
>> digits.
>>
>> You can check OBD II codes on this site: http://www.obdii.com/codes.html
>>
>> P0130 means Bank 1 Sensor 1 O2 sensor malfunction.
>> --
>
> Ray,
> He said in his first post that he has a 1995. OBD II was not used until
> 1996, but I understand there was a "cut-in" period where earlier models
> might get the OBD II. I guess that since we have OBD II Codes, we can be
> sure the car is OBD II, nevermind.
>
> As a Toyots mechanic, do you know with any certainty what the application
> schedule is for OBD II as it relates to Toyotas? I assume that 1996 was
> the drop-dead year, but some makers made the change earlier.
>

Actually, I am not a Toyota mechanic, never was. I did work for Toyota for
about 15 years, had various jobs including a district service manager.

Here is a a web page with a list of OBD II implementations (you have to
scroll quite a ways down to see the list):
http://www.obdii.com/connector.html

OBD II codes are quite a bit different from Toyota's pre-OBD II codes.
Earlier codes had just 2 digits.
--
Ray O
correct the return address punctuation to reply