North American Turbocoupe Organization



TBird overloading
superchikn Offline
Junior Member
#1
I've been working on my bird off and on for awhile now trying to figure out whats going on. The car idles great runs great until it starts building boost, then it stumbles and dies. It is hard to refire unless you hold pedal to the floor. It acts like it is flooding.
This that everything that has been replaced or done
throttle position sensor,fuel pressure regulator,idle air control,egr,fuel filter,walboro 190 fuel pump,new sock filter,plugs,wires,distributor,cap,rotor,module,o2 sensor. took the cat loose behind the manifold ran it just to make sure the cat wasnt plugged. Put fuel pressure gauge on it today at idle about 30psi when turbo starts building boost about 40psi and this is when it starts failing. Anyone else have this problem or any suggestions?
Any codes that came up has been taken care of
Always FORD
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TurboCoupe50 Offline
Posting Freak
#2
40 psi is a zero manifold reading(no boost or vac), from that point it should build one psi fuel pressure for each pound of boost, with a max of approx 55psi at 15 lb boost...
1988 Turbo Coupe331 AOD

1972 Comet GT

1969 Fairlane Cobra 428CJ 4-Speed
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superchikn Offline
Junior Member
#3
A friend of mine is at his garage still working on the car and said that the car is pulling the boost like it should until the motor dies and it can't continue to build anymore boost, and he did say it had another code come up (I forgot to mention) that was 42 and 72 which says rich condition and 02 problem (now replaced)
Thanks for responding
Always FORD
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Jeff K Offline
Administrator
#4
A continuous code 42 does NOT mean the O2 sensor is bad, it means the adaptive lean limit has been reached and it is still running too rich.

You need to measure fuel pressure under boost conditions and see if it increases 1:1 with boost. Even with a new FPR, check the vac line to be sure there is no fuel in it from the diaphram leaking.
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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Jeff K Offline
Administrator
#5
CM code 72 could be an IRCM or ignition switch problem, or an intermittent wiring problem.
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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Ricky03 Offline
Senior Member
#6
do the fuel system dianostics test. Fuel pressure should be around 40psi at idle not 30.
88TC :5 speed swap,255 walbo fuel pump, 3" down pipe with 2 1/2"duals, Ported upper and lower intake, ported E-6, Kiben adjustable fuel pressure regulator,T-3 turbo,Forge BPV,Steeda Tri-x shifter,Autometer gauges,Racer Walsh stage #2 cam, Spec stage 3 clutch,Stinger FMIC
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superchikn Offline
Junior Member
#7
Guys, I am the guy working on the car in question, and my friend, the owner has allowed me to log on under his account. To re-hash, all of the above mentioned parts have been replaced very recently. When I installed the Walbro, I replaced the feed line from the pump to the pick-up body, so I am confident it is not leaking. I visually checked the fuel lines under the chassis, and under the hood for kinks and pinches and have not found any. I checked the intake hose from the VAM to the turbo thoroughly for leaks and verified that the support wire is inside. I also checked the rubber couplings on both sides of the intercooler. I checked over the vacuum lines and replaced any that looked suspect. I tested the VAM, and found no dead spots, except when going to total WOT, it would very momentarily read "0" before registering the correct voltage. Not knowing if this was correct, I put in another used VAM, to no avail.
As far as the fuel pressure test, we taped the gage to the windshield and our particular gage registered closer to 30 psi at idle. We drove the car and were able to achieve 5 psi of boost. The fuel pressure gage appeared to register closer to 40 psi. It is difficult to be completely accurate, as we are relying on the stock boost gage, and we can only build boost very briefly before the car dies.
Once the car dies, you have to hold the throttle wide open to start it, and it runs extremely rough for about 3 minutes or so before it will finally clear out and run smooth again at idle.
When not in boost, the car runs perfectly. In neutral (it is a 5 speed) I can hold the engine at 4,000 to 5,000 rpm's, and even rev it to redline, and it acts normally. It will drive normally if you are at light throttle, and not achieving boost. It is only under driving load when you hit boost that it stalls.
Sorry for the long post, just trying to fill in some gaps in info. Jeff, I will try to check that vac line for fuel. What is the adaptive lean limit, and what all could cause that? I have not noticed any ignition switch issues. Assuming the fuel pressure gage is accurate, what would cause the low initial reading, but then the increase along with boost? I am comfortable working on the car, but am still learning all of the 2.3 turbo "lingo" so, if you can spell things out for me, that would be great. Thank you for any help!
John
Always FORD
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Not B Anymore Offline
Administrator
#8
Depending on idle vacuum, with the FPR reference line hooked up the FP at idle should be in the low 30's. Fuel pressure should be at 39-40psi with the reference line disconnected.

So assuming the base FP is 39-40psi (pressure with reference line disconnected (or at 0in/Hg vacuum & 0psi boost)), FP at 5psi of boost should be at 44-45psi if the FPR is functioning correctly. If the gauge was reading 40psi @ 5lbs boost, either the boost, FP, or both gauges are wrong, or the FPR is not working correctly and you're running lean.
Brian Leavitt
'86 TC 5-Speed -- MS2x w/COP | 83 lb. injectors | T3/T4 50 Trim Stage 3 .63AR | Full 3" Exhaust - No Cat | Motorsport FMIC | Ranger Roller | Ported E6 | Walbro 255HP | Kirban | 20psi | 120-amp 3G | 8.8" 3.55 rear | '03 Cobra Wheels
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