93 RMW rough idle/stalling/surging

vixenpilot

Full Member
34
1
6
Buick Ownership
93 Buick RMW
Hello once again,

93 RMW. I have replaced the TPS, CTS, Idle sensor, O2 sensor and replaced all of the ignition components. The car idles very rough and stalls. It surges and as of this morning it's begun to diesel when i turn it off. The check engine light comes on and then goes back off when the engine smooths out which it does intermittently. I'm new at trouble shooting newer cars. The car does not appear to have been serviced for many years and had a light throttle hesitation to start with. Everything I did made it somewhat better but never cured the problem. It suddenly got worse so I finally changed the O2 sensor and it really got bad. That's when the dieseling began.

Any input is greatly appreciated. Thanks!
 

bdblly

Full Member
812
1
0
Buick Ownership
92 Buick Roadmaster Limited; 05 Mercury Grand Marquis Limited
When you say the Idle sensor, do you mean the Idle Air Control valve towards the back of the passenger side of the throttle body unit? Since you say you are new to trouble shooting new cars, first, do you know about jumping the under dash diagnostic plug? This is known as the assembly line data link (ALDL). It is a 12 plug set up. Take a paper clip or similar item, and bend it into a U shape and plug it into the last 2 terminals on the top towards the passenger side. Then turn the ignition on (DO NOT START THE CAR) and the service engine soon light will flash out any stored codes. Each flash is a number, 1 flash is 1, 2 flashes is 2, and so on. First it will flash code 12, (1 flash, pause, 2 flashes), it will flash 12 three times, then a longer pause, then flash any stored trouble codes. After any stored codes are flashed, it will do code 12 three times again and start over. By the way, location of the ALDL is under the dash just to the passenger side of the steering column. To clear any stored codes, and see if they reset, undo both cables to the battery for a couple of minutes, and/or unplug the computer fuse. This will erase any stored codes, especially since you have already replaced some electrical pieces. The Roadmaster Haynes manual (#24046) lists the codes, or you can look up the list online by typing in something like GM OBD I trouble codes. Or let us know what numbers flashed and someone here will difinately tell you what codes your car is showing. Good luck, hope this helps!
 

vixenpilot

Full Member
34
1
6
Buick Ownership
93 Buick RMW
Thanks for the in depth instructions! They're going in my file for the car.

After throwing all those sensors at it to no avail, I finally put a new EGR valve on.....problem solved!!!!!
 

bdblly

Full Member
812
1
0
Buick Ownership
92 Buick Roadmaster Limited; 05 Mercury Grand Marquis Limited
The E.G.R. valve malfunctioning will throw a code 32. The E.G.R. vacuum solenoid would set a code 27. Just F.Y.I.
______________________________
 

Shakeel

Full Member
25
1
0
Buick Ownership
Buick
When my woody would stall at an red light and idle rough and the rpm gauge was all bouncy it ended up being my ignition coil replaced it and all is well.
 

Klevbomb

New member
1
0
0
Buick Ownership
1993 buick roadmaster estate wagon
I
When my woody would stall at an red light and idle rough and the rpm gauge was all bouncy it ended up being my ignition coil replaced it and all is well.
got a 1993 buick roadmaster it started doing the same thing a few days back and the ignition coil fixed that?
 
Looking to update and upgrade your Buick luxury automobile? Look no further than right here in our own forum store - where orders are shipped immediately!
Top