Cold start

antonio fuller

antonio fuller

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Ok this might not be a big deal so I notice since the temperature is changing a little bit when I start the car and it's cold while allowing the car to warm up the engine tumbles a little bit and the RPM needle will move up and down a little bit this all stops once it gets warm. Is it something to be looked into the plugs and coils I changed not to long ago so I shouldn't have a problem with that


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105 words, one period...

when (date and miles ago) did you last do coils and plugs? How many? what brand?

whats you miles to empty when you fill the tank?
 
antonio fuller said:
... car and it's cold while allowing the car to warm up the engine tumbles a little bit and the RPM needle will move up and down a little bit this all stops once it gets warm ...
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You allowing it to warm up with EVERYTHING OFF or are you messing with the HVAC constantly?
 
By "tumbles" do you mean stumbles upon acceleration when taking off from a stop before warming up... or do you mean a "chugging" while warming up sitting at idle warming up??? Do you get any kind of OBD2 message at the time??? Best case scenario,,, this is somewhat normal... or the MAF and O2 are getting conflicting readings while the engine is in "cold loop" warm up.

If this is happeneing with a completely warm engine,,, and it "stumbles" when you accelerate... this could be your throttle position sensor starting to go,,, and is part of the throttle body. The TPS can be replaced separately,,, but is a bit tricky since the tiny bolts will want to snap off. A heat gun/paint remover gun may be enough to get the TPS screws loose.

If it is the TPS,,, and you are lucky enough to get the screws out... it will only cost you about $50 at the most, (not available throug the dealer,,, only aftermarket). If the screws snap off... then you might be looking at $500 or so for a new throttle body assembly.

Joe... correct me if I am wrong.
 
04_Sport_LS said:
By "tumbles" do you mean stumbles upon acceleration when taking off from a stop before warming up... or do you mean a "chugging" while warming up sitting at idle warming up??? Do you get any kind of OBD2 message at the time??? Best case scenario,,, this is somewhat normal... or the MAF and O2 are getting conflicting readings while the engine is in "cold loop" warm up.

If this is happeneing with a completely warm engine,,, and it "stumbles" when you accelerate... this could be your throttle position sensor starting to go,,, and is part of the throttle body. The TPS can be replaced separately,,, but is a bit tricky since the tiny bolts will want to snap off. A heat gun/paint remover gun may be enough to get the TPS screws loose.

If it is the TPS,,, and you are lucky enough to get the screws out... it will only cost you about $50 at the most, (not available throug the dealer,,, only aftermarket). If the screws snap off... then you might be looking at $500 or so for a new throttle body assembly.

Joe... correct me if I am wrong.
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Lol wow $50 to $500 real quick I so love this car thanks for the info I was referring to chugging while warming up sitting idle no messages just does it a few seconds I just changed the converters and I have seen a few crazy things with these cheap aftermarket bs I haven't done anything to the MAS are the intake I'm thinking the problem might be like you said conflicting reading with the MAS and O2 from the cheap converters thanks for the information


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A TPS problem big enough to cause idling issues would be big enough to trigger ETC failsafe, I believe.
My first thought would be an intake (vacuum) leak somewhere.

Why does anyone ever mess with the HVAC. I leave mine on full auto all the time and very rarely change the temperature. The PCM won't engage the AC clutch until conditions are appropriate to do so.

You're not doing the engine any favors at all letting it just idle with no loads to warm up. The most engine wear occurs when the engine is cold, so it makes sense that the sooner it warms up the better. Leave the AC on and drive off in seconds after starting it. The interstate is about a mile from me, with low speed roads between me and it. By the time I get to the interstate, the engine, and the transmission are warm enough (gauge in the middle) to punch it to get on the interstate. I doubt that the transmission warms up at all just idling.
 
Driggy said:
Try cleaning or replacing the iac valve (idle air control)
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That's going to be really hard to do, since he doesn't have one.

The 2nd gen LSes have electronic throttle control. Since the PCM is in full control of the throttle valve, there is no need at all for a secondary valve, so there isn't one.
 
something else you could try... is disconnecting the battery for 15 minutes. Then after reconnecting,,, put the LS through a drive cycle per the owners manual, (page 254 in mine). It allows the LS to re-learn the fuel trim for idle... and clears learned shifting patterns on the trans.
 
04_Sport_LS said:
....put the LS through a drive cycle per the owners manual, (page 254 in mine).......
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PLEASE don't bring up the "drive-cycle"!! Just checked page 254 of the 2004 Owner's Manual and it speaks of windows and wiper blades and instrument panel and cluster lens.

Just drive normally after a battery disconnect.
 
This sounds like a vacuum leak to me. My '03 LS8 was doing the same thing before I parted it out. Fine in the summer with a cold surging idle once the temperature dropped into the lower 50's. Even when cold outside the idle was fine once the car warmed up. Fuel trims were fine in warm weather and way off in cold weather. I believe the o-rings between the upper and lower intake go bad. Technically these aren't serviceable, but the proper o-rings are available on eBay . The best way to visualize these leaks is with a smoke test. There are several DIY methods on youtube.
 
Really??? My 2004 owners manual says the following on page 254.....

"Because your vehicles engine is electronically controlled by a computer, some control conditionsare maintainedby power from the battery. When the battery is disconnected or a new battery is installed, the engine must relearn it's idle and fuel trim strategy for optimum driveability and performance. To begin this process:

1 - With the vehicle at a complete stop, set the parking brake.

2 - Put the gearshift lever in P (park), turn off all accesories and start the engine.

3 - Run the engine until it reaches normal operating temperature

4 - Allow the engine to idle for at least oner minute.

5 - Turn the A/C on and allow the engine to idle for at least one minute.

6 - Drive the vehicle to complete the learning process

. - The vehicle may need to be driven to relearn the idle and fuel trim strategy

. - (in Bold) if you do not allow the engine to relearn it's idle trim, the idle quality of your vehicle may be adversely affected until the idle trim is eventually relearned."

Below this... (still on page 254),,, it talks about the adaptive stategy of the transmission and how disconnecting the battery affects that. To continue....

"When the battery is disconnected or a new battery installed, the transmission must relearn it's adaptive strategy. As a result of this, the transmission may shift firmly. This operation is considered normal and will not affect function or durability of the transmission. Over time the adaptive learning process will fully update transmission operation to its optimum shift feel"

There have been times when it seems like the computer(s) on the LS get confused... maybe due to the battery being in the trunk and the chassis having minor ground issues. I have done a couple of battery disconnects and "drive cycles" durnig the ownership of my LS,,, and it does seem to cure minor hiccups with the vehicle.

Not saying this is the be-all-end-all... but i would try it first. It's NOT going to fix bad coils,,, and it won't fix bad o-rings on the intake as Gus pointed out... but it is a good place to start.
 
I've had at least a half dozen battery changes and have never done that. The strategies will "learn" on their own with normal driving.
 
LS4me said:
I've had at least a half dozen battery changes and have never done that. The strategies will "learn" on their own with normal driving.
Click to expand...

Same here. I haven't noticed any problems while it was relearning.
 
joegr said:
A TPS problem big enough to cause idling issues would be big enough to trigger ETC failsafe, I believe.
My first thought would be an intake (vacuum) leak somewhere.

Why does anyone ever mess with the HVAC. I leave mine on full auto all the time and very rarely change the temperature. The PCM won't engage the AC clutch until conditions are appropriate to do so.

You're not doing the engine any favors at all letting it just idle with no loads to warm up. The most engine wear occurs when the engine is cold, so it makes sense that the sooner it warms up the better. Leave the AC on and drive off in seconds after starting it. The interstate is about a mile from me, with low speed roads between me and it. By the time I get to the interstate, the engine, and the transmission are warm enough (gauge in the middle) to punch it to get on the interstate. I doubt that the transmission warms up at all just idling.
Click to expand...

Wow I would have never new this information


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The owner's manual only has this to say:
Warming up a vehicle on cold mornings is not required and may reduce fuel economy.
 
joegr said:
The owner's manual only has this to say:
Warming up a vehicle on cold mornings is not required and may reduce fuel economy.
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Lol yeah it will burn gas ⛽️

Hey my issue I think is getting worst it's not just at cold starts the engine stubbles and today got to the point I thought it was going to stall out I have cool issues when the car is driving and i just replaced them and plugs. Even with the starting as hard as it is the engine light doesn't come on I changed to coils and plugs but I remember when I had my old one at the dealer they charged me to calibrate the pcm I think are something and I never had that done on this one what you thing I should have looked at first


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Smoke test. Look for intake air leaks. Alternately, what happens if you unplug the MAF (apart from the eventual ETC failsafe warning)?
 
Quote Joe:

"The owner's manual only has this to say:
Warming up a vehicle on cold mornings is not required and may reduce fuel economy. "

Gee... I wonder why??? :)

As you said elsewhere,,, you drive a mile to the e-way... and your LS is warmed up by then. It must be city driving in your case. I live a mile from the e-way in the country... and if I didn't let my LS warm up for a few minutes I would be jumping on the e-way with a cold engine. You're right that most engine wear occurs when cold... but I would rather it happened at idle,,, rather than 2000+ rpm.
 
04_Sport_LS said:
Quote Joe:

"The owner's manual only has this to say:
Warming up a vehicle on cold mornings is not required and may reduce fuel economy. "

Gee... I wonder why??? :)

As you said elsewhere,,, you drive a mile to the e-way... and your LS is warmed up by then. It must be city driving in your case. I live a mile from the e-way in the country... and if I didn't let my LS warm up for a few minutes I would be jumping on the e-way with a cold engine. You're right that most engine wear occurs when cold... but I would rather it happened at idle,,, rather than 2000+ rpm.
Click to expand...

I'm with you on that I have been with joe on a few things but hear in Atlanta you doing 50 on the main streets lol 90 on the eway I got to warm this baby up can't treat hear like that [emoji23][emoji23][emoji23]


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