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1987 Oldsmobile Firenza banging noise, power drops right of

Tiny
CARILCHASENS
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  • 1987 OLDSMOBILE FIRENZA
Engine Performance problem
1987 Oldsmobile Firenza 4 cyl Front Wheel Drive Automatic

1987 Oldsmobile Firenza, 4-cylinder

Problem developed suddenlyandhas been intermittant.
Revs ok in neutral.
Otherwise, when pushing on the gas, develops loud irregular banging soundlike some kind of preignition or detonation, and power drops right off. Sometimes, one can regain some power by flooring it, other times this doesn't work.
Replacing spark plugs didn't help.
What could be wrong?
This is not a cherished classic car, it is an old beater that we are trying hard to keep running until we can buy something better. We live way up in the bush - not near any repair shop - so having any kind of sophisticated scan is not an option.
Help? Thanks.
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Thursday, November 13th, 2008 AT 5:08 PM

15 Replies

Tiny
JAMES W.
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Do you have a "check engine light" and if you do, do you know how to retrieve the ECM codes? The banging noise, is it from the exhaust or out the air intake duct? Please advise.
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Thursday, November 13th, 2008 AT 6:18 PM
Tiny
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I understand that one can count flashes after connecting terminals A and B in diagnostic connector? I have not, however succeeded in finding a diagnostic connector. Where should I look?
The banging occurs just when accelerating, so locating the source is tricky, but it sounds like it is coming from under the hood and not from underneath the car.
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Friday, November 14th, 2008 AT 1:53 PM
Tiny
JAMES W.
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The diagnostic connector will be on the very bottom of the dash on the driver's side
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Friday, November 14th, 2008 AT 2:06 PM
Tiny
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I see a connector with 12 cells in 2 rows of six, wires white with black stripe and black with white stripe on top right, tan w. Black stripe on other end, orange on bottom right. Should I shove a loop of copper wire in from the back side to connect the white and black wires?
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Friday, November 14th, 2008 AT 4:38 PM
Tiny
JAMES W.
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That is the right connector. I nornally use a paper clip stuck in from the front of the connector. I don't remember the wire colors but, I believe it is A & B, the two on the top right. Most of the other terminals will be empty.
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Friday, November 14th, 2008 AT 5:32 PM
Tiny
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Got codes:
flash pause flash, flash. 12
flash, flash pause flash, flash, flash, flash. Would that be 24?
Then it would go back to 12 and repeat.
Note, that service-engine light has been on all the time for years.I HOPE that the code indicates something new.
Any suggestion that would fix the banging/ extreme
power loss even temporarily would be very verywelcome.
Thanks.
Caril
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Saturday, November 15th, 2008 AT 5:29 PM
Tiny
JAMES W.
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Code 24 is "vehicle speed sensor, VSS". I tells the ECM how fast the vehicle is going. The ECM uses this information to run the cruise control, lock up the torque convertor and other things. You need to more specific about the "banging" noise. I can't hear it so I have absolutely no idea what you are talking about. If you can't describe it any better, have someone else listen to it. I really can't help you unless I get better information. The code 24 may or maynot be part of your problem. Please advise, Jim.
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Saturday, November 15th, 2008 AT 8:39 PM
Tiny
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Vehicle in park or neutral:
Starts and runs ok, revs ok when given gas, engine sounds normal.

Uphill or accelerating (slow or medium speed, haven't tried fast):
Coughs and loses power badly when given gas; better when you let up on the gas.

Flooring the gas:
OCCASIONALLY catches, stops coughing and takes off.

Code 24, service-engine light has been on constantly for years before this problem appeared.
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Wednesday, November 19th, 2008 AT 9:57 AM
Tiny
JAMES W.
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Re-reading your postings, one question pops up. Have you changed the fuel filter? If not, I would change it. It sounds like the engine is starving for fuel.
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Wednesday, November 19th, 2008 AT 12:58 PM
Tiny
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Didn't change the fuel filter, but did add stp stuff to remove water. That was about a week ago. Today, the problem had vanished. When I have had water in the gas in the past, ran badly even with no load on the engine, and this time it was coughing loudly under load rather than missing.
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Wednesday, November 19th, 2008 AT 4:22 PM
Tiny
JAMES W.
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Even though it's a condition almost unheard of nowadays, Water in the fuel will cause the condition you described. You still may want to change the fuel filter in the near future as water will collect in the bottom of it. Hope this takes care of it, Jim.
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Wednesday, November 19th, 2008 AT 5:15 PM
Tiny
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Thanks, Jim. We often get water here, because of the climate.
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Thursday, November 20th, 2008 AT 11:59 AM
Tiny
JAMES W.
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Just checking to see how it's running. You need not respond unless there's a problem, Jim.
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Friday, November 28th, 2008 AT 12:31 PM
Tiny
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Thanks for asking, Jim.
The problem returned, to a much lesser extent, after gassing up at a station where a neighbor of mine claims to have gotten contaminated gas. I added more water remover immediately, and the problem vanished again.
We often see water in gas here when the weather is hovering just above and below freezing and the humidity is 100%
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Friday, November 28th, 2008 AT 2:08 PM
Tiny
JAMES W.
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Thanks for the reply.
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Friday, November 28th, 2008 AT 9:13 PM

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