2.8 hesitaion

[Just_Ben]

Yeah, have the air mass meter's output checked. You should see about 175+g/s at 4500rpm ish minimum.

Also, make sure the inlet manifold is down tight and that the change over valves have not failed or have air leaks.
Leaky ijectors can cause this issue but so to can incorrectly fitted cam belt! Have it fault read. If there is a camshaft retardation fault present either the belt is on wrong or the valve timing variators have been refitted incorrectly. The cam shaft pulleys must be loose when tensioning the belt and this is often missed by garages and this can adversly affect the cam timing. Many of thes engines had the variators out as when the breather system blocks up (which it will) the engine forces oil out of the cam cover gaskets and the variator solenoid bases. On some engines the chain spacing on the 2 cams in each head for the variator can differ from one bank to another and be missed when re fitting.

Does it miss at idle at all??

[B@fink]

nope, smooth as silk at idle, and smooth rest of the time bar 40mph. The maf has been cleaned, and then run disconnected to double check (apart from being a bit sluggish on the uptake when disconnected the maf made no difference to the stutter) There are no fault codes on it at the moment (admittedly with a non vag-com reader, just a gendan engine check, vag-com on the way if the old lappytop will talk to it, it's a bit fussy) The belt was changed (according to paper work over a year back and its only at 88thou now) so they could have made a mess of it and a new one is on my to do list possibly summertime, but i will probably delegate that one out i don't fancy it without the locking kit. I'm fitting a new suction pump within the next week (arrived today in the post) so i will check the inlet manifold nuts are tweaked down when i do that and all the breather pipes a new and shiny (though it wouldn't matter if they were blocked because they had fallen to bits, interesting design using hard walled solid plastic piping.......) is there a way to check the change over valves? If i blip the throttle up the arm moves on the over-run as it winds back down (responding to the vac i assume) so i assumed it was doing something and wasn't stuck, not to say it isn't snapped though. Any big air leaks or mechanical maladies i would expect to show up all over the rev range not just at 40...it's not big or violent but you can feel it. If it makes a difference it's an ACK engine and almost everytime i order bits they're wrong!

[Ska]

Did you sort this at all? If its speed related then wouldn't that point to drive train components. I say this because I had vibration which manifest like engine hesitation on my ACK whichturned out to be a cracked final drive unit! Just checking but have you cleaned out the Throttle body

[B@fink]

I swapped the suction pump to no effect, still for 18 quid it was worth a squirt. I have cleaned the throttle body but again a big old zero. I intend to have a bit of a crawl underneath during the festive break to make sure everything is ok underneath as i have an occasional small knock at <5mph over a reasonable sized bump (say going up a lowered kerb for time to time) that having swapped all the anti roll bar links/bushes didn't improve. Hopefully these 2 niggles aren't connected, i really don't want anything as serious as a final drive in winter :O

[B@fink]

quick update, checked the car on vag-com and it shows no engine issues (not quite true, it showed an immobiliser blocked start, but that was me using a non coded key ) relating to misfire and a load signal intermittent p1857 on the autobox. No other faults. So whatever the hiccough is, the car is oblivious!!!! Joy!