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Author Topic: Boost blip 13 lbs then 0  (Read 505 times)

July 14, 2018, 11:39:24 am

Gizmoman

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Boost blip 13 lbs then 0
« on: July 14, 2018, 11:39:24 am »
I've had a lot of issues with boost gauges but I don't want to go into that now. I finally fixed the issues and trust what I'm seeing. When getting on the freeway and go WOT, boost climbs steadily till it hits 13-15 psi. It hen blips to near zero and the engine stumbles. My target boost pressure is 20 psi and was hoping to set that using the fuel screw and my right foot  ;)
The turbo is the Holset HE200WE and I have the dump-gate zip-tied shut. I have done a pressure test using compressed air into the intake and can't find any leaks other than air seeping past the rings.
 Just to be clear, the boost drops off very quickly (like a switch) when it hits somewhere around 13-15 psi. If I keep my foot into it, the engine seems to stumble and the EGT's climb rather quickly. Don't know if it's smoking at this point because my mirror's aren't all that great or my eyes are too old.

I have messed with the LDA but don't recall where it is at present.

Any ideas on what the issue may be?


Jim W - 82 Vanagon Westy - AAZ 1.9, Mild head port, Cummins Holset HE200WE turbo, Frozen Boost WAIC, 10" Charge-pipe intake, Ball bearing IM shaft, Giles Pump, 215/70R16, AAP 5 speed Trans. 22 lbs max boost

Reply #1August 02, 2018, 06:21:07 pm

burn_your_money

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Re: Boost blip 13 lbs then 0
« Reply #1 on: August 02, 2018, 06:21:07 pm »
If you back off the throttle for a bit will it do it again right away?

How's your fuel supply?
Tyler

Reply #2August 05, 2018, 10:11:36 pm

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Re: Boost blip 13 lbs then 0
« Reply #2 on: August 05, 2018, 10:11:36 pm »
It acts exactly like it did when I was running the 12V fuel pump which had something caught in it's filter.  I removed the pump entirely and ran a new fuel line. I also replaced the fuel filter just a few days ago.
It feels and acts like its running out of fuel at around 13-15 psi. I've turned up the fuel screw enough that it puffs a bit of smoke when I rev it. Also enough that I had to re-mount the throttle lever to get the idle back to 850. Turning in the fuel screw moved the issue from 12 PSI to higher but it's still there.

I still get a quick climb to 1300 F if I hold my foot into it - not floored, but enough to maintain speed up a grade. It's a shame because I know the turbo can provide more air and would keep the EGTs lower.
Jim W - 82 Vanagon Westy - AAZ 1.9, Mild head port, Cummins Holset HE200WE turbo, Frozen Boost WAIC, 10" Charge-pipe intake, Ball bearing IM shaft, Giles Pump, 215/70R16, AAP 5 speed Trans. 22 lbs max boost

Reply #3August 06, 2018, 08:54:20 am

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Re: Boost blip 13 lbs then 0
« Reply #3 on: August 06, 2018, 08:54:20 am »
Do you have a fuel pressure gauge mounting near the inlet to the pump per chance?
Tyler

Reply #4August 06, 2018, 09:01:53 am

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Re: Boost blip 13 lbs then 0
« Reply #4 on: August 06, 2018, 09:01:53 am »
Just to clarify, there is no pump between the tank and the IP (I had one but was told it wasn't needed - it was causing issues due to a tiny filter on the inlet). So there would be no pressure - only vacuum :)

Do you think I need a pump and if I do can you recommend one?
Jim W - 82 Vanagon Westy - AAZ 1.9, Mild head port, Cummins Holset HE200WE turbo, Frozen Boost WAIC, 10" Charge-pipe intake, Ball bearing IM shaft, Giles Pump, 215/70R16, AAP 5 speed Trans. 22 lbs max boost

Reply #5August 07, 2018, 09:41:20 am

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Re: Boost blip 13 lbs then 0
« Reply #5 on: August 07, 2018, 09:41:20 am »
I don't think you need a pump but they can help. They can also cause issues as you've found.

Are you able to hook a vacuum gauge up then? How about running a clear, extra long fuel hose so you can monitor for air in fuel under high demand while driving (or have a helper do it, or a video camera)?

This is an AAZ right?
Tyler

Reply #6August 07, 2018, 11:18:22 am

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Re: Boost blip 13 lbs then 0
« Reply #6 on: August 07, 2018, 11:18:22 am »
An open engine lid is noisy as all heck but makes it really easy to monitor the engine from the back seat while someone else drives.
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Reply #7August 07, 2018, 11:35:32 am

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Re: Boost blip 13 lbs then 0
« Reply #7 on: August 07, 2018, 11:35:32 am »
Yes, its an AAZ (see my sig).
I'm not sure how to monitor fuel delivery other than how it "feels" which is subjective. I am pretty confident that that is what it is though - not enough fuel. Last year I drove from San Diego to Eureka with some crud blocking the intake port on the 12V pump (which I have removed). It acted exactly like it does now - doing the same stumble and boost drop, only it did it at between 6-8 psi of boost instead of the current 13-15 psi.
That was over 12 hours of pure hell - couldn't got over 50 MPH unless I was going downhill. I removed the 12V pump and replaced the fuel line in Eureka.

I'm thinking I need to turn the fuel screw in more, get a new LDA pin and grind it to deliver less fuel at the bottom and more fuel at the top (if you know what I mean).

I have other issues to solve as well like fixing the oil leaks. I finally fixed the valve cover leak but I may need to replace the intermediate shaft seal and replace the hoses to the remote filter and cooler with hydraulic hose and fittings.

It runs like a top though (except for the stumble).
Jim W - 82 Vanagon Westy - AAZ 1.9, Mild head port, Cummins Holset HE200WE turbo, Frozen Boost WAIC, 10" Charge-pipe intake, Ball bearing IM shaft, Giles Pump, 215/70R16, AAP 5 speed Trans. 22 lbs max boost

Reply #8August 26, 2018, 10:30:01 pm

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Re: Boost blip 13 lbs then 0
« Reply #8 on: August 26, 2018, 10:30:01 pm »
Making and progress on this?
Tyler

Reply #9August 27, 2018, 01:00:24 am

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Re: Boost blip 13 lbs then 0
« Reply #9 on: August 27, 2018, 01:00:24 am »
Thanks for asking. Actually I haven't done anything - just living with it. I want to turn the fuel screw in a bit more but I'm already getting some smoke at the bottom end. I may put a stiffer spring in the LDA and then try turning the fuel screw in a bit more. I'll definitely post my findings when I get to it. It's fairly clear it's a fueling issue.

Jim
Jim W - 82 Vanagon Westy - AAZ 1.9, Mild head port, Cummins Holset HE200WE turbo, Frozen Boost WAIC, 10" Charge-pipe intake, Ball bearing IM shaft, Giles Pump, 215/70R16, AAP 5 speed Trans. 22 lbs max boost

Reply #10August 27, 2018, 02:52:38 am

zuhandenheit

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Re: Boost blip 13 lbs then 0
« Reply #10 on: August 27, 2018, 02:52:38 am »
But your EGTs jump when boost drops, right? Even supposing there's a fueling issue, if you're getting enough fuel to push EGT to 1300, there should be plenty to keep your turbo spooled . . . right?

I must be missing something.

I've had more problems with injector pumps and turbos than anything. I now own like three of each and run a new turbo and Giles pump. Previously I was chasing around a number of problems.

Aren't you running a 1.6td Giles pump or something like that?

Sorry to state the obvious, but - have you tried a new fuel filter?

Reply #11August 27, 2018, 07:45:30 am

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Re: Boost blip 13 lbs then 0
« Reply #11 on: August 27, 2018, 07:45:30 am »
It is a 1.6 Giles pump - Giles built it for a K-14 and yes, the EGTs rise quickly when the boost drops off. I changed the fuel filter two weeks ago - issue is still there.
The engine runs very strong up to 15 lbs. I certainly can't afford to have him go through it again.
I really don't understand the pump internals enough to know any other adjustments I could make. Turning the fuel screw in made a huge difference and I could go more, but I don't want smoke. The LDA is fairly simple and I figured if I could add more fuel while keeping it restricted at the bottom end (with a stiffer spring) I might achieve my goal.
Also, it's obvious Giles ground the LDA pin and it's quite aggressive (deep). The grind ramp also starts pretty quickly at the top and goes deep enough that there's not much material left at the bottom.

As I type this, I realize that the smoke is there because the turbo hasn't had time to spool up yet. Adding a stiffer spring and also turning the fuel screw in isn't going to help - I'll still get smoke. In other words, your right, there is something else going on or the pump simply can't provide enough fuel period.

As I mentioned earlier, I drove for many miles with a piece of crap stuck in the pre-filter to a 12V pump I had installed.  It acted exactly the same as it does now but the 15 lb cutoff was around 6 - it was a brutal trip. I removed the pump when I reached my destination and the issue moved back up to 15 lb.
Jim W - 82 Vanagon Westy - AAZ 1.9, Mild head port, Cummins Holset HE200WE turbo, Frozen Boost WAIC, 10" Charge-pipe intake, Ball bearing IM shaft, Giles Pump, 215/70R16, AAP 5 speed Trans. 22 lbs max boost

Reply #12August 27, 2018, 08:10:29 am

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Re: Boost blip 13 lbs then 0
« Reply #12 on: August 27, 2018, 08:10:29 am »
I'd try it with another electric pump and see what happens. To me it sounds like you are getting air in the pump and the timing is dropping off causing smoke, EGTs and lack of power.

Are you saying your EGTs are 1300 when this happens or that 1300 is the max you can hit?
Tyler

Reply #13August 27, 2018, 12:55:00 pm

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Re: Boost blip 13 lbs then 0
« Reply #13 on: August 27, 2018, 12:55:00 pm »
Here's the scenario (just went for a quick spin to verify). . .
I'm getting on the freeway and have it WOT in 4th gear (I have a 5 speed). The boost climbs steadily till it hits around 13 psi - EGTs are around 950-1000 at this point. Instantly the boost drops to zero and the engine acts like it just quits. Also, the EGTs climb pretty quickly to 1250 so I back off the throttle. I can repeat this over and over.  I can't tell how much I'm smoking at this point and if I am, it's not excessive. I would rather it not smoke at all though but it is a diesel ;)
Jim W - 82 Vanagon Westy - AAZ 1.9, Mild head port, Cummins Holset HE200WE turbo, Frozen Boost WAIC, 10" Charge-pipe intake, Ball bearing IM shaft, Giles Pump, 215/70R16, AAP 5 speed Trans. 22 lbs max boost

Reply #14August 27, 2018, 02:23:17 pm

zuhandenheit

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Re: Boost blip 13 lbs then 0
« Reply #14 on: August 27, 2018, 02:23:17 pm »
Here's the scenario (just went for a quick spin to verify). . .
I'm getting on the freeway and have it WOT in 4th gear (I have a 5 speed). The boost climbs steadily till it hits around 13 psi - EGTs are around 950-1000 at this point. Instantly the boost drops to zero and the engine acts like it just quits. Also, the EGTs climb pretty quickly to 1250 so I back off the throttle. I can repeat this over and over.  I can't tell how much I'm smoking at this point and if I am, it's not excessive. I would rather it not smoke at all though but it is a diesel ;)

Okay, I think I get it. I was imagining that boost cut and EGTs jumped immediately, which of course wouldn't suggest a fueling problem.

But it sounds like your fueling cuts out for just a moment and comes back faster than you can achieve a fueling-appropriate boost level.

Are you pretty sure you don't have any fuel leaks / air in your lines?

If I were you and couldn't solve the problem, I'd buy a cheap but known-good IP and try it. It would be hard to eliminate the IP otherwise. And it's nice to have a spare. if I could get one of my several spares working, I'd offer to send it to you to try, in exchange for shipping costs. Unfortunately I only have one pump in good condition.

You removed your lift pump? Maybe try putting another good one on.





« Last Edit: August 27, 2018, 02:25:48 pm by zuhandenheit »

 

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