1994 Oldsmobile Delta 88 rough idle and rough acceleration

NEVER2LOUD

MEMBER
1994 OLDSMOBILE DELTA 88
6 CYL
FWD
AUTOMATIC
60,000 MILES

I have a 94 olds 88 with 60 000 miles on it. Last week all of a sudden it started running really rough and when I accelerate it runs really rough and surges badly. If I floor it and the rpms are high its ok, when it accelarates the motor shakes violently and when I take my foot off the fuel it goes away. I have checked the MAF sensor and it is clean. Plugs and wires are newer. It sat for a year before I bought which was about 2 months ago. Please help me, Im at a dead end. Thank you

Wednesday, November 18th, 2009 AT 11:45 AM

3 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires

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Wednesday, November 18th, 2009 AT 4:32 PM

NEVER2LOUD

MEMBER
3 POSTS

I beleive I found the problem, the main wiring harness that goes the drivers side firewall behind the strut tower seems to be melted. All the wires are melted together. I went to the wreckers today and started taking one off another olds until I realized that there is no clip to it. Is it possible to change that harness, the one that feeds all the sensors and fronty lights? Where it enters the car it seems to go everywhere, theres not just one main clip, I need help, thank you so much guys, awesome site. Im sold

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Monday, November 23rd, 2009 AT 3:54 PM

NEVER2LOUD

MEMBER
3 POSTS

The wiring harness isnt melted, it had some gooey grease on it. I found a broken spark plug wire that was grounding out on the block, I changed the wires and the plugs in case. It calmed down alot however now it does it when im at a steady speed and I slowly go into the pedal to increase my speed. Maybe a sensor is faulty from the grounding wire? Plz help thank you

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Thursday, November 26th, 2009 AT 10:53 PM