1993 Oldsmobile Cutlass Ciera Poor Idle Fix

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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 1:19 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 2:32 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 22, 2007 at 9:32 PM
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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 12:07 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 2:16 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 7:10 AM

Suggested Repair

Replace the Bosch Platinum spark plugs with AC Delco or Autolite plugs and inspect the plug wires for arcing. The confirmed fix was installing AC Delco Professional Platinum plugs.

Conversation Summary

A 1993 Oldsmobile Cutlass Ciera 3.3L had a rough, loping idle and a slight miss at cruise despite new wires, coils, vacuum hoses, and Bosch Platinum plugs, with no codes. Vacuum and oxygen-sensor checks were within range, and cleaning the IAC did not help. A continuous spark was seen jumping near the water pump. The expert identified plug-wire arcing and said Bosch Platinum plugs commonly cause driveability problems, recommending AC Delco or Autolite plugs. Installing AC Delco plugs resolved the issue for the original owner, although a later commenter said the same change did not help their car.

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