North American Turbocoupe Organization



Fresh rebuild problems (Mr. Leavitt read me)
FastN'Fried Offline
Senior Member
#1
Hello natoers :beer:

It was a fine day today. After 4 months of waiting I got to drive my tbird! Makes power and boosts fine under 4000 rpms. But over that she falls flat. Sounded as if it was running out of fuel, I suspect a bad pump or filter.

It's a 100% stock 88' bird with the exception of .030 over CPs and ARP bolts/studs. It also has a MLS head gasket.

I did a boost leak check and all sounded sealed.

This was part of the problem before I did the rebuild. The engine feels much stronger now but I'm still missing something!

It has a fairly new motorcraft cap, rotor, wires, and new coppers gaped at .032"

Thanks guy, I'm heading back out to tinker.
1988 Canyon Red Turbo Coupe
Carrillo pistons +.030, ARP hardware, 3in exhaust, and a magnaflow
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Pete D Offline
Administrator
#2
Do the fuel system diagnostics in the Old Tech Articles
Pete Dunham


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FastN'Fried Offline
Senior Member
#3
Thanks Pete, I'm going to have to figure out how to make my pressure gauge longer :/

Heres a video of my idle on the vac gauge

https://youtu.be/nAMkmvRpi5w
1988 Canyon Red Turbo Coupe
Carrillo pistons +.030, ARP hardware, 3in exhaust, and a magnaflow
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Pete D Offline
Administrator
#4
The engine is down 2 to 4" from desired vacuum at idle. Was the engine at least warm? Was idle at the recommended 900 - 1000 rpms?
Lots of things affect idle. Since yours was fairly steady and only down slightly, I'd look for minor leaks, check cam and ignition timing. Have you pulled the codes.

I think I added some pieces of small diameter copper pipe to mine to get it longer. I'll have to dig it out later today and see.
Pete Dunham


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FastN'Fried Offline
Senior Member
#5
I'm look for some trained ears to confirm a broken valve spring :/

https://youtu.be/AVnbgyqghNQ

https://youtu.be/p3rYRMDlCdU
1988 Canyon Red Turbo Coupe
Carrillo pistons +.030, ARP hardware, 3in exhaust, and a magnaflow
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Jeff K Offline
Administrator
#6
If a valve spring were broken, you would have a BAD miss, not just lower power at high RPM. As Pete said, recheck ignition and cam timing.
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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Ramos617 Offline
Member
#7
That definitely look like the cam is a tooth off
I've always had about 20" of vacuum with the stock and Ranger cam
I like to use the string method to make sure my cam is on point and the recheck the timing,
1987 T-Bird
Too much stuff to list
Running better than ever
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FastN'Fried Offline
Senior Member
#8
Thanks guys I'll check timing too!
1988 Canyon Red Turbo Coupe
Carrillo pistons +.030, ARP hardware, 3in exhaust, and a magnaflow
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FastN'Fried Offline
Senior Member
#9
I found a post by B from 2010 having the same exact symptoms as I'm having and cured it with speedway dual springs..

Could the springs be weak but not broken? I'm not sure if that would explain my shakey vacuum reading. Would the car run if it was off a tooth? It seem to drive pretty normal until I hit that magic number.
1988 Canyon Red Turbo Coupe
Carrillo pistons +.030, ARP hardware, 3in exhaust, and a magnaflow
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Pete D Offline
Administrator
#10
The car could run a tooth off. It could run smooth but feel down on power.

Weak springs will cause the engine to break up at some higher rpm and it will take several seconds to settle down once you back off.
The engine will usually start to break up at the same rpm each time

How many miles on the old springs? If the block needed refreshed,ie rings or bore job, pistons and rings etc, then good chance the valve springs should have been replaced also.

I put in a picture of one of my fuel pressure gauges that was modified to add a little length. I just bought already threaded copper pipe and an elbow, installed as shown. I would use plumbers goop instead of the tape I used. Also I would recommend a little longer pipe than what I used. This setup allows me to get the gauge under the windshield wiper and be view-able from the driver's seat


Attached Files Image(s)
   
Pete Dunham


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