95 Camry Ignition problem hard to start

Car runs great but difficult to start sometimes when warm....
No codes are set..

I put a 2 channel Oscope on the IGT and coil primary. I can see that
when cranking and when the RPM is very low, that the pulses are all
there but that the IGT pulse gets very WIDE and this retards the spark
timing. The coil turns on at the rising edge of iGT and off (which
causes the spark) on the falling edge of iGT. So when iGT get extra
wide, the spark is retarded. I suspect this is the problem, I have
gas and spark but the spark is late when the RPM is low as in when
cranking. I can see that the coil primary spark occurs in time with
the trailing edge of iGT so the ignitor is doing it's job. The
training edge of iGT coming out of the ECM is late... why?

On the oscope...the iGT pulse is about 4 ms when the car is running
normally, but it stretches out to almost 10 ms during low RPM and
cranking.

What can cause the iGT pulse out of the ECM to be extended in time?.
My theory is one of the reluctor pickup signals is weak and at low RPM
when they are even weaker they are marginal and not being picked up
reliably by the ECM so the iGT pulse is messed up.

So question for the Toyota experts.

What is the normal pulse WIDTH for the iGT pulse during run and during
crank?

What can cause the iGT pulse to be too wide?

What is the normal amplitude of the reluctor coil signals during
cranking?

Also is there a better forum instead of rec.autos.tech to get this
kind of detailed info...?

thanks


Mark

On Tue, 15 Feb 2011 16:49:33 -0800, Mark wrote:

> Car runs great but difficult to start sometimes when warm.... No codes are
> set..
>
> I put a 2 channel Oscope on the IGT and coil primary. I can see that
> when cranking and when the RPM is very low, that the pulses are all there
> but that the IGT pulse gets very WIDE and this retards the spark timing.
> The coil turns on at the rising edge of iGT and off (which causes the
> spark) on the falling edge of iGT. So when iGT get extra wide, the spark
> is retarded. I suspect this is the problem, I have gas and spark but the
> spark is late when the RPM is low as in when cranking. I can see that the
> coil primary spark occurs in time with the trailing edge of iGT so the
> ignitor is doing it's job. The training edge of iGT coming out of the ECM
> is late... why?
>
> On the oscope...the iGT pulse is about 4 ms when the car is running
> normally, but it stretches out to almost 10 ms during low RPM and
> cranking.
>
> What can cause the iGT pulse out of the ECM to be extended in time?. My
> theory is one of the reluctor pickup signals is weak and at low RPM when
> they are even weaker they are marginal and not being picked up reliably by
> the ECM so the iGT pulse is messed up.
>
> So question for the Toyota experts.
>
> What is the normal pulse WIDTH for the iGT pulse during run and during
> crank?
>
> What can cause the iGT pulse to be too wide?
>
> What is the normal amplitude of the reluctor coil signals during cranking?
>
> Also is there a better forum instead of rec.autos.tech to get this kind of
> detailed info...?
>
> thanks
>
>
> Mark


I think you're digging down much, much further than you have to.

Ever since the dawn of Toyota (in the US, at least) there is an issue with
older cars that won't start esp when warm. The contacts on the starter
wear down. For some reason, they will start the car just fine cold, but
when the car warms up they like to hesitate.

IIRC, there is a cover over the soleniod you can remove and check the
condition of the contacts. They used to be a few bucks from a Toy dealer,
but $17 seems to stick in my head right now.

THis would be the first place I would look on a Toy that starts hard when
warm...

Mark > wrote in news:6a00f53c-eeec-4816-a995-
:

> Car runs great but difficult to start sometimes when warm....
> No codes are set..


<snip>

Can you /precisely/ describe the /actual behavior/ of the engine/starter
when you turn the key and the engine does not start?



>
> Also is there a better forum instead of rec.autos.tech to get this
> kind of detailed info...?
>


You can try the Yahoo group I help moderate: Toyotas_Only. We have a number
of actual Toyota techs.
<http://autos.groups.yahoo.com/group/Toyotas_Only/>


--
Tegger

On Feb 16, 6:17*am, Tegger > wrote:
> Mark > wrote in news:6a00f53c-eeec-4816-a995-
> :
>
> > Car runs great but difficult to start sometimes when warm....
> > No codes are set..
>
> <snip>
>
> Can you /precisely/ describe the /actual behavior/ of the engine/starter
> when you turn the key and the engine does not start?
>
>
>
> > Also is there a better forum instead of rec.autos.tech to get this
> > kind of detailed info...?
>
> You can try the Yahoo group I help moderate: Toyotas_Only. We have a number
> of actual Toyota techs.
> <http://autos.groups.yahoo.com/group/Toyotas_Only/>
>
> --
> Tegger

Yeah is the engine cranking normally just not firing, or is the
starter dragging while trying to start the motor??

On Feb 16, 8:42*am, m6onz5a > wrote:
> On Feb 16, 6:17*am, Tegger > wrote:
>
>
>
>
>
> > Mark > wrote in news:6a00f53c-eeec-4816-a995-
> > :
>
> > > Car runs great but difficult to start sometimes when warm....
> > > No codes are set..
>
> > <snip>
>
> > Can you /precisely/ describe the /actual behavior/ of the engine/starter
> > when you turn the key and the engine does not start?
>
> > > Also is there a better forum instead of rec.autos.tech to get this
> > > kind of detailed info...?
>
> > You can try the Yahoo group I help moderate: Toyotas_Only. We have a number
> > of actual Toyota techs.
> > <http://autos.groups.yahoo.com/group/Toyotas_Only/>
>
> > --
> > Tegger
>
> Yeah is the engine cranking normally just not firing, or is the
> starter dragging while trying to start the motor??- Hide quoted text -
>
> - Show quoted text -

the starter / engine cranks just fine....it's not the starter..

FYI you are correct about the starter contacts, I had that problem 6
months ago and replaced them,,, this is a different problem, the
engine cranks, there is fuel and spark but the spark appears to be
late...

it will usually catch after several seconds of cranking but it used to
start immedialy, now it needs to crank for a while and I can see the
spark is late due due the iGT pulse being wide...

thanks

Mark

"Mark" wrote in message
> Car runs great but difficult to start sometimes when warm....
> No codes are set..
>
> I put a 2 channel Oscope on the IGT and coil primary. I can see
> that
> when cranking and when the RPM is very low, that the pulses are all
> there but that the IGT pulse gets very WIDE and this retards the
> spark
> timing. The coil turns on at the rising edge of iGT and off (which
> causes the spark) on the falling edge of iGT. So when iGT get extra
> wide, the spark is retarded. I suspect this is the problem, I have
> gas and spark but the spark is late when the RPM is low as in when
> cranking. I can see that the coil primary spark occurs in time with
> the trailing edge of iGT so the ignitor is doing it's job. The
> training edge of iGT coming out of the ECM is late... why?
>
> On the oscope...the iGT pulse is about 4 ms when the car is running
> normally, but it stretches out to almost 10 ms during low RPM and
> cranking.
>
> What can cause the iGT pulse out of the ECM to be extended in time?.
> My theory is one of the reluctor pickup signals is weak and at low
> RPM
> when they are even weaker they are marginal and not being picked up
> reliably by the ECM so the iGT pulse is messed up.
>
> So question for the Toyota experts.
>
> What is the normal pulse WIDTH for the iGT pulse during run and
> during
> crank?
>
> What can cause the iGT pulse to be too wide?
>

I don't know what the iGT pulse is, but sensors to the ECM which will
alter timing have to do with the following...

(For various vehicles in general...)



Crankshaft position sensor.

Engine speed (RPM)

Engine load (manifold pressure or vacuum)

Atmospheric (barometric) pressure

Engine coolant temperature

Intake air temperature (retards timing when hot)



A factory service manual set of books will have detailed testing
instructions and information about what sensors you have. Order from
dealer.



Also might try asking here...

(Automotive Engineering Forum)

http://www.eng-tips.com/threadcategory.cfm?lev2=6

Mark > wrote in
:

> On Feb 16, 8:42*am, m6onz5a > wrote:
>> On Feb 16, 6:17*am, Tegger > wrote:
>>
>>
>>
>>
>>
>> > Mark > wrote in news:6a00f53c-eeec-4816-a995-
>> > :
>>
>> > > Car runs great but difficult to start sometimes when warm....
>> > > No codes are set..
>>
>> > <snip>
>>
>> > Can you /precisely/ describe the /actual behavior/ of the
>> > engine/starte
> r
>> > when you turn the key and the engine does not start?
>>
>> > > Also is there a better forum instead of rec.autos.tech to get
>> > > this kind of detailed info...?
>>
>> > You can try the Yahoo group I help moderate: Toyotas_Only. We have
>> > a nu
> mber
>> > of actual Toyota techs.
>> > <http://autos.groups.yahoo.com/group/Toyotas_Only/>
>>
>> > --
>> > Tegger
>>
>> Yeah is the engine cranking normally just not firing, or is the
>> starter dragging while trying to start the motor??- Hide quoted text
>> -
>>
>> - Show quoted text -
>
> the starter / engine cranks just fine....it's not the starter..
>
> FYI you are correct about the starter contacts, I had that problem 6
> months ago and replaced them,,, this is a different problem, the
> engine cranks, there is fuel and spark but the spark appears to be
> late...
>
> it will usually catch after several seconds of cranking but it used to
> start immedialy, now it needs to crank for a while and I can see the
> spark is late due due the iGT pulse being wide...
>
> thanks
>
> Mark
>
>

when is the last time you put in a fuel filter? I see this a lot on all
makes when the filter is half plugged and the innitial fuel pump shot
will not pressurize the system enough. KB

On Wed, 16 Feb 2011 20:46:21 +0000 (UTC), Kevin Bottorff
> wrote:


>
>when is the last time you put in a fuel filter? I see this a lot on all
>makes when the filter is half plugged and the innitial fuel pump shot
>will not pressurize the system enough. KB

I had a 2.8 Celebrity that bogged when entering the x-way.
Fuel filter fixed that.
Couple years later it started cranking more to start.
Like the OP's.
Went from instant on to 3 or 4 seconds of cranking over a period of a
year or so. Longer when it was hot.
Then one day it wouldn't restart when hot.
I had picked up fried chicken, so we jumped on a bus to get home.
Had my wife drop me off at the car when we went to work in the AM.
Started right up with the now usual 3-4 seconds of cranking.
Drove it to my mech with no issues.
He couldn't believe I drove it in when he found the fuel pump
pressure was 2.5 psi.
New pump fixed that.
Go figure.

--Vic

Mark wrote:
>
> On Feb 16, 8:42 am, m6onz5a ? wrote:
> ? On Feb 16, 6:17 am, Tegger ? wrote:
> ?
> ?
> ?
> ?
> ?
> ? ? Mark ? wrote in news:6a00f53c-eeec-4816-a995-
> ? ? :
> ?
> ? ? ? Car runs great but difficult to start sometimes when warm....
> ? ? ? No codes are set..
> ?
> ? ? ?snip?
> ?
> ? ? Can you /precisely/ describe the /actual behavior/ of the engine/starter
> ? ? when you turn the key and the engine does not start?
> ?
> ? ? ? Also is there a better forum instead of rec.autos.tech to get this
> ? ? ? kind of detailed info...?
> ?
> ? ? You can try the Yahoo group I help moderate: Toyotas_Only. We have a number
> ? ? of actual Toyota techs.
> ? ? ?http://autos.groups.yahoo.com/group/Toyotas_Only/?
> ?
> ? ? --
> ? ? Tegger
> ?
> ? Yeah is the engine cranking normally just not firing, or is the
> ? starter dragging while trying to start the motor??- Hide quoted text -
> ?
> ? - Show quoted text -
>
> the starter / engine cranks just fine....it's not the starter..
>
> FYI you are correct about the starter contacts, I had that problem 6
> months ago and replaced them,,, this is a different problem, the
> engine cranks, there is fuel and spark but the spark appears to be
> late...

If you want to check the timing then check the timing. I don't think you
can draw any mmeaningful conclusions about timing from looking at how
long a period the coil is energized unless you have established a
reference base first.

-jim


>
> it will usually catch after several seconds of cranking but it used to
> start immedialy, now it needs to crank for a while and I can see the
> spark is late due due the iGT pulse being wide...
>
> thanks
>
> Mark

In message
>,
Mark > writes
>it will usually catch after several seconds of cranking but it used to
>start immedialy, now it needs to crank for a while and I can see the
>spark is late due due the iGT pulse being wide...
Surely the width of the pulse in direct related to the cranking speed,
so the slower the speed, the larger the dwell angle.
--
Clive