1993 cadillac eldorado misfire
1993 Eldorado Misfire
Alright folks here we go. 1993 Cadillac Eldorado with the 4.9l non N* engine in it. Just got done swapping motors a week or two ago and finally got tags so I can drive it. I noticed in my leak checking and letting the car idle and warm up that there was a bit of a shake. Assumed that since the motor hadn't been run for quite a while and is on a different PCM that it may be just learning itself or needed to actually get run up to temp.
Turns out, the minor shake gets worse and turned into a noticeable misfire. I don't feel it very bad when I am accelerating slowly or cruising without the TC engaged but when the TC engages at around 25-30 and the engine is in a lot of torque (1100-1300 RPMs) the misfire becomes pretty violent. It seems like it is almost phantom as sometimes it will run seemingly without the miss, others it will be violent.
I bought the engine out of another eldorado but it was a 1991? I think. It was your standard 4.9L with everything being the same. The only difference was the wiring harness for the injectors was incorrect. In my car the wiring ran for all the injectors into a ten pin plug. In the New motor the wiring ran two separate harnesses for front and back bank with the rear bank containing another sensor. So long story short I just pulled both harnesses and switched them. Worked out great.
It has brand new plugs. Wires look great. (I know I should test them or just replace them, but money and time is tight)
EDIT: Update: I pulled the Rotor, coil, and cap from the old motor (they were replaced soon before the other engine died so they're like new) Seems slightly at idle but still missing under load. EDIT2: Update2: I replaced the plug wires now. Still the same. List of new parts. Plugs, wires, cap, rotor, coil, oil pressure sensor, thermostat, coolant, oil, seafoamed engine, etc. (these are all new parts that I've replaced since swapping engines) Also went out to get it up to speed (55) brought it down to 30 and gave it some gas. Seems quite underpowered.
I have the diagnostics from the car. No Check engine codes. I did pull the PCM data though. This is after full warm up driving then at idle took these numbers.
Things that look weird to me: Intake Air temp? Front o2 cross counts. Power steering - I have full power steering,
pd01 .9 TPS (Throttle Position Sensor) in degrees
pd02 38-39 Manifold Absolute Pressure Sensor in Kilo Pascals (kPa)
pd03 102 Barometric Pressure in kPa
pd04 103 Engine Coolant Temperature (ECT) sensor in degrees Celsius
pd05 100 Intake Air Temperature (IAT) sensor in degrees Celsius
pd08 21-24 Spark Advance in degrees Before Top Dead Center (BTDC)
pd10 13.2 Fuel Pump Feedback Voltage (battery voltage)
pd11 625-675 Engine Speed in revolutions per minute (rpm)
pd12 0 Vehicle Speed in miles per hour (mph)
pd19 0 Power Steering Sensor (kPa)
pd30 4.2-4.3 Front Bank Injector Pulse Width in milliseconds (ms)
pd31 4.2-4.3 Rear Bank Injector Pulse Width in milliseconds (ms)
pd32 .58 Front Oxygen Sensor Voltage
pd33 .48 Rear Oxygen Sensor Voltage
pd34 0 Front Oxygen Sensor Cross Counts (per second)
pd35 2-4Rear Oxygen Sensor Cross Counts (per second)
pd36 128 Front Short Term Fuel Trim
pd37 128 Rear Short Term Fuel Trim
pd38 124 Front Long Term Fuel Trim
pd39 124 Rear Long Term Fuel Trim
pd70 19 Cruise Control Feedback (percent)
pd71 11 Transaxle Pressure Switch (PRNDL Code)
pd72 00 Transaxle Input Speed in rpm (PRNDL P/N Sw)
pd98 30 Ignition Cycles (key cycles on/off)
pd99 1506 PROM Calibration-Engine