North American Turbocoupe Organization



3 computers later- still a code 77
boostaddict Offline
Junior Member
#1
I've recently replaced my computer, but the previous computers also gave me a code 77 as well. I've got the new TPS adjusted to .934

I replaced the TPS because the old unit had a dead spot at about 3/4 throttle. I was hoping a new sensor would fix this, but the new TPS does the same thing. The multi meter I use is a digital auto ranging meter set to VDC.

I did a search, and it appears as if the VAM could be out of calibration; causing a code 77? How do you check/adjust the VAM? The car runs great, and no KOEO codes, only 77 with the KOER.
1988 Turbo Coupe, 5 speed, LS diff
1989 F350 4X4, 5 speed, Banks turbo
1978 Bronco, G 4 speed, 400, chopped top (summertime ride)
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Pete D Offline
Administrator
#2
code 77 means the system did not detect a goose of the throttle at the proper time. Did you goose it to WOT quickly at the right time?

http://www.tbirdheritage.com/turbocoupe/...nstepid=M1

77 is not a VAM code for 87-88 TCs
Pete Dunham


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boostaddict Offline
Junior Member
#3
Yes, the throttle was floored twice during the KOER test. I've done it while the engine had the RPM running high, and I've also done it right when the RPM comes down. When would you say the "right time" is? I've tried nailing it slowly, hitting it fast, etc- no change; I still get a code 77.

I'd like to run a resistance test from the TPS pigtail to the EEC pigtail. I'm wondering if there is a problem with the wires connecting the TPS to the computer. I notice that the power and reference wires that run into the TPS connector are real wavy looking- like a ruffles potato chip. It's like the insulation has gotten real hot at one time. There are two other wires running to the EEC pigtail that look the same. I also notice that there is a little splice by the IAC valve, with the plastic piece saying "Diode". If there's a diode in the TPS or the IAC circuit, then what's the purpose of it? Can you test a diode with the contunity tester on the DMM? I ordered a "factory original" wiring schematic for 40 bucks- I should have it tomorrow.

This electrical diagnostic bs is a beating! I guess I shouldn't complain though, at least it runs good. (finally)
1988 Turbo Coupe, 5 speed, LS diff
1989 F350 4X4, 5 speed, Banks turbo
1978 Bronco, G 4 speed, 400, chopped top (summertime ride)
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Pete D Offline
Administrator
#4
From Jeff K's article on retrieving codes ( http://www.turbotbird.com/techinfo/Retri..._codes.htm )

Quote:Soon after starting the test, the engine ID code will flash. This code is ½ the number of cylinders, so on a Turbo Coupe, two flashes will be seen. After a while, the idle will settle down, and a single flash will be seen. This is the Dynamic Response Code. When this flash is seen, tap the brake to exercise BOO (Brake on / off) circuit, and do a brief wide open throttle to bring the RPM up to 3000 to 4000. This tests the TPS and the VAF (vane air flow) meter.
Pete Dunham


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Jeff K Offline
Administrator
#5
You must do the WOT goose within a few seconds of the single flash (the dynamic response code). You cant do it at a random time during the KOER test.
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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boostaddict Offline
Junior Member
#6
Weird- I swear that when I first got the car, I wasn't getting the 77, even though I was flooring it at the times I described above.

Geez- I feel like a jackass. Thanks both of you; thanks so much for helping ALL of us.
1988 Turbo Coupe, 5 speed, LS diff
1989 F350 4X4, 5 speed, Banks turbo
1978 Bronco, G 4 speed, 400, chopped top (summertime ride)
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