1995 Toyota Camry EGR sticking?

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Old 18 Nov 2006, 08:02 pm   #1 (permalink)
bensteadev@comcast.net
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Default 1995 Toyota Camry EGR sticking?

Hi, I've recently been trying to diagnose a rough idle problem on a
1995 Toyota Camry V6 1MZFE engine.

Symptom is: rough idling (no stalling), some power loss, and if you
just take it up to 10 mph, then release the gas, it slows down faster
than normal... feels like a load or drag on the engine with no dragging
noise associated. I know, that last one is weird. I didn't believe it
myself at first.

There is no check engine light. I sucessfully retrieved OBDII codes
from this car... a P0135 heated oxygen sensor problem, but that was
repaired and is another story. Anyway, I know it can code OBDII.

I am thinking a bypass leak at the EGR pintle, as the problem seems
intermittent. Not a blocked EGR, but then again you can't test for a
bypass leak without pulling the EGR, I don't think...

But I was looking through the generic OBDII code list, and it says EGR
flow excessive is a P0402. So I wonder... why wouldn't it code P0402
if my theory here is correct?

I look at the EGR valve, it has no pintle position sensor box on top of
it. It has no electrical plug. It does have an EGR gas temperature
sensor screwed into its housing, I am not sure if this would be the
party responsible for throwing a P0401 / P0402 or not...

Then I look on the Autozone website for the free manual database for a
1995 Camry. In the OBD II list they have, the codes stop at about the
P0300's and pick back up at the P1100's.

So to make a long story long... I am wondering if a 1995 Camry is even
capable of throwing a P0401 / P0402 code.

Any help would be appreciated.

Thanks!

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Old 19 Nov 2006, 12:00 am   #2 (permalink)
johngdole@hotmail.com
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Default Re: 1995 Toyota Camry EGR sticking?

Try Autozone to see if they have a free loaner MityVac pump. Use it to
operate the EGR valve to full engine vacuum several times quickly and
see if you can knock some carbon off and get the valve to close in
minor cases.

Test the EGR valve using the pump and see if the engine stalls. EGR
valves don't usually go bad. You just have to clean it in rare cases.

Could also be a vacuum leak or a sticking IAC valve. Use the MityVac
and see how strong the vacuum is when you are having problems. I think
normal should be 17-22".

Have you ever changed the timing belt?


bensteadev@comcast.net wrote:
> Hi, I've recently been trying to diagnose a rough idle problem on a
> 1995 Toyota Camry V6 1MZFE engine.
>
> Symptom is: rough idling (no stalling), some power loss, and if you
> just take it up to 10 mph, then release the gas, it slows down faster
> than normal... feels like a load or drag on the engine with no dragging
> noise associated. I know, that last one is weird. I didn't believe it
> myself at first.
>
> There is no check engine light. I sucessfully retrieved OBDII codes
> from this car... a P0135 heated oxygen sensor problem, but that was
> repaired and is another story. Anyway, I know it can code OBDII.
>
> I am thinking a bypass leak at the EGR pintle, as the problem seems
> intermittent. Not a blocked EGR, but then again you can't test for a
> bypass leak without pulling the EGR, I don't think...
>
> But I was looking through the generic OBDII code list, and it says EGR
> flow excessive is a P0402. So I wonder... why wouldn't it code P0402
> if my theory here is correct?
>
> I look at the EGR valve, it has no pintle position sensor box on top of
> it. It has no electrical plug. It does have an EGR gas temperature
> sensor screwed into its housing, I am not sure if this would be the
> party responsible for throwing a P0401 / P0402 or not...
>
> Then I look on the Autozone website for the free manual database for a
> 1995 Camry. In the OBD II list they have, the codes stop at about the
> P0300's and pick back up at the P1100's.
>
> So to make a long story long... I am wondering if a 1995 Camry is even
> capable of throwing a P0401 / P0402 code.
>
> Any help would be appreciated.
>
> Thanks!


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Old 19 Nov 2006, 01:49 am   #3 (permalink)
bensteadev@comcast.net
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Default Re: 1995 Toyota Camry EGR sticking?

Timing belt was changed out about 10k miles ago. That would be...
scary... to say the least, if it were that.

Plugs changed also. Also, both front side oxygen sensors (not the
catalytic monitor, after the catalytic converter).

What has not been done is valve lash, which is daunting, from what I
can see of the procedure. Basically have to strip the entire throttle
assembly and plenum to do that. I am not sure... would bad valve lash
present a symptom similar to this?

That thought occurred (and I suppose a valve lash will have to be done
sooner or later), but it would not present as an intermittent condition
if it was valve lash, I wouldn't think...?

IAC valve is a real possibility. That would not code if it's sticking,
only in case of electrical failure. Friend of mine's 4 Runner had
that, but the idle in his case was erratic and prone to dropping off
during starting.

I tried the knocking things loose technique, using a length of hose
and... just... sucking on it like a straw. EGR holds vacuum (diaphragm
is OK). It did not sound as though it was moving at first. After a
while, you could finally hear the pintle whack into the seat when
vacuum was released, little metallic click. I haven't had a chance to
road test it since then.

My thought was it was stuck just a little bit open, and exhaust gas was
getting through. However, for this theory to be true, a few other
things also have to be true...

First, the car can't be able to throw a P0401 / P0402 code... Too
little / too much EGR gas. It can't have a monitor for this condition,
or I would think it would have coded already.

Second, whatever the EGR is dumping in can't be enough to cause the
fuel trim to go out of range. It must be small enough that the
injector could compensate, or you'd get a code once again.

So first of all, in my thought process here, and for future reference
as well, does the car have the ability to throw a P0401 / P0402 code?

Second of all... how do you clean up an IAC valve... and how can you
tell if it's sticking? I've never looked at one, just seen the effects
of a failed one on my friend's 4 Runner.

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Old 29 Nov 2006, 01:38 pm   #4 (permalink)
MizzzCat
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Default Re: 1995 Toyota Camry EGR sticking?

My '95 Camry pulled a P0402 code. I replaced the ERG value and the code
disappeared for about 10 miles then came back on. I am going to air
compress the hoses next.

Does anyone have any other ideas besides spending another $80 for another
modulator/sensor/VSV?

Thanx, Cathie

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