Dancing RPM

Tiny
THA
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  • OLDSMOBILE
1988 Olds Cutlass, It always starts, but the rpms started dancing at 20,000 rpms and the car jerked. Then it danced at 15,000. The check engine light does not come on, but now when I start it, the rpms dance period. The last time I tried to drive it, it died when I put it in gear and tried to go. Last year I had the fuel pump replaced along with 3 sensors. One was the MAF, one was Y shaped and the other was a big box just inside where the glove compartment goes. I guess you have guessed by now I'm female with no car experience, but I'm trying to learn the hard way. My Dad's an old school mechanic and he's stumped. Any ideas why the rpms would dance like that when I'm not even touching the gas pedel at start up? Any help would be greatly appreciated.
Monday, February 5th, 2007 AT 7:53 PM

7 Replies

Tiny
SERVICE WRITER
  • MECHANIC
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Maybe with Dad, You, an the other boys on the forum, we can get this figgured out.

Couple notes: Don't confuse being a female with being oblivious. It just ain't so. Your smarter than you think you are :wink: And your going after it, that alone calls for respect.

It sounds like there is a vacuum leak. However I may not be clearly understanding you.

Is this right?
When you start the car it idles very high? Stalls, when you put it in gear.
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Monday, February 5th, 2007 AT 8:39 PM
Tiny
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Yes, it idles high and low without touching the gas. When I rev the engine the rpms dance and jerk and sometimes it backfires. Could the MAF sensor I replaced last year have gone bad already, or is the vacume leak possibly located somewhere else? Thanks so much for any help you can offer. I love my car and want it back to normal.
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Friday, February 9th, 2007 AT 3:50 PM
Tiny
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Be patient, it will be. :)

The MAF is possible, if may have become contaminated, check for an oily substance in it. The can be cleaned with an electrical component cleaner spray.

More apt to think the IAC motor, after thinking about it-I am a service writer, not a tech :shock:. This component can also be cleaned. I thinkI was off about the vaccum leak :oops:

What size engine do you have? 3.1?

Can you have the codes pulled from the computer?
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Saturday, February 10th, 2007 AT 3:45 AM
Tiny
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The weather has been bad so I'm just now getting back to the car problem. We checked the MAF and there was no oily residue. I checked for codes and there are no codes stored. I'm not sure where the IAC motor is. I bought the car used so I don't have an owners manual. I've been trying to get help from library books, but they are general not spacificly for my car. Today I tried to run it and now it will not even idle without dying. When I give it gas it makes awful backfiring noises and once I thought I smelled something burning. I let it die and checked the engine but saw no smoke or anything that looked fried. Since there are no codes stored I'm guessing that means it's not a sensor. PLEASE HELP! My Dad has given up.
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Wednesday, February 21st, 2007 AT 7:47 PM
Tiny
CHEVY22
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What engine please, and do you know what three sensors were replaced, this may help
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Wednesday, February 21st, 2007 AT 8:50 PM
Tiny
CARUNDELL
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Hey tha,
Sounds like a bit of a fuel/fuel control issue. Try this. Disconnect the O2 sensor and try to restart. If the engine starts and runs ok, then theres your baby. If not, then some more questions are in order. Have you verified that all the vacuum lines/hoses are attached and not broken? Try disconn the coolant temp sensor and restart, see if the condition changes. Do you just have a code reader? Or a scanner that can view data stream? Or are you jumpering the A/B at the Data Connector?
Let us know!

Chris
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Thursday, February 22nd, 2007 AT 4:00 AM
Tiny
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The engine is 3.8 6 cylinder. My brother's trying to help now. He says the vacume lines look okay. He checked the spark plugs and contol box today, because when he looked at it we had trouble even getting it started. It just keeps getting worse each time we check it. Two of the sensors that were replaced are the MAF and the crankshaft sensor. I don't know what the other ones were called yet. I jumped the AB thing with the paper clip to check for codes. My brother showed me this last year before we knew the MAF needed to be replaced. He's stumped because there's no codes either. It will not drive, so I can't take it to have codes read at a shop unless I have it towed. When I see him again I'll get him to check the 02 and coolant sensors. Thanks so much for all your help. I'll get back to you soon.
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Friday, February 23rd, 2007 AT 5:44 PM

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