Hoping someone may have some ideas. I have a 2000 SSEi with an idling issue. When the car is just idling or sitting at a stop light the engine shakes and sputters. Does not matter whether I am in park, drive or reverse all the same. As soon as I press the throttle the car is fine but as soon as i stop at the next redlight it starts shaking again. The SES light has been coming on and I have scanned it to find out I get P0304 (cylinder 4 misfire) and P0300 (Randon Misfire). So this lead me to change spark plugs and cables, no luck there. I then swapped the coil packs and Ignition model from my other 2000 ssei (yes i have 2 bonnevilles ssei both 2000) which has been running great. no luck on this swap either. I read some threads on here and have not been able to find anything on this problem. I tried switching the EGR valve thinking this may be clogged still nothing. When I changed the LIM gasket this past August I swapped the cylinder 4 fuel injector to cylinder 2 thinking that if it was an injector that now I would start seeing Cylinder 2 misfire.

The best way I can explain the shaking is when one of your spark plugs stops firing and the car shakes and sputters but as soon as I hit the throttle the just the slightest it seems to run fine.

I was thinking maybe the MAF sensor is not working correctly. Is it worth swapping the MAF from the one car to the next.

Any suggestions would be much appreciated.

Did you check the Idle Air Control valve?

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2000 SSEi - SilverBullet - 78,000 kms, 4" "straight shot" custom headlight ram air inlet, TOGs, 1.9's, Lsd, 2.9-3.4"MPS 10-15 psi, Ported GenV, EGR eliminated, OR pushrods, oil volume kit, trani cooler & shift kit, Titanium retainers, 90 lb springs, 160 Stat, 42# injectors, Fuel pump voltage increase, Wideband O2, 3" to dual 2 1/2" Magnaflows, Snow Meth/water injection, after SC temp gauge, 255/50WR17, timing commander set 15-18*@WOT, 2 speed Fan over-ride, disabled DRL, Solid motor mount, Meziere Electric water pump, adjustable fuel pressure regulator, Drilled & slotted rotors/ceramics, GXP sway bars and STB, Upgraded and rebuilt transmission with ZZP 2500 rpm stall TC, Pioneer Bluetooth stereo with sub and 800 W amps, PB 13.5 quarter, (April 2014 car of the month)

sounds to me like the intake manifold gasket is bad,i had all the same issues missfires ect.........rough idle at stops,is there any smoke comeing out of the muffler when it shakes does it smell like pure fuel.i had mine replaced had no problems since, car runs like a champ now.

How long has this been occurring? It sounds as if some time? Which plugs did you use? When you did the intake, did you use the aluminum framed gasket? Also, check to be certain that none of the plug wires are touching the oxygen sensor, or its wiring.

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*Gone, but not forgotten* - Black 2000 SSEi, HIR Headlights, Angel Eyes fogs, 3rd brake light overlay, hi-flo cat, 180 degree thermostat, HS 1.9 rockers, LSx yellow springs, Intense FWI, PCM, shift kit, push rods, and 3.4 Pulley. ZZP Power Log.

When my MAF went bad my car did react in a similar way, but I believe there was an additional code that also led me to the MAF. If you have one at your disposal to try out, it probably wouldn't hurt to switch them out but without the presence of the bad MAF code, it may not help. They require a special tool to remove the star shaped screw.

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'00 SLE Maple Red -"Crisis Management" - (125k)- Customized in Silver... Driven with Excitement. RIP 2013 the Crisis is Over
Plugs/wires @ 51k, UIM/LIM gasket @ 59k. Ignition Ctrl Modual @ 109k [b]'04 Monte Carlo SS - "Dream Chaser" - 3.8L SII - (82k miles)...Purchased 8-7-08...Still Driving!

The shaking has been happening for about 6 months. This is one reason I decided to change the LIM (my thinking was that coolant was leaking into the cylinder causing the misfire). I did change the upper intake between the SC and the manifold. Unfortunatly I had installed the cheap plastic gasket on the LIM I did not find out about the aluminum gasket till later. I did replace the upper intake gaskets.

I used AC delco rapid fire. O2 sensor seems to be clear.

I will check the muffler in the morning to see if there is a smell of gas coming from the exhaust.

Did not check Idle Air control Valve. I assume this is near the air intake. But not sure where it is. If you may be able to direct me or have a picture of where this is. When i Find it what would i be looking for to determine if it isworking properly.

This is the idle air control valve.

Swapping the MAF wouldn't hurt, as Tracy suggested. You may also want to pull the plugs and inspect them.

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*Gone, but not forgotten* - Black 2000 SSEi, HIR Headlights, Angel Eyes fogs, 3rd brake light overlay, hi-flo cat, 180 degree thermostat, HS 1.9 rockers, LSx yellow springs, Intense FWI, PCM, shift kit, push rods, and 3.4 Pulley. ZZP Power Log.

Interesting, mine just started idling rough as well and is fine above idle. My Check Engine light is on but I haven't had it scanned yet. At around 80,000 miles I put Bosch Super Plus plugs in, except for the two closest to the passenger seat which I couldn't get to. This weekend I'll try a little harder getting these 2 plugs changed and see if that takes care of it. They're long overdue Anyone have a secret to share for getting to them?

Would it be typical for bad plugs to work ok above idle but not at idle?

Are there any tests or visible inspections for the idle air control valve or is this just one of those things you replace and see if it is better?

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2002 SE 123k mi.
Bosch Super Plus plugs
Alum. LIM gaskets
Dorman UIM
Replaced door watershield seals

You should never use Bosch Plugs in a 3800. Most here use NGK or delco.

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2000 Pontiac Bonneville SE
1997 Oldsmobile Eighty Eight LS
1993 Buick Regal GS Coupe
1992 Buick Regal Limited Coupe

I agree. Change all the plugs, and use Autolite 605 or NGK TR55's. Also, i found it's easiest to remove the alternator to get to the back plugs. PITA, but still easier. Just remember to disconnect the battery beforehand.

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Bye Bye:

RIP sandrock

Thanks guys. I just started a new thread, since I had it scanned and the code is different than mentioned in the Subject of this thread.

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2002 SE 123k mi.
Bosch Super Plus plugs
Alum. LIM gaskets
Dorman UIM
Replaced door watershield seals

Sorry for the long delay, just waiting for a warm day to do change it. Today I changed the IAC new and it works like new again. I did use a new one from autozone $33. The Idle is normal again. Just a question when I removed the 2 screws when changing the IAC one of the screws broke. I will need to get a tapping screw to remove the broken half but it is holding strong with just one screw and a little bit of scilicone to seal it.

Do you guys think I need to fix this broken screw or just leave it go if it is working.

Thanks again for all the help from everyone.

You really need to fix that broken screw.
It will bite you sometime later at the most inconvenient time.

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2000 SSEi - SilverBullet - 78,000 kms, 4" "straight shot" custom headlight ram air inlet, TOGs, 1.9's, Lsd, 2.9-3.4"MPS 10-15 psi, Ported GenV, EGR eliminated, OR pushrods, oil volume kit, trani cooler & shift kit, Titanium retainers, 90 lb springs, 160 Stat, 42# injectors, Fuel pump voltage increase, Wideband O2, 3" to dual 2 1/2" Magnaflows, Snow Meth/water injection, after SC temp gauge, 255/50WR17, timing commander set 15-18*@WOT, 2 speed Fan over-ride, disabled DRL, Solid motor mount, Meziere Electric water pump, adjustable fuel pressure regulator, Drilled & slotted rotors/ceramics, GXP sway bars and STB, Upgraded and rebuilt transmission with ZZP 2500 rpm stall TC, Pioneer Bluetooth stereo with sub and 800 W amps, PB 13.5 quarter, (April 2014 car of the month)

!!!!UPDATE!!!!

After 2 years it finally happened the check engine light came on again like usual but after awhile things started acting funny like during acceleration the car would shake and shutter then the RPM's would drop to zero even though the car kept running. So it turns out it was a bad Crank Shaft Sensor p0340 that has been causing all these problem. Hoped this helps everyone out there.

By the way the Cps is behind the Harmonic Balancer and no its not fun trying to remove it. I accessed it through the passenger side wheel well.