Will Overboost Protection Always Generate a Fault Code?

[Markus]

Well, the subject pretty much says it all.

Will a fault code be generated and stored as soon as the overboost protection routine is activated?

I'm getting hesitation and jerky acceleration at higher boost levels, but I get no fault codes. Am I on the right track thinking the problem might be ignition-related (ht leads, coilpacks, power output stages etc.)? Fuel filter has been replaced recently.

I'm still going to check for boost leaks just to be on the safe side.

[bob69]

This sounds like a problem i had, floor your foot and she starts misfiring and cutting out. Mine turned out to be the Lamda, aprox £60-80 from Audi, they should be replaced every 60000 miles or so.

[Markus]

That's weird... From what I've read, Motronic doesn't use lambda control under WOT. But it might be worth a shot, I've been thinking about replacing the lambda anyhow.

[porkkis]

No it does not use the lambda when WOT but in closed loop lambda value is used to generate an adaptation table and AFAIK the table will affect the mixture all the way.

I'd say that if there is no boost leak (or BP leak!) this could probably be ignition related. Plugs?

[porkkis]

Btw the over boost cut out is not anything near "hesitation". I can tell you know when it happens!

[Sidspud]

I wonder how many of these "replace part X" fixes actually cure an overboost fault. Is it not more likely that by simply removing a hose or two and then reconnecting them, that the fault is cured. I know that when I got overboost protection, if I disconnected the hose at my MAF and then reconnected it, the fault went away.
To change the Lambda you need to remove your airbox - this can only be done by disconnecting and then reconnecting the MAF to turbo hose.

[Markus]

Ok. It really feels like misfire.

The plugs look good, are the correct type (Bosch FD5P0R or whatever they're supposed to be) and as the car has previously been serviced at Audi dealers they should not have more than 35 kkm on them.

Yesterday, as I took off the ht leads I however found some (not much) oil residue between the coilpacks and the ht leads. I used to have a leaking valve cover gasket which explains how it got there. I measured the ht leads and their resistance was ok. I'll still try to test the coilpacks, but I hope that cleaning up the ht lead connectors will help. If not, i'll have to isolate the cylinder that is causing the misfire (if that's what it is) and look at the components closer.

The bypass is new and I previously had this same problem with the old one, so I think the fault lies elsewhere. Needs further investigation...

[NoNonsense]

you should also check your throttle body, throttle position switch and perhaps clean the (inside of the) vaccum lines around there.