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Old 10-11-2018, 04:21 PM   #1
kislov
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Default 760 '84 B23ET - cut off problem

Hello there I have a question that was asked quite a lot... but I have never seen somebody reporting a solution.

My beloved 760 1984 2.3 Turbo with B23ET and M46 has one issue: power cuts off strongly for a second on hard accelerations. The higher is current gear (3rd, 4th or 5th), the earlier (lower revs) it will cut off. If we talk about 3rd gear and WOT, it will cut off on about 4000RPM.

I've removed overboost protection (fuel cut mod), now I can have a boost in red zone of boost gage.
I've tested the fuel pressure: 5 bar out of pump and 3 bar in fuel rail. It is not a fuel.
It does cut off really hard, so that's not the air leak/turbo.

Mods:
- Wastegate with 4 turns shortened rod (around 0.4 more boost as far as I understand)
- Cut springs (2 coils front, 3 rear)
- Welded diff
- Vintage wooded steering wheel
- New MAF sensor
- Stripped interior

Could it be something with the ignition? Like hall sensor or may be knock sensor?

P.S. the issue could be reproduced even before adding boost. But the revs should have been higher for 3rd gear example.
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Old 10-11-2018, 06:02 PM   #2
Fa182
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How much boost are you running? Stock turbo? How is the AFR looking? Maybe the injectors are running out of fuel?
What condition is the turbo intake pipe in? It likes to collapse under boost when it's gotten soft.
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Old 10-12-2018, 01:54 AM   #3
kislov
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Originally Posted by Fa182 View Post
How much boost are you running? Stock turbo? How is the AFR looking? Maybe the injectors are running out of fuel?
What condition is the turbo intake pipe in? It likes to collapse under boost when it's gotten soft.
Stock Garrett turbo, stock boost + 4 turns of wastegate rod, AFR looks good, green injectors feel good as well. Intake pipe is brilliant idea! I can imagine how it collapses. I think that removing air filter may help to validate your idea. Will report back soon, thanks.
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Old 10-12-2018, 03:54 AM   #4
kislov
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Removed the air filter and tested the car without it. Well, the problem is not solved completely but looks like that's the right direction. Cut-offs are appearing not as often now. I've discovered that the intake pipe is not oem and has strange tight bands. Looks like it can still collapse even without an air filter. I'll try to replace the pipe.
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Old 10-12-2018, 08:55 AM   #5
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Didn't happen to me yet luckily, but I read it a lot on here causing similar problems and symptoms and probably gets overlooked a lot of times.
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