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I have a 1992 Olds Cutlass Ciera with a 3.3L motor. this motor only has 45,000 miles on it. I have noticed recently that it is idling very low and rough. I replaced the IAC, MAF sensor, O2 sensor, plugs and wires. I noticed the engine struggles when I turn on the lights or rear defrost or any other major load on the battery. the battery itself is cheap and older. Are there any tips I can try before putting more money into it when it wont be fixed?
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How is the starting? I would recommend first having a parts store test the battery and charging system.
Yup, get the battery load tested at an auto parts store. I assume there are no codes? May want to test the tps by backprobing to see if its sending a signal for the heck of it. Dont need to throw parts at it, just test. Are there coil packs? May be a faulty coil. Id also check pcv valve to make sure its not stuck internally. ..it should rattle. Hows the air filter? A rough idle can be a long list of things to check but look at it as an opportunity to “bond” with your vehicle. Good luck man!
My first thoughts go to a vacuum leak. You might try checking for one. Here’s a video. BTW, you can also use water.
Additional information in this article might be useful to you.
http://www.ericthecarguy.com/faq/solving-automotive-idle-problems
Keep us posted on your progress.
I have checked for leaks and tested coils. it has no trouble starting. is there any known spot on this car for a vacuum leak? I may be missing something with it. but I have covered most of the basics with this issue. could a TPS possibly be a fix.
Vacuum leaks can happen anywhere, so it’s a good idea to check everywhere you can think of when looking for a leak. Vacuum leaks are the most common cause of idle problems in my experience.
Keep us posted.
I replaced the throttle body intake gasket which made a big improvement. I had already ordered a replacement throttle position sensor. now the idle is jumping to 3000 rpm with a check engine light. I got the code 22 out of it which is low voltage to the tps. is this possibly just a bad part?
Low voltage may be high resistance. Ie, corrosion. You could measure this with a meter and check woth oem specs. I haven’t heard a test on exhaust restrictions. Do a vacuum test and slap the throttle open, it should drop to zero. A vacuum gauge is kind of “old school” now days but it can tell you alot or at least point to the next test to do when checking engine health.
Reference the code sent on this website and follow the trail. Look at the code as a symptom of the problem. ..not necessarily the cause of it. Throwing parts does rule out possibilities but dang that can get expensive! Recreate, test and verify.
It is a good idea to test components before replacing them. As pointed out, it’s less expensive that way. With a TPS you’re looking for a 5v reference, a ground, and the signal return. The signal return should show about .5v with the throttle closed and about 5v with the throttle wide open. Also, the voltage should have a clean sweep as you move the throttle. Any jumps or bumps in voltage could indicate an issue.
Keep us posted.
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