Oldsmobile Cutlass Ciera poor idle

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CA441970
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I have a 1993 Oldsmobile Cutlass Ciera S sedan with a 3.3L and 109111 miles. I have an issue with the idle. I have replaced the wires, put Bosch platinum +4 plugs in, and replaced the 3 coil packs. I also replaced all of the vacuum hoses I could find. I just bought a fuel injection pressure tester, and I plan on checking the pressure tomorrow. It runs fine when accelerating, there is no hesitation. At cruising speed you can feel a little miss mostly 45-60MPH. idle though has a very obvious miss or a loping to it, it does this when it's cold or warm. It feels sometimes as if the idle gets too low and then the IAC kicks it up a bit. Is it a bad IAC, TPS, Mass airflow sensor possibly? i have no codes showing up at all. I also bought a can of cleaner for the mass airflow sensor, specifically for delicate electronics. I plan on doing that tomorrow too.

I have a strong mechanical aptitude for car repair, I went to a technical college for suspension, brake, and minor engine repair, but never made it through the ignition/fuel/emissions control part as the school closed down in the middle of my schooling.

Any help will be appreciated.
Feb 20, 2007 at 9:19 PM
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KIN CHAN
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this sounds likes it need a li'lo thinking...let see
okay ..i think u can save buying the tester ..cuz if u have a fuel vol. or pressure issue..u'll definitely have a problem on acceleration ....cruise speed minor missing...chk O2 sensor...chk voltage on signal wire..snap throttle should be around 850-900 mv high and induce vac should be around 100 mv ..hold engine spd around 2000 rpm....ushould be able to see about 1 hertz of high low switching..
now..let see if u have a vac leak ...place a vacuum gage at idle ...u should get like 18 inches of vac or more...needle should be steady ...if it wander ...thats a good indication of vac leak ...that probably cause a lean misfire while idling and runs better when rpm move up..cuz ur vac drop and move toward atmospheric pressure ...make sense?.....u sounds mechanical auto incline ...so..send me a msg if above test didn't nail the cause of ur problem
later man
Feb 20, 2007 at 10:32 PM
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CA441970
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Hello, well I checked theO2 sensor last night, it's within specs. I put my vacuum tester on, and I got 18-19 pounds, but fluctuatin between 18-19. I did the propane test for the manifold gasket leak, no change in idle. I cleaned out the IAC valve, no change. I checked the torque of the throttle body bolts, all were good. I guess next I check the intake manifold bolt torque.
I did notice something wierd to me. It got dark out and I was looking at the plug wires to see if I was getting a spark leak someplace none foud. I did see a small purple spark continuously jumping from a bolt next to the water pump, right to the pully. I have never seen that before. Unless this is friction from the belt grounding?
Feb 23, 2007 at 5:32 AM
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2CARPRO JACK
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That is the plug wire arcing to the engine.There is one misfire. It will NEVER run correctly until either A/C Delco or Autolite spark plugs are installed. Bosch Platinum have more driveability issues than any other plug I have ever seen.
Feb 23, 2007 at 8:07 AM
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CA441970
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Did what you said, pulled the bosch plugs and installed the AC Delco Professional Platinums.... The car runs 120% better. I can't thank you enough!!!!! Now I can start growing my hair back, I pulled most of it out trying to find vacuum leaks, bad sensors, coils, etc!!!!!
Feb 25, 2007 at 10:16 AM
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93SHELLOLDS
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Okay so if you pull the plugs you have an put A/C Delco or Autolite spark plugs in it will run better? I'm sorry but that doesn't work. :( I have done that along with an a ray of other things.
Mar 8, 2015 at 2:10 PM