North American Turbocoupe Organization



Creating Boost in Neutral
Buck Choklit Offline
Member
#1
A couple of weeks ago my father and I changed the timing belt and valvecover gasket. In the process we screwed up the timing belt but got the car back into almost stock running order.

Here is the weird thing, before we did this, when I would rev the car up, I would see maybe 1psi of boost at most. Now I can rev it up and see 15psi. When driving, it's almost impossible to not get into boost. Driving before the timing belt replacement, I didn't see boost unless I was 1/2 to 3/4 throttle. Now I see boost starting to build 1/4 throttle at 2k RPM. It's really killing my gas mileage and I'm wondering what you fine folks think.
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Joe F Offline
Posting Freak
#2
Sounds to me like the cam timing isn't right.
JR's Place - My '87 Turbocoupe
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Jeff K Offline
Administrator
#3
Either cam timing is off, or ignition timing is WAY retarded. Setting the cam timing correctly on these motors can be a PITA, especially if it is your first time doing it. Becomes much easier by the 5th or 6th time Smile
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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k_liff's88 Offline
Member
#4
I thought you had to have a load on the motor to create boost. My 88 doesn't create any just revving it up.
Bone stock except for CAI, Hurst Shifter and a Walbro 255 fuel pump. Gillis 2 stage on the way !
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martin0660 Offline
Posting Freak
#5
Quote:Originally posted by k_liff's88:
I thought you had to have a load on the motor to create boost.
Its not so much of "put a load" on it, it more about passing air through it. Thats part of why a two step rev limiter lets us build boost on the line, we have the throttle wide open, passing air. This is overly simplified, but its all about exhaust flow on the turbine.

Bob Myers
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Buck Choklit Offline
Member
#6
Alright, today I set the timing and I know that the ignition timing is dead on. Also, the cam timing is dead on as well. This is really bugging me. When I drive I have to keep an eye on my aftermarket boost gauge and keep it under 0hg to get somewhat decent gas mileage. I went from getting 350 miles per tank, to about 190. I build 17# of boost in neutral, but the car is running smooth, pulling 18hg @ idle, but I've noticed it cackles (backfires out of the exhaust) alot on decel when I leave it in a gear.

Could I have the ignition timing 180 degrees out? Help would be appreciated. Thanks alot guys.
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Ryan H Offline
Posting Freak
#7
How open is your exhaust? I ask this because when I ran an open downpipe and no mufflers, it would sound like it was backfiring on decel in gear. I've heard a couple 2.3Ts and other motors with straight pipes and they all do that. I think its the car trying to "idle" when the throttle plate is closed/throttle position sensor reads that your foot is off the gas but the revs stay up.. thats just my theory though.

My car builds 14-15 PSI in neutral also if I go WOT and my timing is also dead on. Are you sure your fuel gauge/sender isn't just screwed, because mine goes to near empty after about 190-200 miles!
'88 TC Smile Walbro 255HP, Stinger FMIC, PIT BOV, Pro 5.0, Kirban, RR cam, FRPP strut tower brace, T3
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Buck Choklit Offline
Member
#8
I'm going to try something tomorrow that I think may fix the problem. I'm positive my fuel gauge is in working order. Before this problem, I didnt have to fill up for 2 weeks, now it's only a matter of a couple of days before I need gas. I barely ever get into boost to boot.
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PetzJC Offline
Senior Member
#9
Sounds like the cam is way advanced.....advancing the cam shifts the power band down to a lower rpm.
Former owner of 88 Silver T/C, loaded (except leather & A/T), original owner, 294,815 miles!!!
K&N, Gillis(18 psi), SVO roller #1, big SS valves, ported intake, head, & exhaust.
Short block & turbo original/untouched, spec-II/III clutch combo.
Polyurethane bushings throughout, Goodyear GT-HR 235/55R16
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Jeff K Offline
Administrator
#10
Yup, cam timing is still 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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