Very lumpy idle

[krisbutler02]

My GTI had the AXX engine in that used to idle like it had lairy cams ,

This engine dropped its thrust bearings so now have a Audi S3 BHZ engine fitted with all the AXX sensors and ancillaries.

This engine does the same, it has a different map now (stage 3 revo K04 file) 

Its so lumpy its not right

I have the forge catch can so no PCV issues, i have checked for air leaks and the vacuum in 0.8 bar at idle.

New iridium plugs , new MAF , APR fuel pump ,New in tank fuel pump.  cam lobe and follower are fine, N80 purge valve works fine. cant find any air leaks , all boost pipework is new / silicone.

Dump valve is sealing and perfect

What else could cause this im kinda stuck now


The idle is around 700-750 RPM

[krisbutler02]

Any ideas how to raise idle in vagcom?

[Hurdy]

Have you changed the coilpacks too?

[krisbutler02]

Yes just tried another set of coil packs.

starting to annoy me now haha

[Saintsteve]

Any ideas how to raise idle in vagcom?

You can't.

Clogged up intake valves causing low idle?

How many miles has the new engine done in its previous life?? Emmisions test to check for hydrocarbons would indicate coked up cyl.head.?

[krisbutler02]

Cleaned manifold and intake valves just before engine went in.

[Saintsteve]

Throttle body?

[krisbutler02]

also cleaned and reset via vag com along with the manifold flaps.

also run super unleaded shell v power always and did put some injector cleaner in too

[Saintsteve]

also cleaned and reset via vag com along with the manifold flaps.

also run super unleaded shell v power always and did put some injector cleaner in too

Have you tried running it on the stock map to rule out the remap?

Then I'd look at the bits that don't normally fit the BHZ engine if you've mixed from AXX perhaps?

[krisbutler02]

I have switched the sps to stock and its the same.

the only thing left on the BHZ engine that isnt what i swapped over on the axx is the camshaft sensor. and the injectors

im going to get a new inlet manifold with new thrust sensor.

Thats all i can think of to do next.

Only thing i do wonder is if the single mass flywheel (sachs) would make it idle funny due to the weight difference.

[greygti]

Have you checked/replaced the primary o2 sensor ??

[northyracing]

I have the same problem on my axx engine and can't find why

[krisbutler02]

Is tha pre cat or post? Funny you should say that as my liquid gauge always reads rich even at wot doesnt go below 14 afr

[vRSAlex]

14 is lean for wot. Should be 12. 14.7 when cruising.

Have you read the missfire counters and whats your idle fuel trim like?

[krisbutler02]

It says missfire dissabled.?

The Liquid gauge is lying vag com logs .77 Lambda

How do i read fuel trims ?