Excessive engine vibration close to stalling.

[fka]

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]

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]

Not heard one do that before...

[fka]

Novel isn't it!
Oddly it occasionally makes a good seal, hence my comment 'it's working intermittently'..

[fka]

Sorry to harp on but this is still an issue. I'm reluctant to say as I'm not 100% sure but it seems to rear its head when it's wet outside.
Symptoms are a lumpy idle, like it's missfiring but no missfire codes. Occasionally surging at idle. And when on the move when holding steady rpm (only noticed up to 3k rpm..) feels likes it's missfiring or slightly bucking every second or so.
Runs absolutely fine under all other conditions, very smooth with WOT. And obviously is intermittent so 80% of the time I have none of these symptoms ..

I've looped out the bypass control valve and bypass valve is in good order. I'm 99.9% sure there's no vacuum leak..

So I'm back to:
-CPS (Cheapest thing to try)
-DIC (I've taken it appart, there's no cracking and no missfire codes..)
-Throttle position sensor (I'm hoping not but I've got a funny feeling this might be the issue, especially as the issue is prevelant whist trying to hold the throttle in a constant position .. But again no codes ..)

Is a dodgy injector a possibility or the fuel pressure regulator?

 

[sgould]

Is the fuel filter clean?

[fka]

Good point.. In theory it should have been changed during either it's last or second to last service but I'd planned to do it anyway in the summer when I service.

Would a past it's best fuel filter not also have a noticeable affect during a WOT pull?
And do you know is the tool required for the quick release fuel line fitments on the filter readily available?

Cheers
D

[fka]

Just had a look and the filter is quite corroded (cover is missing...) it won't hurt to get it changed now, so fuel filter ordered along with this tool set for the quick release lines https://www.ebay.co.uk/itm/282369697771.. Should do the job according to this thread on UKS http://www.uksaabs.co.uk/UKS/viewtopic.php?f=2&t=146566

D

[sgould]

That looks about right.  Very similar to the ones we used for undoing push-fit water pipes. 

But some of ours went up to 250mm and had to be used by hitting them with a club hammer!!

[fka]

I'll be trying my best to leave my hammer well alone 

[fka]

Fuel filter replaced today. Had to trim the quick release tool a little to get it to fit. Having run the engine until it stalled with fuse 15 out, I was hopeful the filter might be a resolution, since there was still quite a lot of pressure on the fuel pump side.
Unfortunately it wasn't to be and the problem persists.

I'm ordering a new CPS this afternoon and failing that I'll cough up for a professional diagnostics session, as I'm starting to run out of patience..

[fka]

Re-cap on this one too -
Having written my previous post, the next time I went out in the car, and since, the problem with inconsistent idling/ hunting has gone.
Due to it being annoyingly intermittent I decided to keep my gob shut for a while and see how things went.

When I changed the filter it's possible (Well, certain as the filter was empty, not to mention the fuel that drained from the lines.) there was some air line. When I first started up I'm guessing it would have taken a short while to clear, hence the idle was still inconsistent.

Also possible I've just had a bad batch of fuel, however this issue was present for at least 5 or 6 tanks worth of fuel so I'm less keen on that explanation. Anyway at least I have a spare Bosch CPS sitting in the shed for when the need arises 

[fka]

Final word on this...
Replaced the nearside vibration damper and torque rod bush when I serviced this weekend. Vibration damper wasn't in such bad shape but was noticeably more compliant than the new part so swapped it out anyway. Once I'd jacked the transmission up slightly there was a lot of play in the torque rod.

Shifting is smoother and noticing less judder but there is still some mild judder from the clutch. Mild enough not to worry about!