Hello everyone, I've posted a similar thread here before and now, I'm hoping to get some more needed advice and help.
I have a '93 Cobra with 78k miles on it and it has been giving me a good deal of grief the past year or so. I've owned the car for many years now, and before I've owned two other fox bodies. This Cobra has stock internals, stock GT-40 heads, stock Cobra intake, stock TB and MAF (which has been replaced with a stock replacement calibrated for the stock 24# injectors). It does have BBK 1 5/8 shorty headers, Off Road X pipe, Flowmaster two chambers and stock tips. So far I've replaced the fuel pump, fuel filter, Throttle position sensor, EGR Valve/Position sensor, Idle Air control, Throttle air bypass, MAF, Engine Coolant Temp Sensor, Intake Air Temp Sensor, replaced all vacuum hoses, battery, radiator, air filter (K&N conical), spark plugs, ign. coil, plug wires, cap and rotor. I have also cleaned the injectors individually, replaced the o rings, and it has recently had an oil change. The timing is set at 10 deg BTC as standard.
Bottom line, the car runs absolutely fine at idle. It seems to be a good even idle at 900 RPM. I've ran the KOER, KOEO, and the cylinder balance test. On KOEO, code 34 is the only one that flashes.
Code 34 - EGR Valve Position sensor pressure feedback EGR Voltage above closed limit;
On KOER I get codes 12, and 21;
12 - RPM not withing self test lower limit DC motor did not move , Idle speed control motor or air bypass not controlling idle properly.
21- Engine coolant temp sensor out of self test range.
With the Cylinder Balance test, all cylinders passed.
Okay, so it idles fine and you can rev it in idle just fine. The problem occurs when you are driving. In first gear, it seems to respond at 1/4-1/2 throttle, but anything past that and it hesitates and acts somewhat like it has hit a rev limiter. In second, it pulls to about 3500 and seems like it has hit a rev limiter. It seems like it is starving for fuel, but why would it rev at idle if it is starving for fuel. So, in better words, it will not handle anything over half throttle under load. Not every time, but some of the time, it will back fire in the lower gears under moderate acceleration. It also smells of unburned fuel, so it seems to be running a bit rich.
Any advice to this would be greatly appreciated, so thank you all in advance!
I have a '93 Cobra with 78k miles on it and it has been giving me a good deal of grief the past year or so. I've owned the car for many years now, and before I've owned two other fox bodies. This Cobra has stock internals, stock GT-40 heads, stock Cobra intake, stock TB and MAF (which has been replaced with a stock replacement calibrated for the stock 24# injectors). It does have BBK 1 5/8 shorty headers, Off Road X pipe, Flowmaster two chambers and stock tips. So far I've replaced the fuel pump, fuel filter, Throttle position sensor, EGR Valve/Position sensor, Idle Air control, Throttle air bypass, MAF, Engine Coolant Temp Sensor, Intake Air Temp Sensor, replaced all vacuum hoses, battery, radiator, air filter (K&N conical), spark plugs, ign. coil, plug wires, cap and rotor. I have also cleaned the injectors individually, replaced the o rings, and it has recently had an oil change. The timing is set at 10 deg BTC as standard.
Bottom line, the car runs absolutely fine at idle. It seems to be a good even idle at 900 RPM. I've ran the KOER, KOEO, and the cylinder balance test. On KOEO, code 34 is the only one that flashes.
Code 34 - EGR Valve Position sensor pressure feedback EGR Voltage above closed limit;
On KOER I get codes 12, and 21;
12 - RPM not withing self test lower limit DC motor did not move , Idle speed control motor or air bypass not controlling idle properly.
21- Engine coolant temp sensor out of self test range.
With the Cylinder Balance test, all cylinders passed.
Okay, so it idles fine and you can rev it in idle just fine. The problem occurs when you are driving. In first gear, it seems to respond at 1/4-1/2 throttle, but anything past that and it hesitates and acts somewhat like it has hit a rev limiter. In second, it pulls to about 3500 and seems like it has hit a rev limiter. It seems like it is starving for fuel, but why would it rev at idle if it is starving for fuel. So, in better words, it will not handle anything over half throttle under load. Not every time, but some of the time, it will back fire in the lower gears under moderate acceleration. It also smells of unburned fuel, so it seems to be running a bit rich.
Any advice to this would be greatly appreciated, so thank you all in advance!
