North American Turbocoupe Organization



Weird hesitation
KaseyTC Offline
Junior Member
#1
So i am new to the turbo coupe world. Well site of. I was given an 84 that my grandpa had owned since new. The car had been sitting in a garage for 15+ years. I mostly resurrected the beast. Cleaned out the fuel tank, new fuel pumps and filter, plugs and wires (motorcraft). The car runs fairly well, but between 2k-3k rpms it seems to fall on its face. The turbo is building boost but no power it seems. Its not missing at all just a brief delay until 3k rpms and then it takes off. Any ideas?
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Jeff K Offline
Administrator
#2
Even with new fuel pumps, it would be a good idea to check fuel pressure to be sure it i the correct base pressure (39 psi engine running vac hose off FPR) and that pressure climbs 1:1 with boost(i.e., at 10 psi boost FP should be 49 psi).

What plug gap did you use? Does engine temp effect the problem?

Have you verified correct base ignition timing? Are you getting timing advance?
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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KaseyTC Offline
Junior Member
#3
Thanks for the info. The fuel pressure was around 39 at idle. I have not checked it under boost. I did disconnect the vacuum line at the pressure regulator.

It does seem to act worse when cold. When it warms up it gets a little better but is still very noticeable.

I am leaning towards timing. Does the vam have anything to do with advancing timing? I have not checked base timing yet.

The plugs were gapped at .032

I am going to check a few more things tonight. I appreciate the help.
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Jeff K Offline
Administrator
#4
VAM is a major input to the PCM engine load calculation, which effects timing.

Check base timing (SPOUT plug disconnected). Stock is 10 deg BTDC, but many of us run a little more than that, like 12 or so deg. At idle with the SPOUT plug connected and engine at operating temp, timing will be 25 to 30 deg BTDC and will jump around a few degrees (PCM used timing advance adjustment to hold a steady idle speed).
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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KaseyTC Offline
Junior Member
#5
Car was parked for the winter. I have it back out so I'm going to try and dive into this issue again. I am going to check timing today. More information to the story, the car is only getting about 12mpg. Maybe 15 freeway. I don't know if that information helps any.
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Jeff K Offline
Administrator
#6
Sure you dont have dragging brakes? 12 mpg is horrible. I dont think 84 has a CEL. Run the complete code test (KOEO, CM, and KOER) and report back with the results. I
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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