Author Topic: Excessive engine vibration close to stalling.  (Read 575 times)

fka

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Re: Excessive engine vibration close to stalling.
« Reply #30 on: 13 February 2018, 02:44:54 PM »
Quite an interesting thread about this on the trionictuning forum here: https://www.trionictuning.com/forum/viewtopic.php?f=57&t=5065&hilit=06+evap&start=10
Looks like the EVAP change was made in 05> cars and there is a change to the behavior of the purge valve. It's not 100% clear but it appears the purge valve will no longer operate under boost, which makes sense.

It also states in the Tips Before Tuning" sticky thread on trionictuning-
"Now you ought to check all the hoses that goes from the throttle body to the control valve on the firewall, and that all these hoses are in good condition.
This a very inexpensive measure to prevent future problems. Vacuum-leaks are a common problem and will reduce power significantly...
On Aero's the EVAP line going to the hose between the turbo control valve and the intakepipe for the turbo is to be checked for cracks in the rubber part. If there's a problem with the EVAP valves the boost will drop significantly. Since boost is already very low on the 2.0t-engines this can hardly be noticed. There are several different approaches to address this problem if you read a little more on the forum...
(The later MY's from 2006 on onwards have another EVAP and don't suffer this problem)
"

So it doesn't look like a failure of the check valve on this EVAP setup would result in a boost or vacuum leak. The check valve must be there to prevent the purge valve experiencing boost pressure, maybe to elongate it's life or as a fail safe??


fka

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Re: Excessive engine vibration close to stalling.
« Reply #31 on: 19 February 2018, 06:00:29 PM »
Below is a link to my EVAP check valve sounding much like a distressed cow. I'm thinking of taking it up as a new instrument, the Scandinavian bagpipe!

I've replaced it with a fuel grade check valve and silicon hose. I'm not sure how this can have affected idle but it does now seem to be idling properly. There's a slight rise in rpm when the A/C kicks in, as there should be, but it's steady and no longer hunting. There's still a very slight shudder every few seconds but I think this is normal for the 2.3?

https://www.dropbox.com/s/ssvoc1s512w1arn/2018-02-19%2016.15.33.mp4?dl=0

sgould

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Re: Excessive engine vibration close to stalling.
« Reply #32 on: 19 February 2018, 09:28:06 PM »
Not heard one do that before...
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fka

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Re: Excessive engine vibration close to stalling.
« Reply #33 on: 19 February 2018, 10:13:14 PM »
Novel isn't it!
Oddly it occasionally makes a good seal, hence my comment 'it's working intermittently'..