Engine: B5244: What I found out today (EGR Valve)

[aspireofbrixham]

OK, So not entirely happy that I never found out the reason for 1500RPM tickover and tardy throttle response, even though I cured it by transferring the contents of the inlet plenum in an even coating over my hands, forearms, sleeves, nose, mouth and various other bits I managed to touch....

Having not found these faults or following information documented, or even mentioned on here, I decided to have a dig around, though in the somewhat cleaner environment of the www.

I discovered that certain versions of this engine (mine is V70 MkII, 2007, 2.4D, 163hp Euro IV, and significantly - manual gearbox) have a variation on the EGR assembly.

Attached pic (if I did it right) is a cross section looking from the throttle valve end, but with throttle butterfly valve removed. In addition to the motorised actuator for the EGR valve proper, it has the following.....

Item 2 is a vacuum control valve (electric), item 9 vacuum actuator, item 12 an additional butterfly valve located in the central, uncooled portion of EGR stream. Item 2 has vac tubes in and out. Applying vac to the outlet operates the rod hidden beneath to operate the butterfly progressively up to 25" Hg. I have not worked out the algorithm that triggers (or modulates) the valve.

On this version (manual gearbox option only) the EGR cooler has a straight through pipe down the middle which is open when engine is cold, to speed warm up. When warmed up, this closes and cooled exhaust is suppled from the spiraled tubes around the edges of the cooler, next to the water jacket.

My guess is that the reason my car has almost always stalled at the end of my road after a cold start (1/2 mile exactly) is that it is being fed exhaust gas to aid warm up, but which does nothing to promote combustion. Guess 1B is that this 'feature' proved untennable on all automatics which would be more likely to stall under the latent load of the torque convertor, hence not a included on that engine / gearbox combo.

Guess 2 is that the blocked EGR plenum gave a raft of other problems, but 'cos it was blocked, the car didn't stall as outlined above (but true to form, now it's all cleaned out, it stalled this morning).

Guess 3 is that the knackered engine mounts were limiting the operation of this 'rapid warm-up' feature by leaking too much vac for the butterfly to operate.

Frustration (4) is that I still haven't worked out quite what mechanism was causing throttle lag of up to 3 seconds, and a tickover speed of 1500rpm. I suppose fault codes might help, but i don't have a reader.

Anyway, if anyone can offer any further insights into this seemingly unneccesary complication, I would be very interested to know. If I can really face this particular part of the engine in the near future, I might just monitor the operation to see how it works as the engine warms up. Meanwhile, I think I'll pull the pipe from this one to see if I can cure the stalling for once and for all.....

Happy Daze!

[davebb]

Engine: B5244: Hi I did not know , petrol models had problems with EGR,
Dave

[aspireofbrixham]

If I could edit it, I would, but I can't, so maybe someone else has that capability?
Bizzarely though, I could edit this one... but the OP doesn't have an edit button.