91 Camry ignition problem

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Old 23 Jan 2012, 09:57 pm   #1 (permalink)
Gib Bogle
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Default 91 Camry ignition problem

I have an old but good 91 Toyota Camry wagon, not worth much to sell but
worth a lot me as a useful workhorse. It has an intermittent problem
that I haven't seen for many months, and the fact that it's resurfaced
makes me think it might be temperature-related (it's mid-summer here,
although only about 20-23 deg.C).

The typical symptom is that I drive somewhere, park, come back to the
car an hour or so later, and it will not start. (On a couple of
occasions the engine has stopped when I was driving at a low speed, e.g.
coming up to a traffic light.) The battery is good, the engine turns
over, but no spark (I've checked this using a timing light with a pickup
on the spark plug wires.) In almost all cases it will start after 10-30
minutes, and run as if nothing had happened. On one occasion it didn't
start even the next day, and I had it towed to a mechanic. He couldn't
find anything wrong (not surprising since it was working by the time he
got it), but replaced the distributor on the off-chance. Of course it
made no difference.

I've been over every obvious part of the ignition circuit, but
everything tests out as OK. The error code (in light flashes) is 43,
which according to the manual is:

Starter signal. No STA signal to ECU when vehicle stopped and engine
running over 800 rpm.
1. Main relay circuit
2. IG switch circuit (starter)
3. IG switch
4. ECU

I'm beginning to suspect a faulty relay. The manual has the circuit
diagrams, but it isn't obvious which part is the "Main relay circuit".
I presume it includes the section labelled "Power source and starting
circuit", but possibly also includes the EFI main relay, and maybe some
other stuff. The circuit isn't really that complicated, but it's often
unclear to me where the physical components and connectors are on the car.

I just had a look at the fuse/relay box next to the battery, after
running the engine for a few minutes. Some of the relays have plastic
cases, some metal. In attempting to pull the relays out, I discovered
that a couple of the metal-case ones are very hot - too hot to hold.
These are labelled Fan no.1 and EFI main. Is it normal for these relays
to get very hot?

Thanks
Gib
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Old 24 Jan 2012, 12:40 am   #2 (permalink)
NotMe
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Default Re: 91 Camry ignition problem


"Gib Bogle" <g.bogle@auckland.ac.nz> wrote in message
news:jfla84$r53$3@speranza.aioe.org...
>I have an old but good 91 Toyota Camry wagon, not worth much to sell but
>worth a lot me as a useful workhorse. It has an intermittent problem that
>I haven't seen for many months, and the fact that it's resurfaced makes me
>think it might be temperature-related (it's mid-summer here, although only
>about 20-23 deg.C).
>
> The typical symptom is that I drive somewhere, park, come back to the car
> an hour or so later, and it will not start. (On a couple of occasions the
> engine has stopped when I was driving at a low speed, e.g. coming up to a
> traffic light.) The battery is good, the engine turns over, but no spark
> (I've checked this using a timing light with a pickup on the spark plug
> wires.) In almost all cases it will start after 10-30 minutes, and run as
> if nothing had happened. On one occasion it didn't start even the next
> day, and I had it towed to a mechanic. He couldn't find anything wrong
> (not surprising since it was working by the time he got it), but replaced
> the distributor on the off-chance. Of course it made no difference.
>
> I've been over every obvious part of the ignition circuit, but everything
> tests out as OK. The error code (in light flashes) is 43, which according
> to the manual is:
>
> Starter signal. No STA signal to ECU when vehicle stopped and engine
> running over 800 rpm.
> 1. Main relay circuit
> 2. IG switch circuit (starter)
> 3. IG switch
> 4. ECU
>
> I'm beginning to suspect a faulty relay. The manual has the circuit
> diagrams, but it isn't obvious which part is the "Main relay circuit". I
> presume it includes the section labelled "Power source and starting
> circuit", but possibly also includes the EFI main relay, and maybe some
> other stuff. The circuit isn't really that complicated, but it's often
> unclear to me where the physical components and connectors are on the car.
>
> I just had a look at the fuse/relay box next to the battery, after running
> the engine for a few minutes. Some of the relays have plastic cases, some
> metal. In attempting to pull the relays out, I discovered that a couple
> of the metal-case ones are very hot - too hot to hold. These are labelled
> Fan no.1 and EFI main. Is it normal for these relays to get very hot?
>


Try running the car at night in the dark (as dark as you can get it). Often
there is an electrical leak and that shows up at night. You may have to use
a fine spray from a hose to help the arc over.


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Old 25 Jan 2012, 11:24 am   #3 (permalink)
NM5K
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Default Re: 91 Camry ignition problem

On 1/23/2012 9:57 PM, Gib Bogle wrote:
> I have an old but good 91 Toyota Camry wagon, not worth much to sell but
> worth a lot me as a useful workhorse. It has an intermittent problem
> that I haven't seen for many months, and the fact that it's resurfaced
> makes me think it might be temperature-related (it's mid-summer here,
> although only about 20-23 deg.C).
>
> The typical symptom is that I drive somewhere, park, come back to the
> car an hour or so later, and it will not start. (On a couple of
> occasions the engine has stopped when I was driving at a low speed, e.g.
> coming up to a traffic light.) The battery is good, the engine turns
> over, but no spark (I've checked this using a timing light with a pickup
> on the spark plug wires.) In almost all cases it will start after 10-30
> minutes, and run as if nothing had happened. On one occasion it didn't
> start even the next day, and I had it towed to a mechanic. He couldn't
> find anything wrong (not surprising since it was working by the time he
> got it), but replaced the distributor on the off-chance. Of course it
> made no difference.
>
> I've been over every obvious part of the ignition circuit, but
> everything tests out as OK. The error code (in light flashes) is 43,
> which according to the manual is:
>
> Starter signal. No STA signal to ECU when vehicle stopped and engine
> running over 800 rpm.
> 1. Main relay circuit
> 2. IG switch circuit (starter)
> 3. IG switch
> 4. ECU
>
> I'm beginning to suspect a faulty relay. The manual has the circuit
> diagrams, but it isn't obvious which part is the "Main relay circuit". I
> presume it includes the section labelled "Power source and starting
> circuit", but possibly also includes the EFI main relay, and maybe some
> other stuff. The circuit isn't really that complicated, but it's often
> unclear to me where the physical components and connectors are on the car.
>
> I just had a look at the fuse/relay box next to the battery, after
> running the engine for a few minutes. Some of the relays have plastic
> cases, some metal. In attempting to pull the relays out, I discovered
> that a couple of the metal-case ones are very hot - too hot to hold.
> These are labelled Fan no.1 and EFI main. Is it normal for these relays
> to get very hot?
>
> Thanks
> Gib


I know this may sound weird.. But it's possible you have a severe
buildup of carbon in the combustion chambers, and behind the intake
valves. That would not explain the "no spark" scenario, but a lot of
the other symptoms kind of point to carbon.
I had that problem with a 92 or so Camry once. The problem will
start gradually, and slowly get worse and worse.
What kills the engine in that case is the carbon gets hot, expands
and then keeps the intake valves from fully closing. Then you have
no compression, and the engine won't run. When it cools off, the
carbon shrinks back to it's original size, the valves can close,
and the cycle starts over again.
If this is the case, you may notice that the cranking will sound
irregular due to the lack of compression on some cylinders.
If you lose compression on all cylinders, the starter motor
will sound faster than normal.
Also, when this happens, the car will stall fastest when the
engine has been under a fairly heavy load for a while.
IE: going up hills, etc.
You might try adding a bottle of techron to the gas, maybe two
tanks worth, and see if any improvement.
In my case, the carbon buildup was very severe, and I took
extra measures to clean it out. I would feed techron and other
cleaners directly to the intake via a vacuum hose. It took a
while, but finally cleaned it all out.

When this happened to me, we had the car in three shops, with
a toyota dealer being the last one to have it. They had the car
for two weeks and never could figure out the problem. They blamed
the wiring harness as being bad, even though they told me it could
not be checked.. BS... It's easy to check a wiring harness..
You just have to know how.. They didn't.. Sad era for a dealer
mechanic.. And to top that off, they charged us over $400
for their misdiagnosis..

I did it myself after dragging the car back home from the dealer.
Took me an hour to check every single wire in the harness.
It was good. After going through the engine top to bottom, I
finally figured out that it was severe carbon buildup.
That code 43 can be a fluke error in some cases I think.

Anyway, a couple of tank fulls of techron won't cost too much,
and is good for the engine even if that ends up not being the
problem. But.. it could well be. Those engines are semi prone to
having that problem due to the design. But of course, it usually
takes several years for it to build up enough to cause a non run
problem. Yours is old enough.. It's probably got the same exact
engine as the one we had.. In my case, it was my mothers car.

This may or may not be the problem, but I would keep it in mind.
Your symptoms sound like the early stages of carbonitis.


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