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Old 04-30-2021, 04:06 PM   #1
Drunk_Babies
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Default +T boost issue

B230F+T
LH2.2
Red 315cc injectors
15G
3bar FPR
EZK 117 conversion
541 Turbo ECU
Stock MAF
740 Intercooler / Piping
NGK BP7ES @.035 gap
Manual turbo control, max 12-13 PSI
Compression last tested at 170-175# on all cylinders
20lbs vacuum at idle
12 deg. advance timing

I think that's all the relevant info, let me know if I'm missing anything.

Anyways, this thing runs solid- pulls well in almost all situations. The issue I'm running into is during >75% throttle sustained pulls it will always stumble after a few seconds of holding 10-12 lbs boost. Typically this is during a pull from 70 - 100, I'll be cruising at 3k, and as I near 4k and I'm holding boost above 10lbs it will break up and I have to quick get out of the throttle and it's fine.

I'm thinking likely a fuel issue? I don't have any issue running through the RPM range when I'm banging gears but those long sustained pulls in boost don't ever hold on.
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Old 04-30-2021, 06:03 PM   #2
VB242
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Last fuel filter change? Condition of fuel pump? Sounds like it's starving for fuel.
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Old 04-30-2021, 06:22 PM   #3
Drunk_Babies
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Last fuel filter change? Condition of fuel pump? Sounds like it's starving for fuel.
Fuel filter changed a year ago, no idea on the condition of the tank or inline pump. Might just go ahead and replace them.
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Old 04-30-2021, 07:13 PM   #4
soclosenotnear
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Spark plugs gap looks big?
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Old 04-30-2021, 09:38 PM   #5
Drunk_Babies
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Spark plugs gap looks big?
I did test at .030 and it didn't run quite as well + still broke up in sustained boost.
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Old 04-30-2021, 10:59 PM   #6
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You have afr gauge?
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Old 04-30-2021, 11:06 PM   #7
Drunk_Babies
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You have afr gauge?
No, would probably tell me all I need to know though wouldn't it
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Old 05-01-2021, 02:33 AM   #8
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Originally Posted by Drunk_Babies View Post
Fuel filter changed a year ago, no idea on the condition of the tank or inline pump. Might just go ahead and replace them.
The main pumps were usually bulletproof, the intanks and the small rubber hose on the pump not so much.
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Old 05-01-2021, 03:16 AM   #9
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Quote:
Originally Posted by Drunk_Babies View Post
No, would probably tell me all I need to know though wouldn't it
+1 on the AFR gauge.

Later Turbo cars use 337cc injectors (the green 804's) and although they usually have a bit of headroom from my experience when turning up the boost, I'd make sure your AFR looks good throughout the rev range with your injectors.
Could be that earlier Turbo cars use other injectors with less flow, but I'm not sure on that.

Only way to know for sure is a gauge.

Also, do you run custom chips or stock map?
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Old 05-03-2021, 03:11 PM   #10
Drunk_Babies
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+1 on the AFR gauge.

Later Turbo cars use 337cc injectors (the green 804's) and although they usually have a bit of headroom from my experience when turning up the boost, I'd make sure your AFR looks good throughout the rev range with your injectors.
Could be that earlier Turbo cars use other injectors with less flow, but I'm not sure on that.

Only way to know for sure is a gauge.

Also, do you run custom chips or stock map?
Stock fuel & ignition maps.

I think I've got plenty of information to run with here- I'm going to first try dropping the boost down to 8-10PSI max and see if I can get some long heavy pulls in. I took a peek at my fuel pumps, the inline pump looks incredibly old so maybe it's just not flowing well enough. I have both on order so I'll swap those out when they arrive and update this thread with what I find.

Thanks for the help so far guys, wish me luck!
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