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Idling problem

S

sicayan

New member
No codes, having problems idling. Accelerates fine, when at a complete stop or in reverse, the car almost cuts out. Battery is good. Not sure what it is with no code. I was thinking the muffler, choke or spark plugs/tune up, but wouldn't these render a code?


Thank you

Pontiac Grand Prix SE 3.1

New cat 8 months ago
Transmission service two weeks ago
 
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Well a poor idle can be caused by a punch of stuff. I'll start by saying it isn’t your muffler or spark plugs.

I would personally start by checking for vacuum leaks. Then I would look at the throttle body. Many ppl don’t realize the throttle bodies need cleaning every year or two. Eventually they can/will cause idling and staring issues when the carbon build finally chokes it off enough.
 
That Canadian Guy said:
Plugs actually are the first step really.

Unless they were replaced recently.
Click to expand...

There is always an unless, 75% of the ppl requesting help on this site either neglect to give vital information or have already tried to fix their car only to have made matters worse. I disagree with your disagreement.:th_laugh-lol2: A car that accelerates fine, doesn’t throw a CEL, and I assumed (by default) that starts just fine doesn’t need new plugs in my book. There are about a dozen more fertile paths to take.
 
I havn't replaced any plugs or wires on the car. I got it around 120k and it has almost 150k on it now. I have no records of the plugs. I know what a misfire feels like, when a wire plug is loose it gives a code, this has happened when getting oil changes and tranny flushed. I am changing the plugs and wires soon, I was going to search the site to see what ppl are using. My mechanic charges $16 a plug.

Yes, car does start fine.

I did notice a crack in the pipe near the muffler, 2" away from where the pipe from the cat goes into the muffler.

Thank you. I will start with the plugs and wires on Monday and ask to have the throttle body looked at. What plugs and wires are you guys using?
 
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do the plugs and wires now

catback holes wont cause misfires.

AC delco wires or lifetime warranty wires.

Ask parts store for AC delco plugs for your car.

they should give you the right ones.
 
The small crack is in the pipe two inches close to the muffler. The cat is a Cali emissions performance Magnaflow. I will look at the AC Delco tomorrow and hope to get this fixed on Monday.

Uhhh..what does, "WOT" mean? >.<

I am such a noob. :th_nervous:
 
Thank you.

I am watching a video on throttle body and symptoms of bad throttle. The gas does stick or has a slight delay. I am going to try and clean the throttle body wich is something I have not done before.

Do you guys take the throttle body completely off or just the air duct to spray and wipe out? There are a few videos on youtube, some took the throttle body completely off and some took off the plastic air duct only and sprayed.
 
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Cleaning the throttle body is very easy, and does not require it to be removed. That being said, I’m not a 100% sure the procedure on a 3.1 throttle. But I do clean my throttle body(TB) once a year. The basic steps are to remove the intake air duct on the TB inlet. Disconnect the throttle linkage, my TB is electronic so I disconnect it (same effect). Spray throttle plate with carb cleaner, then open throttle plate with finger and spray and wipe as far in as practicable. Pay the most attention to the seating surfaces of the throttle plate. Don’t force things and use no abrasives.

Another big hitter to look at is the IAC valve. I have never dealt with it, but I found what looks to be a good write up link.

2003 Pontiac Grand Prix Iac Valve Location &Amp; Cleaning
 


Party on, That Canadian Guy. Party on, Cerick08GP.:th_peaceout:

Thank you very much. I picked up throttle body cleaner and a microfiber towel. Brb in an hour or so.
 
Bummer, throttle was super clean. I sprayed cleaner and wiped out as much as I could with a microfiber towel. Not much to wipe out.

Just after I left the shop earlier, the CEL came on, it is feeling like a misfire now and slowly getting worse with a flashing CEL occasionally. Oh well, no car till Monday.
 
:th_peaceout: Main problem is fixed. The plugs were worn but the problem was cylinder one wire was sitting on the engine or something hot, the wire was fried/melted:th_sick1:. The new muffler sounds great, new piece of pipe replaced the cracked part. All together today; new plugs, wires, fuel filter, muffler. Paid about 325 in labor for this with my own parts.

I was going to have the shop replace the resonator with a glasspack, but I need a new belt I forgot about, a passenger side transaxle(leaking grease):th_depressed: and a set of tires, and new wipers.

The car is running great now(and the throttle body is sparkling clean) and has kind of a low purr.....3.1 purr.:th_laugh-lol2:

Thanks guys.
 


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