How smooth is your 3B

[gmac78]

Hi Simon, thanks for your input. Once in boost, even just minimal boost like 0.1 bar the car drives nice and smooth. This problem only manifests itself when in vacuum. I think I need to change the injector seats and see how it drives. Could one leaking injector seat really cause this problem? One thing that is throwing me is the fact the I opened a small hand held burner of propane around the leaking injector seat when the car was running, hoping it would suck it in and affect the idle but it made no difference. This is why I was questioning if the leaking injector seat under boost could be drawing in air under vacuum which it didn't appear to do. Maybe my testing method wasn't the best and it will indeed draw unmetered air in whilst under vacuum??

[Reimond]

Note that you need to disconnect battery every time you change lambda to reset lambda corrections.

[gmac78]

Hi Reimond, fair point, can't remember now if I was resetting using VCDS when I changed them over. It's still the same yesterday as it was a year ago, it really detracts from the driving pleasure, driving anywhere in vacuum is most annoying! It will be good to finally get to the bottom off it though. These things are sent to test us!!

[newsh]

Don’t forget that a simple boost leak test from the MAF hose doesn’t check the DV or the PCV valve.

[gmac78]

I removed my PCV some time ago, been running a catch can to atmosphere. The DV is not old but certainly worth checking again. I'll need to take a couple of videos to show you guys to see what you think, however I guess all you will see is the fluctuation on the AFR gauge on a steady throttle.

Problems just kind of creep up on you without realising, I'm not even sure how long this has been doing this, I think since I've gone down the road of the Volvo turbo route??

[gmac78]

For the injector seats/inserts, I see the original plastic ones can be purchased as well aluminium/stainless ones. Is one type more preferable than an other?

[newsh]

I’m not sure if this is true but I’d say the plastic is best as it will pass less heat from the aluminium manifold into the injector.
The old inserts tend to crumble when you take them out so best to take the Manifold off and you should get the threads in the IM nice and clean before screwing in the new ones. Some recommend a smear of high temp sealant on the threads.

[gmac78]

Just to update this thread.

A couple of days ago I fitted new injector inserts, as one of the old ones was leaking boost at around 0.2 bar when pressure tested, also repaired a kinked injector wire that didn't look too great, cleaned my ISV with petrol while the inlet manifold was off, and cleaned the throttle body of all oily residue. The combination of all these has resulted in a much smoother driving experience when off boost which is where it felt jerky before. Delighted as it was horrible to drive as it was previously. Result.

[Lago Blue]

Well done sir,

It is interesting how much time one spends crossing the on/off throttle boundary in normal driving; and how something so small and simple could disrupt that transition. So do you think it possible that the AFR gauge which was fluctuating (perhaps due to a seat vacuum leak?) that is key in this instance (pointing towards a mixture issue), and is the gauge steady there now?

[gmac78]

Yes I would say the leaking injector seat was the main culprit of the AFR fluctuation, much more pleasant to drive now.