Rough idle At cold start up

Tedstech

Original poster
Member
Jul 14, 2012
4
I have a 2004 Buick Rainier with 80k miles. It idles rough until it gets to operating temperature so far I have replaced spark plugs(delco), fuel filter, camshaft actuator position sensor, cleaned throttle body, and o2 sensors. My question is could it be an engine mount even though the idle gets better when warm? Thank you the help.
 

Irishboy02

Member
Apr 1, 2012
222
Try to run some Fuel injector cleaner, or fuel system cleaner. There is a thread in here somewhere on which ones to use. Just because you have a new fuel filter doesn't mean the injectors (what spits the fuel into the engine) isn't clogged up with the crap from the dirty fuel (prior to the filter change). Also, I recommend running a high octane - let the tank run to the low fuel light, put about 1/4 of a tank of super in it and drive it like you stole it. This purer fuel and hard driving will help blow out some carbon buildup you might have on your valves.

While you at it, wouldn't hurt to clean the throttle body. Step by step instructions are in here somewhere as well.
 

MacMan

Member
Mar 3, 2012
194
Irishboy02 said:
....Also, I recommend running a high octane - let the tank run to the low fuel light, put about 1/4 of a tank of super in it and drive it like you stole it. This purer fuel and hard driving will help blow out some carbon buildup you might have on your valves.....
Sorry to say, but this is the biggest bunch of nonsense I've heard in quite a while. You obviously have NO idea what high octane fuel is, or you wouldn't say what you did. :duh: You are not helping the OP at all. :nono:

High octane is NOT "purer".....and it actually burns slower than low octane. If someone wants to "blow the carbon" out of any engine, just run it hard....high octane will do nothing different.
 

Irishboy02

Member
Apr 1, 2012
222
I explained it in simple terms to keep life easy for someone with a simple question. I am well aware that higher octane technically burns at a slower rate. This is to help with premature ignition, giving a larger burn. With consistent regular fuel COULD lead to fuel not being properly burnt, which can cause buildup on valves especially after 8 years 80k miles. Running higher octane, as well as driving harder, will allow for higher air/fuel flows while the engine is in higher RPMs. These higher RPMs, along with a slightly delayed detonation with the higher octane, will allow for a more full detonation and burn. Having a larger detonation within the cylinder will cause the need for higher exhaust vacuum, which is joined by higher temps within the cylinder. Combine all of the above and it will help clear carbon buildup.
 

mcc

Member
Apr 8, 2012
49
I've had a good experience with Chevron Techron for fuel system cleaning. I did two consecutive treatments and my engine seemed to run smoother afterwards.
 

Tedstech

Original poster
Member
Jul 14, 2012
4
I cleaned the throttle body correctly and I doubt the octane booster will help but might try it. Always seemed like snake oil to me. I guess I'm trying to do everything before the motor mount as that seems to be a pain in the a.. to install in an all wheel drive vehicle. Again thanks for the help.
 

CaptainXL

Member
Dec 4, 2011
2,445
Tedstech said:
I have a 2004 Buick Rainier with 80k miles. It idles rough until it gets to operating temperature so far I have replaced spark plugs(delco), fuel filter, camshaft actuator position sensor, cleaned throttle body, and o2 sensors. My question is could it be an engine mount even though the idle gets better when warm? Thank you the help.

I would be looking for a stuck injector or vacuum leak if it is rough in open loop.
 

Tedstech

Original poster
Member
Jul 14, 2012
4
I already properly cleaned the throttle body. I doubt that octane booster would help but I might give it a shot. I always felt octane booster was a little like snake oil but I might go for it. I'm willing to do anything instead of changing a motor mount as this is an all wheel drive and the installation is a pain in the a.. .Again thanks for the suggestions.
 

McGMT

Member
Jun 17, 2012
621
Tedstech said:
I already properly cleaned the throttle body. I doubt that octane booster would help but I might give it a shot. I always felt octane booster was a little like snake oil but I might go for it. I'm willing to do anything instead of changing a motor mount as this is an all wheel drive and the installation is a pain in the a.. .Again thanks for the suggestions.

The techron additive does clean things up, it is not an octane booster (those really are garbage) it has a chemical in it that actually works to clean up the injectors and such. The mount may be a viable solution. Someone else had a rough engine and vibrations that were caused by a mount. Thing is when it warms up the dimensions of everything and even the running of the engine all change slightly which could cause the mount to tighten up. Ever so slightly but with these tempermental engines it really could be the mount. One thing I didn't notice if you had done is disconnecting the battery for a while to reset the PCM and let it re-learn since you did all this work.

Good luck, let us know what happens...


And guys, come on.... Your wasting time and posts... READ what the posts say, you obviously don't cause all I see anymore is people suggesting and asking things that are clearly in the OP.... Don't get a person all confused and shit arguing about stuff and talking about things you know nothing about. We are here to help, not argue and send the guys head spinning! :banghead:
 

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