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M35 Boost Spike/creep

bigkevracer

By bigkevracer,
in Four Door Family & Wagoneers

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bigkevracer Grand Master

bigkevracer

Posted
Posted

I figured I'd start a new thread for this rather than clog up the "What did you do to your Stagea thread".

I've had issues with boost since I had the car tuned. They had trouble getting it to make more than 7PSI, then after adjusting the EVC (Which they had no experience with), it made 15PSI, but then dropped down to 7PSI up top.

They blamed the wastegate actuator, and I grabbed Scotty's wastegate mod.

But from then on, I was having issues with boost spike/creep, which I wasn't having before. EVC wouldn't hold boost to what it was set to (16.5PSI), and would spike to 19-20PSI.

Installed Scotty's wastegate mod yesterday, changed minimum boost pressure to new wastegate pressure (15PSI), and away I went.

Spiking/creeping continued.

Read everything I could online about the HKS EVC6 to see if it was a setup issue. Found a couple of tricks with setting the offset, and reread the setup instructions.

Went out this morning and adjusted the offset. First set it to 130%, car hit 24PSI, despite being set at 15PSI wastegate, 16.5 target boost. Then set the offset as low as 40%, car hit 20PSI.

Learnt in the book I could turn the EVC off but use it to monitor boost. Did this, so should be getting wastegate pressure I think? Was hitting 19.4PSI.

I'm thinking it's a plumbing issue, but not sure what the issue is. Does anyone else have any ideas or experience?

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Commsman Veteran

Commsman

Posted
Posted

Hi Ryan. Can you attach the instructions or post a link to them? I'm too lazy to search atm

My boost spikes to ~20psi with my IEBC set 'open' (ie wastegate pressure) with Scotty's actuator, but I thought that was more of an issue caused by small wastegate on high flow turbo.

bigkevracer Grand Master

bigkevracer

Posted
  • Author
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Doesn't look like it Leon. All my searches bought up instructions for the old one. This is the one I have: http://www.hks-power.co.jp/en/products/electronics/boost/evc/6evc.html

The issue was there before I switched to Scotty's actuator, but I didn't test the car at wastegate pressure before to know if it was spiking without the EVC.

Tommy Kaira RL Mentor

Tommy Kaira RL

Posted
Posted

I would get a boost spike on my boost controller if I set the gain to high. By the looks of it yours doesn't have gain. Maybe it has something to do with the speed sensor or throttle angle sensor. Try turning those settings down.

scotty nm35 Grand Master

scotty nm35

Posted
Posted

There could be an issue with the actuator spring, I had to change manufacturer so it may actually be a 19psi one now. Thats why I asked you to disconnect all bleeding sources and the controller solenoid to test the actuator on it's own.

Mucking around with the boost like this isn't good without an accurate gauge and wideband.

bigkevracer Grand Master

bigkevracer

Posted
  • Author
Posted

I have a calibrated wideband in the car. Tune seems to be rich. AFRs don't drop below 12 on WOT.

I have no reason to think the boost controllers gauge isn't accurate, and its reading 19PSI with the controller turned off.

Can you double check the spring please Scotty?

If you're free during the week brad can you check the wiring please?

Thanks,

Ryan

scotty nm35 Grand Master

scotty nm35

Posted
Posted

The two actuators I recently sent up to Craig have been holding around 16psi nicely so it must be something in the setup. I would suggest getting a temporary boost gauge on it, or run it up on the dyno with their map sensor running and see what the actuator runs with a new hose directly operating it.

Perhaps the stock turbo wheel being so small means the wastegate is too small also? I didn't have any issues with my stocker though...

bigkevracer Grand Master

bigkevracer

Posted
  • Author
Posted

Are you sure the boost creep isn't to do with the timing? Is it just in between gears with the spike?

Not sure, good thinking Craig, didn't start until the fcon was on it, but its under throttle, not just in between gears.

bigkevracer Grand Master

bigkevracer

Posted
  • Author
Posted

The two actuators I recently sent up to Craig have been holding around 16psi nicely so it must be something in the setup. I would suggest getting a temporary boost gauge on it, or run it up on the dyno with their map sensor running and see what the actuator runs with a new hose directly operating it.

Perhaps the stock turbo wheel being so small means the wastegate is too small also? I didn't have any issues with my stocker though...

So you're positive the spring is right Scotty?

It's going in the dyno in the new year for a check, but I'd like to have this sorted first.

What else should I be looking for?

Brad, I'll give you a buzz when I get back from holidays.

bigkevracer Grand Master

bigkevracer

Posted
  • Author
Posted

Just checked the hoses, everything looks right, and replacing the new additions made no difference.

I did notice an air line to the FPR had blown off, after the other one had previously. I'll probably replace these hoses just in case.

Next thing to do is remove the F-con. I figured it couldn't be tune related but maybe it can...

Seems strange it's repeated with both actuators and with and without the EBC turned on.

bigkevracer Grand Master

bigkevracer

Posted
  • Author
Posted

Replaced the little vacuum hoses at the top of the plenum, which attach to the fuel rail. Looks like they'd just got old and didn't seal properly anymore.

Seems to be better, only spikes to 19PSI, regardless of whether the EBC is on or off. I'm going to start looking at other hoses, maybe it's just coincidental that all of this happened when it did.

Couple of quick questions:

  1. Is it necessary to use hose clamps on these vacuum hoses?
  2. Is the factory heat sleeving on the hoses necessary?

Thanks!

bigkevracer Grand Master

bigkevracer

Posted
  • Author
Posted

Haha gee thanks Scotty.

Got some more vac hose on the way now, I'll get everything cable tied or hose clamped and replace the last couple of factory hoses. See if that improves anything.

Commsman Veteran

Commsman

Posted
Posted

If you are still having issues you may have to look at the split dump unfortunately. Quite often the wastegate pipe flows poorly causing boost to skyrocket once power goes up.

Did a proper check on mine & just on the wastegate spring it hits 24psi at the top of the rev range (holds 15-16psi till then). I'm running your dump pipe Scotty, so in my case I think it's the wastegate itself that is too small.

I think when I had your spring on the factory turbo I had no problem holding 16psi, so you may be onto something re the different dump pipe.

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