North American Turbocoupe Organization



88 Turbo Coupe stutters
EveryDayBirdStuff Offline
Junior Member
#1
I have an 88 Bird 2.3L the car runs great after warmed up or alternator is unplugged. I have pulled codes, found no codes. Checked grounds, all are fine. Played with timing, nothing. 

Started testing, tried new distributor, checked fuel psi, and spark(inline tester) and found that it was losing spark at the coil on cold start-ups. I am at a lose for this, it is beyond me and an auto-mechanic of 30+ years of experience.
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Jeff K Offline
Administrator
#2
What is the alternator output voltage at idle with no electrical loads on the system, and at 2000 RPM with high electrical load like all lights on, heater blower on high, rear defroster on?

Possible bad diode or diodes in the alternator causing large ripple voltage in the system. The electronics like darn near straight DC with very small ripple, I would look at the ripple in the alt output with a scope (best way) or use a DMM on AC volts to see what the magnitude of the ripple voltage is (acceptable but not super accurate way). Ripple should be under a few tenths of a Volt under both low and high electrical loads.
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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EveryDayBirdStuff Offline
Junior Member
#3
DC Voltages at idle, 14.34 at alternator and 14.15 at battery(no loads) with loads at idle 14.3 at alternator and 13.4 at battery(loads a/c, radio, rear defrost and headlights).
DC Voltages at 2000RPM, 14.25 at Alternator and 14.13 at battery(no loads) with loads 14.27 at alternator and 14.3 at battery(loads a/c, radio, rear defrost and headlights).
AC Voltages at idle, 30.5-30.8 at alternator and 30.1 at battery(no loads) with loads at idle 30.3 at alternator and 30.3 at battery(same loads as DC tests)
AC Voltages at 2000RPM, 30.4 at alternator and 30.1 at battery(no loads) with loads 30.5 at alternator and 30.5 at batter(same loads as DC tests)
I hope this is enough information. Going to be looking into the inline fuse links and battery grounds. Sorry for the late reply.
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Jeff K Offline
Administrator
#4
What are the units on the AC volts? Millivolts I hope. Max AC ripple volts under all load conditions should be under .2 V. If volts suspect bad diodes in the alternator. Very unusual to have high voltage drop between alt and batt under low loads and low voltage drop under high load.
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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BigJake Offline
Junior Member
#5
Last month my car would have a dead battery sometimes, after a jump start the car would start the next day but after a few day is was dead again.

I run the Pimp X ECU and voltage would fluctuate between 11 volts to 14 volts on my all in one gauge. Replaced the alternator and voltage stays at 13.7 volts.

If you replace the alternator also install a new pigtail too.
1987 Thunderbird Turbo Coupe 5 speed Boosting 23 PSI
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EveryDayBirdStuff Offline
Junior Member
#6
Millivolts, I was checking the fuse able links around the starter solenoid and found two of the links burnt. Working on those now, should know something later today if the weather holds.
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EveryDayBirdStuff Offline
Junior Member
#7
Fixed the fuse able links and now its not stuttering on start up like before. But now I cant rev the car without it stuttering or shutting off. But with the alternator unplugged it runs fine. Going to check timing and grounds tomorrow. Will have voltage info in the morning.
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firebirdparts Offline
Member
#8
This is a new one on me. Looking forward to hearing the results. I can at least imagine that you have a bad diode and the car just won't run like that, but I have never seen that diagnosis.
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EveryDayBirdStuff Offline
Junior Member
#9
The burnt/broken links did fix the extreme stutter, but now I can not drive the car without having to wait for 10-15 mins for the car to warm up. If not it stutters to the point it shuts off. What is the base timing for the car and where are the temp sending units?
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Jeff K Offline
Administrator
#10
Is the CEL on? Does the CEL even work? It should come on with the key in RUN but engine off.
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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