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1991 Pontiac Firebird: Solving TPI Nightmares

Third-Gen TPI Cars Are Cheap! Our $1,500 '91 Formula Proves It, But First We'll Show You How to Overcome TPI Troubleshooting Nightmares

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Day Three: Tune-up Time

With the EGR problem solved, we moved to the basic tune-up with plugs, fuel filter, distributor cap, and rotor. The No. 5 and 7 plugs were actually easier to reach from underneath the car. We changed them on the lift, where we also changed the fuel filter (it's on the floorpan under the driver-side rear seat) and a broken transmission mount. We also installed new U-joints and a rear transmission seal. Done.

Day Four: Stranded

We got a two-day pass to get the car smogged and reregistered (which really meant we were going drag racing) then made a few blasts near the shop and headed for the freeway. We made it about 15 miles before the car began to lose power. Uh oh. We shifted down and increased the revs but we knew we were in trouble and looked for a place to stall. We found a closed off-ramp and pulled to the side just as the car died. It would crank but not run. Fortunately, California has a state-funded fleet of tow trucks that roam the freeways looking for chicks in white Firebirds with high-heels and flat tires. They stopped for us and dragged the 'Bird off the road.

Day Five: Rich. but in a bad way

Back at the shop we checked the timing to make sure that the chain hadn't fragged or the distributor gear hadn't given up. To check the timing on these cars you must first disconnect the EST (electronic spark timing). It does what the vacuum advance and centrifugal weights do in a regular distributor, but it uses math in the ECM to make the timing adjustments. The base timing checked out at 6 degrees and seemed to be OK. Fresh tune-up, good timing, and the motor wasn't blown up. The only thing left was fuel.

The cool thing about Tuned Port cars is the fuel rail is pretty easy to diagnose. The fuel is pumped from an in-tank electric through a fuel-pressure regulator that bleeds to a return line to control pressure. There is a port on the passenger side where a fuel-pressure tester can be added directly to the system. Our pressure-gauge needle was buried past 50 psi. Oops.

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Car Craft