ktleop1959

I have a 98 2.8 Quattro the car didnt run when I got it and had sat for almost 2 yrs I replaced the timing belt water pump thermostat radiator valve cover gaskets gas filter and a few other items Bought everything from ECS which I think is a good supplier my problem is the car ran fine for a few months recently I have an intermittent studder when driving almost like Im losing ignition on a certain cylinder Ive had various codes come and go MAF code Secondary air box code today I got an insufficent EGR flow code PO402 Any help would be appreciated the parts I have replaced all needed to be done I dont want to be just a parts changer to fix this problem I will say I have good spark good compression and use premium fuel it seems to do it when the car gets hot

John535is

When I have experienced multiple codes in the past, it has always ended up being either a vacuum hose, secondary hose or a crankcase vent hose with a split in it. The last time I got the wired combination of misfires, EGR, secondary air, and exhaust gas errors etc it was the hose from the valve cover back to the inlet. The codes were from everything else trying to compensate.

If you have a single code like a certain number cylinder misfire, you can start swapping the ignition coils, plugs etc to see if the error follows to whichever cylinder you swap it with. Essentially 'trial and error' fault finding.

Start with that, it does not cost anything to check them out before you start spending money on sensors etc.

ktleop1959

Thanks John I need to change vacuum lines anyway I hope this takes care of it I'll post if it does

Highmile

John pretty much hit all the usual suspects. Have you already checled over the fuel system? The fuel system could be a little gummy from the two years of sitting. New fuel filter, service injectors, check over fuel system.

ktleop1959

I did the filter and injectors when I had it apart doing the timing belt the 1 thing I was thinking is the tank itself but the filter is clear