North American Turbocoupe Organization



TFI Problems?
P-Bizzle Offline
Junior Member
#1
I have a 1988 TC (MT)

The issue started a few days ago, the car kept stalling anytime I pushed the clutch in unless I kept my foot on the gas.

Then two days ago the car would not start, It would just crank, like there was no spark. After running into this on my 5.0, I replaced the module both with a known good MSD TFI module from my 5.0 (AT) and still nothing, then with an aftermarket replacement (Duralast), and now the car will start but will not run for more than a few revolutions.

I'm completely lost, any suggestions on where to go from here?
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P-Bizzle Offline
Junior Member
#2
I've also checked codes, One code was for throttle position sensor low voltage, (In my experience with the 5.0 it will still run but will hesitate on throttle application) and the other code was for the O2 sensor stuck lean. The car has 178k miles on it. I have a feeling the fuel pump is dying and will check fuel pressure tomorrow.
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anasazi4st Offline
Senior Member
#3
(09-19-2021, 06:24 PM)P-Bizzle Wrote: I've also checked codes, One code was for throttle position sensor low voltage, (In my experience with the 5.0 it will still run but will hesitate on throttle application) and the other code was for the O2 sensor stuck lean. The car has 178k miles on it. I have a feeling the fuel pump is dying and will check fuel pressure tomorrow.

I think the Throttle Position Sensor Low Voltage could be caused by not “goosing” the gas pedal during the Dynamic Response Test, but perhaps I’m confusing that with the Knock Sensor.

Anyone?
Another proud dues-paying member.

1987 Turbo Coupe w/T5OD, 8.8 axle, grey smoke; most options. Got it in 1991 with 41K miles: 3 turbos, 2 heater cores, 1 T5OD full rebuild, 5 clutches, 1 head gasket, 2 Teves II ABS units, etc. later....
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JT Offline
Posting Freak
#4
You mean Code 63? If so, it's not part of the interactive test. It could either mean the TPS voltage is too low or there's a signal/circuit issue between TPS and EEC or with the TPS itself. The code can make the EEC go into alternate mode.

Not quite clear on the RPM issue. Are you saying it will run with some throttle or not? Make sure the TPS voltage is set correctly, then check fuel pressure and spark.
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P-Bizzle Offline
Junior Member
#5
(09-20-2021, 02:07 AM)JT Wrote: You mean Code 63? If so, it's not part of the interactive test. It could either mean the TPS voltage is too low or there's a signal/circuit issue between TPS and EEC or with the TPS itself. The code can make the EEC go into alternate mode.

Not quite clear on the RPM issue. Are you saying it will run with some throttle or not? Make sure the TPS voltage is set correctly, then check fuel pressure and spark.
It will run longer with some throttle, but still will die within 30 seconds
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Jeff K Offline
Administrator
#6
I assume the lean code you got was a code 41? If so, the most likely cause is a vacuum leak, with a fuel pressure issue being a possibility. If fuel pressure is low when you check it (should be 39 psi with vac reference line to regulator disconnected).

LOTS of possibilities for vac leaks.... split or disconnected vac hoses, failed intake or TB gaskets, PCV valve stuck fully open, etc.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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P-Bizzle Offline
Junior Member
#7
(09-20-2021, 04:21 AM)P-Bizzle Wrote:
(09-20-2021, 02:07 AM)JT Wrote: You mean Code 63? If so, it's not part of the interactive test. It could either mean the TPS voltage is too low or there's a signal/circuit issue between TPS and EEC or with the TPS itself. The code can make the EEC go into alternate mode.

Not quite clear on the RPM issue. Are you saying it will run with some throttle or not? Make sure the TPS voltage is set correctly, then check fuel pressure and spark.
It will run longer with some throttle, but still will die within 30 seconds

Just Checked the TPS with it hooked up today. 5v reference is good, as well as it has a full sweep between .5-4.5V, so Im guessing the ECM just is choosing to ignore it lol.
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P-Bizzle Offline
Junior Member
#8
(09-20-2021, 06:36 PM)Jeff K Wrote: I assume the lean code you got was a code 41? If so, the most likely cause is a vacuum leak, with a fuel pressure issue being a possibility. If fuel pressure is low when you check it (should be 39 psi with vac reference line to regulator disconnected).

LOTS of possibilities for vac leaks.... split or disconnected vac hoses, failed intake or TB gaskets, PCV valve stuck fully open, etc.

I will get around to checking fuel pressure soon. Just need to steal a gauge from work. Have a feeling either the FP was dying or Fuel filter is clogged. But I can hear the pump prime when I can hit the key so I know its still at least getting power.
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Mikey97D Offline
Member
#9
(09-20-2021, 10:25 PM)P-Bizzle Wrote:
(09-20-2021, 06:36 PM)Jeff K Wrote: I assume the lean code you got was a code 41? If so, the most likely cause is a vacuum leak, with a fuel pressure issue being a possibility. If fuel pressure is low when you check it (should be 39 psi with vac reference line to regulator disconnected).

LOTS of possibilities for vac leaks.... split or disconnected vac hoses, failed intake or TB gaskets, PCV valve stuck fully open, etc.

I will get around to checking fuel pressure soon. Just need to steal a gauge from work. Have a feeling either the FP was dying or Fuel filter is clogged. But I can hear the pump prime when I can hit the key so I know its still at least getting power.
Add checking the connector to the inertia switch especially if it is losing fuel pressure.   I was recently chasing a similar problem and found my inertia switch connector had gotten loose and began melting.
1988 TC, 5 spd, Stinger 3" Exhaust, Schneider Roller Cam, -4° Cam Pulley, Cone Filter, Gilles Boost Control Valve set at 17 psi, Walbro 255 lph, CHE Rear Lower and Upper Control Arms, Braided Brake Lines, Hawk HPS 5.0 Front and HPS (F) Rear, CRES Inserts in front calipers, and '93 Cobra Wheels with General 235/50R17 Tires.   
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