Georgia Fiero Club Forum
All Things Fiero => Tech Tips, Tech Questions => Topic started by: GTRS Fiero on May 19, 2021, 06:05:48 pm
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So, the GTRS Fiero seemed to have lost some of its pep, and wasn't idling smoothly. On tip-in, it had hesitation. When coming off the highway to a stop, it would almost die on the after downshifting to first, but then recover. Off the line, it would almost die ahen getting on the throttle.
In the past, I could light up the rear wheels, off the line. There ended up being a vacuum leak around the fitting at the intake for the brake booster.
Another issue was that the GTRS Fiero would run a few miles on a tank, then apparently run out of gas. Adding gas would immediately solve the problem. This started after the float was adjusted to not hit the baffles. Fuel pressure was always low when this occurred. At fill-up, it would only take a few gallons of fuel. On the way home from work, the other day, I filled up with fuel. About 11 miles later, the engine would not make power, but was still running, for a bit. It died. I got over to the shoulder, and it did restart while still rolling, so I drove on home. This dying like this is a new thing, but it has now done this several times. It has about 30 miles on that tank of fuel, and has fuel pressure.
I can't really believe that the ICM would cause the the car to die at the same mileage, avery tank. The ICM does seem to be having issues, though. If it was out of fuel, it wouldn't run another 19 miles.
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On one of my cars, the filter sock came off of the fuel pump, and the pump came out of the round metal support at the bottom, and was turned sideways a bit. The car would run out of gas before the tank as empty, and would sometimes stall on hard braking.
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To be safe, replacing the ICM and pulling the tank to check the fuel pump.
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The ICM may have helped a bit, but there were no visible issues in the fuel tank. It needs a drive, to see if it will run through a full tank without dying.
Now back to running hot. Not overheating, but running hot.
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It's worse than before. Backfires, no power, erratic idle, surges, etc.
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Have you tried a new ignition coil? Mine is having a similar problem but started when I put MSD coils on it. I plan to put the original ones back on as soon as I locate them.
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The ICM may have helped a bit, but there were no visible issues in the fuel tank. It needs a drive, to see if it will run through a full tank without dying.
Now back to running hot. Not overheating, but running hot.
If the ICM isn't shielded well, sometimes the RF signal will reach the ECM and cause some erratic running issues.
If you could get a real-time OBD1 scanner and read the CTS temperature, you could compare it to your gauge. When Pat ran a scan on mine, with a 195 thermostat, it was showing 197* and that pretty much agreed with my gauge. With that info, I knew that the rich exhaust wasn't caused by a faulty CTS or a thermostat that was stuck open.
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You don't need a fancy scanner to read a stock V6 Fiero ECM. You can use WinALDL (https://winaldl.joby.se/) and a notebook computer.
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Have you tried a new ignition coil? Mine is having a similar problem but started when I put MSD coils on it. I plan to put the original ones back on as soon as I locate them.
I have 3 coild, but the same should apply. Ixll have to try. The ICM and coild were already replaced once before.
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If the ICM isn't shielded well, sometimes the RF signal will reach the ECM and cause some erratic running issues.
If you could get a real-time OBD1 scanner and read the CTS temperature, you could compare it to your gauge. When Pat ran a scan on mine, with a 195 thermostat, it was showing 197* and that pretty much agreed with my gauge. With that info, I knew that the rich exhaust wasn't caused by a faulty CTS or a thermostat that was stuck open.
The ICM has the factory shielding.
I have TunerPro, which shows lots of data.
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You don't need a fancy scanner to read a stock V6 Fiero ECM. You can use WinALDL (https://winaldl.joby.se/) and a notebook computer.
Supposedly, WinALDL will not work on mine.
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...and my fuel pump failed. Dead, as in doornail. That pump only lasted 3.5 years.