How do I get out of the "LIMP MODE"?

edspringer

Registered User
My 94 is still idling very rough. When I bought the car it was in the limp mode. It had plenty of boost, no power and would take off in 2nd gear. When the motor was replaced, the mechanic did not tighten the crank bolt. Subsequently, the harmonic balancer 3/16 inch keyway notch grew to 1/2 inch. There was no damage to the key or the crank. The PCM did not see the factory preset 10° BTDC initial timing and thus it went into the limp mode. After 8 weeks of hunting this down, replacing the balancer fixed that. Now it has the same limp mode characteristics. I have no acceleration, plenty of boost and, I assume, no 10° BTDC initial timing. I pulled the balancer off just to make sure the key way was good and it was. Plus my gas mileage is 10 to 11 MPG. I have recently replaced the Magnacore wires with OEM wires, new NGK iridium plugs, crank sensor, knock sensor, CPS, TPS and fuel injectors. I have no CEL codes except when I pull a hill. It is momentary and goes away when I get back on flat road.

Is there a specific procedure that gets this thing out of limp mode?

Any help would be greatly appreciated!

Ed Springer

90 Black XR7 5-speed: 70mm TB, Fresh Air Intake, '94 Supercharger, 5% SC Pulley, Raised SC Top, I/C Fan, UD Pulleys, 190 l/h Fuel Pump, 36 lbs Injectors, Headers, Magnaflow Muffler (no cats) with stock resonators, 3:27 Gears, Ripper Shifter, 73mm CL MAF (Blue Tube), Magnacore Wires, NGK Iridium Plugs, Royal Purple Lubricants and Rear Spring Air Bags.

94 Red SC Auto: 70mm TB, Fresh Air Intake, Stock 90 SC Pulley, Raised SC Top, I/C Fan, 190 l/h Fuel Pump, Headers, Raven Muffler (no cats) with stock resonators, 3:73 Gears, Accel 36# injectors, 76mm CL MAF (Gold Tube), Magnacore Wires, NGK Iridium Plugs, Royal Purple Lubricants, TRANSGO Shift Kit, Pro-Torque 2500 Stall TC, Haydon Auxiliary Transmission Cooler, Tokico Struts & Shocks, American Racing 17” Sniper Wheels, Michelin Pilot Sport A/S Tires and 235 RWHP with 315 LB-FT Torque.
 
The car does not specifically have a "limp mode". It does have a failure management strategy, but that is quite different. Failure management will, in the absence of a good sensor signal, default to substitute signal or will revert to a the last known good value or default. None of which in and of themselves would cause you to have 10mpg fuel mileage.

To get the car back on track all you have to do is fix the source of the problem. There is no "switch" in the EEC software.
 
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