Marc did pass the time by typing:
> Yes, forgot to include that, changed the plugs.. It doesn't cause
> extended cranking times or anything, just a fairly rough idle for about
> 10 seconds then she's fine. No smoke (blue white or black) from the
> tailpipe either..) Cleaned the TB. After that first 10 seconds it
> pretty well idles butter-smooth. Power and response are great on the
> road too.

Did this just happen after your last tank of gas or has it been going
on longer. Might try adding a bottle of fuel injector cleaner with
water disperser (gunk or valvoline) with the next fillup, and try a
different station.

Other causes are sensors or vac leaks that seal with expansion,
the warmup loop is fairly forgiving and bad sensors will cause
rough idle even after warmup.

Start the motor and spray some TB cleaner around the base of the
TB. listen for any RPM change.

 

Marc did pass the time by typing:
> Yes, forgot to include that, changed the plugs.. It doesn't cause
> extended cranking times or anything, just a fairly rough idle for about
> 10 seconds then she's fine. No smoke (blue white or black) from the
> tailpipe either..) Cleaned the TB. After that first 10 seconds it
> pretty well idles butter-smooth. Power and response are great on the
> road too.

Did this just happen after your last tank of gas or has it been going
on longer. Might try adding a bottle of fuel injector cleaner with
water disperser (gunk or valvoline) with the next fillup, and try a
different station.

Other causes are sensors or vac leaks that seal with expansion,
the warmup loop is fairly forgiving and bad sensors will cause
rough idle even after warmup.

Start the motor and spray some TB cleaner around the base of the
TB. listen for any RPM change.

 

Marc did pass the time by typing:
> Ok, just got back in from spraying down that slot, wiped down.. I did
> call the local jeep dealer and there is an issue "rough idle at cold
> start" that is addressed in a PCM update. I'm hoping that this might
> be it, or spraying down that slot. FWIW, that TB was pretty dirty
> yesterday when I took the small brush to it; now it's almost shiny.

Gets nasty doesn't it. Go for the PCM update it might be a programming problem.
If it was real nasty you might benefit from removing the IAC (four antitamper torx
screws) And cleaning the guts.

Before you do that, disconnect the hearness from the TB (IAC and TPS) then
reconnect. They might be a bit corroded. Every once in a while I disconnect,
clean, and apply some dilectric grease to the sensor connectors.

> The dealer mentioned about carbon buildup on the back of the valves;
> that it might be absorbing the first few moments of fuel sprayed in. .
> I think that if the first squirts of fuel were getting absorbed by the
> carbon that I'd get extended cranking time most likely..?

Yep. Generally the fuel is atomized by the injectors before it even gets
to the valve. A dripping injector will cause buildup but it will also cause
a hellaciously rough idle.

> He mentioned
> to use some chevron techron concentrate in a full tank and see if that
> helps, which I have some of that already waiting to use actually.

See my other post. Doing that every year is a good thing. When you use
a fuel injector cleaner read to make sure it is safe for O2 and catalytic
converters. Also look for one that says to use it every 3000 miles or so.
The ones for use with every tank are generally too weak to clean anything.

--
DougW

 

Marc did pass the time by typing:
> Ok, just got back in from spraying down that slot, wiped down.. I did
> call the local jeep dealer and there is an issue "rough idle at cold
> start" that is addressed in a PCM update. I'm hoping that this might
> be it, or spraying down that slot. FWIW, that TB was pretty dirty
> yesterday when I took the small brush to it; now it's almost shiny.

Gets nasty doesn't it. Go for the PCM update it might be a programming problem.
If it was real nasty you might benefit from removing the IAC (four antitamper torx
screws) And cleaning the guts.

Before you do that, disconnect the hearness from the TB (IAC and TPS) then
reconnect. They might be a bit corroded. Every once in a while I disconnect,
clean, and apply some dilectric grease to the sensor connectors.

> The dealer mentioned about carbon buildup on the back of the valves;
> that it might be absorbing the first few moments of fuel sprayed in. .
> I think that if the first squirts of fuel were getting absorbed by the
> carbon that I'd get extended cranking time most likely..?

Yep. Generally the fuel is atomized by the injectors before it even gets
to the valve. A dripping injector will cause buildup but it will also cause
a hellaciously rough idle.

> He mentioned
> to use some chevron techron concentrate in a full tank and see if that
> helps, which I have some of that already waiting to use actually.

See my other post. Doing that every year is a good thing. When you use
a fuel injector cleaner read to make sure it is safe for O2 and catalytic
converters. Also look for one that says to use it every 3000 miles or so.
The ones for use with every tank are generally too weak to clean anything.

--
DougW

 

Marc did pass the time by typing:
> Ok, just got back in from spraying down that slot, wiped down.. I did
> call the local jeep dealer and there is an issue "rough idle at cold
> start" that is addressed in a PCM update. I'm hoping that this might
> be it, or spraying down that slot. FWIW, that TB was pretty dirty
> yesterday when I took the small brush to it; now it's almost shiny.

Gets nasty doesn't it. Go for the PCM update it might be a programming problem.
If it was real nasty you might benefit from removing the IAC (four antitamper torx
screws) And cleaning the guts.

Before you do that, disconnect the hearness from the TB (IAC and TPS) then
reconnect. They might be a bit corroded. Every once in a while I disconnect,
clean, and apply some dilectric grease to the sensor connectors.

> The dealer mentioned about carbon buildup on the back of the valves;
> that it might be absorbing the first few moments of fuel sprayed in. .
> I think that if the first squirts of fuel were getting absorbed by the
> carbon that I'd get extended cranking time most likely..?

Yep. Generally the fuel is atomized by the injectors before it even gets
to the valve. A dripping injector will cause buildup but it will also cause
a hellaciously rough idle.

> He mentioned
> to use some chevron techron concentrate in a full tank and see if that
> helps, which I have some of that already waiting to use actually.

See my other post. Doing that every year is a good thing. When you use
a fuel injector cleaner read to make sure it is safe for O2 and catalytic
converters. Also look for one that says to use it every 3000 miles or so.
The ones for use with every tank are generally too weak to clean anything.

--
DougW

 

Carbon deposits on the back side of the intake valves will cause this
concern, and Techron will likely eliminate it. Very good product, does what
it says it will.

GM has a little trouble with cold misfires in some engine families.
Engineering has traced the cause to these deposits. They put out a bulletin
and actually recommended Techron by name. I have found that it fixes these
sorts of problems nearly 100% of the time.

The deposits we are talking about are like a sponge. Atomized fuel flows
past the top of the valve and into the cylinder, but this sponge-action
actually absorbs a miniscule amount of the fuel on cold start, causing lean
misfire. Once the sponge becomes saturated with fuel, the misfire
disappears.


Jerry


"DougW" <post.replies@invalid.address> wrote in message
news:pc82c.35561$1k.35001@okepread01...
> Marc did pass the time by typing:
> > Yes, forgot to include that, changed the plugs.. It doesn't cause
> > extended cranking times or anything, just a fairly rough idle for about
> > 10 seconds then she's fine. No smoke (blue white or black) from the
> > tailpipe either..) Cleaned the TB. After that first 10 seconds it
> > pretty well idles butter-smooth. Power and response are great on the
> > road too.
>
> Did this just happen after your last tank of gas or has it been going
> on longer. Might try adding a bottle of fuel injector cleaner with
> water disperser (gunk or valvoline) with the next fillup, and try a
> different station.
>
> Other causes are sensors or vac leaks that seal with expansion,
> the warmup loop is fairly forgiving and bad sensors will cause
> rough idle even after warmup.
>
> Start the motor and spray some TB cleaner around the base of the
> TB. listen for any RPM change.
>
>
>
>

 

Carbon deposits on the back side of the intake valves will cause this
concern, and Techron will likely eliminate it. Very good product, does what
it says it will.

GM has a little trouble with cold misfires in some engine families.
Engineering has traced the cause to these deposits. They put out a bulletin
and actually recommended Techron by name. I have found that it fixes these
sorts of problems nearly 100% of the time.

The deposits we are talking about are like a sponge. Atomized fuel flows
past the top of the valve and into the cylinder, but this sponge-action
actually absorbs a miniscule amount of the fuel on cold start, causing lean
misfire. Once the sponge becomes saturated with fuel, the misfire
disappears.


Jerry


"DougW" <post.replies@invalid.address> wrote in message
news:pc82c.35561$1k.35001@okepread01...
> Marc did pass the time by typing:
> > Yes, forgot to include that, changed the plugs.. It doesn't cause
> > extended cranking times or anything, just a fairly rough idle for about
> > 10 seconds then she's fine. No smoke (blue white or black) from the
> > tailpipe either..) Cleaned the TB. After that first 10 seconds it
> > pretty well idles butter-smooth. Power and response are great on the
> > road too.
>
> Did this just happen after your last tank of gas or has it been going
> on longer. Might try adding a bottle of fuel injector cleaner with
> water disperser (gunk or valvoline) with the next fillup, and try a
> different station.
>
> Other causes are sensors or vac leaks that seal with expansion,
> the warmup loop is fairly forgiving and bad sensors will cause
> rough idle even after warmup.
>
> Start the motor and spray some TB cleaner around the base of the
> TB. listen for any RPM change.
>
>
>
>

 

Carbon deposits on the back side of the intake valves will cause this
concern, and Techron will likely eliminate it. Very good product, does what
it says it will.

GM has a little trouble with cold misfires in some engine families.
Engineering has traced the cause to these deposits. They put out a bulletin
and actually recommended Techron by name. I have found that it fixes these
sorts of problems nearly 100% of the time.

The deposits we are talking about are like a sponge. Atomized fuel flows
past the top of the valve and into the cylinder, but this sponge-action
actually absorbs a miniscule amount of the fuel on cold start, causing lean
misfire. Once the sponge becomes saturated with fuel, the misfire
disappears.


Jerry


"DougW" <post.replies@invalid.address> wrote in message
news:pc82c.35561$1k.35001@okepread01...
> Marc did pass the time by typing:
> > Yes, forgot to include that, changed the plugs.. It doesn't cause
> > extended cranking times or anything, just a fairly rough idle for about
> > 10 seconds then she's fine. No smoke (blue white or black) from the
> > tailpipe either..) Cleaned the TB. After that first 10 seconds it
> > pretty well idles butter-smooth. Power and response are great on the
> > road too.
>
> Did this just happen after your last tank of gas or has it been going
> on longer. Might try adding a bottle of fuel injector cleaner with
> water disperser (gunk or valvoline) with the next fillup, and try a
> different station.
>
> Other causes are sensors or vac leaks that seal with expansion,
> the warmup loop is fairly forgiving and bad sensors will cause
> rough idle even after warmup.
>
> Start the motor and spray some TB cleaner around the base of the
> TB. listen for any RPM change.
>
>
>
>

 

In article <oj82c.35562$1k.6979@okepread01>,
>
> Gets nasty doesn't it. Go for the PCM update it might be a programming problem.
> If it was real nasty you might benefit from removing the IAC (four antitamper torx
> screws) And cleaning the guts.

Sounds like a plan.. I have a Haynes manual and what I'd consider a
pretty good understanding of under the hood (thanks Dad). Have the
appt. for next Thursday for that PCM flash.



>
> Before you do that, disconnect the hearness from the TB (IAC and TPS) then
> reconnect. They might be a bit corroded. Every once in a while I disconnect,
> clean, and apply some dilectric grease to the sensor connectors.


Check. I'll get that tomorrow too.


>
> Yep. Generally the fuel is atomized by the injectors before it even gets
> to the valve. A dripping injector will cause buildup but it will also cause
> a hellaciously rough idle.


Idle is butter smooth after about 10 seconds. The engine always lights
up within 2 seconds of turning the key, hot or cold.

>
> > He mentioned
> > to use some chevron techron concentrate in a full tank and see if that
> > helps, which I have some of that already waiting to use actually.
>
> See my other post. Doing that every year is a good thing. When you use
> a fuel injector cleaner read to make sure it is safe for O2 and catalytic
> converters. Also look for one that says to use it every 3000 miles or so.
> The ones for use with every tank are generally too weak to clean anything.

Yup, every 3000 right on the bottle. I will change the oil in about
400 miles, so I'll dump that in the fuel on Monday.


I'll check those connections and all this weekend and report back.

thanks!

Marc

 

In article <oj82c.35562$1k.6979@okepread01>,
>
> Gets nasty doesn't it. Go for the PCM update it might be a programming problem.
> If it was real nasty you might benefit from removing the IAC (four antitamper torx
> screws) And cleaning the guts.

Sounds like a plan.. I have a Haynes manual and what I'd consider a
pretty good understanding of under the hood (thanks Dad). Have the
appt. for next Thursday for that PCM flash.



>
> Before you do that, disconnect the hearness from the TB (IAC and TPS) then
> reconnect. They might be a bit corroded. Every once in a while I disconnect,
> clean, and apply some dilectric grease to the sensor connectors.


Check. I'll get that tomorrow too.


>
> Yep. Generally the fuel is atomized by the injectors before it even gets
> to the valve. A dripping injector will cause buildup but it will also cause
> a hellaciously rough idle.


Idle is butter smooth after about 10 seconds. The engine always lights
up within 2 seconds of turning the key, hot or cold.

>
> > He mentioned
> > to use some chevron techron concentrate in a full tank and see if that
> > helps, which I have some of that already waiting to use actually.
>
> See my other post. Doing that every year is a good thing. When you use
> a fuel injector cleaner read to make sure it is safe for O2 and catalytic
> converters. Also look for one that says to use it every 3000 miles or so.
> The ones for use with every tank are generally too weak to clean anything.

Yup, every 3000 right on the bottle. I will change the oil in about
400 miles, so I'll dump that in the fuel on Monday.


I'll check those connections and all this weekend and report back.

thanks!

Marc