Chugging after clearing CELs.

[yeoj112689]

Hello all,

I recently did a bunch of engine work and the 1.8t oil pump and such. This is on a 2.0t.

I recently FINALLY got my first start up and all is well outside of chugging and dropping idle at start up. Oil pressure is great and everything was running well after I replaced the HPFP fuel pressure regulator valve.

I had a code for that valve, mass air flow, and exhaust related CEL.

After the CEL came out the engine smoothed itself out and idled fine. I replaced the Fuel pressure regulator valve and reset the CELs to see if it would come back. When I started up the CEL was gone but the chugging was back. It is not throwing any codes yet but eventually stalls out after about a min of trying. Oil pressure is fine still.

I did not have any mass airflow codes prior so I suppose its possible that I ruined that while doing the work but I don't see how.

Its obviously a sensor causing it to chug then once the sensor cuts itself off (or whatever it does) the engine runs smooth.

Sorry if this is hard to follow. Any advice? I am going to try to get it to throw codes again so I can see if the fuel pressure code went away but I am leaning to me either missing a plug or the mass air flow.

Another option could be the car reading the o2 from the test pipe but I have the JHM flash which I am going to install that will take care of that.

[AudiTechS4]

sounds like you have a vac leak
disconnect maf sensor and start it and see how it runs

[yeoj112689]

sounds like you have a vac leak
disconnect maf sensor and start it and see how it runs

Will do when I get home, it's gotta be something like that because it trips the sensor off and then it's fine.

[yeoj112689]

sounds like you have a vac leak
disconnect maf sensor and start it and see how it runs

Yup, unplugged the mass air flow and runs solid. Now to find the leak... lol

[shahk62]

Yup, unplugged the mass air flow and runs solid. Now to find the leak... lol

Check your Pcv breather hoses.

Those bad boys crack faster than a water boarded Boy Scout.

[yeoj112689]

Check your Pcv breather hoses.

Those bad boys crack faster than a water boarded Boy Scout.

Will do. I want to replace them but ill have to find a hose strong enough to not collapse under vacuum.

[shahk62]

Will do. I want to replace them but ill have to find a hose strong enough to not collapse under vacuum.

They're honesty not that bad from factory - stiff plastic but age and mishandling means they tend to crack far too easily.

[yeoj112689]

So I am a fool and never put the fucking hose back on from the turbo to the intercooler.... sorry. Side note. Stage 2 JHM 93 oct..... holy hell. If you do not have it, get it.

[yeoj112689]

Just an update for future people who may use the search button. The main chugging ended up being a lose intercooler pipe, the secondary chugging on acceleration was due to the plugs, replaced with a cooler set gapped properly and solved that.