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Discussion Starter #1
OK guys, I know I could post this in the engines forum, But I keep getting bumped from a search on the Quad 4. So I'm here. My wife's daily driver is a '90 Olds Cutlass Supreme 4 door with a Quad 4. This car will go weeks at a time running great and then, Bam!, start running on 1 cylinder. I'm thinking bad fuel injectors, but I'm not sure. We get gas at the same station every fill-up. It shouldn't be bad gas. We dump in injector cleaner every other fill-up also. The car will cough and sputter and die unless you two foot it to keep it running. I've tried my GM scan tool, but all I get is code 12 (diagnostic system normal) and nothing more. It has decent compression and enough fuel pressure according to my Haynes book. It runs great wide open, but off idle it stumbles really bad. Gas milage is about 25 to 30 per gallon which is supposed to be normal for the car. $90 for one injector is a bit spendy for me if that's not the problem. Two shops locally tried telling me it's the O2 sensor, but I've changed that twice with no change.

I'm stumped. Maybe this is the reason Olds was shut down by GM. Even the car can't tell you what's wrong. Technology can kiss my buns when the Monte hits the street!
 

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I hear you on those quad 4's man. My girlfriend has a 90 oldsmobile cutlass calias international edition with the 2.3 DOHC the head recently cracked on that, then it threw a rod bearing. her dad told me it was almost water injected it was using so much coolant. lol
 

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Hotrodders.com Moderator
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Have you removed the top cover that houses the ignition coil assembly and spark plug boots? Have you changed plugs? You could very well be suffering from spark plug boot leakage to ground or just misfire from badly worn spark plugs. You could also have moisture problems causing a misfire situation.
 

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Discussion Starter #4
I changed the plugs about 4500 miles ago, but it's possible that the the AC Delco's could be bad. I never thought about a ground leakage at the boot. Is there a way to check them out? The cough and miss doesn't happen once it hits about 2000 rpm or so (no tach, so I'm kinda guessing on the actual rpm), so I'm not really sure on moisture. Dang, these computer cars are a challenge to work on. Thanks for the advice. I'll probably change plugs and check the boots after work tomorrow and see if that helps.
 

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I'll have to go out on a limb and say that it is more than likely ignition related. I would replace the boots first. They are the cheapest. If misfire still exists, I would probably look hard at the coils.
 
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