94 Seville STS Slow acceleration, Rough idle

I just bought a 1994 Seville STS, I was told to change the spark plugs...I did with the correct AC Delco 41-950 if I could remember correctly. It still accelerates slow until it reaches past 2000rpm and sometimes when in Drive it pulls 35MPH!!!! on its own. I GAPPED THE SPARK PLUGS AT .050, CORRECT RIGHT?

It runs loud it sounds like a camaro would, I was told to get a new muffler, could anything eles be wrong.

Lastly my gas guage doesn' work, but the dash indicates Im getting a LOW 10.1 MPG???

I'd check the engine codes to see what's going on. It sounds like there's several sensors that might be bad.

I really don't know much about cars, How would I go about doing that? Is there any special equipment I need?

Follow these instructions, and write down the codes that come up. Post what they are here, and I'll let you know what the codes mean.


To enter diagnostic mode:

1. Turn ignition "ON."
2. Depress the "OFF" and "WARMER" buttons on the Climate Control Center (CCC) simultaneously and hold until the segment check appears on the Instrument Panel Cluster (IPC).

After entering On-Board Diagnostics, a segment check is automatically performed and then any trouble code stored in computer memory will be displayed. Codes may be stored for the Powertrain Control Module (PCM), Instrument Panel Cluster (IPC), Air Conditioning Programer (ACP), Supplemental Inflatable Restraint (SIR) Traction Control System (TCS) or Road Sensing Suspension (RSS) systems.

Each trouble code consists of the system abbreviation: (E: Engine), (P: PCM), (I: IPC), (A: ACP), (R: SIR), (T: TCS), (S: RSS), a three digit code identifier, and the letter C or H. All codes for each system are displayed together, in the order of their three digit number (lowest first). The final digit of the code, a "C" or "H" is used to indicate whether the code is Current or History. A "C" means the fault was still present the last time the diagnostic test was run, while "H" means the failure was not present the last time the code was tested for.

If no codes are present for a system, a "NO X CODE" message (with "X" being the system i.e. E, I, A, R, T or S) will be displayed. If the communication line to a component is not operating, a "NO X DATA" message will be displayed, indicating that the IPC could not communicate with that system.

To get out of the diagnostic mode anytime during the test, depress the "AUTO" or "DEFOG" button, or turn the ignition switch "OFF." Trouble codes are not erased if this is done prior to selecting "CODES CLEARED."

You are so informative, thanks. Anyway I got the codes exactly as I saw them:
P017HISTORY
P034HISTORY
P036HISTORY
P052HISTORY
P071HISTORY
P094HISTORY
P095HISTORY
P109HISTORY
P132CURRENT
NO IPC CODES
A011CURRENT
R061CURRENT
R062CURRENT
T023CURRENT
S044HISTORY
PCM?

Here's what the codes mean, and my comments on them. Did you check them with the engine running, or off? If the engine is off, most of the Pxxx codes will be a History. That means that the problem has occurred, but is not currently. The ones that are current, mean they were a problem when the computer checked.


P017HISTORY Left Oxygen Sensor not ready - Could be a bad O2 sensor that is taking too long to warm up.

P034HISTORY MAP Sensor Signal Out of Range -possible bad MAP sensor.

P036HISTORY EGR Valve Pintle Position Out of Range - I have fixed this before by cleaning the pintle on the EGR valve. Most dealers will tell you to replace it for several hundred dollars!


P052HISTORY PCM Memory Reset - just means that the battery was disconnected at one time and the computer reset.

P071HISTORY Intermittent MAP Signal -another sign of a bad MAP sensor

P094HISTORY Vehicle Speed Sensor - does the car shift hard into 2nd gear when cold? Or service engine soon light come on just when cold?

P095HISTORY Engine Stall Detected -the engine had stalled before

P109HISTORY PCM has lost primary battery power

P132CURRENT Knock Sensor Circuitry Failure- not sure about that one, could be a bad wire or connection to the knock sensor.

NO IPC CODES
A011CURRENT A/C System - High Side Temperature Sensor Circuit

R061CURRENT SIR Indicator Circuit Failure

R062CURRENT Redundant SIR Indicator Circuit Failure

T023CURRENT RF Wheel Speed Sensor Continuity Fault -time for a new wheel bearing/speed sensor assembly!

S044HISTORY Lift or Dive Signal Fault -could be an intermittent sensor failure

PCM? -The computers asks this if you want to further look into the PCMs parameters.

If you haven't already, I'd clear the codes that you have not. Drive the car if you can for a bit, and check the codes again and see which ones are still in the history.

For the heck of it, I ran the diagnostics while the engine is running, all of the codes appeared again plus S036 History & S044 History showed up. How do I clear the codes.

**QUOTE** "P094HISTORY Vehicle Speed Sensor - does the car shift hard into 2nd gear when cold? Or service engine soon light come on just when cold?"

I haven't shifted gears yet, but the car speedometer seems to be 5mph faster. The Service Engine Soon light hasn't come on.

You have a lot of seemingly unrelated codes. Some or all may be bogus. This is often caused by low battery voltage. You might want to clean the battery cable connections as well as look for loose or corroded ground wires. With the engine off, measure the voltage across the terminals with a volt meter. You should have approximately 12.6 volts. Do the same with the engine running. It should show it charging at 13.5+ volts.

Before I started driving it I just replaced the battery with a new one because the car sat for a while, the dash reads the battery volts as 0.0 I'll clean and look but as far as a volt meter goes, I'll have to find one.

A lot of those codes will be from disconnecting the battery. That's why I suggested clearing them, and seeing what new codes appeared.