Still idling really rough

richthofen · 11-07-2009, 06:47 PM

I had a thread last week about the hesitation but I figured, different issue new thread---the hesitation issue was fixed by disconnecting the O2 sensor (will replace when I can get one, on order) but the car still runs like total crap. I have replaced, at this point, the plugs, plug boots, coil housing, and fuel filter, as well as run some seafoam through it today (only got 1/4 can down the intake before it cut off--that should be enough to help, right? 1/2 can in the tank as well).

And still, it idles really rough/shaky and feels like it wants to die at stoplights. Holds around 600 RPM but it shakes and bucks; also, often times when braking to approach a stoplight, just before I come to a complete stop the RPMs will dip down to about 400 and the car will shudder really hard, before coming back up to idle. It's worse once the car is warmed up, and worse in drive, though still not good in neutral or park. It has kind of a chugging sound to the idle that makes me think it could be missing still, but the coils were voltage tested when we had it apart and tested good. I used bosch plugs without knowing any better--should I yank them and replace with better plugs, and if so what? Thanks...

[ion] C2 · 11-07-2009, 07:26 PM

Vacuum leak..

richthofen · 11-07-2009, 08:03 PM

Distinct possibility. I'm debating whether or not it's worth the effort to replace the bosch plugs with better ones tonight just in case that helps...

[ion] C2 · 11-07-2009, 08:34 PM

Bosch are total garbage in GM engines. I didn't even see that you mentioned that.

Put in NGK TR55.

Nate's Alero · 11-07-2009, 09:42 PM

NGK or any ACdelco

a4d2a0m · 11-07-2009, 11:25 PM

I have bosch +4's for 6 months and they are great! (ecotec)

richthofen · 11-07-2009, 11:28 PM

Mine are just the garden variety single-electrode bosch, and in the 2.4L--Heard enough negative to wonder if they're partially responsible. I picked up some AC Delco Platinum to see if that will help, the store I went to didn't have those NGKs. May yet install tonight, more likely tomorrow as it's late, and will report back.

jayson_waltz · 11-07-2009, 11:34 PM

Quote:

Originally Posted by a4d2a0m

I have bosch +4's for 6 months and they are great! (ecotec)

give it 1 or 2 more. it'll start idling rough and seem like its bogging for a sec when you floor it. had my bosch's for about 6-8 months before i had to replace with ACD, haven't had a problem since and that was 3 yrs ago.