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

Marc

In article <pc82c.35561$1k.35001@okepread01>,
post.replies@invalid.address says...
> 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.

It's been since I got it, about 10 days ago, but it was going on most
likely before that. When I test drove it someone else had just come
back with it, so I got it with a warm engine. Otherwise cosmetically
it is perfect and after that cold start it runs beautifully.

Just rather disconcerting to get an initial idle rough enough to jostle
the vehicle for a number of seconds till it levels out..

I'll check your other suggestions this weekend and report back..

thanks
Marc


>
> 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

In article <pc82c.35561$1k.35001@okepread01>,
post.replies@invalid.address says...
> 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.

It's been since I got it, about 10 days ago, but it was going on most
likely before that. When I test drove it someone else had just come
back with it, so I got it with a warm engine. Otherwise cosmetically
it is perfect and after that cold start it runs beautifully.

Just rather disconcerting to get an initial idle rough enough to jostle
the vehicle for a number of seconds till it levels out..

I'll check your other suggestions this weekend and report back..

thanks
Marc


>
> 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

In article <pc82c.35561$1k.35001@okepread01>,
post.replies@invalid.address says...
> 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.

It's been since I got it, about 10 days ago, but it was going on most
likely before that. When I test drove it someone else had just come
back with it, so I got it with a warm engine. Otherwise cosmetically
it is perfect and after that cold start it runs beautifully.

Just rather disconcerting to get an initial idle rough enough to jostle
the vehicle for a number of seconds till it levels out..

I'll check your other suggestions this weekend and report back..

thanks
Marc


>
> 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

I have a bottle of techron concentrate (up to 20 gallons treatment),
that I picked up at Target for $4.84 (on clearance I think), so I plan
to load up the tank this weekend with it.

Hoping that between the techron and the pcm update, one of them will get
it. What kind of time frame would I be looking at to see if the techron
is making a difference? The whole tank run through, 100 miles, etc?

Marc



In article <40491f98_2@newspeer2.tds.net>, "Jerry Newton"
<figatmcttelecom.com> says...
> 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.
>
>

Marc

I have a bottle of techron concentrate (up to 20 gallons treatment),
that I picked up at Target for $4.84 (on clearance I think), so I plan
to load up the tank this weekend with it.

Hoping that between the techron and the pcm update, one of them will get
it. What kind of time frame would I be looking at to see if the techron
is making a difference? The whole tank run through, 100 miles, etc?

Marc



In article <40491f98_2@newspeer2.tds.net>, "Jerry Newton"
<figatmcttelecom.com> says...
> 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.
>
>

Marc

I have a bottle of techron concentrate (up to 20 gallons treatment),
that I picked up at Target for $4.84 (on clearance I think), so I plan
to load up the tank this weekend with it.

Hoping that between the techron and the pcm update, one of them will get
it. What kind of time frame would I be looking at to see if the techron
is making a difference? The whole tank run through, 100 miles, etc?

Marc



In article <40491f98_2@newspeer2.tds.net>, "Jerry Newton"
<figatmcttelecom.com> says...
> 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.
>
>

Rob Mills

"Marc" <none@all.com> wrote in message
news:MPG.1ab2b8906514b426989685@netnews.mchsi.com. ..

>>> '00 Cherokee XJ with 4.0L, 48k miles. Runs perfectly in every way
EXCEPT: cold starts will result in about 10 seconds of roughness<<<

My 96 4.0 which now has 82k on it has done just that since the day I drove
it off the show room floor. Like yours it's a tad rough for the first few
seconds (half block) then levels out. I just figured it was the nature of
the beast.

The only thing that I've had to do other than brakes, plugs and normal
maintenance in 82k was to replace
something in the steering column called a "clock spring" (don't have a clue
what it does) and that was done while it was still in warranty. RM~

Rob Mills

"Marc" <none@all.com> wrote in message
news:MPG.1ab2b8906514b426989685@netnews.mchsi.com. ..

>>> '00 Cherokee XJ with 4.0L, 48k miles. Runs perfectly in every way
EXCEPT: cold starts will result in about 10 seconds of roughness<<<

My 96 4.0 which now has 82k on it has done just that since the day I drove
it off the show room floor. Like yours it's a tad rough for the first few
seconds (half block) then levels out. I just figured it was the nature of
the beast.

The only thing that I've had to do other than brakes, plugs and normal
maintenance in 82k was to replace
something in the steering column called a "clock spring" (don't have a clue
what it does) and that was done while it was still in warranty. RM~

Rob Mills

"Marc" <none@all.com> wrote in message
news:MPG.1ab2b8906514b426989685@netnews.mchsi.com. ..

>>> '00 Cherokee XJ with 4.0L, 48k miles. Runs perfectly in every way
EXCEPT: cold starts will result in about 10 seconds of roughness<<<

My 96 4.0 which now has 82k on it has done just that since the day I drove
it off the show room floor. Like yours it's a tad rough for the first few
seconds (half block) then levels out. I just figured it was the nature of
the beast.

The only thing that I've had to do other than brakes, plugs and normal
maintenance in 82k was to replace
something in the steering column called a "clock spring" (don't have a clue
what it does) and that was done while it was still in warranty. RM~