I have noticed a few posts about the differences that the 93's have. So, here is a list that with many as differences with the 93's as I could find . If you have any other differences or corrections PLEASE let me know.
Mechanical
•Non-vented Optispark until 1995
•Does not have a MAF (it is speed density)
•93 had 2 different gearboxes. The M29 that came with the 3.23 car and the M28 that came with the 2.73 cars. Here are the transmission gear ratios:
M28 M29 94+
3.36 2.97 2.66 1st gear
2.07 2.07 1.78 2nd gear
1.35 1.43 1.30 3rd gear
1.00 1.00 1.00 4th gear
0.80 0.80 0.74 5th gear
0.62 0.62 0.50 6th gear
•For gear change - You must change the speedo gear in the tailshaft of automatics. The speedometers on the '93 A4's were not electronic like in later years. M6’s require an electronic calibration box to correct speedo. However, the speedo can be corrected for 3.23 and numerically lower gears by modifying the eprom.
•Headers/manifolds are different. EGR gasses are only taken from right above #8 cylinder. The tube above #1 is for air injection. (94+ have an extra hole on the passenger side for a 2nd A.I.R. input.
•Fuel rails don't have a front x-over tube and thus use an intake manifold without the recess for it. The fuel line junction at the driver's side is near the TB instead of near the back.
•93’s came with 22lb injectors instead of 24lb
•The fuel system schrader valve is mounted on the drivers side fuel rail instead of behind the intake manifold.
•93s are usually more responsive to fuel pressure changes. It must have something to do with having a speed density system.
•Heater hose has a “T” in it going to the throttle body and also in the upper radiator return hose until the 1995 model.
•The front brakes are different. I believe the pads are smaller (unconfirmed yet).
•Fuel pressure regulator is mounted on the passenger side as opposed to being on the driver side for 94+. Thus requiring a 93 specific FPR. TPI AFPR's are also useable on 93's.
•93’s have a non-electronically controlled 4L60 automatic transmission (internals are swappable with 700R4’s).
•The throttle body in an automatic equipped 93 has a connection for the TV cable. 94+ do not have the connection.
•Pink rods instead of powdered metal rods (unconfirmed)
•1.46” valve springs instead of 1.25” in the newer LT1’s (unconfirmed)
•Oil pressure sender is directly above the oil filter instead of on the back of the intake manifold (unconfirmed that 94+ is on the manifold)
•93’s have a metal fan on the CS 144 alternator and is rated @ 124 amps. The positive ‘bat’ wire for it is attached with a bolt.The 94+ cars have a 140 amp alternator with a plastic fan. It uses a stud and nut to attach the positive 'BAT cable.
•Hardened pushrods until 95
•Traction control was not an option on 93's.
•93 Formulas and Trans Ams did not have the 'performance shift' option.
•93's only hold 4.5 quarts of engine oil according to the owners manual (not sure if actual capacity is different)
•93's only have the A.I.R. pump mounted to the frame. Later years are mounted to the engine block.
Electrical
•93 is the only year 4th Gen that you can flash the computer codes by using a jumper wire between pins A & B (upper right 2 pins)on the DLC (under dash next to steering column). After the jumper is installed turn the ignition to "on" (not start). The engine light will then flash the codes. A 12 code will be given at the beginning and the end of the sequence which just tells you that the self diagnostic is good.
•O2 sensors have only one wire and they are not heated. If converting to long tube headers you will have to upgrade to later heated style O2 sensors to keep them hot because they are moved further back.
•Removeable computer chip instead of reprogramable PCM. This is actually nice if you are a tuner since all you have to do to change programming is swap chips. Although, that makes it a little tougher to do your own custom programming, as it requires burning your own chips.
•1993 and early-1994 cars don't have dual speed fans making them much easier to put in a manual “on” switch. They have no #3 (J) fan relay. For these cars you can just ground D2 for the primary fan and F5 for the secondary one.
•Batch fire injection (each pair of injectors fire simultaneously instead of individually) instead of port injection. No real detriment as far as performance or fuel mileage.
•93s don’t have a provision for the lt4 knock module.
•No CAGS on the M6 so you don’t have to worry about the annoying skip shift feature!
•Temp guage on 93's start at 100*. 94+ temp guages start at 160*
•Wire harness for the fuel injectors is not tagged with the position # as newer model f-bods are.
•The "change oil" light is not used on 93's
Appearance
•93's do not have the oil cap extension tube. The cap is connected directly to the valve cover.
•Pontiacs could get steering wheel radio controls.
•Chevys f-car had Yellow highlighted switches and instrument cluster the Pontiacs did not
•93 Camaros do not have “Camaro” indented or printed on the passenger side air bag cover.
•No stretchy stuff on the sun visors to hold things
•93’s and 94’s are the only ones with a dot-matrix pattern on the t-tops
•Chevys Did not have leather as an option, but the Pontiacs did
•convertible was not available as an option
•Pace car option was available
•All 93 Z28 Camaros came with black tops standard. V6's couldn't get them. In later years it became an option.
•All 93 TA's had the GT package with leather & upper level wing
Hope this info helps.......
Mechanical
•Non-vented Optispark until 1995
•Does not have a MAF (it is speed density)
•93 had 2 different gearboxes. The M29 that came with the 3.23 car and the M28 that came with the 2.73 cars. Here are the transmission gear ratios:
M28 M29 94+
3.36 2.97 2.66 1st gear
2.07 2.07 1.78 2nd gear
1.35 1.43 1.30 3rd gear
1.00 1.00 1.00 4th gear
0.80 0.80 0.74 5th gear
0.62 0.62 0.50 6th gear
•For gear change - You must change the speedo gear in the tailshaft of automatics. The speedometers on the '93 A4's were not electronic like in later years. M6’s require an electronic calibration box to correct speedo. However, the speedo can be corrected for 3.23 and numerically lower gears by modifying the eprom.
•Headers/manifolds are different. EGR gasses are only taken from right above #8 cylinder. The tube above #1 is for air injection. (94+ have an extra hole on the passenger side for a 2nd A.I.R. input.
•Fuel rails don't have a front x-over tube and thus use an intake manifold without the recess for it. The fuel line junction at the driver's side is near the TB instead of near the back.
•93’s came with 22lb injectors instead of 24lb
•The fuel system schrader valve is mounted on the drivers side fuel rail instead of behind the intake manifold.
•93s are usually more responsive to fuel pressure changes. It must have something to do with having a speed density system.
•Heater hose has a “T” in it going to the throttle body and also in the upper radiator return hose until the 1995 model.
•The front brakes are different. I believe the pads are smaller (unconfirmed yet).
•Fuel pressure regulator is mounted on the passenger side as opposed to being on the driver side for 94+. Thus requiring a 93 specific FPR. TPI AFPR's are also useable on 93's.
•93’s have a non-electronically controlled 4L60 automatic transmission (internals are swappable with 700R4’s).
•The throttle body in an automatic equipped 93 has a connection for the TV cable. 94+ do not have the connection.
•Pink rods instead of powdered metal rods (unconfirmed)
•1.46” valve springs instead of 1.25” in the newer LT1’s (unconfirmed)
•Oil pressure sender is directly above the oil filter instead of on the back of the intake manifold (unconfirmed that 94+ is on the manifold)
•93’s have a metal fan on the CS 144 alternator and is rated @ 124 amps. The positive ‘bat’ wire for it is attached with a bolt.The 94+ cars have a 140 amp alternator with a plastic fan. It uses a stud and nut to attach the positive 'BAT cable.
•Hardened pushrods until 95
•Traction control was not an option on 93's.
•93 Formulas and Trans Ams did not have the 'performance shift' option.
•93's only hold 4.5 quarts of engine oil according to the owners manual (not sure if actual capacity is different)
•93's only have the A.I.R. pump mounted to the frame. Later years are mounted to the engine block.
Electrical
•93 is the only year 4th Gen that you can flash the computer codes by using a jumper wire between pins A & B (upper right 2 pins)on the DLC (under dash next to steering column). After the jumper is installed turn the ignition to "on" (not start). The engine light will then flash the codes. A 12 code will be given at the beginning and the end of the sequence which just tells you that the self diagnostic is good.
•O2 sensors have only one wire and they are not heated. If converting to long tube headers you will have to upgrade to later heated style O2 sensors to keep them hot because they are moved further back.
•Removeable computer chip instead of reprogramable PCM. This is actually nice if you are a tuner since all you have to do to change programming is swap chips. Although, that makes it a little tougher to do your own custom programming, as it requires burning your own chips.
•1993 and early-1994 cars don't have dual speed fans making them much easier to put in a manual “on” switch. They have no #3 (J) fan relay. For these cars you can just ground D2 for the primary fan and F5 for the secondary one.
•Batch fire injection (each pair of injectors fire simultaneously instead of individually) instead of port injection. No real detriment as far as performance or fuel mileage.
•93s don’t have a provision for the lt4 knock module.
•No CAGS on the M6 so you don’t have to worry about the annoying skip shift feature!
•Temp guage on 93's start at 100*. 94+ temp guages start at 160*
•Wire harness for the fuel injectors is not tagged with the position # as newer model f-bods are.
•The "change oil" light is not used on 93's
Appearance
•93's do not have the oil cap extension tube. The cap is connected directly to the valve cover.
•Pontiacs could get steering wheel radio controls.
•Chevys f-car had Yellow highlighted switches and instrument cluster the Pontiacs did not
•93 Camaros do not have “Camaro” indented or printed on the passenger side air bag cover.
•No stretchy stuff on the sun visors to hold things
•93’s and 94’s are the only ones with a dot-matrix pattern on the t-tops
•Chevys Did not have leather as an option, but the Pontiacs did
•convertible was not available as an option
•Pace car option was available
•All 93 Z28 Camaros came with black tops standard. V6's couldn't get them. In later years it became an option.
•All 93 TA's had the GT package with leather & upper level wing
Hope this info helps.......
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